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Have changes in selectivity masked recruitment declines in crustacean trap fisheries?


Frusher, SD and Hoenig, J and Gardner, C, Have changes in selectivity masked recruitment declines in crustacean trap fisheries?, Fisheries Research, 65, (1) pp. 467-474. ISSN 0165-7836 (2003) [Refereed Article]

DOI: doi:10.1016/j.fishres.2003.09.032


In the Tasmanian rock lobster assessment model, as in many other assessment models, selectivity is treated as a fixed effect. The actual size composition in the population is estimated by dividing the survey catch in each size class by the size-specific selectivity. Recently, it has been found that larger lobsters tend to inhibit smaller lobsters from entering traps. We suggest that, as larger lobsters are removed from the population by harvesting, the number of smaller lobsters in the catch increases because they become more catchable. To determine the effect of a change in selectivity pattern on our perception of population composition, we applied selectivity curves that accounted for the effects of a change in size composition to sampling data from a population of lobsters that had seen a substantial decline in large legal-sized lobsters due to harvesting over the last 35 years. The results suggest that recent recruitment is lower than the recruitment that occurred in the 1960s, but this is masked in the unadjusted sampling data by changes in selectivity. This could contribute to masking of a stock-recruitment relationship. If this is a common phenomenon in crustacean trap fisheries, the assessment approaches now in use may be more risk prone than previously realised. © 2003 Elsevier B.V. All rights reserved.

Item Details

Item Type:Refereed Article
Research Division:Agricultural, Veterinary and Food Sciences
Research Group:Fisheries sciences
Research Field:Aquaculture and fisheries stock assessment
Objective Division:Animal Production and Animal Primary Products
Objective Group:Fisheries - wild caught
Objective Field:Fisheries - wild caught not elsewhere classified
UTAS Author:Frusher, SD (Professor Stewart Frusher)
UTAS Author:Gardner, C (Professor Caleb Gardner)
ID Code:28692
Year Published:2003
Web of Science® Times Cited:11
Deposited By:TAFI - Marine Research Laboratory
Deposited On:2003-08-01
Last Modified:2004-04-07

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