Galaxias

Last updated

Galaxias
Mountain Galaxias (1).jpg
A Galaxias olidus from southeast Australia
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Galaxiiformes
Family: Galaxiidae
Subfamily: Galaxiinae
Genus: Galaxias
G. Cuvier, 1816

Galaxias is a genus of small freshwater fish in the family Galaxiidae, and are frequently referred to as the galaxiids. These highly adaptable fish are typically found at temperate latitudes across the Southern Hemisphere.

Contents

Galaxiids are scaleless and somewhat tubular in body form, ranging from very slender to quite bulky. They are somewhat torpedo-shaped, with the dorsal and anal fins positioned close to the tail. They are generally small, with typical adults ranging between 4–15 cm (1.6–5.9 in) in total length, with some stocky species attaining around 25 cm (10 in). The largest, Galaxias argenteus, has been recorded at 58 cm (22.8 in; 1.9 ft), although 30–40 cm (12–16 in) is a more typical adult length.

Species

The 46 recognized species in this genus are:

Distribution

Galaxiids are restricted to the Southern Hemisphere, and generally only occur in temperate latitudes. Only one species is known from subtropical habitats. [3]

Galaxiids are the dominant group of native freshwater fish in New Zealand, and, along with the Percichthyidae, one of two dominant groups of native freshwater fish in southeastern Australia. Only one of the species ( G. zebratus ) is found in Africa, and only three ( G. globiceps , G. maculatus , and G. platei ) are found in South America. One species ( G. neocaledonicus ) is endemic to the New Caledonia

Habitat

Galaxiids are coolwater species, with many wholly freshwater species specialising in high-altitude upland streams (including very small streams), rivers, and lakes. Some galaxiids include a marine stage in their lifecycles where larvae are washed out to sea to develop, and return to rivers as juveniles. This type of diadromous fish migration is known as amphidromy. These species are consequently also found in low-altitude habitats, but frequently migrate to high-altitude reaches of river systems in their adult stage.

Threats

Wholly freshwater galaxiids are gravely threatened by exotic salmonid species, particularly exotic trout species, which prey heavily upon them and compete with them for food and habitat. This is a major concern, as exotic trout species have been introduced to many different land masses (e.g. Australia, New Zealand, South Africa) with no thought as to impacts on native fish such as galaxiids, and no attempt to preserve some exotic trout-free habitats for native fish. [4]

In most situations, wholly freshwater galaxiids are unable to persist in the presence of exotic trout species, and many are now restricted to the few remaining trout-free habitats. Where these species are found in the presence of trout, the galaxiids usually consist entirely of individuals which dispersed there from an upstream trout-free population, and are not self-sustaining. Numerous localised extinctions of wholly freshwater galaxiid species (i.e. mountain galaxias) have been caused by the introduction of exotic trout species (including ongoing illegal stockings) and a number of wholly freshwater galaxiid species are threatened with extinction by exotic trout species and other exotic salmonids. [3]

Introduced salmoniids also have a negative impact on diadromous galaxiids, competing with them for food and habitat, as well as preying on them. However, the impact is not as great and they appear to be able to persist in the presence of trout.[ citation needed ]


Related Research Articles

<span class="mw-page-title-main">Australian grayling</span> Species of fish

The Australian grayling is a primarily freshwater fish found in coastal rivers in south-eastern mainland Australia and Tasmania. In past decades it has also been known as the cucumber mullet or cucumber herring, for its cucumber-like odour.

<span class="mw-page-title-main">Galaxiidae</span> Family of mostly small freshwater fish

The Galaxiidae are a family of mostly small freshwater fish in the Southern Hemisphere. The majority live in Southern Australia or New Zealand, but some are found in South Africa, southern South America, Lord Howe Island, New Caledonia, and the Falkland Islands. One galaxiid species, the common galaxias, is probably the most widely naturally distributed freshwater fish in the Southern Hemisphere. They are coolwater species, found in temperate latitudes, with only one species known from subtropical habitats. Many specialise in living in cold, high-altitude upland rivers, streams, and lakes.

<span class="mw-page-title-main">Climbing galaxias</span> Species of fish

The climbing galaxias or kōaro is a fish of the family Galaxiidae found in Australia, New Zealand, and nearby islands. The name climbing galaxias is used in Australia, and koaro or kōaro in New Zealand. Further vernacular names include short-finned galaxias, broad-finned galaxias, Cox's mountain galaxias, and Pieman galaxias.

<span class="mw-page-title-main">Mountain galaxias (species complex)</span> Group of fishes

The mountain galaxias is a species complex of freshwater galaxiid fish found all over southeast Australia.

<span class="mw-page-title-main">Common galaxias</span> Species of fish

The common galaxias or inanga is a very widespread Southern Hemisphere fish in the family Galaxiidae. It is a slim, narrow fish with a forked tail and a mottled, spotty pattern, typically about 10 cm (4 in) long when fully grown. It lives in fresh water, but spawns at river mouths and spends the first six months of its life at sea, returning en masse in spring. Its vernacular names include cowfish, jollytail, common jollytail, eel gudgeon, inaka, native trout, pulangi, puye, slippery tarki, spotted minnow, Falklands minnow and whitebait.

