Pink Salmon, Oncorhynchus Gorbuscha, Tagging Experiments in Southeastern Alaska, 1938-42 and 1945

Download or read book Pink Salmon, Oncorhynchus Gorbuscha, Tagging Experiments in Southeastern Alaska, 1938-42 and 1945 written by Roy E. Nakatani and published by . This book was released on 1975 with total page 48 pages. Available in PDF, EPUB and Kindle. Book excerpt: A total of 20, 532 pink salmon (Oncorhynchus gorbuscha) were tagged and released in southeastern Alaska north of Sumner Strait during the years of 1938 to 1942 inclusive, and in 1945. The recovery of 7, 027 of these tags in the fish traps confirmed the findings of other investigators that the pink salmon stocks of the northern part of southeast Alaska are separate from those in the southern part. They also show that pink salmon enter the northern part of southeast Alaska through two paths: (1) through Icy Strait, and (2) through the lower end of Chatham Strait. No evidence was found of movement through Peril Strait from Salisbury Sound into Chatham Strait. The centers of density of each group of tags appeared to move in a consistent manner, but a smaller number of tags from each release were dispersed throughout the northern part of southeastern Alaska. Differences were noted between the movements of fish in odd and even years. Also a larger proportion of earlier tagged fish moved to recovery locations father [sic] inland. In all areas and in all years the fishing season closed about the time of the greatest abundance of fish in the fishery, therefore the later parts of the runs were not studied. Apparently the 1941 run was the largest and that in 1945 the smallest. Migration rates were studied by plotting the catch per trap as well as by the recovery of tags. The latter showed movements of 9.05 to 33.37 miles per day. Survival rates computed for thirty releases with total tag recovery periods of two or more weeks averaged 0.384. Weekly exploitation rates varied from 0.142 to 0.452 averaging 0.250. The weekly F exponential rate of fishing averaged 0.514. Recoveries of tags from seines were not used since their proportion of tags recovered was less than one-half their proportion of the catch. Recommendations are made for future tagging experiments based upon the results of this analysis.