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Movements and Mortality of Tagged Male and Female Lingeod in the Strait of Georgia, British Columbia
Author(s) -
Smith Barry D.,
McFarlane Gordon A.,
Cass Alan J.
Publication year - 1990
Publication title -
transactions of the american fisheries society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.696
H-Index - 86
eISSN - 1548-8659
pISSN - 0002-8487
DOI - 10.1577/1548-8659(1990)119<0813:mamotm>2.3.co;2
Subject(s) - biological dispersal , fishing , biology , fishery , confidence interval , demography , ecology , population , statistics , mathematics , sociology
Using mark‐recovery data obtained from 1982 to 1987, we estimated rates of dispersal from release locations and mortality for mature male and female lingcod Ophiodon elongatus in the Strait of Georgia, British Columbia. Under the assumption of random dispersal from release locations, and incorporating sport‐fishery effort data obtained by an independent creel survey, we determined from sport‐fishery tag recoveries that male lingcod dispersed at a mean rate of 500 m/d (95% confidence interval, 400–600 m/d) and females dispersed at 1,040 m/d (900–1,180 m/d). In an unbounded environment, this can be interpreted as 95% of tagged males remaining within 17 km and 95% of females within 34 km of the release location after 1 year at large, In the confines of the Strait of Georgia, actual dispersal would be less. Males dispersed significantly ( P < 0.01) more slowly than females, and they had a higher annual instantaneous total (fishing plus natural) mortality rate (95% confidence intervals 0.72–1.25 for males and 0.29–0.77 for females) after adjustments for tag loss. Our mortality estimates were consistent with our understanding of the history and current status of the commercial and sport fisheries for lingcod in the Strait of Georgia, but our movement rate estimates were greater than those suggested by previous studies. We argue that the sport fishery is likely becoming the main human cause of a continuing decline in lingcod landings, and that, in recent years, natural mortality, particularly for males and small females, has included increased predation by marine mammals. Movements appeared extensive enough for us to propose that the lingcod population within the Strait of Georgia be considered a stock unit.