Science Advisory Report 2016/029

Preliminary Estimates of Human-Induced Injury to and Mortality of Cetaceans in Atlantic Canada

Summary

• Sources of information on human-induced injury and mortality to cetaceans include at-sea observations of the commercial fisheries that incidentally catch marine animals recorded in Fisheries and Oceans Canada (DFO) databases and strandings and entanglements recorded by marine mammal response networks and disentanglement teams (i.e., opportunistic data).
• Marine mammal response networks provide opportunistic data that are useful for examining causes and sources of human-induced injury and mortality, particularly of some larger cetaceans, but these data cannot be used to estimate the total fishery-specific bycatch.
• Based on the current, but incomplete response network information, the cause of more than 50% of all reported cetacean mortalities could not be identified. Detailed study of carcasses could improve assessment of human-induced injuries.
• Effort-based data (such as at-sea fisheries observer data) is required to calculate fisheries-specific bycatch rates of cetaceans and estimates of uncertainty. However, observer coverage of commercial fisheries is low for many fisheries known to incidentally catch cetaceans (i.e.  snow crab and lobster pot/trap, groundfish fixed gillnet and longline and mobile gear).
• Existing data are insufficient or outdated to estimate fishery-specific rates of human-induced mortality and injury to cetaceans in Atlantic Canada, and to convert these rates to total bycatch. Estimates of fishery-specific bycatch for most cetacean species will benefit from enhanced at-sea observer coverage.
• Estimates of current abundance are unavailable for most cetacean species occurring in Atlantic Canadian waters. This is a knowledge gap that will need to be addressed before evaluating the impacts of human-induced mortality on populations.
• Opportunistic data from response networks indicate that the magnitude of human-induced injury and mortality of North Atlantic Right Whale exceeds the potential biological removal calculated for the population occurring in the northwest Atlantic.
• The DFO Marine Mammal Response Program (MMRP) receives opportunistic data on cetacean strandings and entanglements from all DFO regions. These data would be more valuable for determining causes and sources of cetacean injury and mortality if reporting protocols among regions were standardized.
• Effort-based data collection on human-induced cetacean injury and mortality should be standardized nationally and made available for analysis.

This Science Advisory Report is from the October 20-23, 2015, Annual Meeting of the National Marine Mammal Peer Review Committee (NMMPRC). Additional publications from this meeting will be posted on the Fisheries and Oceans Canada (DFO) Science Advisory Schedule as they become available.

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