Journal of Aquaculture Research & Development

Conserving a threatened endemic, landlocked Atlantic salmon population

International Conference on Aquaculture & Fisheries

July 20-22, 2015 Brisbane, Australia

Eva Bergman

Posters-Accepted Abstracts: J Aquac Res Development

Abstract:

Populations of migratory salmon decline worldwide due to human activities and numerous measures have been undertaken to maintain these populations. The regulated River Klarälven and Lake Vänern host endemic populations of land locked Atlantic salmon (Salmo salar). Historically high abundances of the salmonids in Klarälven in the 1800s have decreased dramatically, reaching all-time lows after the completion of nine Swedish hydroelectric plants in the 1960s. After extensive stocking and transportation of wild and hatchery-raised spawners past eight hydroelectric plants catches have again increased. Recently, increases in the proportion of wild salmon returning to river Klarälven have generated interest in establishment of wild salmon throughout the entire river. To obtain information needed to produce a management plan for the salmon, we conducted multiple studies of upstream-migrating spawners and downstream-migrating smolts and kelts. We compared migratory behaviour of wild and hatchery reared salmon. For spawners we found that wild fish swam directly to the spawning grounds, whereas the few hatchery salmon that arrived at the spawning grounds swam considerably more before settling down and they held positions for shorter periods of time. For smolt, only 16-30% passed all eight dams and losses in the dam-free lower 25 km of the river were higher for hatchery-raised smolts than for wild. Moreover, losses of hatchery-raised smolts varied depending on feeding routines in the hatchery. For kelts, only 2% passed all eight dams. Thus, the production of high quality hatchery-raised fish together with remedial measures to increase the number of wild salmon is needed.