River blackfish

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River blackfish
Gadopsis marmoratus by Arthur Bartholomew.jpg
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Perciformes
Family: Percichthyidae
Genus: Gadopsis
Species:
G. marmoratus
Binomial name
Gadopsis marmoratus

The river blackfish (Gadopsis marmoratus) is a freshwater fish endemic to the temperate waters of south-eastern Australia. [2] It is found from southern Queensland through to central Victoria, including in the Murray-Darling river system. It is also found in some eastern and southern flowing coastal rivers. Found primarily in upland and "midland" habitats, though early records of fish fauna suggest it was originally far more extensively distributed and was found in some lowland habitats as well. Originally, river blackfish co-inhabited many of its lowland and "midland" habitats with species such as Murray cod and golden perch, and its upland habitats with species such as trout cod and Macquarie perch. It is a popular angling fish in some parts of its range. [2]

Contents

Description

River blackfish are elongated with a rounded body, distinct snout and large mouth, and small to moderate sized eyes. The caudal fin, soft dorsal fin and anal fin are rounded. The spiny dorsal fin is low, weak and blends into the soft dorsal fin. Colour varies but is usually either yellow or green with dark green mottling, or a very dark purple/black colour.

It is an ambush predator that takes crayfish, shrimp, small fish and aquatic insects. [2] It is strongly nocturnal.

Murray-Darling river blackfish show a maximum size of around 30 cm and < 0.8  kg, with larger specimens from coastal drainages reaching up to 60 cm (Gellibrand River).

It is a highly underrated sportsfish, particularly the Southern form (see below). It is fast and strong, and has been shown to take flies and lures, even surface lures, in addition to the more usual worm baits. There is an unofficial world record caught by Piotr Pomorski on a WildBait Lure, in Victoria Australia that measured 70 cm in length.

Range and classification

Endemic to south-eastern Australia, river blackfish like many Murray-Darling native fishes have managed to cross the Great Dividing Range via natural river capture events and so are found in south-flowing coastal rivers and streams in the eastern half of Victoria. These fish are now often referred to as southern river blackfish. This population shows a far great maximum size of 60 cm or more and about 5.5 kg (12 lb). Specimens this large were likely to be very old — 30 years or more — and are rarely seen now. Southern river blackfish may be a separate species.[ citation needed ] The taxonomy does not yet reflect to this.

River blackfish continue the trend present in Murray-Darling native fish of speciating into primarily lowland species and upland species, with the upland species being in this case the two-spined blackfish, Gadopsis bispinosus. The two-spined blackfish is a more specialised upland inhabitant, and is found in the strongly flowing, cobble-bottomed sub-alpine rivers and streams of northeast Victoria, southeast New South Wales, and the Australian Capital Territory. While the split may be between lowland (or midland) and upland, there are overlaps in their range, and river blackfish are found in many upland habitats. There are also indications river blackfish populations in the southern and northern halves of the Murray-Darling river system may represent two distinct species or sub-species, with genetic and other differences.

The Gadopsis blackfish and the Maccullochella cods (such as the Murray cod, Maccullochella peelii) are strongly similar. There are some grounds for believing[ citation needed ] blackfish may be a smaller version of Murray cod, inhabiting similar niches but in habitats are too small for Murray cod (having said this, their distributions originally overlapped substantially), and there are grounds for believing that blackfish and Murray cod have drawn heavily on common genes at the family level.[ citation needed ] FishBase, for instance, has scrapped the family Gadopsidae and listed the blackfishes as members of the temperate perch family, Percichthyidae . A mitochondrial DNA study has confirmed a relationship between the Blackfish and the Percichthyidae but the exact relationship was not resolved in that study. [3] Further study is needed to resolve the relationship between the blackfish and the Percichthyidae. In addition, molecular studies have supported the view that G. marmoratus is a species complex of five different species, these include a species in the Murray-Darling Basin and four species in coastal freshwaters. [1] One of these forms from Victoria has been named as Gadopsis gracilis. [4]

Blackfish have a recruitment method similar to Murray cod, but with more specialisation to upland habitats. Blackfish spawn in spring and lay a very limited number of large, adhesive eggs (<1000) on sunken timber (snags), or in the case of two-spined blackfish on submerged rocks. Similar to Murray cod, the male guards the eggs until they hatch. Upon hatching the larval blackfish are, uniquely, attached to their ruptured egg case by a tether until the yolk sac is largely used and the larvae are ready to commence exogenous feeding. (This unique structure is presumably an adaptation to upland river/stream habitats, to prevent larvae being swept away in currents.)

