Revisiting safe biological limits in fisheries |
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| Authors: | Rainer Froese Gianpaolo Coro Kristin Kleisner Nazli Demirel |
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| Affiliation: | 1. GEOMAR Helmholtz‐Centre for Ocean Research, Kiel, Germany;2. Istituto di Scienza e Tecnologie dell'Informazione “A. Faedo”, Consiglio Nazionale delle Ricerche (CNR), Pisa, Italy;3. Sea Around Us Project, Fisheries Centre, UBC, Vancouver, BC, Canada;4. Institute of Marine Sciences and Management, Istanbul University, Muskule Sok. No: 17, Vefa, Fatih Istanbul, Turkey |
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| Abstract: | The appropriateness of three official fisheries management reference points used in the north‐east Atlantic was investigated: (i) the smallest stock size that is still within safe biological limits (SSBpa), (ii) the maximum sustainable rate of exploitation (Fmsy) and (iii) the age at first capture. As for (i), in 45% of the examined stocks, the official value for SSBpa was below the consensus estimates determined from three different methods. With respect to (ii), the official estimates of Fmsy exceeded natural mortality M in 76% of the stocks, although M is widely regarded as natural upper limit for Fmsy. And regarding (iii), the age at first capture was below the age at maturity in 74% of the stocks. No official estimates of the stock size (SSBmsy) that can produce the maximum sustainable yield (MSY) are available for the north‐east Atlantic. An analysis of stocks from other areas confirmed that twice SSBpa provides a reasonable preliminary estimate. Comparing stock sizes in 2013 against this proxy showed that 88% were below the level that can produce MSY. Also, 52% of the stocks were outside of safe biological limits, and 12% were severely depleted. Fishing mortality in 2013 exceeded natural mortality in 73% of the stocks, including those that were severely depleted. These results point to the urgent need to re‐assess fisheries reference points in the north‐east Atlantic and to implement the regulations of the new European Common Fisheries Policy regarding sustainable fishing pressure, healthy stock sizes and adult age/size at first capture. |
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| Keywords: | Bayesian hockey stick fisheries reference points maximum sustainable yield natural mortality north‐east Atlantic safe biological limits |
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