Recovery potential and management options for European hake, Merluccius merluccius (Linnaeus, 1758), stocks in Turkish waters

Abstract

Overfishing has been a topic of fierce discussion over the past several decades. However, a lack of information regarding fish stocks makes proper stock assessment through good fisheries management difficult. This study addresses a problematic question for declining European hake, Merluccius merluccius (Linnaeus, 1758), stocks in the Turkish Aegean, Mediterranean, and Marmara seas. The present stock status and fisheries reference points were estimated using novel, data-limited assessment methods with recovery potential and management options for European hake stocks under different exploitation scenarios for each sea. Assessment results show that the ratio of the biomass (B) corresponding to the maximum sustainable yield (MSY) (B/BMSY) was under the threshold, and the ratio of fishing mortality (F) corresponding to the MSY (F/FMSY) was over the threshold, indicating that hake stocks were under ongoing overfishing since 2002 in each sea. After that, the biomass values gradually decreased from outside the safe biological limits, under the critical limits of 0.5 BMSY, while fishing mortality continued over the threshold. Reducing the fishing mortality to half of the estimated FMSY could lead to Marmara Sea hake stocks gradually increase in biomass and close to reaching its BMSY. Reducing fishing mortality to its 0.8 FMSY for Aegean Sea stock, and 0.5 FMSY for Mediterranean stock may help rebuild stocks until 2025. However, even the current estimated FMSY (0.95 FMSY is presented as FMSY), cannot assist in rebuilding any European hake stocks in 15 years projection. It is obvious to say that fisheries regulations must be carefully considered and rearranged, especially for depleted stocks such as those of European hake in Turkish waters.