Conservation

Blackfish have declined very seriously due to overfishing, stream siltation and snag removal, and predation and competition by introduced species, particularly introduced trout species. Recent bushfires in south-eastern Australia (2003–2006) have filled many blackfish rivers with large quantities of silt, and infilled the interstices ("gaps") between larger rocks that blackfish normally use as a refuge from predatory alien trout species. The presumed result will be increased levels of alien trout predation on blackfish, and the long-term future of blackfish species is now of some concern. The blackfish species are very low in fecundity, slow-growing and long-lived, and have low migratory tendencies, so are extremely vulnerable to overfishing and localised extinctions.

River Blackfish are a protected species in South Australia. [2]

Related Research Articles

<span class="mw-page-title-main">Murray cod</span> The largest Australian predatory freshwater fish in the family Percichthyidae

The Murray cod is a large Australian predatory freshwater fish of the genus Maccullochella in the family Percichthyidae. Although the species is called a cod in the vernacular, it is not related to the Northern Hemisphere marine cod (Gadus) species. The Murray cod is an important part of Australia's vertebrate wildlife—as an apex predator in the Murray-Darling River system—and also significant in Australia's human culture. The Murray cod is the largest exclusively freshwater fish in Australia, and one of the largest in the world. Other common names for Murray cod include cod, greenfish, goodoo, Mary River cod, Murray perch, ponde, pondi and Queensland freshwater cod.

<span class="mw-page-title-main">Eastern freshwater cod</span> Species of fish

The eastern freshwater cod, also known as the eastern cod or Clarence River cod, is a large predatory freshwater fish of the genus Maccullochella and the family Percichthyidae, that occur in the coastal Clarence River system of north-eastern New South Wales. Eastern freshwater cod are closely related to the Murray cod of the Murray-Darling River system, and are considered an icon of the Clarence River system.

<span class="mw-page-title-main">Trout cod</span> Species of fish

The trout cod or bluenose cod, is a large predatory freshwater fish of the genus Maccullochella and the family Percichthyidae, closely related to the Murray cod. It was originally widespread in the south-east corner of the Murray-Darling river system in Australia, but is now an endangered species.

<span class="mw-page-title-main">Temperate perch</span> Family of fishes

The members of the family Percichthyidae are known as the temperate perches. They belong to the order Perciformes, the perch-like fishes.

<span class="mw-page-title-main">Macquarie perch</span> Species of fish

The Macquarie perch is an Australian native freshwater fish of the Murray-Darling river system. It is a member of the family Percichthyidae and is closely related to the golden perch.

<span class="mw-page-title-main">Golden perch</span> Species of fish

The golden perch is a medium-sized, yellow or gold-coloured species of Australian freshwater fish found primarily in the Murray-Darling River system, though a subspecies is found in the Lake Eyre-Cooper Creek system, and another subspecies, suspected to be ancestral to all other populations, is found in the Fitzroy River system in Queensland. Other common names for golden perch are "goldens", “yellowbelly” and "callop", the last generally used only in South Australia.

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

The Australian bass is a small- to medium-sized species of primarily freshwater fish found in coastal rivers and streams along the east coast of Australia. A member of the genus Macquaria from the family Percichthyidae, the Australian bass is an important member of the native fish assemblages found in east coast river systems. It is a native predatory fish and an extremely popular game fish species among anglers. The species was simply called perch in most coastal rivers where it was caught until the 1960s, when the name "Australian bass" started to gain popularity.

<span class="mw-page-title-main">Two-spined blackfish</span> Species of fish

The two-spined blackfish is a species of temperate perch endemic to Australia.

The Mary River cod is a species of temperate perch native to the coastal Mary River system of southern Queensland, Australia. Mary River cod are one of Australia's most endangered freshwater fishes and are notable for being the most northerly of the four Maccullochella cods found or once found in coastal river systems of eastern Australia.

