Density of the Commercial Spider Crab, Chionoecetes opilio , and Calibration of Effective Area Fished Per Trap Using Bottom Photography
Bottom photography was found to be a more accurate method of censusing the commercial spider crab, Chionoecetes opilio, than trawling or sight counting from a submersible. Because of their highly aggregated distributions, estimating abundance of mature female crabs and immature crabs of both sexes w...
| Published in: | Journal of the Fisheries Research Board of Canada |
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| Main Author: | |
| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
Canadian Science Publishing
1975
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| Subjects: | |
| Online Access: | http://dx.doi.org/10.1139/f75-099 http://www.nrcresearchpress.com/doi/pdf/10.1139/f75-099 |
| Summary: | Bottom photography was found to be a more accurate method of censusing the commercial spider crab, Chionoecetes opilio, than trawling or sight counting from a submersible. Because of their highly aggregated distributions, estimating abundance of mature female crabs and immature crabs of both sexes was not practical by any method. The larger males (≥ 40 mm carapace width), including those of commercial value, approached a random distribution, however; and abundance estimates for four study areas ranged from 5.2 to 9.2 crabs/500 m 2 and from 2.2 to 4.2 kg live weight/500 m 2 . To permit results of exploratory fishing with traps to be converted to crab density and size of crab stocks available to a commercial fishery, a commercial crab trap was calibrated for "effective" area fished. The effective fishing area per trap averaged 4100 m 2 over four study areas. |
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