F i s h e s o F t h e M u r r ay- Da r l i n g B a s i n 79An introductory guide78 F i s h e s o F t h e M u r r ay- Da r l i n g B a s i n 79An introductory guide7878 F i s h e s o F t h e M u r r ay- Da r l i n g B a s i n

identificationA large, deep-bodied fish with a large mouth reaching to below the back of the eye. Maximum size 16 kg and 850 mm; usually < 5kg. The head profile is straight, and the upper jaw overhangs the lower. The tail is rounded and the pelvic fins are located below the pectorals. The overhanging upper jaw and a speckled body pattern which is blue-grey rather than yellow-green, distinguishes this species from the otherwise similarly-shaped Murray cod. Most individuals have a dark stripe through the eye, although this feature is also present in young Murray cod.

Biology and habitatOnly formally recognised as a separate species from Murray cod in 1972, some aspects of the biology of Trout cod are poorly known. The species is usually associated with deeper water (pools) and instream cover such as logs and boulders. In the Murray River, where it is found with Murray cod, it occupies slightly faster-flowing locations. Sexual maturity is reached at 3–5 years of age when

fish are 0.75–1.5 kg and spawning occurs in late spring (mid-October–mid-November). Fecundity is ~1200–11,000 eggs per female. The eggs are large (2.5–3.6 mm diameter), adhesive, and probably deposited on hard substrates such as logs and rocks. After 5–10 days, larvae of about 6–9 mm length hatch.

The diet includes fish, yabbies, mudeyes, aquatic insect larvae, shrimps and freshwater prawns. Recent research in the lowlands of the Murrumbidgee River has demonstrated that adults occupy small areas of less than 500 m centred on a ‘home snag’, and occasionally undertake exploratory movements of 20–60 km involving a return to their home.

Distribution and abundanceThere are now only three self-sustaining populations of Trout cod remaining in the wild. The largest is in the Murray River between Yarrawonga and Barmah (approximately 200 km of river), the others are small translocated populations present in Cataract Dam, and in about 15 km of the upper reaches of Sevens Creek near Euroa

Common name trout cod (Blue-nose cod) threatened

scientific name Maccullochella macquariensis (cuvier, 1829)

natiVe sPeCies

Phot

o: G

unth

er S

chm

ida

F i s h e s o F t h e M u r r ay- Da r l i n g B a s i n 79An introductory guide78 F i s h e s o F t h e M u r r ay- Da r l i n g B a s i n 79An introductory guide78 An introductory guide 79

in Vic. Because of early confusion regarding the identification of Trout cod, information on the historic distribution of the species is unclear.

Trout cod was originally described from the Macquarie River, where it has not been recorded since the 1820s, other than a single unconfirmed record from the Turon River in the 1970s. It was not known from the Darling River. Formerly widespread in the southern Murray-Darling Basin (Murray, Murrumbidgee and Macquarie rivers, NSW/ACT; Ovens, Goulburn, Campaspe, King, Buffalo, Mitta Mitta rivers, Vic; Murray River, SA), the species declined significantly in the 1970s. A long-term stocking program since the late 1980s has reintroduced Trout cod to a number of locations in the Basin including sites on the Murrumbidgee, Macquarie, Ovens, Goulburn, Tumut and upper Murray drainages. The species has also been stocked in Bendora Reservoir, ACT, and Talbingo Reservoir, NSW. Unfortunately, these reintroductions have not resulted in the establishment of viable populations, although

breeding has been recorded in the Goulburn and Cotter rivers and is suspected in the mid-Murrumbidgee River.

Potential threatsThreats include interactions with alien species such as trout and Redfin perch, and habitat modification such as desnagging, sedimentation, clearing of riparian vegetation, river regulation and cold-water pollution from dams. Overfishing of remnant populations has also contributed to declines and needs to be carefully managed if reintroductions are to be successful.

general referencesBerra & Weatherley 1972; Cadwallader & Gooley 1984; Douglas et al. 1994; Ebner et al. 2006; Harris & Rowland 1996; Ingram & Rimmer 1992; King et al. 2005; Koehn & Harrington 2006; Lintermans et al. 1988, 2005; Morris et al. 2001.

iD VALLey 1 Avoca 2 Border rivers 3 Broken 4 campaspe 5 castlereagh 6 central Murray 7 condamine 8 darling 9 goulburn 10 gwydir 11 Kiewa 12 Lachlan 13 Loddon 14 Lower Murray 15 Macquarie 16 Mitta Mitta 17 Murrumbidgee 18 namoi 19 ovens 20 Paroo 21 upper Murray 22 Warrego 23 Wimmera

Published by the Murray-Darling Basin Commission Postal address: GPO Box 409, Canberra ACT 2601 Office location: Level 3, 51 Allara Street, Canberra City ACT Telephone: (02) 6279 0100, international + 61 2 6279 0100 Facsimile: (02) 6248 8053, international + 61 2 6248 8053 Email: info@mdbc.gov.au Internet: http://www.mdbc.gov.au

For further information contact the Murray-Darling Basin Commission office on (02) 6279 0100

This fish fact sheet is an extract derived from the report: Lintermans, M. 2007, Fishes of the Murray-Darling Basin: An introductory guide.

MDBC Publication No. 10/07

ISBN 1 921257 20 2

© Murray-Darling Basin Commission 2007

This work is copyright. Graphical and textual information in the work (with the exception of photographs, artwork and the MDBC logo) may be stored, retrieved and reproduced in whole or in part provided the information is not sold or used for commercial benefit and its source (Fishes of the Murray-Darling Basin) is acknowledged. Such reproduction includes fair dealing for the purpose of private study, research, criticism or review as permitted under the Copyright Act 1968. Reproduction for other purposes is prohibited without the permission of the Murray-Darling Basin Commission or the individual photographers and artists with whom copyright applies.

To extent permitted by law, the copyright holders (including its employees and consultants) exclude all liability to any person for any consequences, including but not limited to all losses, damages, costs, expenses and any other compensation, arising directly or indirectly from using this report (in part or whole) and any information or material contained in it.

F i s h e s o F t h e M u r r ay- Da r l i n g B a s i nii