Jump to content

User:Epipelagic/sandbox/sources

From Wikipedia, the free encyclopedia
This is an old revision of this page, as edited by Epipelagic (talk | contribs) at 18:39, 15 September 2015 (-). The present address (URL) is a permanent link to this revision, which may differ significantly from the current revision.

Template:Userpage Blue

RESOURCES AND WORKING DRAFTS ONLY

Freshwater fish of New Zealand

Map of the southern part of Zealandia, a "substantial ancient continent that is now evident as a series of emergent island, of which... New Zealand is much the largest, these and other smaller islands being connected by various submerged rises and plateaus".[1]
The New Zealand longfin eel is the largest freshwater eel in the world.

"Native freshwater fishes of New Zealand. The fauna is sparse (~ 40 species) and characterised by a high degree of diadromy... this fauna offered an opportunity to 'explore pattern and process, cause and effect, evolution and biogeography,in a way that would have been much more difficult in areas with more speciose faunas'... The family Galaxiidae comprises a group of southern hemisphere fishes whose wide geographic range and the diversity of habitats they have colonised are somewhat akin to the northern hemisphere salmonids... studying the ecology of the migrations of juvenile galaxiids (known locally as 'whitebait', and considered a delicacy)"[1]

"At present, 50 genetically distinct, extant fish species are recognised in freshwaters in New Zealand with another three or four species yet to be formally named (Allibone et al. 2010) (Table 1). However, the actual species number is hard to define because eight are classified as ‘freshwater indeterminate’: they are essentially marine species but move far into fresh waters for long periods. Only one native fish, the endemic grayling (Prototroctes oxyrhynchus), is known to have become extinct since the first human settlement of New Zealand c. 700 years ago, although many other species have become locally extinct over much of their pre-European range. New Zealand’s freshwater fish fauna is unique, with 92% of the named species found nowhere else in the world."[2]

"Diadromy: One feature of the New Zealand freshwater fish fauna is the large proportion of diadromous species: namely, fish that undertake two migratory movements between the ocean and fresh water in their life cycles. Diadromous fish employ three very distinctly different strategies: anadromy, catadromy, and amphidromy (Table 3). Anadromous fish spend their adult life in the sea, move to fresh water to breed, then die; catadromy is essentially the opposite, with fish spending most of their adult life in fresh water before a final migration to the ocean to breed and die; and amphidromy is an intermediate strategy in which adults live in fresh water, usually breed yearly, and the juveniles spend time in the ocean before returning to fresh water (McDowall 1988). A few decades ago diadromy was thought to be obligatory in most diadromous species, but we now know that in some species diadromy seems to be facultative, as not all individuals migrate. In the currently recognised extant taxa, diadromy is thought to be obligatory in 13 species and facultative in 6, and at least one diadromous species is present in each of the nine families in the New Zealand fauna (Ling 2010). Seven diadromous species include landlocked populations, usually, but not always, are formed when a lake outlet is blocked (Closs et al. 2003)"[3]

Overview

"Compared to other countries, New Zealand has a sparse freshwater fish fauna of just over fifty species. But it is unique and comprises at least thirty-five native species of which thirty-one are found only in New Zealand. Most of the native species belong to just four families of fish, and include twenty galaxiids, seven bullies, two eels, and two smelts. Nine potentially new galaxiid species have been recently found in Otago but are yet to be named so the list is not yet complete."[2]


"Because of the sparse native fish fauna, a large number of species have been introduced (legally, illegally and accidently). Of the fifteen species that are known to have established breeding populations in more than one location, six are salmonids (Salmonidae), four are cyprinids (cyprinidae), and three are live-bearers (Poecillidae). The redfin perch and the bullhead catfish are also well established. A further two species (grass and silver carp) are present, but do not breed. Five other species have very restricted populations and their current status is uncertain."[2]

"An unusually high proportion of the native fish are diadromous (i.e. they all have a marine phase in their lifecycle). Although several grow to adulthood in freshwater then migrate downriver to breed in the sea (e.g., eels, mullet, freshwater flounder), most breed in freshwater with their juveniles travelling downriver to develop at sea (e.g., galaxiids, smelt and bullies). Only the lamprey breeds and develops in freshwater streams and spends its entire adult life at sea."[2]

"Because these diadromous species all need to migrate upriver from the sea at some stage, they are vulnerable to barriers created by falls, chutes, dams, weirs, and culverts. They also vary widely in their ability to move upriver. Some species (eels and certain galaxiids) can climb vertical wet rock faces and they penetrate far upriver to high altitudes. Others cannot climb and are restricted to lowland, coastal streams. As a consequence, the geographical distributions of the species vary widely within rivers and are greatly affected by both altitude and distance from the sea."[2]

"Many of the native species are small, cryptic and/or are nocturnal so it is not surprising that most people are not aware that they are present. They express surprise when they learn that there is more to the native fauna than just eels and galaxiids. For example, redfin bullies are brightly coloured and good in aquaria, whereas torrent fish are shaped like a stealth fighter and are well adapted to cope with the high water velocities found in rapids where they live."[2]

"Many of the largest native galaxiids (called kokopu) live mostly in small streams running beneath forest or bush canopies. Widespread conversion of forest to pasture has resulted in their decline, and the introduction of predatory trout restricts their distributions within forested streams. As a consequence of these changes, together with the creation of migration barriers and loss of habitats, a number of the native fish are now endangered. A 2010 report indicated that whereas only the grayling is extinct, eight species are nationally threatened and another twelve are now in decline."[2]

"Eels and galaxiids are responsible for commercial and cultural fisheries in New Zealand rivers with five species of galaxiids comprising the national delicacy known as 'whitebait'. Sports fisheries are based on introduced species, including chinook salmon (South Island rivers), rainbow and brown trout (lakes and rivers nationally), and coarse fish (perch, rudd, tench, koi carp), mainly in small North Island lakes. Other introduced species (i.e., gambusia, catfish, goldfish) have few if any values and some of the introduced species are pests in some places because they either reduce native biodiversity, degrade other species habitats, or contribute to the decline of water quality in lakes."[2]

Native species

"The latest information indicates that New Zealand has around 40 native species of freshwater fish. This count may increase as new genetic techniques bring a better understanding of the diversity within some fish groups. Thirty-three species are known only in New Zealand. Kōaro, longfin eels and spotted eels are also found in Australia, while lamprey and īnanga also occur in Australia, Chile and Argentina. New Zealand’s native freshwater fish belong to eight distinct families: the jawless lamprey, eels, smelts, southern graylings, galaxiids, torrentfish, bullies and flounder. Most are relatively small, although the eels are an obvious exception – some female longfin eels are up to 2 metres long and 25 kilograms in weight."[3]

Age

"Longfin eels are the longest-living native fish, generally taking 20–30 years to reach maturity. Some large female eels stay in fresh water for over 80 years. In contrast, smaller species, such as īnanga, reach maturity in just one year and rarely live longer than three years."[3]

Diet

"Almost all native fish prey on invertebrates or other fish. However, historical accounts indicate that the now-extinct grayling (Prototroctes oxyrhynchus) was an exception and grazed on algae from river rocks."[3]

Migration and life cycles

"Nearly half the native fish species migrate to and from the sea during their life cycle. As not all species can climb rapids and waterfalls, freshwater fish are most diverse at low altitudes, closer to the coast.

  • Lampreys reproduce in fresh water but develop mostly at sea.
  • Eels reproduce at sea, but most of their growth occurs in fresh waters.
  • The five species of galaxiids that form the whitebait catch lay their eggs in fresh water, but their larvae quickly migrate to sea and spend a few months there before heading back to fresh water."[3]

Distribution

"Although not found elsewhere, many of New Zealand’s freshwater fish do have close relatives in Australia, South America and Southern Africa. Two species that do exist beyond New Zealand are lampreys and īnanga. This distribution, with other evidence, indicates that migration across the oceans is an important factor explaining the global spread of these fish."[3]

Factors affecting life in fresh water

"A range of factors influence the types of species that live in different parts of New Zealand.

  • At a broad level, evolutionary history and climate determine which species are found in certain regions.
  • At a finer level, factors such as water quality, land use, channel shape, or lake type influence the range of species found in a river reach or lake.
  • Small-scale factors (light and food availability, cover, predation, competition, water depth and speed) also control which species live at certain sites within a river or lake. All these factors can interact to shape freshwater ecosystems."[4]

Light availability

"Without light, plants cannot grow. There are big differences between the communities living in the well-lit surface and edges of lakes, and those in the depths, which receive little or no light. Turbid (muddy) water also restricts the amount of light that reaches the bed. Lakes with large shallow areas tend to be more productive than lakes with little shallow water (because more light reaches the lake bed). A similar situation exists in river systems, where heavily shaded streams rely on leaves and other organic material from the surrounding catchment to fuel the ecosystem. In larger rivers the canopy opens up, allowing algal production to become more important."[4]

Predators versus available food

"There is debate about whether the number of invertebrates (insects and other animals without backbones) in a habitat is controlled by the number of predators that will eat them, or by the amount of food available for them. Both factors are important, but their relative importance may vary. For example, the introduction of trout appears to have changed some streams from systems controlled by the available food to those controlled by trout as predators."[4]

Disturbances: floods and droughts

"Rivers and streams are particularly prone to disturbance, due to huge changes in flows, as in floods and droughts. Although these are often seen as harmful, it appears that a moderate level of disturbance can promote higher diversity in some systems. This makes sense: if there is some variation in an environment, more life forms may be able to live there."[4]

Human impact

"Irrigation and hydroelectricity projects. Water is currently in high demand, and the value of freshwater systems is often weighed against the potential value of using the water. Hydroelectric dams and large irrigation projects can turn running waters into lakes, affect water quality, and restrict fish movement along river systems."[4]

Farming

"Many rivers and lakes now have high concentrations of nutrients, sediment and faecal bacteria, and problems with algal blooms (a heavy growth of algae). This is because more intense farming leads to excessive runoff of sediment and fertilisers into waterways. Taking water for irrigation has also harmed the water quality of lowland streams and some lakes. The Rotorua lakes are classic examples. Too many nutrients enter the lakes, causing algal blooms, which in turn starve the water of oxygen. At times, the lakes are closed for swimming, due to low water quality."[4]

Pests

"Various pests have become established in freshwater systems. Pest fish prey on native species and can stir up mud and alter the water quality. Invasive aquatic plants grow profusely, changing the habitat and causing problems for recreational activities. For example the introduced weed Lagarosiphon major can grow so profusely that it clogs the shoreline, making it unattractive for swimming. Even tiny algae can cause problems. In 2004 outbreaks of Didymosphenia geminata smothered South Island riverbeds, affecting everything living there."[4]

Where are the fish?

"New Zealand has an abundance of cool clear rivers, streams and lakes, but if you look into the water you will not usually see many fish. The journals of many early settlers refer to empty rivers. Believing there were no native fish, they introduced trout and salmon – species that would meet their expectations as game and a source of food. But it was a mistake to think the rivers were empty, as Māori had long caught a wide variety of native fish. European settlers soon discovered the delight of fresh whitebait, and learned to fish for upokororo (grayling). As Māori knew well, eels were a nutritious addition, and livened up an often plain colonial diet. Many New Zealanders are surprised to learn that fisheries biologists recognise more than 40 native freshwater fish species. If asked about freshwater fish, most people will mention trout (which are not native), eels, and perhaps whitebait. There is little awareness of the variety of native fish in rivers and lakes."[5]

Ousted by trout

"New Zealanders are more familiar with trout and salmon than with native fish. Trout and salmon were introduced in the late 19th and early 20th centuries. Massive trout populations rapidly developed, with adverse effects on native fish through predation, competition for food and displacement from favoured habitats."[5]

Secretive and nocturnal

"For some reason that scientists do not understand, nearly all native freshwater fish are very furtive creatures. By day they typically live among boulders and pebbles of streams and lake beds, or hide beneath overhanging stream banks, or among logs and woody debris. Most species are also quite small. New Zealand’s eels are nocturnal, as are many other native freshwater fish. An effective, low-tech way of identifying fish, especially in small streams, is spotlighting – shining a broad-beamed torch into a stream at night to see what is out and about."[5]

Small streams

"The greatest diversity of native fish occurs in small streams – many of them no more than a metre wide. It is not clear why they prefer this habitat. It could be partly because introduced trout have forced them into smaller headwater streams, preying on them or displacing them from their habitats. It is likely that there are other reasons as well."[5]

Protection

"Freshwater fish are not protected under the Wildlife Act 1953, although native fish are protected in national parks or other conservation lands. For many species, legal protection from being caught is not really an issue as land use and developments that damage their habitats pose far greater threats to their survival. There are some regulations to manage the harvest of eels, whitebait, smelt and lamprey that form small fisheries."[5]

Evolution and characteristics

Geography

"New Zealand’s freshwater fish have strong connections with fish of other southern lands. The shortfin eel, īnanga and kōaro are found in eastern Australia, and īnanga in Patagonian South America and the Falkland Islands. In the past some researchers suggested that this spread was because New Zealand, like Australia, was once part of the supercontinent Gondwana. Recent DNA research indicates that it is far more likely that these fish are more recent arrivals, carried around the southern hemisphere on oceanic currents. Some endemic groups such as the pencil galaxias may have an ancient Gondwana heritage."[6]

Evolving from marine species

"Some species that evolved as marine fish have established themselves in fresh water. Just how this happens is unknown, but at some stage an event must have caused a shift into fresh water. Perhaps a lack of fish diversity in river rapids provided an opportunity for a marine species to invade this environment. The torrentfish still retains its marine connections by living at sea during larval and early juvenile life. The black flounder must still return to sea for spawning and early juvenile life. Several flounder (mainly marine) can also live in river estuaries and lowland lakes. But the black flounder has taken the process a little further – it may be found many kilometres up some rivers."[6]

