Science Advisory Report 2016/055

Assessment of Dolly Varden from the Babbage River, Yukon Territory 2010–2014

Summary

• Based on mark-recapture studies, the estimated population abundance of Dolly Varden ≥365 mm from the Babbage River ranged between 5,861 and 6,553 between 2010 and 2012.
• The estimated count of Dolly Varden ≥365 mm from the Babbage River using a DIDSON sonar was estimated to be between 2,839 and 3,119 in 2011.
• Biological information collected annually from seining at the spawning and overwintering area at the end of September between 2010 and 2014 consistently demonstrated similar median length with a wide range of sizes, a high proportion of large fish (≥550 mm), and a large composition of spawners (≥40%). The population demographics were similar to a sample collected in 1987.
• Biological data from the mark-recapture studies indicated females spawned in consecutive-years more often than did males. The growth of Dolly Varden based on the recapture of tagged fish has increased compared to the early 1990s.
• Genetic mixed-stock fishery analysis of samples collected along the Beaufort Sea coast between 2011 and 2014 indicated that Dolly Varden from the Babbage River were harvested at multiple locations along the Canadian Beaufort Sea coast.
• At Herschel Island and Shingle Point, locations where the majority of the harvest occurs, Dolly Varden from the Babbage River contributed between 2 and 14%, and 30 and 89% of the catch, respectively, between 2011 and 2014.
• It is estimated that the harvest rate in Canadian waters of Dolly Varden from the Babbage River in Canada from 2011 to 2014 ranged between 1.2 and 7.5%. The total harvest rate is unknown due to the absence of information from Alaska.
• Estimates of effective population size determined using genetic data suggest there are no immediate conservation concerns for the population.
• The available population estimates, biological, and harvest information suggest that the population is currently stable and is sustainably harvested.

This Science Advisory Report is from the meeting held on February 9, 2015 to assess the population status of Dolly Varden from the Babbage River, Yukon Territory. Additional publications from this meeting will be posted on the DFO Science Advisory Schedule as they become available.

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