Journal Article

Did over-reliance on commercial catch rate data precipitate the collapse of northern cod?

Peter A. Shelton

in ICES Journal of Marine Science

Published on behalf of ICES/CIEM

Volume 62, issue 6, pages 1139-1149
Published in print January 2005 | ISSN: 1054-3139
Published online January 2005 | e-ISSN: 1095-9289 | DOI: http://dx.doi.org/10.1016/j.icesjms.2005.04.009
Did over-reliance on commercial catch rate data precipitate the collapse of northern cod?

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It has been suggested that a number of “lessons” can be learned from the collapse of the northern cod stock off Newfoundland and Labrador. However, not all purported lessons have been validated with available data. One lesson is thought to be that over-reliance on commercial catch rate data and an incorrect assumption regarding the functional relationship between catch rate and population size were major contributors to overestimating stock size, precipitating the collapse. The current study describes calibration approaches used in assessments, and evaluates alternative functional relationships between commercial catch rates and stock size. In addition, historical population size is re-estimated using only research vessel data and compared with estimates obtained based on both commercial catch rate and research vessel data. Calibration with commercial catch rate contributed to overestimating stock size in some years, but there is no evidence that the assumed functional relationship between commercial catch rate and population size was a significant factor in the collapse.

Keywords: catch rate; cod; collapse; model calibration; population estimation; stock assessment

Journal Article.  6235 words.  Illustrated.

Subjects: Environmental Science ; Marine and Estuarine Biology

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