Analysis of F msy in light of life‐history traits—Effects on its proxies and length‐based indicators

• Published in: Fish and fisheries (Oxford, England) England), 2022-05, Vol.23 (3), p.663-679
• Main Authors: Horbowy, Jan, Hommik, Kristiina
• Format: Article
• Language: English
• ISSN: 1467-2960; 1467-2979
• DOI: 10.1111/faf.12640

Equilibrium yields and biomasses in relation to fishing mortality were generated for a wide range of life‐history traits (LHTs), which included growth parameters, natural mortality, maturity, selectivity and steepness of the Beverton and Holt stock–recruitment relationship. For each combination of LHTs, the fishing mortality expected to produce maximum sustainable yield ( F msy ), its selected proxies ( F 0.1 , F 40% , F 40%SSB and F max ) and mean length at F msy ( L msy ) were estimated. Next, linear models combining the estimated F msy and L msy with the traits were fitted ( R 2  > .95). Almost all of the LHTs were statistically significant, and the largest effect on F msy was from steepness, while natural mortality and growth rate had smaller effects. In the case of L msy , however, the largest effect in the fitted model was from the growth rate, while steepness influenced L msy only slightly. The F msy proxies were evaluated, and F 40%SSB appeared to be a generally conservative F msy proxy, while F max always overestimated F msy , generally to a large extent. F 0.1 and F 40% may be used as F msy proxies or conservative proxies mainly for steepness values of 0.6 and higher; for lower steepness, they may markedly overestimate F msy . The ratio of biomass at F msy to virgin biomass was on average 0.34, and for a steepness of 0.9, some values were lower than 0.2. The analysis indicates that the use of the mean length of a catch in relation to L msy for evaluating stock status should be done with caution, especially for species with a high growth rate.