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 31An introductory guide30 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 31An introductory guide3030 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

natiVe sPeCies

identificationMedium sized, slender and elongated, with a scaleless, eel-like body. Adults are commonly 500–700 mm long in freshwater situations (larger than the Short-headed lamprey). Two, low dorsal fins are situated well back on the body near the rounded caudal fin, and paired pectoral and pelvic fins are absent. Lampreys lack jaws; instead adults have a well-developed suctorial oral disc with blunt teeth in irregular spirals. Fimbriae (fringing filaments) are present surrounding the oral disc (absent in Short-headed lamprey), and the eyes of adults are lateral in position (rather than dorsolateral in Short-headed lamprey). Adults and ammocetes both have seven small oval gill apertures on each side of the body behind the head. During the spawning run, adult males develop a large pouch below the head. Newly metamorphosed young adults are bright silvery with blue bands along the back. The bands persist throughout the marine phase and early in the return to freshwaters, before fading and disappearing, leaving the adults a muddy grey-brown.

The larval juvenile life phase (ammocete) is usually less than 120 mm long, worm-like, lacks eyes and tooth plates, and the dorsal fins are very low, not extending very far above the body surface. Sandy-brown to blue in colour, these ammocetes are darker on the dorsal surface. They can be distinguished from ammocetes of the Short-headed lamprey by the position of the vent, which is below the start of the second dorsal fin.

Biology and habitatLittle is known of the species’ ecology in the Basin, so information below is drawn from studies in Western Australia. Most of the adult life is spent at sea. Young adults

Common name Pouched lamprey rare

scientific name Geotria australis gray, 1851

Phot

o: N

eil A

rmst

rong

Phot

o: M

icha

el H

amm

er

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 31An introductory guide30 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 31An introductory guide30 An introductory guide 31

migrate upstream from the sea, usually in mid-winter, to breed. The spawning run can involve distances of hundreds of kilometres, and like the Short-headed lamprey is thought to be mainly by nocturnal movements. The spawning run lasts for about 15–16 months, before spawning the following spring. Ammocetes are sedentary, and live in soft substrates (mud and silt) for about 4.25 years, before metamorphosing (at around 80–120 mm length) and migrating down to the sea, usually in late winter. Details of spawning are not known but spawning probably occurs in headwater streams and adults probably die after spawning. Females lay on average 58,000 eggs, which are small (~1.1 mm diameter).

The ammocetes are toothless, probably feeding on algae, detritus and micro-organisms filtered from the water. After metamorphosis to adulthood, they become parasitic on other fish, rasping a hole in the side and feeding on blood and/or muscle. Adults cease feeding prior to their spawning migration.

Distribution and abundanceGenerally restricted to the lower Murray River in the Basin, but otherwise found in coastal rivers in Vic, SA, Tas and WA. This species is now rarely recorded in the Basin because of its cryptic habits, but could formerly be seen in large numbers on spawning runs in the lower Murray at migration barriers such as weirs. There are recent records of this species in SA from below the Goolwa Barrage and in the Lower Lakes.

Potential threatsBarriers to fish movement can interfere with spawning migrations, although the species can climb wet vertical surfaces.

general referencesAllen et al. 2002; Cadwallader & Backhouse 1983; Hammer 2004; Hardisty et al. 1986; Koehn & O’Connor 1990; Potter 1996b; Potter et al. 1996; Wedderburn & Hammer 2003.

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