Science Advisory Report 2011/080
Harvest advice for Nunavik beluga (Delphinapterus leucas)
Summary
- Nunavik hunters harvest beluga from a mix of several discrete stocks (previously referred to as populations), designated after their specific summering areas: Western Hudson Bay (WHB), Eastern Hudson Bay (EHB), and Ungava Bay (UB).
- The 2011 reported harvest consisted of 32 beluga killed near Sanikiluaq (Belcher Islands), 19 in the eastern Hudson Bay area, 17 in Ungava Bay, 115 in Hudson Strait in the spring and 86 in the fall. Based on proportions derived from genetic analyses, this harvest is equivalent to 55 EHB beluga.
- Population modeling, using catch data and abundance estimates corrected for diving, indicate that the EHB stock has likely declined from ~4,100 whales in 1985 to ~3,000 in 2011. At current harvest levels, the stock has probably remained stable in recent years.
- Removing 49 EHB animals in future harvests has a 50% probability of causing a decline in the stock, while lower harvests would likely allow some recovery. The probability of decline in the absence of harvest is 19%.
- No whales were counted on transect lines during four systematic aerial surveys of Ungava Bay, although there were some off-line observations. According to a Bayesian binomial model, there is a strong probability that there are less than 100 individuals in the UB stock (95% CI 0–94). Any harvest from the UB stock clearly poses a threat to its recovery.
- Based on the combination of genetic and telemetry studies, beluga in James Bay are considered a separate stock. Estimates of the number of JB beluga from aerial surveys flown in 1993, 2001, 2004, 2008 were highly variable and ranged from ~8,200 to ~19,400.
- All available information indicates that the EHB stock is straddling the limits of Nunavut and Nunavik. Although current harvesting by Sanikiluaq hunters is limited to the early summer or late fall, when few EHB animals are taken, changes in their harvesting practices could have an important impact on the EHB beluga stock.
- The Little Whale and Nastapoka river estuaries are places of regular aggregations for large numbers of whales. Satellite telemetry data show that beluga return repeatedly to specific estuaries over the course of the summer.
- Recent genetic analyses indicate that beluga killed in the same hunting event tend to be related. Hunting in estuaries usually leads to the capture of larger numbers of beluga, and is thus more likely to remove several whales from the same family unit. Given the strong philopatry documented in beluga, estuarine hunts have a higher risk of extirpating animals from estuaries and compromising future recolonization.
This Science Advisory Report is from the Fisheries and Oceans Canada, Canadian Science Advisory Secretariat, National Marine Mammal Peer-Review Committee advisory meeting of October 17-21, 2011. Additional publications from this process will be posted as they become available on the DFO Science Advisory Schedule.
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