Lake Dartmouth's wild trout fishery is still topnotch!

Note Number: FN0534
Published: 23 September 2002

John Douglas, Marine and Freshwater Resources Institute

Lake Dartmouth is still one of Victorias best wild trout angling locations, holding self sustaining populations of both brown and rainbow trout. This is the major finding of a recent assessment of the Lake Dartmouth fishery conducted by the Marine and Freshwater Resources Institute (MAFRI) for Fisheries Victoria.

Lake Dartmouth was formed in 1979 when an embankment was built on the Mitta Mitta River. At full capacity the lake covers 6,400 ha and stores 4 million megalitres of water. Brown trout, rainbow trout and the threatened Macquarie perch all thrived in the newly formed lake during the 1980s, creating an excellent reputation among anglers.

However, during the late 1990s local angling groups expressed concerns this trout fishery was in decline and stocking was required to maintain the fishery. In response to these concerns and a lack of recent scientific data about the status of this fishery, Fisheries Victoria commissioned MAFRI to assess the condition of Lake Dartmouths trout fishery, with particular emphasis on determining if stocking of trout was required.

The fishery assessment found brown trout was the most abundant of the nine fish species resident in the lake.

MAFRIs assessment found that there were adequate spawning areas for trout in Lake Dartmouth and recruitment of brown trout appeared to be constant and adequate to support the population. Recruitment of rainbow trout however appeared more variable.

The assessment also showed that there has been no decline in the population of trout in Lake Dartmouth since the 1980s. Current brown trout catches are comparable with historical catches. The estimated hourly catch rate for trout (brown and rainbow) was 0.24 fish per angler hour in 1984/85 and 0.27 fish per angler hour in 2000. Overfishing is not occurring.

There has been a shift in the size composition of the fishery. Whereas in the 1980s the fishery produced a mix of medium sized trout and a few large trophy sized fish, the current trout fishery now produces large numbers of medium sized fish. This shift is thought to reflect changes in fish growth, which in turn is a result of a decrease in the productivity of Lake Dartmouth as it ages.

"Production levels in man-made reservoirs are high immediately after the water is impounded, but after the initial bloom period, a decline of production occurs and is reflected in a decrease in the size of fish the lake can produce," explained John Douglas, MAFRIs project leader.

"Stocking of Lake Dartmouth with either brown or rainbow trout is not justified on a biological basis," says John," as there is enough breeding in the lake to maintain the fishery and putting more fish in will not improve the overall size of the trout present."

To maximise the fishing experience at Lake Dartmouth, John encourages anglers to continually explore different fishing methods, such as fly fishing windlanes. This technique is successful in other lakes but seldom seen in Lake Dartmouth.

For more information about this project and fishing tips for Lake Dartmouth, please contact John Douglas at MAFRI on (03) 57742208.