Modelling harvesting strategies for the lobster fishery in northern Europe: the importance of protecting egg-bearing females

摘要

European lobster populations in Norway and Sweden are severely reduced as a result of intense harvesting over a long time. Various alternative management options have been proposed or endorsed to both facilitate recovery and increase yield. Accordingly, Minimum Landing Size (MLS) regulations are widely used for the European lobster. We developed an individual-based population model which integrates biological knowledge about lobsters' population dynamics to explore how available harvesting strategies and management options influence abundance and yield. The model reproduced basic features of a real lobster population in Sweden. Even for a relatively large MLS high fishing effort may still be detrimental to the long term production of the stock, while increasing the MLS further prevents this recruitment overfishing. A moratorium on berried females, in combination with the MLS appears to stabilize population fluctuations and yield, leading to higher yield for all MLS's considered. The female moratorium harvesting strategy also performed better than a maximum size limit. Yield per recruit calculations gave similar quantitative results, and also shows that a larger MLS reduce the risk of growth overfishing. A smaller MLS enables the harvest of many individuals but is very sensitive to increase in effort which easily promotes overfishing.