"Nearly half the native freshwater species are found in the sea at some life stage. This may be as larvae and juveniles (as with whitebait species and several bullies), after which they return to fresh water. Some adults (such as eels) may migrate to sea to spawn. In another example, the smelts living in rivers spend most of their lives at sea before returning to fresh water as adults, to spawn. Fish migrate between rivers and the sea at most times of the year, but especially in spring and autumn. These species are known as diadromous (from Greek words meaning ‘running across’)."[6]

Climbing

"The distribution of the migratory species depends on how far upstream they can move. Rapids and waterfalls are not necessarily barriers. Some species have extraordinary climbing abilities, and can be found upstream of waterfalls tens of metres high. Eels are able to climb like this, and some of the whitebait species, especially kōaro, banded kōkopu and shortjaw kōkopu. These fish climb mostly when small, moving up the wet margins of falls, and using their fins to hold onto rocks by surface adhesion. Some are well known for climbing out of buckets, and if in captivity, often climb out of aquariums (they can climb glass as long as it is damp)."[6]

Stuck in the Nevis

"For the past half million years Otago’s Nevis River has flowed north into the Kawarau River, which then flows into the Clutha River. But it is thought that the Nevis once flowed south, into Southland’s Mataura River. Supporting evidence is that the Nevis has a Galaxiid species (Galaxias gollumoides) that is otherwise found only in the Mataura and other Southland waterways. The fish is found only in one other isolated locality in the Clutha catchment."[6]

Flexible behaviour

"Many species can vary their behaviour. Although the ancestral pattern is for them to go to sea, they can establish landlocked populations in the open water of lakes rather than the sea – mostly at the juvenile stage."[6]

Nocturnal activity

"A high number of native species are nocturnal, moving from under cover to be active at night. Why they are so nocturnal is not understood. The most likely explanation is that it might minimise predation by aquatic birds, especially shags, and perhaps herons. But if it is an avoidance strategy then a paradox emerges. Some fish are habitual prey for large eels, which are also more active at night, emerging from cover to feed."[6]

Galaxiids

"Most native freshwater fish species are called galaxiids (from the family name Galaxiidae)... The name refers to their profusion of small, silvery-gold spots, which were compared to the stars in a galaxy by those who first identified them."[7]

"Most native freshwater fish species are called galaxiids (from the family name Galaxiidae). There are seven genera in the family and two (Galaxias and Neochanna) occur in New Zealand. The name refers to their profusion of small, silvery-gold spots, which were compared to the stars in a galaxy by those who first identified them... In New Zealand there are at least 25 species in this family. New species are still being discovered, with eight recognised since the early 1990s. Galaxiids are a fascinatingly diverse group. Most are shy creatures that few people ever see. A small number of enthusiasts find them appealing and keep them in captivity... Galaxiids have no scales, and their dorsal fin lies toward the rear of the body. The main fins form a propulsion unit towards the tail, making them adept at rapid acceleration and short bursts of speed, though not so well designed for long-distance swimming."[8]

"The galaxioid fishes are the dominant, most speciose group of freshwater fishes (with >50 species) in the lands of the cool southern hemisphere, with representatives in western and eastern Australia, Tasmania, New Caledonia, Lord Howe Island, New Zealand, the Chatham, Auckland and Campbell Islands, Patagonian South America (Chile, Argentina), the Falkland Islands and South Africa. The group is most diverse in Australia and New Zealand. Lepidogalaxiidae is found only in Australia, Retropinnidae in Australia and New Zealand, and Galaxiidae across the entire range of the group. Many species are in serious conservation crisis for a diversity of reasons, including habitat deterioration and possibly fisheries exploitation, but there is enduring and pervasive information that shows that the group has been seriously impacted by the acclimatisation of salmonid fishes originating in the cool-temperate northern hemisphere, particularly brown and rainbow trout. With few exceptions, where these trout have been introduced there has been major decline in the galaxioids, especially Galaxiidae, as a result of a complexly interacting series of adverse impacts from these introduced fishes. In some places, centrarchids and cichlids may also have adverse impacts. In addition, there appear to have been adverse impacts from the translocation of galaxioids into communities where they do not naturally occur. In many instances it appears that displacement of the galaxioids has led to a situation where galaxioids and salmonids no longer co-occur, owing either to displacement or predation, leading to fish communities in which there is no explicit evidence for displacement. These effects are resulting in the galaxioid fishes being amongst the most seriously threatened fishes known."[9]


Īnanga

Banded kōkopu

Kōaro

"Another Galaxias species, kōaro (G. brevipinnis), is found in swift-flowing mountain streams. Many people know it as ‘mountain trout’, but it is not a trout. The kōaro is a handsome fish, dark olive with paler markings, and if you see one out in open water on a fine day, the sunlight glistens along its sides. Some anglers know it as lake whitebait, although the species in lakes do not go to sea like those in rivers. It can grow up to 27 centimetres long."[10]

Kōaro relatives

"There is a group of species that are closely related to the kōaro. Scientists are beginning to discover these highly secretive fish in the headwaters of streams in the eastern and southern South Island. Although very similar to the kōaro, they do not have larvae that go to sea. They spawn in spring. Over spring and summer small shoals of whitebait-like juveniles appear in pools and backwaters. They live in open water for several months and grow to about 4 centimetres long, when they disappear into gravels of stream beds and are rarely seen."[10]

Giant kōkopu

"The giant kōkopu (G. argenteus) is a large bulky fish that may grow to more than half a metre long and weigh nearly 3 kilograms – though it is very rarely that big. Notable for their silvery-gold markings, these fish prefer slow-moving waters and lakes, and do not move far inland from the coast. In its juvenile form it is caught as whitebait, along with juveniles of four other native species. When it was first discovered that the adults belong to the same species as whitebait, there was widespread disbelief. It is possible that the common name cockabully originated as a European adaptation of ‘kōkopu’ or a variant such as kōkopuru."[10]

Pencil galaxias

"The little-known group of small, thin galaxiids known as pencil galaxias live most of their lives in the gravels of stream beds. Most distinctive are the longjaw galaxias – two similar and closely related species with a protruding lower jaw. These little fish (up to 7.5 centimetres long) are superbly adapted for picking small aquatic insects from under stones in pools and shallows. Researchers are only now learning about their habits. It is possible that some of these fish may actually live deep in river gravels."[10]

Mudfish

"Also belonging to the galaxiid family are the Neochanna mudfishes. These are specialised for living in wetlands and swampy spring heads. Best described as cigar-shaped, some may be up to 15 centimetres long. Of five species, three have completely lost their pelvic fins (fins under the body about halfway back to the tail), and in the others these are much reduced. Using their dorsal and anal fins, and well-adapted broad, rounded tails, they swim among the debris of bush wetlands. They are known for their ability to aestivate – spend summer in a state of semi-torpor, surviving if water disappears. Mudfish can survive a long drought. When their wetlands dry out in summer, they find cavities and objects to lie under, breathing air through their skin. As the autumn rains fill the wetlands, the fish are washed out again."[10]

Bullies, smelt and grayling

Bullies

"After galaxiids, bullies form the second largest native fish family, known as Eleotridae. They are often called cockabullies, but these are a different family of mostly marine fish. Seven species are widespread across the country. Small fish seen around a lake shore will probably be bullies, most likely the species known as common bullies. Bullies are mostly small, with adults commonly around 10 centimetres long. They have scales and two dorsal fins. The redfin bully male has vivid red coloration, especially on the tail and dorsal and anal fins. These fish are found almost everywhere, although mostly at low elevations. This is partly because the young of four of the seven species spend their first few months at sea: the adults can be found only in places that are accessible from the sea. They have interesting breeding habits. The male establishes his territory, usually in a cavity beneath a large rock, and while guarding it, tends to turn a darker colour. The spawning female is lured into the territory and deposits the eggs, one by one, forming a single layer on the underside of a rock. The male, following along, fertilises them. He then guards them until they hatch.c[11]

Smelt

"New Zealand has two fish of the Retropinnidae family. These are the common smelt (Retropinna retropinna) and Stokell’s smelt (Stokellia anisodon). Although smelt have a very strong cucumber odour when they are first captured, the name smelt has nothing to do with this. It is an ancient word for silvery – referring to their colour. Growing to around 10 centimetres, smelt move into lowland rivers from the sea as mature adults to spawn – often being caught towards the end of the whitebait fishing season, in spring. They are very fragile, dying within a minute or two if handled. The smelt populations in some inland lakes, especially in the central North Island, belong to the same species, but have abandoned migrations to and from the sea, spending their whole lives in fresh water."[11]

Grayling (Upokororo)

"Closely related to the smelt was a fish, now extinct, known as upokororo (Prototroctes oxyrhynchus). The early settlers called it grayling, but it is not related to the true grayling of the northern hemisphere. It is New Zealand’s only extinct freshwater fish species, having disappeared by the 1920s for reasons that have not been identified. It was among the larger native fish – probably growing up to 45 centimetres – and looked like an overgrown smelt."[11]

Torrentfish, lamprey and black flounder

Torrentfish

"The little torrentfish (Cheimarrichthys fosteri) spends most of its life in flowing torrents. Its superbly adapted fins act as depressors, keeping it on the stream bed under swiftly flowing water. It may be a close relative of the marine blue cod. Like many New Zealand freshwater fish, torrentfish spend a part of their lives at sea, though it is uncertain how this happens. Nothing is known of their reproduction. What is known is that in spring, juveniles (around 2 centimetres long) can be found swimming into estuaries from the sea. Scientists suspect that they migrate to sea as newly hatched larvae."[12]

Lamprey

"Lamprey are parasitic fishes, and New Zealand’s one species (Geotria australis) spends most of its life at sea. It attaches itself to larger marine fish with its sucking mouth, and rasps away its host’s flesh. Lamprey migrate into rivers in late winter and spring. When they first arrive they are bright silver, with a blue back that has two vivid, paler blue stripes. But they soon lose their brilliant colours, becoming dull, drab and brownish. They penetrate long distances up rivers and probably spawn in the headwaters of small bush streams. The larvae hatch, and spend a few years living in sandy or silty sediments of stream margins, before moving to sea for several years. Nothing is known of their breeding habits."[12]

Black flounder

"The black flounder (Rhombosolea retiaria) spends much of its life in either rivers or lowland lakes. It is notable for the bright brick-red spots on its back. It migrates to sea to spawn, probably during winter, though little is known about this. Small juveniles, around the size of a thumbnail, can be found making their way into the rivers over spring."[12]

Conservation status

Resident native species (40)

Conservation status of New Zealand native freshwater fish species (sortable)
Family Image Scientific name Common name Fish-
base
IUCN status NZTCS status[13] Notes
Anguillidae
(eels)
Anguilla australis Shortfin eel
Not assessed
1. Not Threatened
Anguilla dieffenbachii Longfin eel
Not assessed
2. At Risk
Declining
Eleotridae
(bullies)
Gobiomorphus alpinus Tarndale bully Least concern[17]
2. At Risk
Declining
Gobiomorphus basalis Cran's bully Least concern[19]
1. Not Threatened
Gobiomorphus breviceps Upland bully Least concern[21]
1. Not Threatened
Gobiomorphus cotidianus Common bully Least concern[23]
1. Not Threatened
Gobiomorphus gobioides Giant bully Least concern[25]
1. Not Threatened
Gobiomorphus hubbsi Bluegill bully Vulnerable[27]
2. At Risk
Declining
Gobiomorphus huttoni Redfin bully Near threatened[29]
2. At Risk
Declining
Galaxiidae Galaxias anomalus Roundhead galaxias Critically endangered[31]
4. Threatened
Nationally Endangered
Galaxias argenteus Giant kokopu Vulnerable[33]
2. At Risk
Declining
Galaxias brevipinnis Climbing galaxias Least concern[35]
2. At Risk
Declining
Galaxias cobitinis Lowland longjawed galaxias Critically endangered[37]
5. Threatened
Nationally Critical
Galaxias depressiceps Flathead galaxias Vulnerable[39]
3. Threatened
Nationally Vulnerable
Galaxias divergens Dwarf galaxias Endangered[41]
2. At Risk
Declining
Galaxias eldoni Eldon's galaxias Critically endangered[43]
4. Threatened
Nationally Endangered
Galaxias fasciatus Banded kokopu Least concern[45]
1. Not Threatened
 Whitebait species  "Some other species of Galaxias are fairly well-known. The banded kōkopu (Galaxias fasciatus) is another of the whitebait species, with adults commonly growing to around 20 centimetres. It is known as ‘native trout’ or ‘Māori trout’ – but it is no trout... It is greyish-brown with vertical pale bands across its sides – providing camouflage in the dappled light on small bush streams. Banded kōkopu inhabit pools in the smallest streams, some of which are only half a metre wide with scarcely enough room for the bigger fish to turn round. When people live nearby, the fish can be quite tame, taking food from the surface of pools, and even jumping to take it from your hand."[8]
Galaxias gollumoides
3. Threatened
Nationally Vulnerable
Galaxias gracilis Dwarf inanga Vulnerable
2. At Risk
Declining
Galaxias macronasus Bignose galaxias
3. Threatened
Nationally Vulnerable
Galaxias maculatus Common galaxias Least concern[50]
2. At Risk
Declining
 Whitebait species  "The most widespread and best known of the galaxiids is īnanga (Galaxias maculatus). Unlike most of its relatives, it is the one Galaxias species that lives in the open waters of pools. It swims in smallish, roving shoals, in pools and runs of lowland rivers and in wetlands".[8]
Galaxias paucispondylus Alpine galaxias Least concern[52]
2. At Risk
Naturally Uncommon
Galaxias postvectis Shortjaw kokopu Endangered[54]
3. Threatened
Nationally Vulnerable
Galaxias prognathus Longjawed galaxias Critically endangered[56]
3. Threatened
Nationally Vulnerable
Galaxias pullus Dusky galaxias Critically endangered[58]
4. Threatened
Nationally Endangered
Galaxias vulgaris Common river galaxias Least concern[60]
2. At Risk
Declining
* O'Brien, L. (2005). The conservation ecology of Canterbury mudfish (Neochanna burrowsius). PhD thesis, University of Canterbury. [http://ir.canterbury.ac.nz/bitstream/10092/3464/1/Thesis_fulltext.pdf Full text
Neochanna apoda Brown mudfish Endangered[62]
2. At Risk
Declining
Neochanna burrowsius Canterbury mudfish Critically endangered[64]
5. Threatened
Nationally Critical
Neochanna diversus Black mudfish Endangered[66]
2. At Risk
Declining
Neochanna heleios Northland mudfish Critically endangered[68]
3. Threatened
Nationally Vulnerable
Neochanna rekohua Chatham mudfish Least concern[70]
2. At Risk
Naturally Uncommon
Geotriidae Geotria australis Pouched lamprey Data deficient[72]
3. Threatened
Nationally Vulnerable
Mugilidae Aldrichetta forsteri Yellow-eye mullet Least concern[74]
1. Not Threatened
Mugil cephalus Flathead grey mullet Least concern[76]
1. Not Threatened
Pingui-
pedidae
Cheimarrichthys fosteri Torrentfish Vulnerable[78]
2. At Risk
Declining
Pleuro-
nectidae
Rhombosolea retiaria Black flounder Data deficient[80]
1. Not Threatened
Retro-
pinnidae
(smelts)
Prototroctes oxyrhynchus New Zealand grayling Extinct[82]
† Extinct
"Although once common in New Zealand, grayling (Prototroctes oxyrhynchus) began to decline soon after European settlement. They were last noted in the early 1920s. It is not clear what caused their disappearance, but it could be linked to land use or the introduction of trout."[3]
Retropinna retropinna New Zealand smelt Least concern[84]
1. Not Threatened
Stokellia anisodon Stokell's smelt Least concern[86]
2. At Risk
Naturally Uncommon
Triptery-
giidae
Forsterygion nigripenne Estuarine triplefin Least concern[88]
1. Not Threatened

