Science Advisory Report 2010/074
Harvest advice for Nunavik beluga (Delphinapterus leucas)
Summary
- Beluga hunted in Nunavik come from separate summering populations. Genetic analyses support the existence of an eastern Hudson Bay stock (EHB) and one or more western Hudson Bay stocks (WHB). There is insufficient genetic information to confirm the stock identity of whales summering in Ungava Bay (UB).
- The 2010 harvest consisted of 45 beluga killed near Sanikiluaq (Belcher Islands), 16 in the eastern Hudson Bay area, 15 in Ungava Bay, 146 in Hudson Strait in the spring and 58 in the fall. Since 2009, it is assumed based on genetic data that all animals killed in EHB, 10% of those killed in the spring and summer in Hudson Strait, and 20% of those killed in Ungava Bay and during the fall in Hudson Strait are EHB beluga. It is also assumed that 12% of beluga killed by Sanikiluaq hunters belong to the EHB stock. Using these proportions, the 2010 harvest is equivalent to 51 EHB beluga.
- Population modeling, using abundance estimates corrected for diving, indicates that the eastern Hudson Bay population has likely declined from 4,120 whales in 1985 to about 3,030 in 2010. At current harvest levels, the population has probably remained stable over the last few years.
- Removing 50 EHB animals in future harvests has a 50% probability of causing a decline in the population, while lower harvests would likely allow some recovery. Limiting the harvest of EHB animals to 10 reduced the probability of decline to 25%. Conversely, a harvest of 100 EHB whales would have a 75% probability of leading to population decline. No harvest scenario could produce a 5% chance of decline, since in the absence of harvest the probability of decline was 18%.
- Analyses on beluga harvested in Hudson Strait, combining age information from teeth and probabilistic information on stock of origin determined from mitochondrial DNA, showed that the age structure of EHB beluga was strongly skewed towards younger individuals and contained less older individuals compared to the non-EHB whales. These results could indicate a disproportional catch of younger EHB animals, significant harvesting pressure on the EHB stock or both. Additional research is needed to better inform management efforts.
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