The catch characteristics and population structure of the brown crab (Cancer pagurus) fishery in the Isle of Man, Irish Sea

• Published in: Journal of the Marine Biological Association of the United Kingdom 2019-02, Vol.99 (1), p.119-133
• Main Authors: Öndes, Fikret, Emmerson, Jack A., Kaiser, Michel J., Murray, Lee G., Kennington, Kevin
• Format: Article
• Language: English
• Subjects: Cancer; Catch per unit effort; Commercial fishing; Crabs; Crustaceans; Decapoda; Females; Fisheries; Fishery data; Fishing; Generalized linear models; Landing statistics; Logbooks; Marine crustaceans; Migration; Observers; Population; Population structure; Questionnaires; Reproductive behaviour; Sex; Sex ratio; Size distribution; Small-scale fisheries; Spatial distribution; Surveying; Temporal variations
• ISSN: 0025-3154; 1469-7769
• DOI: 10.1017/S0025315417001849

Brown crab contributes to small-scale fisheries in the Isle of Man and landings (495 t) were worth in excess of £0.5 million in 2012. The present study sought to fill evidence gaps needed to improve the scientific understanding of this fishery. Observer data were collected to examine the spatial and temporal variations in the size distribution and sex ratio of crabs around the Isle of Man. This study also aimed to evaluate the catch characteristics of brown crab using logbook data (2007–2012), observer data (2012–2013) and questionnaire survey data (2013). The sex ratio is highly variable in different areas across seasons and was perhaps indicative of migration patterns in relation to mating. This change was most notable with a strong increase in the proportion of females to the south and west of the Isle of Man in the autumn months. The depth and pot volume were important factors that influenced the catch per unit effort (CPUE). Future survey designs would need to ensure adequate spatial coverage of the east and west coast of the Isle of Man together with a seasonal sampling regime that captures the spatial change in the distribution and abundance of male and female crabs.