Eels

"Freshwater eels are fish, and belong to the family Anguillidae. Slow growing and long lived, they begin life in the sea, and then spend many years in fresh water as adults. Finally they return to sea to spawn, after which they die. Many people are scared of eels, because they are snakelike and slimy, and can slither over land. There are very few reports of eels attacking, but if they do, their teeth can grip. In one incident a longfin eel bit the wetsuit of a diver, who had to use a knife to release its hold. Unlike nearly all other freshwater fish, eels have a long cylindrical shape, and continuous dorsal (back), caudal (tail) and anal fins. They have pectoral (side) fins but no pelvic fins. Covered in a layer of mucus, eels are extremely slippery. Although they seem to lack scales, under the microscope you can see a mosaic of tiny scales in the leathery, slimy skin. Eels can travel over land, slithering through wet grass to get to a pond or lake. As long as their skin stays moist they can absorb oxygen through it, surviving long periods out of water. Freshwater eels are found worldwide. Of 15 recognised species, most occur in the waterways that flow into western Pacific and Indian oceans. There are none that spawn in the eastern Pacific or the South Atlantic."[89]

New Zealand eels

"Eels are New Zealand’s top native freshwater predators – no other species prey on them when they are adult. Māori identified many different varieties, mainly by colour. But when European settlers first arrived in New Zealand there was debate about the number of species. There are three species, all from the Anguillidae family of fish:

  • longfin eel (Anguilla dieffenbachii), found further inland
  • shortfin eel (A. australis), found on the coast
  • spotted eel (A. reinhardtii), which may have recently arrived from Australia and is found only in northern rivers.

The longfin and shortfin eels are found all around New Zealand. They have very varied coloration, so this is not the best way to identify them. The most reliable distinguishing feature is the length of the back fin – hence their names."[90]

Longfin eel

"The longfin eel is found only in New Zealand. Travelling far inland, it may be the country’s most widely distributed freshwater fish. The pectoral (side) fins have 16–20 bony rays. This species is usually dark brown to grey-black on the back. One study found that males swim out to sea to breed and die at an average age of 23 years and females at an average age of 34. They are probably the world’s biggest eels. They may grow up to 1.75 metres, and the biggest caught and measured so far weighed 24 kilograms. Any New Zealand eel over 1 metre long and caught inland is probably a longfin specimen."[90]

Shortfin eel

"The shortfin eel is quite widely distributed in the South Pacific, and occurs in Australia, New Caledonia, Lord Howe Island, Norfolk Island, Fiji and possibly Tahiti. Its dorsal fin starts close to the anal fin, and the pectoral fin has 14–16 rays. This eel is olive green and frequents lowland waterways. It can grow to 1 metre and 3.5 kilograms. Males mature, breed and die at 14 years, and females at 22."[90]

Spotted eel

"The spotted eel also occurs in eastern Australia, New Caledonia and Lord Howe Island. It was first confirmed in New Zealand waters in 1997, and is currently only found in rivers from Taranaki to Northland. It has a distinctive colour pattern – mottled or blotched on the back, with yellowish pectoral fins. This eel grows to 1.5 metres and 14 kilograms. The maximum reported age is 41 years."[90]

"Diet and feeding: Eels were once considered a threat because they ate introduced trout. But they are now economically important in New Zealand, and there has been considerable research into their diet. Big longfin eels may eat species such as juvenile trout – larger prey than that of the shortfin or spotted eel. One 9-kilogram eel was reported to have eaten an entire shoveller duck. Small (less than 50-centimetre) longfin and shortfin eels generally feed on snails, insects, worms, grubs, crayfish and small fish. Eels feed mainly at night, using their powerful sense of smell to track prey. Once an eel is close, taste buds on its head and sensors along its sides help locate the victim."[91]

"The largest recorded longfin eel is a 24-kilo specimen taken from Lake Waihola, south of Dunedin, in 1974. At Lake Ellesmere (Te Waihora) in Canterbury, shortfin eels longer than 50 centimetres increasingly become fish-eaters, preying on cockabullies and smelt. Feeding drops off during winter in both species, especially in southern New Zealand. Growth rates are slow. Longfin eels grow at around 2.5 centimetres a year at a length of 30 centimetres, and they slow down to only 1.5 centimetres a year at a length of 1 metre. Shortfin eels grow a little faster. These slow rates are a result of temperature, food supply and competition. Faster growth rates have been achieved in trials to fatten eels in farm ponds."[91]

Life cycle
Hydroelectric dams can present obstacles to migrating fishes

"Freshwater eels have a remarkable life cycle, which begins and ends in the ocean. Spawning has never been observed. Adult eels probably spawn at some depth in warm seas. New Zealand’s shortfin eels produce 1.5–3 million eggs, and the longfins 1–20 million eggs. Males fertilise the eggs. After spawning, the adults die.cFertilised eggs hatch at the surface and become leaf-shaped larvae, floating on ocean currents towards the coast. They have teeth, but it is not clear for what purpose – they may store calcium for bone development. Their skin may absorb nutrients, as researchers have not found food in the larvae.cOnce the larvae reach land, an extraordinary transformation takes place: they become slender, transparent eels, known as glass eels. They arrive at New Zealand’s coast from July to December, with numbers peaking in spring (August–October) – the time of whitebait migration. Glass eels migrate into river mouths or estuaries in astounding numbers.cHydroelectric dams are an obstacle to elvers (young eels) swimming upriver. Some dams have special passes, allowing them to get round the massive concrete walls. But they don’t always need this help. Elvers can climb the 43-metre Arapuni Dam on the Waikato River, and the 75-metre Patea River dam in Taranaki. Glass eels soon turn grey-brown, and in this form they are known as elvers. They migrate upriver, often in swarms and usually at night. Young elvers can climb waterfalls, but lose this skill as they grow. Elvers become adults, with bigger heads and fatter bodies. After many years in fresh water, eels migrate back down the waterways to the sea. It is thought that males fertilise the eggs once the females spawn out at sea. When they reach breeding size, eels change from ‘yellow-bellies’ to ‘silver-bellies’. The yellow-grey underside becomes grey-white, the head shape changes and the head, back and pectoral fins darken."[92]

"Shortfin males migrate in February–March, and longfin males in April. The females soon follow, and both males and females die after spawning. Studies show the species also migrate at different ages: Shortfin males at an average of 14 years (38–58 centimetres), females at 22 years (50–100 centimetres). Longfin males an average of 23 years (48–74 centimetres), females at 34 years (75–180 centimetres). It is not known how long the journey takes. One female longfin eel that was tagged took 161 days to swim from Canterbury’s Lake Ellesmere (Te Waihora) to a point 160 kilometres north-east of New Caledonia. Barriers across waterways have hampered their route. One estimate suggests that hydroelectric dams have blocked the longfin eel’s access to the sea in 35% of its habitat."[92]

"For centuries, larval eels were thought to be a separate species: they occur in the ocean and look different from adult, freshwater eels. Then in 1896 the Italian zoologist Giovanni Grassi reported that Leptocephalus brevirostris, known as a saltwater fish, was in fact the larva of the European freshwater eel. But just where at sea they bred was a mystery. Searching for breeding grounds: In a 1923 paper, Danish biologist Johannes Schmidt stated that American and European eels spawned in the Sargasso Sea, in the Atlantic. In 1926, after sailing his research vessel Dana II to Australia and New Zealand, he concluded that New Zealand eels probably bred somewhere east of New Caledonia. But the exact locations are still not fully known."[92]

"Longfin eels: At migration, longfin eels are more ready to reproduce than shortfin eels. Scientists thought this meant their spawning grounds were closer to shore. However, a study showed that the longfin eel had the longest larval stage of any Pacific freshwater eel reported. This suggests that the larvae actually hatch further away from New Zealand, possibly near Tonga. They were also the biggest specimens when they reached coastal waters – so they may have been at sea longer, and travelled further."[92]

Export and fishery management

"Freshwater eels have become an important export, often live or as processed products. They go mainly to South-East Asia, Europe and Canada. Annual sales ranged from $800,000 to $3.5 million between 1990 and 2004. Live eels and products such as smoked fillets, whole smoked eels or skinned segments are available from local processors and restaurants. Worldwide, eel production is declining because of overfishing of glass eels (juveniles) and adults, and damage to the environment. Many countries farm eels, usually sourced from wild glass eels. International demand for wild glass eels for use in eel farms is strong. The market is subject to fluctuations, and high prices can be paid. Through the Quota Management System the New Zealand government controls and monitors commercial fishing, limiting the total catch to ensure sustainability."[93]

"In 2000, the South Island’s shortfin and longfin eels came under the quota system. Both species were treated as a single stock. In 2004 the North Island eel fisheries were included, but the two species were managed separately. Treating South Island shortfin and longfin eel fisheries as a single stock is questionable. Longfin eels breed later in their lives than shortfin eels, which makes them more vulnerable to overfishing."[93] Long-lived longfins

"Scientist Don Jellyman figured out the great age of some longfin eels in Lake Rotoiti – the oldest eels yet documented. He found that one female eel was 106 years old by reading the growth rings on its ear bones (otoliths). An average generation time of 93 years suggests that conservative harvest levels must be set in managing these fish. A New Zealand research team at the Mahurangi Technical Institute in Warkworth has hatched baby eels from eggs of the shortfin eel – the first time that commercial quantities of freshwater eel have been bred in captivity. The commercial and ecological implications of this breakthrough could be considerable. Tame eels have become a tourist attraction in places such as Tasman in Nelson and the Anatoki River in Golden Bay."[93]

Human impacts

Overview

"In, ecology, and status of New Zealand's freshwater Fisheries resources are reviewed. Rivers are the main freshwater features in these Pacific temperate-zone islands. Geological events, the islands' remoteness, and the recent nature of human colonization (first Maori and then European) have shaped the freshwater ichthyofauna. Diadromy is a dominant ecological feature for many indigenous species. Many species have also been introduced to create Fisheries. Traditional Maori Fisheries are focussed on indigenous eels and whitebait while recreational Fisheries target introduced salmonids. Management of New Zealand freshwater Fish is dispersed among several departments. New Zealand habitats are pristine by global standards due largely to the recent settlement of European colonists. Many rivers have been impounded for electricity generation; this constitutes the main environmental issue for freshwater Fish. Intensification of agriculture also poses a growing eutrophication threat. The ecologies of indigenous species are becoming better known but much knowledge is anecdotal. Efforts to conserve indigenous freshwater species are increasing. Impoundment, irrigation, deforestation, and introduced salmonids, are the main threats to the native fauna."[94]

New Zealand whitebait

"74 per cent of the country's native freshwater fish are now listed as threatened. Dr Joy said that was up on 68 per cent in 2009 and 30 per cent at the first review in 1992. New Zealand's figures were worse than any other country that kept such measurements. The global average was 35 to 37 per cent threatened. Dr Joy said native freshwater fish were like miner's canaries measuring the health of rivers."[95]

"Many New Zealanders consider whitebait a delicacy, with its sweet, tender flavour. Often lightly cooked in fritters, the tiny fish are eaten head and all. They fetch a high price in the netting season... In their juvenile form, īnanga are well known as the chief species in the whitebait fishery, which is made up of juvenile fish of five different Galaxias species".[8]

About 90% of the whitebait is made up of juvenile īnanga <ref?>

Videos
misc
  • Tempero, G. W., Ling, N., Hicks, B. J., & Osborne, M. W. (2006). Age composition, growth, and reproduction of koi carp (Cyprinus carpio) in the lower Waikato region, New Zealand. New Zealand Journal of Marine and Freshwater Research, 40(4), 571-583.

