ALIEN SPECIES

Common Name Brown trout

Scientific Name Salmo trutta Linnaeus, 1758 Photo: Neil Armstrong Photo: Neil

Identification less tolerant than Rainbow trout of warm A medium sized, fish, similar in body shape to water, preferring temperatures below 25°C. the Rainbow trout, but lacking the fine, black Brown trout is often found with the parasitic spotting on the tail and the pink stripe on the copepod Lernaea sp. attached, particularly sides. Maximum weight 20 kg; commonly around the fins. It is generally a longer-lived 1–4 kg. Often have large spots on the back species than Rainbow trout, often surviving and sides, but none on the tail, and usually to six years of age, although individuals have have an orange rear-edge to the adipose fin. been recorded in excess of 25 years of age The spots on the back are usually dark and overseas. those on the sides are either dark or reddish- orange surrounded by a light halo. Brown trout form the basis of important recreational fisheries in southeastern Biology and Habitat and is widely stocked. However, in light of Brown trout is found in cool upland streams its serious impact on a number of threatened and lakes. The diet contains a wide variety native fish, particularly galaxiid species, it is of freshwater larvae, snails and no longer stocked in a number of streams and wind-blown terrestrial arthropods, aquatic dams where threatened species are known to , and small fish. be present. Brown trout spawn between April and Impacts on Native Fish August, earlier than Rainbow trout. As in As with Rainbow trout, Brown trout has Rainbow trout, the eggs are deposited in a had a serious impact on the distribution and gravel nest (‘redd’) constructed by the female abundance of south-east Australia’s native in flowing water. The eggs are large (4–5 mm galaxiids, such as Mountain galaxias and diameter) and hatch in 6–20 weeks depending Barred galaxias. Brown trout is suspected on water temperature. Brown trout is slightly of having deleterious impacts on Trout

110 Fishes of the Murray-Darling Basin 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

and and a number of other General References threatened native species. Trout species are Cadwallader 1996; Clements 1988; Davies & also thought to impact on a number of McDowall 1996; Jackson et al. 2004; Jackson threatened frogs, such as the Spotted tree frog & Williams 1980; McDowall 2003, 2006; (Litoria spenceri). Tilzey 1976. Distribution and Abundance Brown trout is native to Europe and western Asia and was first introduced to Australia in 1864. Fisheries agencies in the Basin have substantial stocking programs for this and other trout species. Vic and NSW fisheries agencies release approximately five million salmonids each year; and private hatcheries also make releases. Brown trout is widely distributed in the cooler upland streams of Vic, NSW and the ACT, as well as a small number of streams in SA. It is not present in Qld. There is a tendency for Brown trout to become the dominant species in lakes and dams where both Rainbow and Brown trout are present.

An introductory guide 111 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: [email protected] 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.

ii Fishes of the Murray-Darling Basin