Body size-dependent responses of a marine fish assemblage to climate change and fishing over a century-long scale

• Published in: Global change biology Vol. 16; no. 2; pp. 517 - 527
• Main Authors: GENNER, MARTIN J., SIMS, DAVID W., SOUTHWARD, ALAN J., BUDD, GEORGINA C., MASTERSON, PATRICIA, MCHUGH, MATTHEW, RENDLE, PETER, SOUTHALL, EMILY J., WEARMOUTH, VICTORIA J., HAWKINS, STEPHEN J.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.02.2010; Wiley-Blackwell
• Subjects: Animal and plant ecology; Animal populations; Animal, plant and microbial ecology; Biological and medical sciences; Body size; Climate change; Commercial fishing; demersal fish; English Channel; Fauna; Fish; Fisheries; Fundamental and applied biological sciences. Psychology; General aspects; humans; Impact analysis; Life history; life history traits; Marine; Marine fish; marine monitoring; Ocean temperature; overfishing; Physical growth; Sea water ecosystems; Synecology; temperature; English Channel; ANE, Europe, English Channel; Overexploitation; marine monitoring; life history traits; Corporal biometry; Life history trait; Fishing; Dynamical climatology; Marine environment; Aquatic environment; Climate change; Vertebrata; Fishery; Animal community; Pisces; Body size; Overfishing; Global change; fisheries
• ISSN: 1354-1013; 1365-2486
• DOI: 10.1111/j.1365-2486.2009.02027.x

Commercial fishing and climate change have influenced the composition of marine fish assemblages worldwide, but we require a better understanding of their relative influence on long‐term changes in species abundance and body‐size distributions. In this study, we investigated long‐term (1911–2007) variability within a demersal fish assemblage in the western English Channel. The region has been subject to commercial fisheries throughout most of the past century, and has undergone interannual changes in sea temperature of over 2.0 °C. We focussed on a core 30 species that comprised 99% of total individuals sampled in the assemblage. Analyses showed that temporal trends in the abundance of smaller multispecies size classes followed thermal regime changes, but that there were persistent declines in abundance of larger size classes. Consistent with these results, larger‐growing individual species had the greatest declines in body size, and the most constant declines in abundance, while abundance changes of smaller‐growing species were more closely linked to preceding sea temperatures. Together these analyses are suggestive of dichotomous size‐dependent responses of species to long‐term climate change and commercial fishing over a century scale. Small species had rapid responses to the prevailing thermal environment, suggesting their life history traits predisposed populations to respond quickly to changing climates. Larger species declined in abundance and size, reflecting expectations from sustained size‐selective overharvesting. These results demonstrate the importance of considering species traits when developing indicators of human and climatic impacts on marine fauna.