Migration, Tagging Response, and Distribution of Taku River Sockeye Salmon, 2019
Author: Raymond F. Vinzant
Publisher:
Published: 2022
Total Pages: 0
ISBN-13:
DOWNLOAD EBOOKIn 2019, we conducted a radiotelemetry study to assess dropout rates (and potential bias) in the annual U.S./Canada Taku River sockeye salmon (Oncorhynchus nerka) capture–recapture study, and to estimate the distribution of spawning populations and migration rates of stocks. Every 6th fish captured in fish wheels in the lower river was radiotagged (534 fish) and 22 aerial surveys were conducted to determine their fates. The proportion of radiotagged fish that did not cross the U.S./Canada border (i.e., dropout rate) was 16.8%. Of the remainder, 17.4% were harvested in the Canadian commercial fishery, 78.5% were tracked to a probable spawning location, and 4.1% were assigned an unknown fate. Based on the two-sample Kolmogorov-Smirnov nonparametric test, there was no difference between the length distributions of radiotagged fish and nonradiotagged fish (i.e., spaghetti tagged fish in the capture–recapture study), and the time of recovery between release at the fish wheels and harvest in the Canadian fishery was similar for radiotagged and nonradiotagged fish. Genetic stock identification of radiotagged fish was used to estimate the stock composition of the total fish wheel catch. The estimated proportion of river-type stocks was 71.1% and lake-type stocks was 28.9%. By reporting group, the mainstem Taku River was the largest contributor (66.8%), followed by King Salmon Lake (8.6%), Little Trapper Lake (8.3%), Tatsamenie Lake (7.5%), Kuthai Lake (4.5%), Tatsatua Lake (3.2%), Other (0.6%), and Nahlin River (0.5%). A total of 462 radiotagged fish met or exceeded the 95% probability threshold required for individual assignment to reporting group and were tracked to probable spawning locations. Seventy-one individually assigned fish were harvested in the Canadian commercial fishery between 0 and 23 days after being radiotagged. On average, radiotagged fish were harvested 4 days after tagging and 62% were harvested less than 5 days after tagging.