<i>Galaxias olidus</i> Species of fish

Galaxias olidus, the mountain galaxias, is a species of freshwater galaxiid fish widely found in southeastern Australia.

Galaxias fuscus, the barred galaxias, is a galaxiid of the genus Galaxias, a member of the Mountain Galaxias species complex group of freshwater fish, found in Australia.

<span class="mw-page-title-main">Banded kōkopu</span> Species of fish

The banded kōkopu is a galaxiid of the genus Galaxias, found only in New Zealand, including the Chatham and Stewart/Rakiura islands. It commonly grows to 20–25 cm, but has been recorded growing to around 30 cm. Juvenile banded kōkopu are good climbers and can climb up waterfalls and other vertical surfaces by moving into the splash zone and wriggling up the surface, using the water surface tension and their large downturned fins for grip.

<span class="mw-page-title-main">Shortjaw kōkopu</span> Species of fish

The shortjaw kōkopu is a galaxiid fish, endemic to New Zealand. They are large, scaleless fish which inhabit stable pools in cascading, bouldery streams with forest cover. Shortjaw kōkopu are amphidromous, with the fry going to sea after hatching, and returning as juveniles to fresh water where they grow to adulthood. They may grow to a maximum of 350 mm (14 in) in total length, but more commonly reach 150–200 mm (5.9–7.9 in).

<span class="mw-page-title-main">Giant kōkopu</span> Species of fish

The giant kōkopu is a threatened species of ray-finned fish in the genus Galaxias, found only in New Zealand. It can reach up to 58 cm (23 in) in length and 2.7 kg (6.0 lb) in weight, making it the largest species in the family Galaxiidae. It is a mainly lowland species, commonly found in slow-flowing streams, wetlands, lakes, and lagoons. Most populations have an amphidromous life cycle, with larvae going to sea soon after hatching and returning about four months later as small juveniles, 4.5–5 cm (1.8–2.0 in). Juvenile giant kōkopu form a small part of the annual whitebait catch.

<span class="mw-page-title-main">Eldon's galaxias</span> Species of fish

Eldon's galaxias is an endangered galaxiid fish endemic to New Zealand. One of several fishes in the genus Galaxias found in Central Otago, it has a very small home range and is at risk of being driven to extinction by trout introduced for recreational fishing.

<span class="mw-page-title-main">Common river galaxias</span> Species of fish

The common river galaxias or Canterbury galaxias is a galaxiid fish of the genus Galaxias, found only in Canterbury, New Zealand.

Gollum galaxias is a galaxiid of the genus Galaxias, found only in southern temperate regions in New Zealand. The species is widespread in rivers throughout the Southland Plains as well as the Von River and Nevis River tributaries of the Clutha River The species is found on Stewart Island/Rakiura, and throughout the Catlins.

<span class="mw-page-title-main">Cape galaxias</span> Species of fish

The Cape galaxias is a species of freshwater fish of the family Galaxiidae.

<span class="mw-page-title-main">Spotted galaxias</span> Species of fish

Spotted galaxias is a largish, primarily-freshwater galaxias species found in southern Australia. Spotted galaxias are perhaps the most beautiful of the Australian galaxias species. They are a somewhat tubular, deep-bodied fish, with a dusky brownish-red colouration overlain with dark, haloed spots, dramatic black edges to dorsal, anal and pelvic fins, and a dark diagonal stripe through the eye.

Robert Montgomery McDowall was one of New Zealand's most prominent freshwater ichthyologists.

Galaxias brevissimus, the short-tail galaxias, is a galaxiid of the genus Galaxias, a member of the Mountain Galaxias species complex group of freshwater fish, found in Australia.

Galaxias lanceolatus, the tapered galaxias, is a galaxiid of the genus Galaxias, a member of the Mountain Galaxias species complex group of freshwater fish, found in Australia.

Galaxias mcdowalli, McDowall's galaxias, is a galaxiid of the genus Galaxias, a member of the Mountain Galaxias species complex group of freshwater fish, found in Australia.

Galaxias mungadhan, the Dargo galaxias, is a galaxiid of the genus Galaxias, a member of the Mountain Galaxias species complex group of freshwater fish, found in Victoria, Australia.

References

  1. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Raadik, T.A. (2014). "Fifteen from one: a revision of the Galaxias olidus Günther, 1866 complex (Teleostei, Galaxiidae) in south-eastern Australia recognises three previously described taxa and describes 12 new species" (PDF). Zootaxa. 3898 (1): 1–198. doi:10.11646/zootaxa.3898.1.1.
  2. Precious: Gollum (the fish) risks extinction in New Zealand
  3. 1 2 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: 233–422. doi:10.1007/s11160-006-9017-7.
  4. Biodiversity, Alien trout, and the "So what" attitude [ permanent dead link ]