Modelling seasonal and annual variation in size at functional maturity in the European lobster (Homarus gammarus) from self-sampling data

Abstract

Abstract Laurans, M., Fifas, S., Demaneche, S., Brérette, S., and Debec, O. 2009. Modelling seasonal and annual variation in size at functional maturity in the European lobster (Homarus gammarus) from self-sampling data. – ICES Journal of Marine Science, 66: 1892–1898. Fishers from Le Croisic (France) measure all the lobsters (Homarus gammarus) they capture, indicating their sex and whether the females are ovigerous or non-ovigerous. Between 2003 and 2006 and mainly between April and September, 16 884 lobsters were measured in this manner. These self-sampled data were used to study catchability and functional maturity of lobsters. The sex ratio was 50%, and catchability did not change if a female was ovigerous or non-ovigerous. With the help of a logistic function, a relationship was established between body size and the proportion of ovigerous females. For the study area, 100% of the females were mature upon reaching a carapace length (CL) of 115 mm, and the proportion of ovigerous females reached 70% each year. The L50 value evolved over a CL of 103–106 mm. From the size when 100% of the females matured (115 mm), there was a larger proportion of ovigerous females than in other studies carried out in more northern European areas.