Biogeography

"New Zealand has been isolated in the southwestern Pacific Ocean since it separated from Gondwana during the Cretaceous period, some 80 million years ago. This prolonged geological isolation, combined with the islands’ very vigorous geological history, impacted by oceanic submergence, tectonic activity, mountain building extreme volcanism, and great climatic variability, create a dynamic scenario within which the New Zealand biota, including its freshwater fishes, have evolved over millions of years. These impacts have contributed to a highly dynamic biological history with undoubted though little understood extinction and vigorous colonisation of the islands’ fresh water. One of the key elements for understanding the origins and derivations of this fish fauna is that in all groups some or all of the species are diadromous, customarily spending a significant phase of their lives at sea. This has no doubt contributed in an important way the fauna’s origins as well, there has been frequent loss of diadromous behaviours leading, to species that have abandoned their sea-migratory behaviours and which now complete their entire lives in fresh water. The distribution patterns reflect these changing habits, with diadromous species being broadly distributed but tending to be lowland in range, whereas the derived, non-diadromous species have narrower ranges, but are often found further inland and at high elevations." [15]

According to McDowall, New Zealand has a biota that" has broad relationships, primarily around the cool Southern Hemisphere, as well as with New Caledonia to the north. There are hints of ancient Gondwanan taxa, although the long-argued predominance of taxa derived by vicariant processes, driven by plate tectonics and the fragmentation of Gondwana, is no longer accepted as a principal explanation of the biota’s origins and relationships... Most of the terrestrial New Zealand flora and fauna has clearly arrived in New Zealand much more recently than the postulated separation of New Zealand from Gondwana, dated at c. 80 Ma. There is a view that New Zealand may have disappeared completely beneath the sea in the early Cenozoic, and acceptance of this would mean derivation of the entire biota by transoceanic dispersal. However, there are elements in the biota that seem to have broad distributions that date back to Gondwanan times, and also some that are thought unlikely to have been able to disperse to New Zealand across ocean gaps, especially freshwater organisms. Very strong connections to the biota of Australia, rather than to South America, are inconsistent with the timing of New Zealand’s ancient and early separation from Gondwana and seem likely to have resulted from dispersal."[96]

Dispersal biogeography

"The broad distribution of freshwater fishes of the lamprey families Geotriidae and Mordaciidae and the salmoniform Galaxiidae and Retropinnidae in the southern cool temperate zone, has caused prolonged perplexity and debate. Arguments in favour of both a dispersal biogeography and a Gondwana-based vicariance biogeography have been presented. These are not necessarily alternatives. Main conclusions – Evidence from:

  •  Distribution patterns in relation to life-history strategies;
  •  Genetics and morphology;
  •  Different elements in the New Zealand fauna and their relationships;
  •  Recent dispersal events;
  •  Geological history of the Falkland Islands and the relationships of its freshwater fishes; and
  •  Parasitology;

all support, or are consistent with, a dispersal biogeography of this southern cool temperate fauna. The groups involved are sufficiently ancient to have formerly inhabited Gondwana, but no compelling evidence indicates that present distributions reflect a former broad Gondwana-based range. A role for dispersal in these fishes is consistent with increasingly common claims for dispersal in other taxa. This does not mean that there was no ancient influence from Gondwanan vicariance."[97]

See also

  • Waters, J. M., Dijkstra, L. H., & Wallis, G. P. (2000). "Biogeography of a southern hemisphere freshwater fish: how important is marine dispersal?" Molecular Ecology, 9 (11): 1815–1821. doi:10.1046/j.1365-294x.2000.01082.x Full text

Other references

  • Goodman, J. M., Dunn, N. R., Ravenscroft, P. J., Allibone, R. M., Boubee, J. A., David, B. O., ... & Rolfe, J. R. (2014). "Conservation status of New Zealand freshwater fish, 2013" New Zealand Threat Classification Series, series 7, New Zealand Department of Conservation. ISBN 9780478150148.

34 (1): 185–194.

  • McDowall, R. M. and Whitaker A.H. (2012) "The freshwater fishes" In: G. Kuschel (Ed) Biogeography and Ecology in New Zealand, pp. 277–286. Springer Science. ISBN 9789401019415.

  • Jellyman, P. G., & Harding, J. S. (2012). The role of dams in altering freshwater fish communities in New Zealand. New Zealand Journal of Marine and Freshwater Research, 46(4), 475-489.
  • Joy, M. K., & Death, R. G. (2013). "Freshwater biodiversity" Ecosystem Services In New Zealand, Manaaki Whenua Press, Lincoln, New Zealand.
  • Weeks, E., Kingsford, R. T., Taylor, A., & Joy, M. (2014). Protecting the future of New Zealand’s freshwater ecosystems.
  • McDowall, Bob . Freshwater fish Te Ara - the Encyclopedia of New Zealand, updated 9-Jul-13.

Taxonomically undetermined species (14)

"Fourteen native entities are listed as taxonomically indeterminate and are awaiting formal description.

Non-resident native species (3)

Introduced and naturalised species (20)

Defined by the Department of Conservation as "taxa that have become naturalised in the wild after being deliberately or accidentally introduced into New Zealand by human agency".

20 species

Introduced fish

"In the late 1800s and early 1900s, British settlers introduced fish of the Salmonidae family – trout and salmon – to New Zealand. Some of these species now form important recreational fisheries. Less well known, and usually much less widespread, are 15 other introduced species. These are known as coarse fish – many have coarser scales than trout and salmon."[104]

Trout and salmon

"From the late 1800s, British settlers introduced fish of the Salmonidae family – trout and salmon – to New Zealand. Many species were released, yet only three established themselves well enough to form important fisheries: brown trout, rainbow trout and Chinook salmon. European settlers brought trout and salmon to New Zealand’s lakes and rivers so they could fish them for sport. The most common species today are brown trout, rainbow trout and Chinook salmon."[105]

=Sea-going trout

"In the late 1800s and early 1900s it was thought that sea trout were a different species from riverine trout. But it has long been known that some brown trout live in estuaries and also go out to sea. Today it is accepted that riverine and sea trout are merely variants of brown trout. Brown trout’s colours can change depending upon the waterway they live in. Sea-run trout can be a bright silvery colour, brown trout from rivers tend to be golden brown, and those from lakes are a duller silver. All have black spots, and riverine browns also have red spots."[106]

Taupō trout

"Soon after they were brought to New Zealand, rainbow trout grew very large in Lake Taupō, but then declined in size. The average weight of trout in one angler’s bag was 10½ pounds (4.8 kilograms) in 1911, but by 1918 it had dwindled to 4 pounds (1.8 kilograms). The early bonanza was probably due to the trout feeding on the then plentiful native fish."[107]

Chinook salmon life cycle

"Life cycle: Females and males pair up and the female digs a depression in a gravel stream bed and lays eggs. The male deposits his milt to fertilise them. Eggs hatch into alevins (fry with yolk sacs attached) in spring. After the yolk sac is used up, the fry emerge from river gravels in streams that they use for spawning. They spend about three months swimming downstream, entering the ocean in summer. In the sea the young salmon feed on small fish and crustaceans, and grow rapidly into adults. At maturity (3–4 years) they swim upstream in ‘runs’ or large numbers to spawn in the upper reaches of rivers. After spawning all adults die. The size of salmon runs changes from year to year. The best river was the Waitaki, but much of its glory was lost after the government built a dam at Kurow in 1935 – greatly reducing the size of the salmon run from perhaps 100,000 fish to 10,000. A fish ladder was built up the side of the dam but it was poorly designed and never worked. In the 2000s, upriver runs consist of a few thousand fish in each of the main rivers. Anglers probably catch 35–40% of them. In any given year the total run has varied between 10,000 and 75,000 fish – most years being at the lower end. Hatcheries: attempts to raise numbers' The variability of salmon runs led to efforts to enhance the size by hatching and releasing young salmon. In Canterbury, wild salmon were trapped and stripped of ova in spawning streams. During the 1980s, fish reared in hatcheries on the Rakaia River increased the size of runs. But the cost per fish reared was too high, and runs were still variable."[108]

"There were also plans for "ocean ranching" – commercialising the fishery – in the 1970s and 1980s. The theory was that hundreds of thousands of salmon would be hatched from ova and released. They would go to sea and feed at no cost and come back as adults to be harvested. The plans went ahead and the salmon were released, but they did not come back. In the 2000s commercial salmon farms operated at South Island freshwater sites such as Waikoropupū Springs near Tākaka, and the Tekapo canal in the Mackenzie country. But most farmed salmon were reared in sea cages in the Marlborough Sounds and Stewart Island."[108]

"The average survival rate for smolt [young salmon migrating to the sea] is less than one per cent, and anglers catch about a third of the returning fish, so for every salmon caught you have to release 300 smolt. To significantly improve the number of returning salmon you’d have to annually release 300,000 to 500,000 smolt, and they cost a dollar each to rear. This means each fish costs between $300 and $500."[109]

"Research suggests that conditions out at sea may determine the number of salmon that return. Conditions in the rivers are also a factor. In spring and summer, juvenile salmon make their way downriver to the sea. Floods can kill juveniles or wash them out to sea. Stable flows give them a chance to stay longer in the river and so reach a greater size by the time they go to sea. Those that get to sea at three months of age make up 75% of returning adults."[108]

Other salmonids

"In the late 1800s and early 1900s attempts were made to introduce other salmonid species such as whitefish, Atlantic salmon, brook char and mackinaw – but with little success."[110]

"Whitefish (Coregonus clupeaformis): Much effort went into acclimatising this species, native to high-latitude lakes in the northern hemisphere. From 1876 to 1907 nearly 10 million ova were brought in. Some whitefish were hatched and released into lakes, but the species never became established."[110]

Introduced and naturalised: Game fish
Family Image Scientific name Common name Fish-
base
IUCN status Comments
Salmonidae Oncorhynchus mykiss Rainbow trout
Not assessed
"Rainbow trout were imported in the 1880s. They did not spread and breed as well as brown trout. Today, anglers often catch rainbow trout weighing 2–3 kilograms. They live in lakes such as Lake Rotorua and Lake Taupō, and rivers flowing in and out of these lakes. They do not migrate to sea. They are easier to catch than brown trout. In winter, fishermen catch them in the Tongariro River, upstream from Lake Taupō. They usually live for four to five years."[105]

"Rainbow trout (Oncorhynchus mykiss) were first introduced to New Zealand in the early 1880s. They are descended mainly from Californian steelheads – rainbow trout that migrate to sea and spend most of their lives there. However, New Zealand rainbow trout do not migrate to sea. Rainbow trout are less widespread than brown trout. There has been virtually no natural dispersal. Ova imported in 1883 by the Auckland Acclimatisation Society survived, and fry were released into local waterways. In 1892 the species was liberated in Lake Rotorua, and in 1897 in Lake Taupō. Rainbow trout can tolerate higher water temperatures than brown trout: they are found in warmer waters such as the Kai Iwi lakes in Northland. They also occur in a few rivers. Stocks were also released into many rivers, but they mostly disappeared. Nearly all the rivers where they did establish themselves flow into large lakes – in the central North Island, and the southern South Island. It is not understood why rainbows have failed to become established in many waterways. Adding to the mystery is their presence in a few rivers that do not drain into lakes, such as the Pelorus and Rai in the South Island, and the Mōhaka in the North Island. These have very stable riverbeds, which may be a factor."[107]

"Rainbow trout eat more and grow faster than brown trout. In rivers they feed in fast water, using energy to stay in the same place while feeding on drifting invertebrates. In lakes, rainbows tend to live in deeper water than brown trout and often feed on different prey – usually small fish, such as smelt in Lake Taupō. This may explain why rainbow trout are bold feeders, more easily caught than the wary brown trout. Rainbow trout may reach 750 millimetres and more than 10 kilograms in New Zealand. Fish of 600 millimetres and 2–3 kilograms are often caught, and fish weighing 4–5 kg are not uncommon. Most rainbows tend to live for four or five years, although individuals up to 11 years old have been recorded. Life cycle: Several hundred to several thousand eggs are laid in a small hole by the female and fertilised by the male. After 1–3 months the eggs hatch into alevins (fry with yolk sacs attached). These live in the gravel, feeding from their yolk sac. They then emerge as fry, about 25 millimetres long. By late summer they have reached 50–70 millimetres. As juveniles and spawning adults they live in streams, where they are exposed to predators on the banks. Adults usually run upstream from a lake to spawn in late winter and early spring, in headwater streams with gravel beds. Not all rainbow trout survive spawning."[107]

"Much of the central North Island winter fishing is centred on rainbow trout running upstream from Lake Taupō to spawn in tributaries such as the famed Tongariro River."[107]

Oncorhynchus nerka Sockeye salmon Least concern[113] "Sockeye salmon (Oncorhynchus nerka): Sockeye were released into the Waitaki River catchment in 1902, after some 500,000 ova were gifted by the Canadian government. Young that hatched were released in the hope of yielding a returning run, to develop a commercial fishery based on canning salmon. The species established itself in Lake Ōhau but a sea-going population never developed. A remnant population still exists in Lake Ōhau and its tributaries."[110]
Oncorhynchus tshawytscha Chinook salmon
Not assessed
"Chinook or quinnat salmon are native to North America and Asia, and were brought to New Zealand in the early 1900s. They are big, often weighing 10–15 kilograms. They spawn (breed) in tributaries of rivers on the east coast of the South Island, such as the Waitaki, Rakaia and Rangitātā. New Zealand is the only place in the world where they have been successfully released outside their native home. Some salmon habitats have been harmed because river water is taken to irrigate farms, and rivers have been dammed. This reduces salmon numbers. Young salmon swim out to sea, then after three or four years return upstream to spawn. Unlike trout, they die after spawning."[105]

