Spatial overlap between the leafscale gulper shark and the black scabbardfish off Portugal

Abstract

-Information about the spatial distribution of bycatch species and their spatial overlap with the target species is essential for fisheries management. The present study used fishery-dependent data (vessel monitoring systems, logbooks and official daily landings) to study the spatial distribution and overlap between black scabbardfish Aphanopus carbo and leafscale gulper shark Centrophorus squamosus taken by the longline fishery operating off mainland Portugal. The geostatistical method kriging was applied to estimate the distribution of the leafscale gulper shark in relation to black scabbardfish and thus assess the impact of the fishery on the leafscale gulper shark. Results indicate that in fishing grounds where the black scabbardfish is more abundant, the relative occurrence of deepwater sharks is reduced. These findings have implications for alternative management measures to be adopted in this particular fishery, particularly where it concerns the minimization of deepwater shark bycatch.

The Status of Marine Megafauna Research in Macaronesia: A Systematic Review

“…Fisheries-related research only represents 6% of the total research effort in Macaronesia, yet is an essential component to managing populations as there is little evidence that currently legal fisheries are sustainable without adequate baseline information and bycatch statistics (Hareide et al, 2007;EASME, 2017). For example, there is an absence of detailed information regarding species distribution and spatial overlap with regional fisheries, such as those targeting black scabbardfish Aphanopus carbo (Veiga et al, 2013), which may further increase the vulnerability of biologically sensitive sites to fisheries. Moreover, inconsistencies between the catch and landing of sharks (i.e., unreported or misreported discards) have been documented in the Azores (Machete et al, 2011;Das and Afonso, 2017) and the Canaries (Pajuelo et al, 2010), yet have not been investigated in Madeira.…”

Editorial: Management and monitoring of deep-sea fisheries and stocks

“…26, 289-291 (2013) which are generally considered data-consuming Trenkel et al (2013) performed simulation testing of spatial indicators derived from EU-logbooks for the four main deepwater stocks exploited to the west of the British Isles. Veiga et al (2013) assessed the spatial overlap between catches of deepwater sharks and black scabbardfish to the west of Portugal using logbook and EU vessel monitoring system (VMS) data. Lastly, Burgos et al (2013) assessed the fishing effort and its spatial distribution over time in the small-scale fishery for the blackspot seabream, Pagellus bogaraveo, in the Strait of Gibraltar using a regional VMS data based upon the GPRS/GSM mobile phone network; this technology could substantially improve the monitoring of fishing effort in small-scale fisheries.…”