Abstract
The status of harbour porpoise (Phocoena phocoena) populations in the North Atlantic has raised numerous concerns. Although a number of factors that may be adversely affecting harbour porpoise populations have been identified, focus has been on the impact of removals, primarily due to incidental catches in fishing gear. As a result, considerable efforts have been made to determine the levels and/or impact of bycatch in a number of areas. Unfortunately, many areas remain little studied. Currently, harbour porpoise are listed as threatened or vulnerable in many parts of their range. In order to determine if the current levels of removals are sustainable, information on stock identity and seasonal movements, population parameters, abundance, and the magnitude of removals is required. Although substantial progress has been made to improve our knowledge of these parameters in the last decade, significant gaps still exist. After reviewing the available data for each sub-population in the North Atlantic, it is clear that the information required to assess the status of harbour porpoise populations is still not available for most areas. Attempts have been made to assess the status of harbour porpoise based on trends in sightings or, in areas where information on abundance and bycatch are available, on models using arbitrary criteria and/or theoretical estimates of potential population growth. Detailed case-specific population models have been proposed but are not yet available.
Highlights
Serious concerns have been raised about the sustainability of harbour porpoise (Phocoena phocoena) populations in the North Atlantic
A number of potential limiting factors such as pollutants, habitat change or global warming have been identified (Donovan and Bjørge 1995, Aguilar and Borrell 1995, Brodie 1995, Hutchinson 1996, Teilmann and Lowry 1996, Anonymous 1999, Koschinski 2002) the primary focus has remained on the documented levels of direct mortality, primarily through incidental catches in fishing gear (Fig. 1)
The objective of this paper is to update this review, focusing on areas where new information is available or not included in the International Whaling Commission (IWC) report, in order to examine the state of current knowledge required to assess the sustainability of removals on harbour porpoise populations in the North Atlantic
Summary
Serious concerns have been raised about the sustainability of harbour porpoise (Phocoena phocoena) populations in the North Atlantic. Jefferson and Curry 1994, Read 1994, Donovan and Bjørge 1995, Anonymous 1998, CEC 2002) have shown that large numbers of harbour porpoise are caught in commercial fishing gear throughout their range. Based upon declining sightings and/or the perceived impacts of incidental catches, harbour porpoise populations have been classified as being in danger in many parts of their range. In Atlantic Canada, the harbour porpoise was recently reassessed as a population of Special Concern by the Committee on the Status of NAMMCO Scientific Publications, Volume 5. The United States currently lists the Gulf of Maine/Bay of Fundy population as a ‘strategic’ species (Waring et al 2001)
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