"Chinook or quinnat salmon (Oncorhynchus tshawytscha) are native to the north-west coast of North America, and north-east Asia. New Zealand remains the only place in the world where Chinook salmon have become established successfully outside their natural range. In the early 1900s they were introduced from ova sourced from the McCloud River in California. They were released into the Hakataramea River, a tributary of the Waitaki River in the South Island. They were soon running up other Canterbury rivers such as the Rakaia and Rangitātā."[108]

"Chinook are the largest species of the Salmonidae family in New Zealand, commonly reaching 10–15 kilograms. Most adults are three years old when they spawn. When they enter river mouths on their spawning runs, they are very silvery in colour – but this gets duller the longer they stay in fresh water. Salmon are found mainly on the South Island’s east coast, from the Waiau River in North Canterbury to the Clutha River in South Otago. There are also small runs in the Paringa, Taramakau and Hokitika rivers on the West Coast. The renowned fisheries are the Waitaki, Rangitātā, Rakaia and Waimakariri rivers. Once, smaller rivers such as the Ashburton and Ōpihi also supported salmon. Taking water for irrigation has seen these rivers suffer from river mouth closure in summer. In the 2000s they were no longer regarded as good salmon fisheries. Small landlocked Chinook salmon can also be caught in some South Island lakes such as Lake Wakatipu. Dams on the Clutha River prevent them migrating to sea, so they never grow to any great size (they are typically less than 1 kilogram). Occasionally stray salmon are found in North Island rivers."[108]

Salmo salar Atlantic salmon Least concern[116] "Atlantic salmon (Salmo salar): The Atlantic salmon is native to rivers draining to the North Atlantic Ocean. Early settlers from Britain were familiar with the fish and eager to establish sea-going salmon populations. Between 1864 and 1910, 24 introductions were attempted involving 5 million ova, but with very little success. There were local fisheries at Lake Te Anau and Lake Manapōuri and in the Waiau River in the 1920s and 1930s, but the fish were poorly conditioned and did not swim out to sea. They weighed only about 2 kilograms, whereas Atlantic salmon in Britain returning from the sea were typically four times that weight. The species is considered to be close to extinction in New Zealand, with remnant wild stocks confined to lakes in Southland’s upper Waiau catchment."[110]
Salmo trutta Brown trout Least concern[118] "Brown trout were brought in during the 1860s and quickly spread into the rivers and lakes. With plenty of native fish to eat, the trout grew fat – weighing up to 10 kilograms. Today, most brown trout caught by fishermen weigh 1–2 kilograms. They prefer cooler water and live in rivers, lakes and estuaries south of the Coromandel Peninsula. They hide under rocks or streamside plants, and are difficult to catch. Their colours change with the habitat. Brown trout that swim out to sea are bright silver, those in lakes are dull silver, and those in rivers are golden brown. All have black spots. They usually live for eight to ten years."[105]

"Brown trout (Salmo trutta) form the basis of most freshwater fishing in New Zealand. From the late 1860s brown trout, from Europe, were introduced throughout New Zealand for fishing. They established themselves rapidly where they were released – and also spread by going out to sea and swimming up other rivers. In the early years they were very well conditioned. Some were so fat they looked like rugby balls, and could weigh over 10 kilograms. After the initial boom, average trout sizes dropped. Acclimatisation societies had set up hatcheries and continued to release small fish into the rivers for decades. The rationale was that there was competition from predators such as eels and shags, but research has since shown this to be a waste of effort, as natural spawning provides more than enough young fish."[106]

"Brown trout live mainly in rivers, but are also found in diverse habitats from estuaries to subalpine lakes. Brown trout are predatory fish that eat small aquatic insects and small fish. In flowing water they tend to face upstream, feeding on drifting aquatic insects. In slow-moving pools, brown trout cruise looking for food. In lakes they cruise the shallow zone close to shore, feeding on small fish such as bullies, and invertebrates such as dragonfly nymphs and snails in weed beds. Brown trout often hide under rocks and streamside vegetation, and immediately seek cover if they see movement on the riverbank. As a result, they are one of the most difficult freshwater fish to catch. The body form and behaviour of brown trout are adapted for living in rivers. For example, their pectoral fins are much larger than those of rainbow trout. This allows them to use the river flow to hug the riverbed, where the current is slower and it takes less energy to stay in the feeding position. In New Zealand brown trout often reach 800 millimetres and 5 kilograms. Most fish caught by anglers are smaller – typically 1–2 kilograms."[106]

"Brown trout are found south of the Coromandel Peninsula. They prefer lower summer water temperatures than rainbow trout do, and winter water temperatures over 11°C kill brown trout eggs. Life cycle: The female lays several hundred to several thousand eggs in a small hole. These are fertilised by the male. After a month or two the eggs hatch, and the fry live in the gravel before emerging and feeding along stream margins. Adults spawn in early winter, usually in the headwaters of streams with gravel beds. Adults usually survive spawning and spawn annually. Brown trout live for 8–10 years, although individuals up to 15 years old have been recorded in New Zealand."[106]

Salvelinus fontinalis Brook trout
Not assessed
"Brook char (Salvelinus fontinalis): Brook char were first introduced in the late 1870s or early 1880s. They were widely released, but it seems they could not compete with brown trout. They still exist in headwaters of some catchments, such as the upper reaches of the Shag River in Otago, but they are usually very small (typically only 150 millimetres). Lake Emily, inland from Ashburton, is the best fishery, where brook char up to 600 millimetres and 3 kilograms may be caught."[110]
Salvelinus namaycush Lake trout
Not assessed
"Lake char or mackinaw (Salvelinus namaycush): The mackinaw is native to northern North American lakes, where it can grow up to 46 kilograms. The only New Zealand population occurs in Lake Pearson, in the headwaters of the Waimakariri River. The species arrived in 1906 and was destined for Lake Kaniere on the West Coast. But as they were being transported towards Arthur’s Pass, the temperature of the water containing the fish rose too high. Fearing that the mackinaw would die, the acclimatisers dumped them in nearby Lake Pearson and Lake Grassmere. A population still exists in Lake Pearson, but the typical weight of less than 1 kilogram suggests that it is not an ideal habitat. In New Zealand mackinaw are little more than a curiosity."[110]

Other reading

  • Fishing in New Zealand
  • NIWA Atlas of NZ Freshwater Fishes
  • Hayes, John, and Les Hill. The artful science of trout fishing. Christchurch: Canterbury University Press, 2005.
  • Millichamp, Ross. Salmon fever: a guide to salmon fishing in New Zealand. Christchurch: Shoal Bay, 1997.
  • McDowall, R. M. The Reed field guide to New Zealand freshwater fishes. Auckland: Reed, 2000.

Coarse fish

"Coarse fish are freshwater fish other than trout or salmon. They are called coarse fish because their scales are usually larger and coarser than those of trout or salmon. They were introduced in the late 1800s and early 1900s by British settlers, for aquariums or fishing. Many have been illegally set free by anglers wanting to stock up rivers and lakes.[121]

Types of coarse fish

"Coarse fish found in New Zealand are:

  • Cyprinidae family – goldfish, koi carp, tench, rudd, orfe, gudgeon, grass carp, silver carp
  • Poeciliidae family – gambusia, caudo, common guppy, sailfin molly, swordtail
  • Percidae family – European perch
  • Ictaluridae family – brown bullhead catfish.

Most belong to Cyprinidae, a family which contains almost 2,500 species, including carps, minnows, and a host of other small fish found across Europe, Asia, Africa and North America."[104]

Coarse fishing

"Coarse fish are caught by anglers with a baited hook attached to a float. Some species have been illegally introduced and spread by anglers wanting to fish for them. Some species such as goldfish are usually too small to be targeted by anglers. Some very keen coarse anglers aim to catch a variety of species or the largest fish species. A few species, including silver carp and grass carp, do not breed naturally in New Zealand waterways and populations are maintained by releasing fish reared in captivity. It is doubtful whether some species, such as caudo, are established at all, despite records of their presence in New Zealand."[104]

"Introduced fish can have four statuses under various pieces of legislation:

  • sports fish (e.g. perch, tench) – it is an offence to fish for them without a licence.
  • noxious fish (e.g. koi carp, rudd) – illegal to possess, breed or release under the Freshwater Fisheries Regulations 1987.
  • unwanted organism (e.g. koi carp, gambusia) – illegal to release, spread, sell or breed under the Biosecurity Act 1993.
  • restricted species (e.g. silver carp, grass carp) – releases require the approval of the minister of conservation.

Offenders can attract a maximum sentence of five years and/or a fine of up to $100,000. The legal status of some species varies. For example, rudd is only a ‘sports fish’ in the Auckland–Waikato fish and game region, but a ‘noxious fish’ elsewhere. Some species, such as caudo, goldfish and orfe, have no legal status."[104]

Value or pest?

"Some coarse fish are valued as food (European perch), or for recreational angling (European perch, koi carp, rudd, tench). Some have adverse effects on ecosystems (koi carp, rudd, tench, gambusia), while others are valued for their use in biological control (grass carp and silver carp). When ‘noxious fish’ or ‘unwanted organisms’ are found in contained areas such as ponds or small lakes, authorities sometimes eradicate them using the natural toxin rotenone, known as Derris Dust to gardeners."[104]

Morihana on horseback

"Sub-inspector Morrison of the Armed Constabulary released goldfish into Lake Taupō in 1873, after bringing the fish on horseback from Napier. Goldfish became known to Māori as morihana – a transliteration of Morrison’s name. For some time morihana were a food for Rotorua Māori."[122]

Introduced and naturalised: Coarse fish
Family Image Scientific name Common name Fish-
base
IUCN status Comments
Cyprinidae Cyprinidae is the carp or minnow family. It includes the carps, the true minnows, and their relatives such as the barbs and barbels.

"The Cyprinidae family is one of the largest of the freshwater fish families with about 1450 known species. None are native to New Zealand, but several species have been introduced here. Generally carp have large scales, small barbels around their mouth, and no adipose fin. There are many exceptions to this, however, as might be expected in such a large family. Cyprinids have been cultured as a food fish for thousands of years in their native countries. No such industry exists in New Zealand, although two of the species listed above, grass and silver carp, were brought here as potential aquatic plant or algal control agents. Neither of these species has established feral stocks here, but the other carp species have, although the precise status of orfe is uncertain. With the exception of goldfish, rudd and tench, the carps are confined to the North Island in New Zealand. None have spread to Chatham or Stewart Island. Most of the carp species in New Zealand have no teeth and so as adults they feed mainly on plants and algae. However, juvenile fish will eat small animals such as snails. Spawning occurs during summer and carp prefer aquatic vegetation as an egg laying substrate. Because of their feeding and spawning requirements, carps tend to be found in warm, weedy waters in lakes and slow-flowing rivers."[123]

Carassius auratus Goldfish Least concern[125] "Goldfish (Carassius auratus) were imported early after Europeans settled in New Zealand, although exactly when is uncertain. They were probably introduced by aquarists and pond-keepers as an ornamental species. They were liberated into wild habitats such as Lake Taupō and Lake Rotorua in the 1870s, and by the 2000s were widespread, mostly living in ponds and small lakes, and probably harmless."[122]

"Goldfish were first brought to New Zealand in the late 1860s. Aquarists and breeders carried out further introductions and goldfish are now widespread and well established in the North Island. Their South Island distribution is more restricted, but recent surveys by the Department of Conservation have shown that they are in Nelson, central Otago, Southland and the West Coast. In the early 1900s, feral goldfish populations in central North Island lakes were important to the Maori as a food fish."[126]

Ctenopharyngodon idella Grass carp
Not assessed
"Grass carp (Ctenopharyngodon idella) and silver carp (Hypophthalmichthys molitrix) were introduced for biological control. It is unlikely either species will reproduce in the wild – all populations were established and are maintained by hatchery production. These carp grow to several kilograms in weight, and are found intermittently around the country. Grass carp eat large, leafy aquatic plants and in doing so they help control excessive plant growth in ponds and drainage ditches, reducing the need to spray water weeds or use draglines to clean drains. Silver carp eat phytoplankton (small, single-celled algae that make the water in ponds green and turbid), and were imported to help control it. However, their effectiveness is unproven."[122]

"Grass carp were first brought to New Zealand in the 1960s because of their potential to control the growth of aquatic plants. Unlike the other introduced fish brought to New Zealand, the potential value and impact of grass carp was investigated in secure facilities prior to their use in field trials. Although these fish mature, they have extremely specific spawning and rearing requirements and the establishment of a wild population is extremely unlikely. There has been much controversy surrounding the use of grass carp as a weed control agent in New Zealand. So far, the main value of grrass carp in New Zealand has been to eradicate problem weed species from lakes, thus allowing native plant communities to re-establish. This means they have a role to play in lake restoration, as well as weed control, but their use for weed control in drains is still being investigated. Today, stocks of grass carp are maintained for breeding at a private hatchery north of Auckland. Grass carp are a large and robust fish. They commonly exceed 500 mm in length, 10kg in weight, and can live for 15-20 years. Their backs are a dark bronze colour, but this gradually fades to silver on the belly. The margins of their large scales are outlined in a darker colour, giving them a crosshatched appearance. Grass carp have no barbels, but can be distinguished from goldfish by the short dorsal fin with only 7–9 rays."[128]

Cyprinus carpio Wild common carp/Koi carp Vulnerable[130] "Koi or European carp (Cyprinus carpio) were brought to New Zealand in the 1800s, but did not become established in the wild until the 1960s, when ornamental koi were released. They are now abundant in the lakes of the lower Waikato, and present in some other areas, especially the north. Globally koi carp are a problem. They churn up the beds of wetlands while searching for food, causing environmental deterioration. In New Zealand koi are classed as a ‘noxious fish’ and an ‘unwanted organism’, making their possession unlawful. Nevertheless, they are a target of recreational coarse fishers (who are illegally spreading the fish around the country), because of their size (10 kilograms or more) and fighting ability. Bow hunters look for koi carp in the Waikato wetlands."[122]

