Recent incidental catch of sharks in gillnet fisheries of Newfoundland and Labrador, Canada

[摘要] ABSTRACT: Waters of Newfoundland and Labrador, Canada, are home to a variety of shark species, many of which have been previously reported as incidental catch in several gillnet fisheries. However, defensible estimates of incidental catch rates are unavailable. This mortality is of concern, given reports of considerable declines in abundance of several large shark species in this area. On the basis of several data sources (incidental catch rates derived using different methods of reporting; fish landings and net days as measures of effort, with fishing trips as sampling units), the total numbers of incidentally caught sharks were estimated in 8 gillnet fisheries for 2001, 2002, and 2003. Confidence intervals were estimated using resampling techniques. Most fisheries reported incidental catch of some sharks, although there were distinct differences between different fisheries in diversity and abundance of species encountered. Spiny dogfish Squalus acanthias was the most commonly captured species, occurring in various fisheries along the south coast of the island of Newfoundland. Large sharks, including basking shark Cetorhinus maximus, shortfin mako Isurus oxyrinchus, porbeagle Lamna nasus, and blue shark Prionace glauca, were reported in small numbers in all fisheries. Deepwater fisheries targeting e.g. Greenland halibut Reinhardtius hippoglossoides caught mainly sharks of the continental slope, such as Greenland shark Somniosus microcephalus, black dogfish Centroscyllium fabricii, and several other deepwater species. Catch rates of several species appear high and may warrant conservation action. For the majority, however, there is insufficient information on abundance, and sometimes even basic biology, to accurately assess the impact of this incidental mortality.

[学科分类] 动物科学

[关键词] Sharks;Incidental catch;Bycatch;Canada;Northwest Atlantic;Mortality;Dogfish;Gillnets