Science Advisory Report 2020/037

Updated information on the distribution of North Atlantic Right Whale in Canadian waters

Summary

• Considerable surveillance effort has been conducted for NARW since 2017 in Canadian waters. Here we report on the results from systematic aerial surveys and passive acoustic monitoring in Newfoundland waters, conducted by DFO. There are other surveillance programmes to assess the occurrence of NARW in Canadian waters and these are reported elsewhere.
• In systematic aerial surveys from 2017 through 2019, the largest aggregations of NARWs were observed in the southwestern GSL. Smaller numbers were observed in the northwestern GSL, with few observed in identified critical habitat areas in the Roseway and Grand Manan Basins.
• At finer spatial and temporal scales in the southwest GSL, there was variability in NARW distribution among years. More years of data are needed to describe this variability.
• The numbers of NARWs in the southern GSL estimated from DFO aerial surveys were similar in 2018 and 2019. The abundance indices support our understanding that a substantial proportion of the population was in the southern GSL.
• The aerial survey sightings indicate that NARWs are present in the GSL in May and are still present in November. This is the period during which sighting effort occurred.
• No NARWs were detected in GSL waters of less than 37 m (20 fathoms) during systematic surveys in which 12% of effort occurred in these shallow areas for 2017 through 2019. Nevertheless, NARWs are known to occur in shallow waters and some individuals were reported in Canadian waters shallower than 37 m (20 fathoms) in 2019.
• Although rare, there are sightings of NARWs in Newfoundland (NL) waters. Ongoing analysis of recent passive acoustic data from NL confirms that NARWs occasionally occur in these waters, particularly in Placentia Bay where there have been a few confirmed acoustic detections in 2017, 2018, and 2019.
• All abundance indices based on systematic surveys have sources of error and potential bias because of the clumped behaviour of the whales and the fact that diving whales will not be detected. Better information of the diving behaviour of whales can be used to reduce bias and thereby improve indices of abundance and distribution.
• Passive acoustic monitoring of NARWs is limited by our incomplete understanding of calling behaviour and the call detection range on the recorder systems used. Studies of calling behaviour, noise modelling efforts, and increasing the number of recording sites will improve our ability to acoustically monitor for NARWs.

This Science Advisory Report is from the National Marine Mammal Peer Review Committee (NMMPRC) 2019 Meeting: Update on North Atlantic right whale occurrence and distribution in Atlantic Canadian waters, held October 21-26, 2019, in St. Johns, Newfoundland. Additional publications from this meeting will be posted on the Fisheries and Oceans Canada (DFO) Science Advisory Schedule as they become available.

Science Advisory Report 2020/037 (PDF, 1,221 KB)

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