"Koi carp: This brightly coloured member of the Cyprinidae family is a variety of the common carp. The common carp is native to Asia, although it has been introduced so widely and for so many centuries that its precise origins are uncertain. Today, it occurs on every continent except Antarctica. It is not known whether the introduction of koi carp here was deliberate or accidental, but feral breeding stocks were first noticed in the Waikato in 1983. They are now common throughout the lower Waikato system, and have been spread mainly into ponds throughout the North Island. The first South Island record of koi carp occurred in Nelson in 2000, but most of the South Island populations have now been successfully eradicated. Wild common carp tend to be an olive green colour, but the New Zealand stocks are derived from the highly bred ornamental Japanese koi and thus can exhibit a calico pattern of black, red, orange, gold and white blotches. So far, our feral stocks have not reverted back to the wild colouration. Although their colour pattern is a useful distinguishing characteristic, they also have two pairs of barbels that the other Cyprinidae found here lack. Koi eat a wide variety of organisms, including both plants and animals. One way they feed is by sucking up and expelling material from the bottom, filtering out edible material as they do so. This habit means that, at high densities in shallow lakes, they can greatly increase the turbidity of the water because they are constantly disturbing the substrate.This makes waterways unattractive and reduces the abundance of aquatic plants. In other countries, common carp have caused such an increase in turbidity that vast amounts of money and effort have been spent trying to eradicate them; unfortunately these have largely been unsuccessful. Although similar problems have not yet been documented in New Zealand, the spread of this fish should certainly be minimised."[131]

Leuciscus idus Ide/Orfe Least concern[133] "Orfe (Leuciscus idus) and gudgeon (Gobio gobio) were introduced illegally with a view to establishing populations for anglers. Orfe possibly occur in a single lake near Auckland, although it is uncertain if they are still present. Gudgeon became established in another Auckland pond. Once discovered, attempts were made to exterminate them, and as far as is known, there are now no gudgeon in New Zealand."[122]

"This member of the Cryprinidae family is native to northern Europe where it is valued as a coarse angling fish. Orfe eggs were illegally imported to New Zealand by mail sometime in the 1980s. Subsequent releases occurred between 1985–86 in at least 8 and possibly 5 more sites north of Auckland. The current status of these populations is in doubt; some believe orfe failed to survive in at least 7 of these sites while others are less certain. At least one release site remains unknown and it seems likely that orfe persist in the wild in at least one location in New Zealand. In Europe, wild orfe are usually greyish brown with silver bellies. However, the variety of orfe present in New Zealand (the golden orfe) is derived from ornamental pond stocks and thus closely resembles rudd. Although it is not known if the two species co-exist, on orfe the scales are smaller and the fins more orange than red coloured. Rudd also have a small projection at the base of their pelvic and pectoral fins. Eventually, the orfe’s golden colouration may revert to the wild type. Little is known about the biology of orfe in New Zealand. In Europe they primarily inhabit slow-flowing waters. Their food consists of aquatic invertebrates such as worms and snails, but large orfe may consume other fish and aquatic vegetation. Like the other Cyprinidae, orfe are prolific breeders and large females may contain tens of thousands of eggs. Whether they become a nuisance species in New Zealand or will be successfully eradicated remains to be seen."[134]

Scardinius erythrophthalmus Common rudd Least concern[136] "A fish of ponds and lakes, rudd (Scardinius erythrophthalmus) were smuggled into New Zealand in the 1960s and liberated quite widely – illegally and to provide game for sport (they can reach 2 kilograms). They are common in the hydro lakes of Waikato. Concerns about their potential adverse effects on the environment have led to their classification as ‘noxious fish’, except in the Auckland/Waikato fish and game region, where they are ‘sports fish’ and a licence is needed to fish for them."[122]

"This member of the Cyprinidae family is native to Eurasia and was illegally imported to New Zealand in 1967. Stock bred from this importation was subsequently widely released and rudd are now well established in many North Island waterways, particularly in the Waikato River catchment. Rudd have also been recorded around Christchurch, and more recently from other parts of the South Island. Like goldfish, rudd do not have any barbels around their mouth, a feature that tells them apart from koi. They can be distinguished from goldfish because they lack the stout spines on the front edge of the dorsal fin, and from orfe by the projections that occur at the bases of their pectoral and pelvis fins. Rudd can also be confused with perch, but perch have two dorsal fins, the first with several firm spines. Rudd are darker on their backs than on their bellies and have bronze highlights when the light catches their scales. Their fins are usually bright reddish orange. Juvenile rudd are planktivorous, but as adults their diet consists mainly of aquatic plants. As a herbivore, rudd are likely to have a role in supressing the regeneration of aquatic plants in lakes and hence in maintaining poor water quality. A high-density rudd population ruined the trout fishery in an Auckland lake becuse they outcompeted trout for anglers lures. This suggests their introduction into new waters could be detrimental to fish and native plant communities as well as to water quality. Like all the Cyprinidae, rudd are prolific breeders and large females can produce literally hundreds of thousands of eggs. The largest rudd ever recorded was over 400 mm in length, but fish 200–250 mm in size are much more common."[137]

Tinca tinca Tench Least concern[139] "Tench (Tinca tinca) were introduced by acclimatisation societies in the 1870s. They lived mainly in some North Otago waters, and did not become widespread or abundant for many decades. Recently, anglers and others have spread tench more widely – often illegally (it is illegal to liberate fish into new waters without approval from the minister of conservation). Tench appeal to coarse fishers because they grow large, are powerful swimmers, and a challenge to catch. In the early 2000s they were widespread, mostly in small lakes. They are classed as ‘sports fish’, so a licence is needed to fish for them."[122]

"This member of the Cyprinidae family is native to Europe and was first introduced to New Zealand in 1867. Although imported as a sports fish, there has been little angler interest in tench until recently. Tench grow to a large size in New Zealand, and some northern lakes have now gained an international reputation among anglers who prefer fishing for coarse fish. Fish over 2 kg in weight are not uncommon, and in some instances 4-kg fish have been caught. Tench are generally an olive green colour although this varies from dark to light. There is a single small barbel at each corner of the mouth. The fins tend to be thick and fleshy and the body is covered in small scales. Their eyes are bright orange, and this is their most distinctive characteristic. The biology of tench in New Zealand has not been studied, but is probably similar to that of fish in their native waters. Tench generally live in still or slow-flowing waters and are carnivorous, feeding mainly on crustaceans, molluscs and insect larvae. Males have longer and fatter pelvic fins than females. Spawning occurs in spring and summer and, like all the Cyprinidae, tench are prolific breeders; a large female may produce hundreds of thousands of small eggs. Although most fishing for tench occurs in the Auckland area, tench are also present in some lakes and ponds in Northland, Tauranga and Wellington. They have been present in the South Island near Oamaru for many years, but have also been found recently in Nelson, Marlborough and Canterbury during recent surveys by the Department of Conservation. A golden variety of tench, which is bright yellow-orange, is thought to be present in some small lakes and ponds near Auckland. This variety of tench was illegally imported in about 1980."[140]

Gobiidae Arenigobius bifrenatus Bridled goby
Not assessed
[142]
Ictaluridae Ameiurus nebulosus Brown bullhead (catfish) Least concern[144] "North American brown bullhead catfish (Ameiurus nebulosus) were introduced for unknown reasons in the 1870s. They became abundant in the lower Waikato River, and were not found elsewhere for many decades apart from small numbers in Lake Māhinapua, near Hokitika, the only confirmed South Island population. Their range increased from the 1980s – perhaps spread by commercial eel fishers who caught them in their fyke nets (large, funnel-shaped nets that trap fish). Intermittent catfish populations are now widespread in northern waters, including Lake Taupō, although how they reached this lake is uncertain. They have spread from Lake Taupō to the series of hydro lakes in the Waikato River."[145]

"The catfish is not native to New Zealand and is the only member of the Ictaluridae family that occurs in New Zealand waters. The Ictaluridae, or North American catfish, is one of the smallest of more than 30 catfish families worldwide with about 45 species. Ictalurids are characterised by having barbels around the mouth – these look rather like whiskers and hence the common name catfish. However in North America, where there are many species of catfish, the species found in New Zealand is known as the brown bullhead. The brown bullhead catfish is dark brown to olive green colour with paler sides and bellies. In addition to the eight distinctive barbels around their mouth, catfish also have relatively small eyes and a smooth skin. The leading edge on their dorsal and pectoral fins has a sharp spine, and thus catfish should be handled very carefully to avoid injury from the spine. Catfish are an extremely robust fish and can survive for long periods out of water. They commonly grow to 200–300 mm in length. Catfish have been present in New Zealand since the late 1800s. For many years, they were rarely encountered with the only known populations occurring in the lower Waikato River and in Lake Mahinapua south of Hokitika. They were first recorded from Lake Taupo in 1985. Since then, catfish have gradually spread throughout Lake Taupo and down the Waikato River. In 1997, catfish were recorded for the first time from the Kaituna Lagoon near Lake Ellesmere, and in 2003 from a stream entering Hokianga Harbour. Accidental introductions via boat trailers and especially fyke nets used for eeling is continuing to spread this species around New Zealand. Catfish spawn in shallow depressions on the substrate in the shallows. The male guards and fans the eggs during development, and also guards the larvae for about a week after hatching. Catfish are carnivorous and use their sensitive barbels to probe the substrate and locate insects, crustaceans, molluscs and small fish. Freshwater crayfish are a major prey species for catfish in Lake Taupo."[146]

Percidae Perca fluviatilis European perch Least concern[148] "European perch (Perca fluviatilis) are a desired angling species, brought to New Zealand in the late 1860s. They are classed as ‘sports fish’, so anglers need a licence to fish for them. Perch are widespread but intermittent around the country. Concentrated populations are in the western and southern North Island, around Hokitika, and in the eastern and southern South Island. The fish has firm, white, tasty flesh, and is much the best eating of the exotic non-salmonid species."[145]

"Redfin perch belong in the Percidae family, a family of about 60 species that are native to the Northern Hemisphere. One species has become established in New Zealand and it is known simply as the perch. New Zealand perch come from Tasmanian stocks that were originally imported from England. They have become well established in Otago and Southland, but also occur in many other parts of New Zealand, especially around Auckland, the Waikato and in North Island west coast lakes south of New Plymouth. Perch can be distinguished from other species by the presence of the two dorsal fins, the first having 13–17 firm sharp spines. There is also a broad flat spine on the gill cover. Perch have six or more dark bands along their sides; these are most prominent in small fish. The bottom edge of the caudal fin is bright red-orange, as are the anal and pectoral fins. These features make perch easy to recognize. Although perch were liberated widely in the late 1870s, there was little interest in their angling potential until after 1990. They are a fine table fish with firm white flesh, but their small size and lack of fighting ability meant that they never became as popular with anglers as the salmonids. Perch are suitable game fish for youngsters because they are relatively easy to catch. Most perch in New Zealand are between 1–2 kg in weight. Perch prefer slow-flowing and still water habitats. They are strictly carnivorous and adults feed mainly on other fish. Perch have been shown to reduce the abundance of common bullies in lakes. They also reduce inanga, smelt and crayfish in lakes where they have been introduced. At high densities, small fish predominate and can cause toxic cyanobacterial blooms."[149]

Poeciliidae Poeciliidae include live-bearing aquarium fish, such as the guppy, molly, platy, and swordtail. "A group of exotic species belongs to the family Poeciliidae, sometimes known as the livebearers because they give birth to live young rather than lay eggs. There are five small livebearers in natural habitats in New Zealand – one (gambusia) was introduced for biological control, the others for aquariums."[145]

"As the common name of this family implies, the Poeciliidae are characterised by giving birth to live young. Other family characteristics include a single soft-rayed dorsal fin and no lateral line. On male poeciliids, the anal fin has evolved into a structure known as a gonopodium that is used to transfer sperm bundles to the female fish. Poeciliidae are generally small; less than 100 mm in length, and usually the female is much larger than the male. The Poeciliidae are native to the Americas, extending from the upper Mississippi valley through Central America down to Argentina. There may be up to 300 species in this family and many are popular with aquarists. Five species have been introduced to New Zealand but only gambusia is widespread. The other members generally require warm water habitats, and are mostly confined to thermal areas in the central North Island."[150]

"In addition to mosquitofish, there are four other species of Poeciliidae in New Zealand. As all of these have a very restricted distribution, they have been combined for this discussion. They are all popular aquarium species (who has not heard of the guppy) and probably came to be released by aquarists either tired of looking after their fish or eager to establish feral populations in New Zealand. All except the caudo require warm water, and thus are unlikely to spread from their current locations in geothermal waters of the central North Island."[151]

Gambusia affinis Mosquitofish Least concern[153] "Gambusia (Gambusia affinis) were introduced, probably in the 1930s, in the hope they would help control mosquitoes. This is unproven in New Zealand, and they may be no more useful than native fish. Gambusia have become increasingly widespread since the 1980s, and are now common from the Waikato and Bay of Plenty northwards. A few populations have been reported in the northern South Island, where efforts have been made to exterminate them as they may be detrimental to native fish."[145]

"Gambusia or mosquitofish have been introduced to many countries to combat mosquitoes – they eat the larvae and pupae. They were first released in New Zealand in the 1930s. In a number of countries they have become pests by competing with native fish, and in New Zealand they are classed as an "unwanted organism" under the Biosecurity Act 1993."[154]

[155]

Phallocerus caudimaculatus Speckled mosquitofish
Not assessed
"Resembling gambusia, caudo (Phalloceros caudimaculatus) have been reported from waters around Whāngārei, but it is uncertain if there are wild populations. Aquarists have stocks that could become established if released into suitable habitats."[145]

