Science Advisory Report 2009/082
Survey index of the northern Hudson Bay narwhal stock, August 2008
- The index estimate obtained from the 21-22 August 2008 survey was 610 narwhals (95% CI: 377 - 988).
- This estimate is less than half of the index survey estimates obtained in 1984 and 2000 so it is plausible that the population has declined.
- If so, the decline may have resulted from increased hunting mortality and killer whale predation.
- However, several factors may have affected the estimate including ice cover, camera precision, survey altitude and possible movement of narwhals out of their range, but the importance of these factors is unknown.
- A full assessment using population indices and the catch history should be done to inform the future co-management of this stock.
- A new survey should be done in the near future to add to the series of indices, revisit issues of survey bias, and improve parameter estimates of population dynamics.
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