Are St. Lawrence harbour porpoise still victims of bycatch?
In 2003, the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) revised and lowered the status of the Northwest Atlantic harbour porpoise population from “threatened” to that of “special concern”. It is estimated that fewer harbour porpoises are dying because of accidental entanglement in fishing gear since fishing efforts have diminished. What is the situation in the St. Lawrence?
To go through the looking glass
Questionnaires concerning the 2000 and 2001 fishing seasons were distributed to fishermen in an attempt to estimate the number of accidental deaths of harbour porpoises associated to gillnetting in the St. Lawrence. In other studies, observers posted on commercial fishing vessels in 2001 and 2002 collected data through Fisheries and Oceans Canada’s At-Sea Observer and Sentinel Fisheries programs.
Results have revealed a drop in the incidence of the gillnet bycatch of harbour porpoises. Yet, these occurrences are by no means insignificant. Based on the questionnaires, 2215 and 2409 harbour porpoises were accidentally caught in the Gulf and Estuary of the St. Lawrence in 2000 and 2001 respectively. These estimates suggest a drop in the incidence of accidental entanglements of between 24 and 63 percent since the end of the 1980s. The data collected by observers did not result in reliable estimates. Yet, this second sampling method did illustrate that changes in the time of the year and the fishing zone can significantly influence bycatch rates. Fishing at the end of August and September in approximately 60 m of water accidentally killed the largest number of harbour porpoises. Further data will be collected to gain a better understanding of the problem of bycatch in the St. Lawrence and determine how to best mitigate impacts of the groundfish fishery on harbour porpoises.
Véronique Lesage, Judy Keays, Samuel Turgeon and Sylvain Hurtubise of Fisheries and Oceans Canada’s Maurice Lamontagne Institute (MLI-DFO).
Fisheries and Oceans Canada’s Species At Risk Research Program.
Lesage, V., J. Keays, S. Turgeon et S. Hurtubise. 2004. Incidental catches of harbour porpoises (Phocoena phocoena) in the gillnet fishery of the Estuary and Gulf of St. Lawrence in 2000-2002. Canadian Technical Report of Fisheries and Aquatic Sciences. 2552 : 37p.
Lesage, V., J. Keays, S. Turgeon et S. Hurtubise. 2006. Bycatch of harbour porpoises (Phocoena phocoena) in gillnet fisheries of the Estuary and Gulf of St. Lawrence, Canada, 2000-02. J. Ceteacean Res. Manage. 8(1) : 67-78.