"Caudo (Phallocerus caudimaculatus) Caudo were only recently discovered in New Zealand. The only known population occurs in stock water troughs near Whangarei, but the origins of this population are a mystery. They are thought to have come from a nearby stream, but no population can be found there today. The discovery of yet another illegally introduced fish in New Zealand is of concern because it is unknown what impact these fish might have on the ecology. Caudo do not require particularly warm water, and thus could easily spread to other parts of Northland."[151]

Poecilia latipinna Sailfin molly Least concern[158] "Three poeciliids liberated into the wild by aquarists now live in geothermally heated waters in the central North Island. The common guppy (Poecilia reticulata) has been found in streams near Reporoa, the sailfin molly (Poecilia latipinna) in a wetland at the southern end of Lake Taupō, and the swordtail (Xiphophorus helleri) in a stream near Taupō. None of these species is likely to become established in waters of normal ambient temperature, so their geographical range will be restricted. Some were once in the Waipāhīhī Stream, near Taupō, but when water flows were manipulated, temperatures rose and the fish died out."[145]

"Sailfin molly (Poecilia latipinna) As its name implies, the sailfin molly has a large dorsal fin. In male fish this can be twice as high as their body. Sailfin molly are only found at the southern end of Lake Taupo in the warm geothermal swamps around Tokaanu and Waihi, but are quite abundant there. Sailfin molly are one of the largest poeciliids in New Zealand with female fish known to reach 120 mm."[151]

Poecilia reticulata Guppy
Not assessed
"Guppy (Poecilia reticulata) Guppies are restricted to warm geothermal waters near Reporoa where they have probably been present since the 1920s. They closely resemble mosquitofish, although the male is more brightly coloured. Reaching a maximum length of 60 mm, guppies mature just a few weeks after being born. Like many live bearers, the female guppy can use sperm from one copulation to produce several broods of young."[151]
Xiphophorus helleri Green swordtail
Not assessed
"Swordtail (Xiphophorus helleri) Feral swordtail in New Zealand are bright orange on the back and sides, a feature that distinguishes them from the other Poeciliidae. The lower part of the caudal fin in male swordtail is elongated into a tapering sword-like projection, hence the common name. They were probably only released in the last 15 years or so, and may eventually revert to the olive-brown colour typical of wild populations. They are only known to occur in Waipahihi Stream near Taupo. A survey of this stream in 1999 failed to catch any swordtail, and this population may now be extinct."[151]

The status and exploitation of non-salmonid exotic fish in New Zealand

"The first effort to introduce fish into New Zealand was made in 1864 when a private individual tried to import 15 species of British..."

invasive species
  • Dean, T. (2001). "Invasive freshwater fish in New Zealand: DOC’s present and future management". In Managing invasive freshwater fish in New Zealand. Proceedings of a workshop hosted by Department of Conservation, pp. 59–69. ISBN 0478224230.
  • Chadderton, W. L. (2001). "Management of invasive freshwater fish: striking the right balance". In Managing invasive freshwater fish in New Zealand. Proceedings of a workshop hosted by the Department of Conservation, pp. 59–69. ISBN 0478224230.
  • de Winton, M., Dugdale, T., & Clayton, J. (2001). "Coarse fish: the demise of plants and malaise of lakes". In Managing invasive freshwater fish in New Zealand. Proceedings of a workshop hosted by the Department of Conservation, pp. 59–69. ISBN 0478224230.
  • Rowe, D. K. and Wilding, T. (2012). "Risk assessment model for the introduction of non‐native freshwater fish into New Zealand". Journal of Applied Ichthyology, 28 (4): 582–589.
  • McDowall, R. M. (2006). Crying wolf, crying foul, or crying shame: alien salmonids and a biodiversity crisis in the southern cool-temperate galaxioid fishes?. Reviews in Fish Biology and Fisheries, 16(3-4), 233-422.
  • Invasive species in New Zealand
  • List of introduced species

References

  1. ^ Cite error: The named reference McDowall2010 was invoked but never defined (see the help page).
  2. ^ a b c d e f g An Overview of New Zealand's Freshwater Fish Fauna NIWA Atlas of NZ Freshwater Fishes.
  3. ^ a b c d e f Young, Roger. Life in fresh water - Fish, Te Ara - the Encyclopedia of New Zealand. Updated 13 July 2012.
  4. ^ a b c d e f g Young, Roger. Life in fresh water - Factors affecting life in fresh water, Te Ara - the Encyclopedia of New Zealand. Updated 13 July 2012.
  5. ^ a b c d e McDowall, Bob. Freshwater fish - Shy species, seldom seen, Te Ara - the Encyclopedia of New Zealand. Updated 13 July 2012.
  6. ^ a b c d e f g McDowall, Bob. Freshwater fish - Evolution and characteristics, Te Ara - the Encyclopedia of New Zealand. Updated 13 July 2012.
  7. ^ Bob McDowall. "Freshwater fish - Galaxiids: īnanga and kōkopu" Te Ara - the Encyclopedia of New Zealand, updated 13 July 2012.
  8. ^ a b c d Bob McDowall. Freshwater fish - Galaxiids: īnanga and kōkopu, Te Ara - the Encyclopedia of New Zealand. Updated 13 July 2012.
  9. ^ McDowall, R. M. (2006). "Crying wolf, crying foul, or crying shame: alien salmonids and a biodiversity crisis in the southern cool-temperate galaxioid fishes?". Reviews in Fish Biology and Fisheries, 16 (3-4): 233–422.
  10. ^ a b c d e McDowall, Bob. Freshwater fish - More galaxiids, Te Ara - the Encyclopedia of New Zealand. Updated 13 July 2012.
  11. ^ a b c McDowall, Bob. Freshwater fish - Bullies, smelt and grayling, Te Ara - the Encyclopedia of New Zealand. Updated 13 July 2012.
  12. ^ a b c McDowall, Bob. Freshwater fish - Torrentfish, lamprey and black flounder, Te Ara - the Encyclopedia of New Zealand. Updated 13 July 2012.
  13. ^ a b c Goodman, J.M.; Dunn, N.R.; Ravenscroft, P.J.; Allibone, R.M.; Boubee, J.A.T.; David, B.O.; Griffiths, M.; Ling, N.; Hitchmough, R.A; Rolfe, J.R. (2014). "Conservation status of New Zealand freshwater fish, 2013" (PDF). New Zealand Threat Classification Series 7. ISBN 9780478150148.
  14. ^ Froese, Rainer; Pauly, Daniel (eds.). "Anguilla australis". FishBase. April 2015 version.
  15. ^ Froese, Rainer; Pauly, Daniel (eds.). "Anguilla dieffenbachii". FishBase. April 2015 version.
  16. ^ Froese, Rainer; Pauly, Daniel (eds.). "Gobiomorphus alpinus". FishBase. April 2015 version.
  17. ^ Template:IUCN2015.2
  18. ^ FishBase species |genus= Gobiomorphus|species= basalis| month = April | year = 2015}}
  19. ^ Template:IUCN2015.2
  20. ^ Froese, Rainer; Pauly, Daniel (eds.). "Gobiomorphus breviceps". FishBase. April 2015 version.
  21. ^ Template:IUCN2015.2
  22. ^ Froese, Rainer; Pauly, Daniel (eds.). "Gobiomorphus cotidianus". FishBase. April 2015 version.
  23. ^ Template:IUCN2015.2
  24. ^ Froese, Rainer; Pauly, Daniel (eds.). "Gobiomorphus gobioides". FishBase. April 2015 version.
  25. ^ Template:IUCN2015.2
  26. ^ Froese, Rainer; Pauly, Daniel (eds.). "Gobiomorphus hubbsi". FishBase. April 2015 version.
  27. ^ Template:IUCN2015.2
  28. ^ Froese, Rainer; Pauly, Daniel (eds.). "Gobiomorphus huttoni". FishBase. April 2015 version.
  29. ^ Template:IUCN2015.2
  30. ^ Froese, Rainer; Pauly, Daniel (eds.). "Galaxias anomalus". FishBase. April 2015 version.
  31. ^ Template:IUCN2015.2
  32. ^ Froese, Rainer; Pauly, Daniel (eds.). "Galaxias argenteus". FishBase. April 2015 version.
  33. ^ Template:IUCN2015.2
  34. ^ Froese, Rainer; Pauly, Daniel (eds.). "Galaxias brevipinnis". FishBase. April 2015 version.
  35. ^ Template:IUCN2015.2
  36. ^ Froese, Rainer; Pauly, Daniel (eds.). "Galaxias cobitinis". FishBase. April 2015 version.
  37. ^ Template:IUCN2015.2
  38. ^ Froese, Rainer; Pauly, Daniel (eds.). "Galaxias depressiceps". FishBase. April 2015 version.
  39. ^ Template:IUCN2015.2
  40. ^ Froese, Rainer; Pauly, Daniel (eds.). "Galaxias divergens". FishBase. April 2015 version.
  41. ^ Template:IUCN2015.2
  42. ^ Froese, Rainer; Pauly, Daniel (eds.). "Galaxias eldoni". FishBase. April 2015 version.
  43. ^ Template:IUCN2015.2
  44. ^ Froese, Rainer; Pauly, Daniel (eds.). "Galaxias fasciatus". FishBase. April 2015 version.
  45. ^ Template:IUCN2015.2
  46. ^ Froese, Rainer; Pauly, Daniel (eds.). "Galaxias gollumoides". FishBase. April 2015 version.
  47. ^ Froese, Rainer; Pauly, Daniel (eds.). "Galaxias gracilis". FishBase. April 2015 version.
  48. ^ Froese, Rainer; Pauly, Daniel (eds.). "Galaxias macronasus". FishBase. April 2015 version.
  49. ^ Froese, Rainer; Pauly, Daniel (eds.). "Galaxias maculatus". FishBase. April 2015 version.
  50. ^ Template:IUCN2015.2
  51. ^ Froese, Rainer; Pauly, Daniel (eds.). "Galaxias paucispondylus". FishBase. April 2015 version.
  52. ^ Template:IUCN2015.2
  53. ^ Froese, Rainer; Pauly, Daniel (eds.). "Galaxias postvectis". FishBase. April 2015 version.
  54. ^ Template:IUCN2015.2
  55. ^ Froese, Rainer; Pauly, Daniel (eds.). "Galaxias prognathus". FishBase. April 2015 version.
  56. ^ Template:IUCN2015.2
  57. ^ Froese, Rainer; Pauly, Daniel (eds.). "Galaxias pullus". FishBase. April 2015 version.
  58. ^ Template:IUCN2015.2
  59. ^ Froese, Rainer; Pauly, Daniel (eds.). "Galaxias vulgaris". FishBase. April 2015 version.
  60. ^ Template:IUCN2015.2
  61. ^ Froese, Rainer; Pauly, Daniel (eds.). "Neochanna apoda". FishBase. April 2015 version.
  62. ^ Template:IUCN2015.2
  63. ^ Froese, Rainer; Pauly, Daniel (eds.). "Neochanna burrowsius". FishBase. April 2015 version.
  64. ^ Template:IUCN2015.2
  65. ^ Froese, Rainer; Pauly, Daniel (eds.). "Neochanna diversus". FishBase. April 2015 version.
  66. ^ Template:IUCN2015.2
  67. ^ Froese, Rainer; Pauly, Daniel (eds.). "Neochanna heleios". FishBase. April 2015 version.
  68. ^ Template:IUCN2015.2
  69. ^ Froese, Rainer; Pauly, Daniel (eds.). "Neochanna rekohua". FishBase. April 2015 version.
  70. ^ Template:IUCN2015.2
  71. ^ Froese, Rainer; Pauly, Daniel (eds.). "Rhombosolea retiaria". FishBase. April 2015 version.
  72. ^ Template:IUCN2015.2
  73. ^ Froese, Rainer; Pauly, Daniel (eds.). "Aldrichetta forsteri". FishBase. April 2015 version.
  74. ^ Template:IUCN2015.2
  75. ^ Froese, Rainer; Pauly, Daniel (eds.). "Mugil cephalus". FishBase. April 2015 version.
  76. ^ Template:IUCN2015.2
  77. ^ Froese, Rainer; Pauly, Daniel (eds.). "Cheimarrichthys fosteri". FishBase. April 2015 version.
  78. ^ Template:IUCN2015.2
  79. ^ Froese, Rainer; Pauly, Daniel (eds.). "Rhombosolea retiaria". FishBase. April 2015 version.
  80. ^ Template:IUCN2015.2
  81. ^ Froese, Rainer; Pauly, Daniel (eds.). "Prototroctes oxyrhynchus". FishBase. April 2015 version.
  82. ^ Template:IUCN2015.2
  83. ^ Froese, Rainer; Pauly, Daniel (eds.). "Retropinna retropinna". FishBase. April 2015 version.
  84. ^ Template:IUCN2015.2
  85. ^ Froese, Rainer; Pauly, Daniel (eds.). "Stokellia anisodon". FishBase. April 2015 version.
  86. ^ Template:IUCN2015.2
  87. ^ Froese, Rainer; Pauly, Daniel (eds.). "Forsterygion nigripenne". FishBase. April 2015 version.
  88. ^ Template:IUCN2015.2
  89. ^ Ryan, Paddy. http://www.TeAra.govt.nz/en/eels/page-1 Eels - Overview: features and distribution], Te Ara - the Encyclopedia of New Zealand. Updated 13 July 2012.
  90. ^ a b c d Ryan, Paddy. http://www.TeAra.govt.nz/en/eels/page-2 Eels: New Zealand eels], Te Ara - the Encyclopedia of New Zealand. Updated 13 July 2012.
  91. ^ a b Cite error: The named reference RyanEels1 was invoked but never defined (see the help page).
  92. ^ a b c d Ryan, Paddy. http://www.TeAra.govt.nz/en/eels/page-3 Eels: Life cycle and breeding grounds], Te Ara - the Encyclopedia of New Zealand. Updated 13 July 2012.
  93. ^ a b c Ryan, Paddy. http://www.TeAra.govt.nz/en/eels/page-4 Eels: Export and fishery management], Te Ara - the Encyclopedia of New Zealand. Updated 13 July 2012.
  94. ^ McDowall, R. M. (2006). Fish, fish habitats and fisheries in New Zealand. Aquatic Ecosystem Health & Management, 9(4), 391-405.
  95. ^ Are whitebait headed for extinction? Westport News, 10 June 2014.
  96. ^ McDowall, R. M. (2008). Process and pattern in the biogeography of New Zealand–a global microcosm? Journal of Biogeography, 35 (2): 197–212. doi:10.1111/j.1365-2699.2007.01830.x
  97. ^ McDowall, R. M. (2002). "Accumulating evidence for a dispersal biogeography of southern cool temperate freshwater fishes" Journal of Biogeography, 29 (2): 207–219. doi:10.1046/j.1365-2699.2002.00670.x
  98. ^ Goodman, J.M.; Dunn, N.R.; Ravenscroft, P.J.; Allibone, R.M.; Boubee, J.A.T.; David, B.O.; Griffiths, M.; Ling, N.; Hitchmough, R.A; Rolfe, J.R. (2014). "Conservation status of New Zealand freshwater fish, 2013" (PDF). New Zealand Threat Classification Series 7. ISBN 9780478150148.
  99. ^ Goodman, J.M.; Dunn, N.R.; Ravenscroft, P.J.; Allibone, R.M.; Boubee, J.A.T.; David, B.O.; Griffiths, M.; Ling, N.; Hitchmough, R.A; Rolfe, J.R. (2014). "Conservation status of New Zealand freshwater fish, 2013" (PDF). New Zealand Threat Classification Series 7. ISBN 9780478150148.
  100. ^ Froese, Rainer; Pauly, Daniel (eds.). "Anguilla reinhardtii". FishBase. April 2015 version.
  101. ^ Froese, Rainer; Pauly, Daniel (eds.). "Gobiopterus semivestitus". FishBase. April 2015 version.
  102. ^ Froese, Rainer; Pauly, Daniel (eds.). "Parioglossus marginalis". FishBase. April 2015 version.
  103. ^ Template:IUCN2015.2
  104. ^ a b c d e McDowall, Bob. Coarse fish: Introduction, Te Ara - the Encyclopedia of New Zealand. Updated 13 July 2012.
  105. ^ a b c d Walrond, Carl. Trout and salmon, Te Ara - the Encyclopedia of New Zealand. Updated 20 May 2013.
  106. ^ a b c d Walrond, Carl. Trout and salmon: Brown trout, Te Ara - the Encyclopedia of New Zealand. Updated 13 July 2013.
  107. ^ a b c d Walrond, Carl. Trout and salmon: Rainbow trout, Te Ara - the Encyclopedia of New Zealand. Updated 13 July 2013.
  108. ^ a b c d e Walrond, Carl. Trout and salmon: Chinook salmon, Te Ara - the Encyclopedia of New Zealand. Updated 13 July 2013.
  109. ^ Martin Unwin, quoted in Derek Grzelewski, "Salmon the miracle fish." New Zealand Geographic 63 (May–June 2003), pp. 39–40.
  110. ^ a b c d e f Walrond, Carl. Trout and salmon: Other salmonids, Te Ara - the Encyclopedia of New Zealand. Updated 13 July 2013.
  111. ^ Froese, Rainer; Pauly, Daniel (eds.). "Oncorhynchus mykiss". FishBase. April 2015 version.
  112. ^ Froese, Rainer; Pauly, Daniel (eds.). "Oncorhynchus nerka". FishBase. April 2015 version.
  113. ^ Template:IUCN2015.2
  114. ^ Froese, Rainer; Pauly, Daniel (eds.). "Oncorhynchus tshawytscha". FishBase. April 2015 version.
  115. ^ Froese, Rainer; Pauly, Daniel (eds.). "Salmo salar". FishBase. April 2015 version.
  116. ^ Template:IUCN2015.2 (needs updating)
  117. ^ Froese, Rainer; Pauly, Daniel (eds.). "Salmo trutta". FishBase. April 2015 version.
  118. ^ Template:IUCN2015.2
  119. ^ Froese, Rainer; Pauly, Daniel (eds.). "Salvelinus fontinalis". FishBase. April 2015 version.
  120. ^ Froese, Rainer; Pauly, Daniel (eds.). "Salvelinus namaycush". FishBase. April 2015 version.
  121. ^ McDowall, Bob. Coarse fish, Te Ara - the Encyclopedia of New Zealand. Updated 20 May 2013.
  122. ^ a b c d e f g McDowall, Bob. Coarse fish: Cyprinids – goldfish, carp and others, Te Ara - the Encyclopedia of New Zealand. Updated 13 July 2012.
  123. ^ Carps NIWA. Accessed 15 September 2015.
  124. ^ Froese, Rainer; Pauly, Daniel (eds.). "Carassius auratus". FishBase. April 2015 version.
  125. ^ Template:IUCN2015.2
  126. ^ Goldfish NIWA. Accessed 15 September 2015.
  127. ^ Froese, Rainer; Pauly, Daniel (eds.). "Ctenopharyngodon idella". FishBase. April 2015 version.
  128. ^ Grass carp NIWA. Accessed 15 September 2015.
  129. ^ Froese, Rainer; Pauly, Daniel (eds.). "Cyprinus carpio". FishBase. April 2015 version.
  130. ^ Template:IUCN2015.2
  131. ^ Koi Carp NIWA. Accessed 15 September 2015.
  132. ^ Froese, Rainer; Pauly, Daniel (eds.). "Leuciscus idus". FishBase. April 2015 version.
  133. ^ Template:IUCN2015.2
  134. ^ Orfe NIWA. Accessed 15 September 2015.
  135. ^ Froese, Rainer; Pauly, Daniel (eds.). "Scardinius erythrophthalmus". FishBase. April 2015 version.
  136. ^ Template:IUCN2015.2
  137. ^ Rudd NIWA. Accessed 15 September 2015.
  138. ^ Froese, Rainer; Pauly, Daniel (eds.). "Tinca tinca". FishBase. April 2015 version.
  139. ^ Template:IUCN2015.2
  140. ^ Tench NIWA. Accessed 15 September 2015.
  141. ^ Froese, Rainer; Pauly, Daniel (eds.). "Arenigobius bifrenatus". FishBase. April 2015 version.
  142. ^ Willis, T. J., Saunders, J. E., Blackwood, D. L., & Archer, J. E. (1999). "First New Zealand record of the Australian bridled goby, arenigobius bifrenatus (Pisces: Gobiidae)". New Zealand Journal of Marine and Freshwater Research, 33 (2): 189–192. doi:10.1080/00288330.1999.9516869
  143. ^ Froese, Rainer; Pauly, Daniel (eds.). "Ameiurus nebulosus". FishBase. April 2015 version.
  144. ^ Template:IUCN2015.2
  145. ^ a b c d e f McDowall, Bob. Coarse fish: Livebearers, catfish and perch, Te Ara - the Encyclopedia of New Zealand. Updated 13 July 2012.
  146. ^ Catfish NIWA. Accessed 15 September 2015.
  147. ^ Froese, Rainer; Pauly, Daniel (eds.). "Perca fluviatilis". FishBase. April 2015 version.
  148. ^ Template:IUCN2015.2
  149. ^ Perch NIWA. Accessed 15 September 2015.
  150. ^ Poeciliidae NIWA. Accessed 15 September 2015.
  151. ^ a b c d e Other Poeciliidae NIWA. Accessed 15 September 2015.
  152. ^ Froese, Rainer; Pauly, Daniel (eds.). "Gambusia affinis". FishBase. April 2015 version.
  153. ^ Template:IUCN2015.2
  154. ^ Bob McDowall. Coarse fish - Livebearers, catfish and perch Te Ara - the Encyclopedia of New Zealand. Updated 14 November 2012.
  155. ^ Mosquitofish NIWA. Accessed 15 September 2015.
  156. ^ Froese, Rainer; Pauly, Daniel (eds.). "Phallocerus caudimaculatus". FishBase. April 2015 version.
  157. ^ Froese, Rainer; Pauly, Daniel (eds.). "Poecilia latipinna". FishBase. April 2015 version.
  158. ^ Template:IUCN2015.2
  159. ^ Froese, Rainer; Pauly, Daniel (eds.). "Poecilia reticulata". FishBase. April 2015 version.
  160. ^ Froese, Rainer; Pauly, Daniel (eds.). "Xiphophorus helleri". FishBase. April 2015 version.