The Richmond River cod was a form of Maccullochella cod, now believed to have been eastern freshwater cod, Maccullochella ikei, that occurred naturally in the Richmond River system, an east coast river system in north-east New South Wales, Australia.

The Brisbane River cod was a unique form of Maccullochella cod that occurred naturally in the Brisbane River system, an east coast river system in south east Queensland, Australia. The Brisbane River Cod was known as the Bumgur by the Jinibara people centred in the Kilcoy region and the junction of the Stanley and Brisbane Rivers. Their exact taxonomic status is not known, but based on several genetic studies it is suspected that Brisbane River Cod were a species intermediate between eastern freshwater cod of the Clarence River and Richmond River systems in northern New South Wales and Mary River cod of the Mary River in central Queensland.

<i>Maccullochella</i> Genus of fishes

Maccullochella is a genus of large Australian predatory freshwater fish within the family Percichthyidae. The genus Maccullochella was named after an early Australian fish researcher with the surname McCulloch.

Australia has over 5000 described species of fish, a quarter of which are endemic. Seafood and aquaculture are major and highly regulated industries, and fishing for marine and freshwater native fish is popular.

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

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

<i>Galaxias</i> Genus of fishes

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.

<i>Gadopsis</i> Genus of fishes

Gadopsis is a genus of temperate perches endemic to freshwater habitats in southeastern Australia. The genus was formerly considered to be in a family of its own, Gadopsidae.

Scottsdale Reserve is a 1,328-hectare (3,280-acre) nature reserve on the Murrumbidgee River in south-central New South Wales, Australia. It is 79 kilometres (49 mi) south of Canberra, and 4 kilometres (2.5 mi) north of Bredbo. It is owned and managed by Bush Heritage Australia (BHA), which purchased it in 2006. The purchase was supportive of projects aiming to connect existing fragmented remnant habitat such as K2C. Since the 1870s up until 2006, the land was used for agriculture – primarily sheep grazing with some minor cropping. A significant component of the Reserve has been cleared of native vegetation.

<span class="mw-page-title-main">Southern pygmy perch</span> Species of fish

The southern pygmy perch, also known as the Tasmanian pygmy perch, is a species of freshwater ray-finned fish, a temperate perch from the family Percichthyidae which is native to south-eastern Australia and Tasmania.

<span class="mw-page-title-main">Centrarchiformes</span> Order of fishes

Centrarchiformes is an obsolete order of ray-finned fish, now included amongst the perciformes, with 17 previously included families. This order first appeared about 55.8 million years ago in the Eocene Era, and is composed primarily of omnivores. The order has a wide range that includes the continents of Australia and South America. Many Centrarchiformes look essentially perch-like, featuring a stocky build and a spine-bearing dorsal fin, and range in size from 2.5 cm in length, to 1.8 meters for the Maccullochella peelii. The order Centrachiformes is not recognized in the 5th Edition of Fishes of the World.

References

  1. 1 2 Lintermans, M.; Freeman, R.; Unmack, P.; Raadik, T. (2019). "Gadopsis marmoratus". IUCN Red List of Threatened Species . 2019: e.T123358463A123382771. doi: 10.2305/IUCN.UK.2019-3.RLTS.T123358463A123382771.en . Retrieved 20 November 2021.
  2. 1 2 3 4 Bray, Dianne. "River Blackfish, Gadopsis marmoratus". Fishes of Australia. Retrieved 3 September 2014.
  3. ↑ Jerry, Dean; Elphinstone, Martin & Baverstock, Peter (2001). "Phylogenetic Relationships of Australian Members of the Family Percichthyidae Inferred from Mitochondrial 12S rRNA Sequence Data". Molecular Phylogenetics and Evolution. 18 (3): 335–47. doi:10.1006/mpev.2000.0871. PMID   11277628.
  4. ↑ Eschmeyer, William N.; Fricke, Ron & van der Laan, Richard (eds.). "Species in the genus Gadopsis". Catalog of Fishes . California Academy of Sciences . Retrieved 13 May 2020.
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