Galaxiidae

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Galaxiidae
A mountain galaxias (Galaxias olidus)
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Subphylum: Vertebrata
Class: Actinopterygii
Order: Osmeriformes
Family: Galaxiidae
Genera

Aplochiton
Brachygalaxias
Galaxias
Galaxiella
Lovettia
Neochanna
Paragalaxias

The Galaxiidae, also known by the anglicised name as galaxiids, are a family of mostly small freshwater fish in the southern hemisphere. The majority of species live in Australia or New Zealand, some are also found in South Africa, South America, Lord Howe Island, New Caledonia and the Falkland Islands. One of the galaxiid species, the common galaxias (Galaxias maculatus), is probably the most widely naturally distributed freshwater fish in the world. They are cool water species, found in temperate latitudes, with only one species known from sub-tropical habitat.[1] Many specialise in living in cold, high altitude upland rivers, streams and lakes.

Some galaxiids live in freshwater all their lives but many have a partially marine life cycle. In these cases, larvae are hatched in a river but are washed downstream to the ocean, later returning to rivers as juveniles to complete their development to full adulthood. This pattern differs from that of salmon, which only return to freshwater to breed, and is described as amphidromous.[2]

Freshwater galaxiid species are gravely threatened by exotic salmonid species, particularly trout species, which prey upon galaxiids and compete with them for food. Exotic salmonids have been recklessly introduced to many different landmasses (e.g. Australia, New Zealand), with no thought as to impacts on native fish, or attempts to preserve salmonid-free habitats for them. Numerous localised extinctions of galaxiid species have been caused by the introduction of exotic salmonids and a number of freshwater galaxiid species are threatened with overall extinction by exotic salmonids.[1]

Contents

[edit] Taxonomic diversity

There are about fifty species in the Galaxiidae family, grouped into seven genera.[3]

[edit] Genera

[edit] Species by geography

[edit] Australia

Galaxiids are found around the south eastern seaboard of Australia and in some parts of south western Australia. Species that are common to all areas are:

South East Australian mainland

Threatened species are:

Western Australia

Tasmania Fifteen species of galaxiids have been found in Tasmania. The most common species are:

While endangered species are:

[edit] New Zealand

Twenty-two species of galaxiids have been discovered in New Zealand. Most of these live in freshwater all their lives. However, the larvae of five species of the Galaxias genus develop in the ocean where they form part of the plankton and return to rivers and streams as juveniles (whitebait) where they develop and remain as adults. All Galaxias species found in New Zealand are endemic, except for Galaxias brevipinnis (koaro) and Galaxias maculatus (inanga).

[edit] South America

[edit] South Africa

[edit] Fishing

The juveniles of those galaxiids that develop in the ocean and then move into rivers for their adult life are caught as whitebait while moving upstream and are much valued as a delicacy. Adult galaxiids may be caught for food but they are generally not large. In some cases their exploitation may be banned (i.e. New Zealand) unless available to indigenous tribes.

In addition to serious impacts from exotic trout species, Australian adult galaxiids suffer a disregard from anglers for being "too small" and "not being trout". This is despite the fact that several Australian galaxiid species, though smallish, grow to a sufficient size to be catchable and readily take wet and dry flies, and that one of these species — the spotted galaxias — was keenly fished for in Australia before the introduction of exotic trout species. A handful of fly-fishing exponents in Australia are rediscovering the pleasure of catching (and releasing) these fascinating[says who?] Australian native fish on ultra-light fly-fishing tackle.

[edit] References

  1. ^ a b McDowall, R.M. (2006) Crying wolf, crying foul, or crying shame: alien salmonids and a biodiversity crisis in the southern cool-temperate galaxioid fishes? Rev Fish Biol Fisheries 16: 233–422.
  2. ^ McDowall, Robert M. (1998). In: Paxton, J.R. & Eschmeyer, W.N.. ed. Encyclopedia of Fishes. San Diego: Academic Press. p. 117. ISBN 0-12-547665-5. 
  3. ^ Froese, Rainer, and Daniel Pauly, eds. (2008). "Galaxiidae" in FishBase. December 2008 version.

[edit] External links

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