Robert (Bob) McDowall

Focus

Planetary boundaries
The Great Acceleration
Animal consciousness
Swarm intelligence

Fish intelligence

Fish hold the records for the relative brain weights of vertebrates. Most vertebrate species have brains that weigh about the same in proportion to their total body mass. The deep sea bathopelagic cusk-eel Acanthonus armatus,[1] is an ambush predator with a huge head. This fish has the smallest relative brain of all known vertebrates.[2] At the other extreme, the elephantnose fish, an African freshwater fish, has the largest relative brain of all known vertebrates.[3]

from goldfish

Goldfish can be trained to recognize and to react to light signals of different colors by using positive reinforcement.[4] Goldfish have a memory-span of at least three months and can distinguish between different shapes, colours and sounds.[5] Another experiment demonstrated retention of more than 1 month.[6] Fish respond to certain colors most evidently in relation to feeding.[7] Fish learn to anticipate feedings provided they occur at around the same time everyday. Goldfish can learn tricks, such as the limbo, slalom, fetch and soccer, using positive reinforcement training techniques.[8]


intelligence

From [16]:

A recent issue of Fish and Fisheries, devoted to learning, cited more than 500 research papers on fish intelligence, proving that fish are smart, that they can use tools, and that they have impressive long-term memories and sophisticated social structures. The introductory chapter said that fish are "steeped in social intelligence, pursuing Machiavellian strategies of manipulation, punishment and reconciliation … exhibiting stable cultural traditions and cooperating to inspect predators and catch food."

• Culum Brown, a University of Edinburgh biologist who is studying the evolution of cognition in fish, says, "Fish are more intelligent than they appear. In many areas, such as memory, their cognitive powers match or exceed those of 'higher' vertebrates, including non-human primates." Their long-term memories help fish keep track of complex social relationships. Their spatial memory—"equal in all respects to any other vertebrate"—allows them to create cognitive maps that guide them through their watery homes, using cues such as polarized light, sounds, smells, and visual landmarks.

• Dr. Phil Gee, a psychologist from the University of Plymouth, says that fish can tell what time of day it is, and he trained fish to collect food by pressing a lever at specific times. He says "fish have a memory span of at least three months," and they "are probably able to adapt to changes in their circumstances, like any other small animals and birds."

• "We're now finding that [fish] are very capable of learning and remembering, and possess a range of cognitive skills that would surprise many people." —Dr. Theresa Burt de Perera, Oxford University

• A scientific review presented to the Australian Veterinary Association completely disproved the old myth that goldfish have three-second memories; instead, the veterinarians found that goldfish have impressive memories and problem-solving abilities. One of the researchers said that after conducting the review, they wanted “to get the message out to vets to start looking more closely at fish and considering their welfare like they do other animals.” —The Sunday Times, May 28, 2006

• "Australian crimson spotted rainbowfish, which learnt to escape from a net in their tank, remembered how they did it 11 months later. This is equivalent to a human recalling a lesson learnt 40 years ago." —Sunday Telegraph, Oct. 3, 2004

memory


collective intelligence
swarm intelligence
The playful curiosity of this eagle ray reminded me of a story from the inventor of the " Deepflight “flying submarine.” On an early test dive, he found himself dancing with a curious eagle ray.... Moving like they do might be a signal of kinship... and may help express universal gestures for play... "Warm-blooded animals play; fish and reptiles do not... We are designed to play. We need 3D motion. The smarter the creature the more they play. The sea squirt auto-digests its brain when it becomes sessile." – Stuart Brown, founder of the Institute for Play
  • Victoria A. Braithwaite, Felicity Huntingford, Ruud den Bos. 2011. Variation in Emotion and Cognition Among Fishes. Journal of Agricultural and Environmental Ethics
  • Miklósi Á (2002) ["On the usefulness and limits of functional analogies"] Springer,

"Machiavellian Intelligence hypothesis" fish

video

References

  1. ^ Froese, Rainer; Pauly, Daniel (eds.). "Acanthonus armatus". FishBase. August 2009 version.
  2. ^ Fine ML, Horn MH and Cox B (1987) "Acanthonus armatus, a Deep-Sea Teleost Fish with a Minute Brain and Large Ears" Proceedings of the Royal Society B, 230(1259)257-265.
  3. ^ Nilsson G (1996) "Brain and body oxygen requirements of Gnathonemus petersii, a fish with an exceptionally large brain" Journal of Experimental Biology, 199(3): 603-607. Download
  4. ^ "Poissons rouges: la mémoire dans l'eau". Revue du Palais de la découverte. 217. April 1994.In a 1994 public experiment at the Palais de la Découverte science museum.
  5. ^ More recent research by the School of Psychology at the University of Plymouth in 2003. They were trained to push a lever to earn a food reward; when the lever was fixed to work only for an hour a day, the fish soon learned to activate it at the correct time.
  6. ^ The Discovery Channel's show Mythbusters tested the contemporary legend that goldfish only had a memory span of 3 seconds and were able to prove that goldfish had a longer memory span than commonly believed. The experiment involved training the fish to navigate a maze. It was evident that they were able to remember the correct path of the maze after more than a month.Mythbuster Results: A goldfish’s memory lasts only three seconds
  7. ^ According to a study at the start of the 2000s
  8. ^ Send Your Fish to School. ABC News: Good Morning America. Posted: May 7, 2008.