Cost of selectivity: inducing of density dependent growth in Eastern Baltic cod (Gadus morhua)

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Over the last decades, views on fisheries have oscillated between mistrust and confidence in management progress. The predominating policy remedy to world fish crisis, promoted by the Johannesburg declaration, aims at Maximum Sustainable Yield (MSY) by adjusting gear selectivity and fishing effort. Here we show a strong case study on how the strive for higher yields from the Eastern Baltic cod stock by increasing selectivity has become exceedingly detrimental for its productivity. As fish number in non-‐fishable sizes successively increase, growth potential is severely reduced, whereas fishing mortality increases on fishable sizes. Our findings suggest that policies focusing on maximum yield and targeting greater sizes are risky and should instead be redirected towards more risk-‐‑averting combinations of selectivity and effort, giving less yield but higher catch-‐‑per-‐‑unit-‐‑effort. Disregard of dynamic interactions will have dire consequences for the cod stock functioning, profitability of the fishing industry and overall ecosystem structure and function.