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- Title
Use of length-based models to estimate biological parameters and conduct yield analyses for male Dungeness crab (Cancer magister).
- Authors
Zhang, Z.; Hajas, W.; Phillips, A.; Boutillier, J. A.
- Abstract
Length-based models were developed for the male Dungeness crab (Cancer magister) population on the Fraser delta near Vancouver, British Columbia. The models incorporate the probability of moulting, moult increments, natural mortality during moulting and non-moulting periods, direct fishing mortality, and handling mortality that occurs when sublegal-sized crabs are caught and released. The models were used to investigate how long-term yield might be affected by the combination of handling mortality and an intensive fishery. The models were calibrated to survey data, and key biological parameters were estimated. The probability of moulting is near one for male crabs in the 130- to 150-mm carapace width range and decreases as crabs get larger. There is a 70.1% probability a crab will survive the 1-month period beginning with a moult. The non-moulting natural mortality rate is 0.97 year–1. When handling mortality is incorporated into the model, yield per recruit increases with the exploitation rate until it reaches approximately 94%. F0.1 is equivalent to 70%. An approach was developed to calculate the threshold ratio of discarded to retained crabs beyond which fishing would reduce the long-term yield.
- Subjects
DUNGENESS crab; MATHEMATICAL models; PROBABILITY theory; MOLTING; MORTALITY
- Publication
Canadian Journal of Fisheries & Aquatic Sciences, 2004, Vol 61, Issue 11, p2126
- ISSN
0706-652X
- Publication type
Article
- DOI
10.1139/F04-155