Aquatic Living Resources Environmental and stock effects on recruitment variability in the English Channel squid Loligo forbesi

• Main Authors: Challier, Laurence, Royer, Juliette, Pierce, Graham, Bailey, Nick, Roel, Beatriz, Robin, Jean-Paul
• Other Authors: School of Biological Sciences, University of Aberdeen
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2005
• Subjects: [SDV.SA.STP]Life Sciences [q-bio]/Agricultural sciences/Sciences and technics of fishery; [SDV.BA.ZI]Life Sciences [q-bio]/Animal biology/Invertebrate Zoology; [SDV.EE]Life Sciences [q-bio]/Ecology; environment; [SDV.EE.BIO]Life Sciences [q-bio]/Ecology; environment/Bioclimatology; North Atlantic; North Atlantic oscillation
• Online Access: https://hal.archives-ouvertes.fr/hal-02895531; https://doi.org/10.1051/alr:2005024

International audience Recruitment variability is commonly attributed to variation in spawning stock size and environmental variability. Here, the abundance of Loligo forbesi in the English Channel was estimated using cohort analysis. Environmental and adult biomass effects on recruitment variation were then tested. A stochastic length-age key was included in the cohort analysis, considering inter-individual variability in age at length. The number of recruits and parental stock biomass per monthly age-class were computed for a series of 13 fishing seasons (1989-2002). Recruitment was examined in relation to adult biomass and environmental parameters (sea surface temperature, SST, and the North Atlantic Oscillation, NAO) at the time of hatching. Recruits were approximately 7 months old and recruitment for each annual cohort occurred between April and August. Squid bigger than the length at maturity were assumed to be spawners. In the spawning season (September December), spawners were 11-13 months old. Parametric stock-recruitment curves (Ricker, Beverton and Holt, Shepherd, etc.) fitted poorly, while SST was negatively correlated with recruitment in a simple linear model. Recruitment was unrelated to NAO. A model combining SST and adult biomass showed that recruitment is probably density-dependent when stock size is high, and negatively correlated with temperature. The study did not indicate obvious recruitment overfishing in the English Channel L. forbesi population. Résumé-Effets de l'environnement et du stock sur la variabilité du recrutement chez le calmar, Loligo forbesi, en Manche. La variabilité du recrutement est généralement attribuée à la taille du stock de géniteurs et à l'environ-nement. Dans cette étude, les estimations de stock du calmar Loligo forbesi en Manche sont mises à jour et affinées. Cette nouvelle série d'estimation est utilisée pour tester l'influence du niveau de géniteurs et celle des conditions de milieu sur le recrutement. La modélisation des stocks est améliorée par l'utilisation ...