Preliminary observations on elasmobranchs bycatch-at-size and sex-ratios on the Portuguese pelagic longline fishery in the Atlantic Ocean

Citation
Santos MN, Coelho R, Lino PG, Fernandez-Carvalho J (2014) Preliminary observations on elasmobranchs bycatch-at-size and sex-ratios on the Portuguese pelagic longline fishery in the Atlantic Ocean. ICCAT Collect Vol Sci Papers 70:2416–2432
Abstract

This paper provides an overview of the elasmobranchs catch-at-size and sex-ratios on the Portuguese pelagic longline fishery in the Atlantic Ocean. The analysis was based on data collected from fishery observers, port sampling and from skippers logbooks (self sampling), collected between 1997 and 2012. Data was analyzed in terms of bycatch-at-size and comparisons were made between years, seasons (quarters), stocks (North and South, separated at 5º N) and major fishing areas for the Portuguese fleet (North, Tropical North, Equatorial and South). For the blue shark a general increasing trend on mean sizes was observed for both hemispheres with a decrease in the more recent years. For the shortfin mako the mean size has remained stable in the North and tended to decrease in the South. Some variability was noted in the seasonal and spatial comparisons. The sex-ratios proportions were compared between regions and seasons, and for the main species significant differences were found. The data presented in this working document is still preliminary, but provides new information on the catch-at-size trends and sex-ratios for the major pelagic sharks captured by the Portuguese pelagic longline fishery in the Atlantic Ocean.