|
Freshwater Fish of Victoria - Brown Trout | FN0037 |
Charles Barnham, PSM
April, 1998 |  |
To view the Adobe Acrobat file, you will need the Adobe Acrobat reader. |  PDF 105 kb | |
Figure 1: Brown Trout (Salmo trutta)
Common Name:
Brown trout
Other Name/s:
Sea trout
Scientific Name:
Salmo trutta (Linnaeus, 1758)
Status:
Desirable Introduced
Brown trout supports a major recreational fishery in Victoria. The classification of "introduced" reflects its translocation to Australia and Victoria, and this category is noted in the Flora and Fauna Guarantee Act 1988 (introduced to Australia after 1788 AD).
Description
Thick body with a large head, and a large mouth extending backwards to below the eye. A very distinct lateral line with 110-120 scales. Tail fin is slightly forked.
Colour varies considerably, reflecting age of fish, habitat and food, usually brown to olive on the upper body. Dark spots on the upper body, upper fins and gill covers. Below the lateral line body colour is lighter with some red spots.
Many brown trout have a red halo around the larger dark spots. Few if any spots on the tail.
Sea run fish such as occur in Port Phillip Bay may be olive-green on the back, with silvery sides and very few and indistinct spots on the sides.
Distribution
Widespread and common through much of Victoria. Self-maintaining populations exist in many waters.
Habitat
Cool, well-oxygenated waters, usually in gravel-bottomed streams with a moderate to swift flow, but also in cool, clear lakes and impoundments. Optimum temperature range 4-19oC. Some brown trout in coastal streams move out to sea, and small numbers are taken in Port Phillip Bay.
Brief Biology
Spawning occurs, usually at three years of age, during autumn-winter often following a flood, typically in small tributaries with gravel beds. Males may become sexually mature at 2 years of age.
Female fish excavates depressions in the stream bed with her tail. Females lay an average of 1,600 eggs for each kg of body weight. After spawning eggs are covered by dislodging gravel upstream of the spawning site. Mature males develop a curved bottom jaw which develops into a hook.
Eggs may take about 6 weeks to hatch, and require high levels of dissolved oxygen for successful hatching. Newly hatched fish have a prominent eggs sac and may remain in the gravel for 4-6 weeks as alevains before emerging and commencing to feed.
Brown trout are carnivorous and largely a sight feeder, young fish feeding throughout the water column, the more mature fish feeding mainly on the bottom. Diet includes insects, crustaceans, molluscs, worms and small fish such as minnows (galaxiids).
Few brown trout in Victoria live beyond 5-6 years.
Management
The brown trout fishery in Victoria is roughly divided into two parts. The eastern half of Victoria has mainly self-supporting populations which exist where suitable habitat is available, which most suitable waters in the western half of the State depend on stocking with hatchery-produced fish.
Details of brown trout releases by the Department are available in Fisheries Notes which report each year's stocking program.
Other Notes
Introduced to Australia via Tasmania in 1864 through the first successful importation of fertilised eggs after more than 20 years of efforts by various persons and groups.
May exceed 1 metre in length and 16 kg in weight in its native habitat of Europe and Western Asia, and is known to have reached 900 mm and 14 kg in Australia, but the species in Victoria is commonly much smaller, achieving weights of up to 8 kg.
Given good habitat and food, brown develop rapidly in the second and third years.
Considered to be a "residential" fish as it is very territorial and mature fish are likely to stay in a limited area for their lifetime.
Brown trout appears to dominate rainbow trout in waters where both species exist naturally or have been stocked.
Many naturally self-supporting populations of brown trout occur in Victoria, and quite a few of these populations have reached numbers of fish which over-tax the available food supply. This results in either populations of fish that continue to grow but the majority of fish are poor in condition (e.g. Lake Dartmouth, Lake Eildon), or stunted populations which may contain 2 and 3-year-old fish of 275-400g (e.g. Cobungra R., Jim Crow Creek)
Current Regulations
The Fishing Regulations specify Recreational Fishing Licence requirements and the means by which angler may take brown trout. Details of licencing requirements and fishing regulations are available in the Victorian Recreational Fishing Guide which is available free of charge from DPI Offices and RFL sales agents.
Illustration - Brown Trout
Peter Buerschaper, from Freshwater Fishes of Canada,
Bulletin 184, Fisheries Research Board of Canada,
W. B. Scott and E. J. Crossman
Infosheets - Freshwater Fish of Victoria
is a series of brief information material on the native and introduced freshwater fish of Victoria's inland waters. Further, detailed reading on brown trout is contained in:
A Guide to Freshwater Fish of Victoria
Phillip Cadwallader & Gary Backhouse,
Department of Conservation and Environment
Australian Freshwater Fishes
John R. Merrick & Gunther E. Schmida
Salmonids in the Antipodes
John Clements
|
