How does exploitation of prey fish affect population growth rate in changing seas?

No abstracts are to be cited without prior reference to the author.

Population growth, hence the population’s persistence, is affected by several factors such as climate, species interaction, and harvesting pressure the last having been shown to make the marine populations more sensitive to climate forcing. The age truncated or juvenescent populations are a worldwide consequence of the protracted size-selective mortality of commercial fishing on the older and larger individuals. This process also increases a populations’ ability to directly respond to environmental fluctuations, emphasizing the importance of the interaction between fisheries, environment and internal dynamics that produces complex synergic effects on the population dynamics of marine species. We used a comparative approach investigating commercially fished species on different systems: the Norwegian sea-Barents Sea (Northeast Arctic cod), the Atlantic Ocean (European hake), the Mediterranean Sea (European hake), and the Bering Sea (Pollock). Our objective was to address in a comparative way the ecological consequences of fisheries effect on population properties (e.g., intrinsic growth rate) in relation to different external conditions (fishing intensity or climate). For this, we have applied techniques based upon age-structured population matrices to analyze estimated stock sizes. By combining all sources of information, we investigated differences in the coupling between life history traits and population dynamics for all stocks that display different level of juvenescence. This study will advance our understanding of the underlying mechanisms behind the transitory relationships between climate and fish populations.