Evidence that size‐selective mortality affects growth of Atlantic cod ( Gadus morhua L.) in the southern Gulf of St Lawrence

• Published in: Journal of Fish Biology
• Main Authors: Hanson, J. M., Chouinard, G. A.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 1992
• Subjects: atlantic cod; Gadus morhua
• Online Access: http://dx.doi.org/10.1111/j.1095-8649.1992.tb03168.x; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1095-8649.1992.tb03168.x; https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1095-8649.1992.tb03168.x

The effects of size‐selective fishing mortality on the growth of Atlantic cod ( Gadus morhuu L.) in the southern Gulf of St Lawrence were investigated and compared between: (1) a period when fishing mortality was relatively high, growth was relatively rapid, and abundance low (1967–1972 year classes): and (2) a period when fishing mortality was lower, growth was slow, and density high (1977–1982 year classes). Cod first entered the fishery at age 3 during both periods. The 1967–1972 year classes (fast growing) were fully recruited to the fishery by age 5 or 6 and the fishery removed over twice as many fish from the lower than upper quartiles of length‐at‐age distributions for cod 4 to 10 years old (disproportionately high exploitation of slow‐growing fish). In contrast. the 1977–1982 year classes (slow growing) did not fully recruit to the fishery until age 9 or 10 and the fishery removed four times as many fish from the upper than lower quartiles of the length‐at‐age distributions for 4‐ to 10‐year‐old cod (disproportionately high exploitation of fast‐growing fish). The reduced mean lengths‐at‐age of the 1977–1982 year classes compared with the 1967–I972 year‐classes is consistent with the different patterns of exploitation of fast‐ and slow‐growing fish for the two periods.