Harbour porpoise (Northwest Atlantic population) COSEWIC assessment and status report: chapter 15
Technical summary
Harbour porpoise
Northwest Atlantic population
Marsouin commun
Population de l’Atlantique Nord-Ouest
Extent and area information
Population information
Threats (actual or imminent threats to populations or habitats)
- Bycatches in commercial fisheries
- Habitat degradation and loss caused by acoustic harassment devices
Rescue effect (immigration from an outside source): Low
Quantitative Analysis
Yes for Bay of Fundy/Gulf of Maine subpopulation
Current status
Committee on the Status of Endangered Wildlife in Canada (COSEWIC): Designated Threatened in April 1990. Status re-examined and confirmed in April 1991. Status re-examined and designated Special Concern in May 2003. Status re-examined and confirmed in April 2006.
Status and reasons for designation
Reasons for Designation: The species is widely distributed in eastern Canadian marine waters. Surveys of portions of the range (Bay of Fundy/Gulf of Maine and the Gulf of St. Lawrence) during the late 1990s indicated more than 100 000 porpoises. Incidental catch (bycatch) in fishing gear, especially gillnets, is a major source of mortality. Bycatch probably has declined in areas where use of gillnets has decreased. Management measures in the Bay of Fundy and Gulf of Maine have been shown to reduce porpoise bycatch rates in gillnets. However, these measures have not been implemented in much of the species’ range, including the Gulf of St. Lawrence and Newfoundland and Labrador, where annual mortality in several gillnet fisheries is still estimated to be in the thousands. There is also some concern that porpoises in the Bay of Fundy and possibly other areas may be excluded from portions of their habitat by acoustic harassment devices associated with aquaculture. Although the population remains abundant, the particular susceptibility of harbour porpoises to bycatch in fishing gear represents an incipient threat. Given that, the lack of good abundance information in some parts of the range and the lack of porpoise bycatch monitoring and mitigation in many of the relevant fisheries are reasons for concern.
Applicability of criteria
Criterion A (Declining Total Population): Not applicable.
Criterion B (Small Distribution, and Decline or Fluctuation): Not applicable.
Criterion C (Small Total Population Size and Decline): Not applicable.
Criterion D (Very Small Population or Restricted Distribution): Not applicable.
Criterion E (Quantitative Analysis): Not available.
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