Long-term changes and effects of significant fishery closures on marine survival and biological characteristics of wild and hatchery-reared Atlantic salmon Salmo salar.

Long-term data, over four decades, were analysed to examine temporal trends in survival indices and phenotypic characteristics of Atlantic salmon Salmo salar returning to the Burrishoole national salmonid monitored river in Ireland. Before 2007, the marine drift net fishery was the major capture method for salmon in Irish home waters, accounting for over 70% of the commercial catch and targeting mixed stocks from multiple rivers. The authors examined size differences in fish captured in marine and freshwater environments and the impact of closure of this fishery on long-term survival indices and fish size.

Timing and pattern of annual silver eel migration in two European watersheds are determined by similar cues.

Many animals perform long-distance migrations in order to maximize lifetime reproductive success. The European eel migrates several thousand kilometers between their feeding habitats in continental waters (fresh-, brackish, and sea water) and their spawning area in the Sargasso Sea. Eels residing in freshwaters usually initiate their spawning migration as silver eels during autumn, triggered by diverse environmental cues.

Impact of naturally spawning captive-bred Atlantic salmon on wild populations: depressed recruitment and increased risk of climate-mediated extinction.

The assessment report of the 4th International Panel on Climate Change confirms that global warming is strongly affecting biological systems and that 20-30% of species risk extinction from projected future increases in temperature. It is essential that any measures taken to conserve individual species and their constituent populations against climate-mediated declines are appropriate. The release of captive bred animals to augment wild populations is a widespread management strategy for many species but has proven controversial.