Vital Statistics of Esox masquinongy in Nogies Creek, Ontario.: I. Tag Loss, Mortality Due to Tagging, and the Estimate of Exploitation

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Abstract
A small population of maskinonge was exploited by a 9-year fishery, using fixed nets under control of the investigator. During the period 1952 to 1960, approximately 4000 maskinonge were handled, 2000 of them being tagged and returned to the population.The rate of loss of the preopercular disc tag increased progressively with time out, so that an estimated 8.5% of the tags had been lost after the end of the first year, 30% after the second and virtually all after the third. The total mortality and tag loss is estimated to range from 25% to 66% during the period from spring to fall for various years. These estimates are used as correcting factors to determine the numbers of tags extant at the start of the fall fishery each year. The rates of recapture of these tags give estimates of exploitation during the fall fisheries, and the average coefficient of catchability, derived from these data, is 0.0026 for fish age IV and older.A method, using simultaneous tag and recapture data, is developed to estimate the coefficient of catchability for each age-group. The estimated coefficients of catchability increase, almost linearly, from 0.0013 for age-group III to 0.0032 for age-group VI+. The average coefficient estimated by this method, 0.0025 for age-group IV and older, agrees well with that estimated independently by the method above.