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Population abundance depends on production of young and survival of adults. Assessing the contribution of young production to population growth and identify the main drivers of its variability may help to identify appropriate stock management measures. What happens when several stocks, belonging to different trophic levels and habitats, as well as having different exploitation histories are sharing the same environment?
Where the fish are spawning is of tremendous importance for the population (see our post) but also for the industry relying on it, especially since harvesting is often concentrated on fish that aggregate for to spawn. Climate change and harvesting are known to strongly affect the fish population with effect on the spawning location. In a recent paper (Langangen et al. Global Change Biology) we explore the question: “who is the culprit of spawning location change: Climate or fishing?”
Spatial Ecosystem models can be useful but need to be validated with data. Our study validates for the first time the spatial version of the commonly used Ecopath with Ecosim ecosystem modelling suite. We find that spatial distribution of fish species is well predicted by the model, but fishing effort distribution is not.
Understanding the drivers that determine the productivity of marine ecosystems is an important issue. Climate and exploitation interact in their effects, such that climate alterations may cause failure in a fishery management scheme while fisheries may disrupt the ability of a population to withstand, or adjust to, climate changes.