Research Document - 2015/041
Recovery Potential Assessment for Porbeagle (Lamna nasus) in Atlantic Canada
By S.E. Campana, M. Fowler, D. Houlihan, W. Joyce, M. Showell, M. Simpson, C. Miri and M. Eagles
Abstract
Porbeagle (Lamna nasus) were designated as Endangered by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) in 2014, and are currently under consideration for addition to Schedule 1 of the Species at Risk Act (SARA). The Recovery Potential Assessment (RPA) presented here provides the necessary background information, population status and mitigation options in support of the listing decision. Porbeagle are long-lived, slow-growing sharks with a delayed age of sexual maturation and a low fecundity, rendering them susceptible to overexploitation. Since they are widespread in Atlantic Canadian waters, habitat is not limiting to their recovery. Population size in 2009 was about 25% of its size in 1961, while female spawner abundance was about 14% of its 1961 level. Overfishing is the only known cause of their decline, and the only impediment to their recovery. Although a directed pelagic longline fishery contributed to their population decline, recent fishing mortality is largely due to capture and post-release mortality as bycatch in pelagic longlines and groundfish mobile gear. Mitigation options to reduce the threat due to fishing include a variety of options for reducing bycatch and post-release mortality. Recovery at 80% of female spawning stock numbers, or SSN80%, is expected to occur around 2042 under recent fishing mortality rates (approximately 2%).
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