Effects of end-of-the-century ocean acidification on Atlantic cod larvae of different populations in terms of survival, growth and recruitment to the fished stocks

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The effect of climate change on fish populations and fisheries is poorly understood. While fish may respond to increased temperatures with range shifts, they cannot escape ocean acidification, an inevitable consequence of increasing carbon dioxide concentrations in the oceans and in the atmosphere. Here, we tested the effect of ocean acidification (OA) on larvae of Atlantic cod of two different populations, from the Barents Sea and the Western Baltic Sea. Survival and growth was measured during the first weeks of development post-hatching. Mortality rates doubled in both populations in ocean acidification conditions as they are expected for the end of the century. When these results were included in a Ricker-type recruitment model, the recruitment collapsed. Furthermore the experimental results show an increase in larval size after seven weeks post-hatching. These results highlight the importance of including the effect of ocean acidification on vulnerable early life stages into fisheries models and management.