Community Research and Development Information Service - CORDIS

Interactions between sea lice infestation and variations in ocean climate on condition factor of wild Atlantic salmon

Significant between-year variations in condition factor, CF (= plumpness ) of wild salmon were noted during the analyses of sea lice infestations at Strathy Point (1998-2005). Having confirmed that parasite infestations have no relation to host CF we extended the analyses of CF back to 1993 by incorporating previous Fisheries Research Services (FRS) monitoring data. Detailed analyses with colleagues at FRS Aberdeen have demonstrated clear and geographically defined negative correlations between recent ocean climate warming at the NE Atlantic feeding grounds and reduced CF of salmon.

This result runs counter to the emerging paradigm of warmer ocean surface temperatures being beneficial to wild salmon. We have also confirmed that the annual time-series of variation in CF at Strathy Point (multiple stocks) is consistent with a contemporary time-series for a single, definable stock for an east Scotland river.

That is, CF varies significantly among years, is set for entire year classes, and applies equally across multiple stocks within the southern European 1SW population component; the effects of global climate warming are, therefore, detectable across all stocks within each year and indicate a major, widespread, chronic and predictable negative impact on fish feeding, growth success and perhaps also their survival to return to spawn.

These results have fundamental implications for wild salmon management because reduced condition/size of spawning adults will lead to reduced egg deposition. We estimate a 13-22% difference in fecundity for females in good versus bad years.

Reported by

University of St Andrews, Gatty Marine Laboratory
East Sands
KY16 8HL St Andrews, Fife
United Kingdom
Follow us on: RSS Facebook Twitter YouTube Managed by the EU Publications Office Top