Trout Cod, Maccullochella macquariensis (Cuvier 1829)


Other Names: Blue Cod, Blue Nose, Bluenosed Cod, Murray Trout, Rock Cod

Trout Cod, Maccullochella macquariensis. Source: Gunther Schmida / http://www.guntherschmida.com.au - via ALA. License: CC BY Attribution-Noncommercial-ShareAlike 3.0

Summary:

A long-lived large freshwater fish with a deep body, a straight head profile and a protruding upper jaw. Body bluish-grey to brown, pale below, with irregular spots and dashes; fins greyish to dark grey with broad white margins; head without markings except for a dusky horizontal stripe from the snout through the eyes to the gill cover.


Once common and widespread throughout the Murray Darling Basin, over the past 50-60 years, Trout Cod suffered a catastrophic decline in their range and abundance due to habitat degradation, overfishing, and the introduction of trout into their habitat. Trout Cod are considered endangered and are protected throughout their range.

Read Will Trueman's wonderful and comprehensive history of the Trout Cod: True Tales of the Trout Cod: River Histories of the Murray-Darling Basin.



Cite this page as:
Bray, D.J. & Thompson, V.J. 2018, Maccullochella macquariensis in Fishes of Australia, accessed 21 Nov 2018, http://fishesofaustralia.net.au/home/species/4654

Trout Cod, Maccullochella macquariensis (Cuvier 1829)

More Info


Distribution

Endemic to the Murray-Darling Basin (MDB). Once widespread in the southern tributaries of the MDB, Trout Cod have declined dramatically in both abundance and distribution and are now known only from scattered localities. The last remaining natural populations in the wild are in the Murray River between Yarrawonga, Barmah and Seven Creeks.

Self-sustaining populations have been successfully re-established (from a captive-breeding program) into the Goulburn, Ovens and Murrumbidgee Rivers (Ingram & Thurstan 2008; Lyon et al. 2012). Some fish have also been translocated into the Cataract Dam in New South Wales. It is also thought that Trout Cod were introduced to the Yarra River, Victoria in the latter half of the 19th Century.

Trout Cod inhabit rapidly flowing streams with rocky or gravel bottoms, and pools with woody instream debris such as logs and snags.

Features

Dorsal fin XI-XII, 14-16; Anal fin III, 10-13; Pectoral fin 18-20; Pelvic fin  I, 5; Lateral line scales 63-82
Body large, slightly compressed, relatively elongate, deep, greatest body depth 2.8-4.5 in SL; head broad, depressed; snout rounded; dorsal profile weakly convex from nape to caudal peduncle; dorsal profile of head straight, steep; eye relatively large, dorso-laterally positioned; mouth terminal, large, gape extending to beyond eye; upper jaw overhanging lower jaw; jaws, vomer and palatines with villiform teeth; operculum with wide fleshy margins and two distinct spines.

Scales small, mainly ctenoid; cheeks and opercula scaled; lateral line extending onto base of caudal fin.

A single dorsal fin with an anterior spiny portion and posterior soft portion, separated by a deep notch, 5th and 6th spines longest; anal fin rounded, opposite soft portion of dorsal fin with 3 stout spines; pectoral fins large, rounded, upper rays longer than lower rays; pelvic fins inserted in front of pectoral fins, 1st ray elongated into 2 filaments; caudal fin large, rounded.

Size

Historically reported to reach about 85 cm SL and 16kg; commonly reaches 40-50 cm and less than 5kg.

Colour

Dorsal surface and upper sides bluish-grey with small dark grey to black spots or dashes, spots extending onto lower sides and fin bases; head dark bluish-grey with a few spots. Belly pale greyish to white. Iris brown. A dark, bluish-black to black stripe extends from nostrils through the eyes to the edge of the gill cover.

Fins greyish to dark grey; caudal fin, soft dorsal, anal, pectoral and pelvic fins with broad white margin.

Juveniles much paler than adults; dorsal surface and upper sides grey to greyish-brown or fawn, often with a rosy tinge along sides, and dark grey to black spots; dark eye-stripe very distinct; fins unpigmented to pale grey, white fin margins not as obvious as in adults.

Feeding

Feeds on crustaceans, fishes and aquatic and terrestrial insects, taken mainly from or near the surface. Larvae are pelagic and feed on zooplankton.

Biology

Spawning occurs in spring when eggs are deposited on hard surfaces. Known to hybridise with Maccullochella peelii. Eggs are large and adhesive. Larvae hatch after 5-10 days at 20ºC. 

Fisheries

Once popular with recreational anglers, it is now illegal for anglers to take Trout Cod.

Conservation

ASFB: Critically Endangered

IUCN Red List: Endangered
EPBC Act 1999: Endangered
ACT Nature Conservation Act 1980: Endangered
NSW Fisheries Management Act 1994: Endangered
Victorian Flora and Fauna Guarantee Act 1998: Threatened

Once common and widespread throughout the Murray Darling Basin, Trout Cod have suffered a catastrophic decline in their range and abundance. The decline is thought to be linked to a combination of habitat loss, desnagging of rivers, altered and reduced water flows leading to poor water quality and barriers to movement. The species has also suffered from over-fishing and the introduction of trout into their habitat.

An Australian government recovery plan now exists for the Trout Cod and small numbers of captive bred juveniles have been released into sites within their historical range.

A Conservation Good News Story for an Endangered Fish: Trout Cod, once historically abundant in the Ovens River (Victoria), had become locally extinct by the 1980's. A captive breeding program was established in the 1980's in an attempt to re-introduce the species into the Ovens River. In 1997, and in every following year to 2006, juvenile hatchery-reared Trout Cod were released into the river. 

In a recent paper, Lyon et al. (2012) report on the success of this program. The authors found that natural recruitment did not begin until almost 5 years after the restocking program began. The re-established Ovens River population has now grown, is self-sustaining, and is as genetically diverse as the last remaining natural population in the Murray River downstream of Lake Mulwala.

The authors suggest that this program may have been successful because fingerlings and one-year olds were re-introduced annually for 10 years, whereas shorter-term programs have had limited success. Although Trout Cod have been re-introduced into 32 sites in eight river catchments within the Murray Darling Basin, self-sustaining populations are only known from three areas: the Goulburn, Ovens and Murrumbidgee Rivers (Ingram & Thurstan 2008).

Remarks


Similar Species

The Trout Cod differs from the similar Murray Cod, Maccullochella peelii, in having a relatively longer snout with a protruding upper jaw (vs. a shorter snout with the upper jaw not protruding), a greyish-blue body with fine spotted markings that are absent from the head (vs. a marbled or mosaic pattern that extends onto the head), and a horizontal stripe through the eye (no stripe in Murray Cod).

Etymology

The genus was named for Allan R. McCulloch, an ichthyologist from the Australian Museum. The species is named macquariensis after the Macquarie River, the type locality.

Species Citation

Grystes macquariensis Cuvier in Cuvier & Valenciennes 1829, Histoire Naturelle des Poissons.  Paris : Levrault Vol. 3: 58. Type Locality: Macquarie River, Bathurst, New South Wales.

Author

Bray, D.J. & Thompson, V.J. 2018

Resources

Australian Faunal Directory

Trout Cod, Maccullochella macquariensis (Cuvier 1829)

References


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Quick Facts


CAAB Code:37311087

Conservation:ASFB Critically Endangered; EPBC & IUCN Endangered

Habitat:Freshwater uplands

Max Size:85 cm SL; 16 kg

Native:Endemic

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