Stock assessment of Pacific cod (Gadus macrocephalus) in Georgia and Juan de Fuca Straits, 1954-84 / by S.J. Westrheim and R.P. Foucher. : Fs97-4/1905E-PDF

"Four important stocks of Pacific cod were delineated in Georgia and Juan de Fuca straits, primarily based on results of extensive Canadian and U.S. tagging experiments during 1954-79. All four stocks were exploited seasonally, almost exclusively by on-bottom trawls. Two stocks were resident year-round (MSA 14 and Gulf Islands), and two were itinerant and seasonal (Nanoose and MSA 19). Standardized landing statistics and landings-at-age were employed to assess each stock. No stock exhibited symptoms of recruitment overfishing, despite relatively high estimates of total mortality rate (Z = 1.03 - 1.50). Estimates of M (0.59) and q (1.373 x 10 ⁻³) were obtained from only one stock (MSA 14), by regressing Z on effort. Yield-per-recruit analysis indicated that maximizing YPR was impractical because the required mesh size was too large for the mixed-species fishery. Current legal, minimum mesh (4.25", synthetic materials) was satisfactory for maximizing catch profitability (YPR/F)"--Abstract, page iii.

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