Historical and Current Population Characteristics and Subsistence Harvest of Arctic Char from the Sylvia Grinnell River, Nunavut, Canada

摘要

Data describing Arctic char Salvelinus alpinus were collected in 2002 and 2004 and compared with historical data collected over the past 60 years from the Sylvia Grinnell River, Nunavut, Canada, to determine population status. The goal of the study was to provide information that could be used to manage the stock. Current subsistence harvest was estimated based on data collected from gillnetting, angling, and snagging. The Arctic char subsistence harvest was estimated at 8,364 kg in 2002 and 7,956 kg in 2004. The current population remains well below historic levels, but it has improved since 1976-1977. The improved status of the stock is based on increased length at age, increased mean weight, longer and older fish, decreased mortality rate, and improved catch indices from experimental gill nets and angling. Future benchmarks useful for evaluating the population's status include (1) proportion of females that have reached reproductive age, (2) proportion of older and longer fish, (3) mortality rate, and (4) catch per angler-hour. The fishery should be monitored by enumerating the harvest, quantifying fishing effort from all gear types, and recording biological data. Experimental gill nets should be periodically used to obtain biological data for comparison with the 2002 and 2004 data. Snagging should be prohibited since most young Arctic char (<200-300 mm) are injured and are not utilized by the fishery, and it is impossible to estimate the number of Arctic char larger than 200 mm that are struck and lost instead of landed. We recommend (1) closing all fishing at the base of the falls and at least 500 m into the estuary, (2) limiting gill-net mesh size to no less than 114 mm, (3) implementing benchmarks to evaluate population status, (4) obtaining an estimate of the population size, and (5) determining the exploitation rate.