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Mortality of Dungeness Crabs Caused by Lost Traps in the Fraser River Estuary, British Columbia
Author(s) -
Breen Paul A.
Publication year - 1987
Publication title -
north american journal of fisheries management
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.587
H-Index - 72
eISSN - 1548-8675
pISSN - 0275-5947
DOI - 10.1577/1548-8659(1987)7<429:modccb>2.0.co;2
Subject(s) - fishery , estuary , fishing , bay , trap (plumbing) , fish <actinopterygii> , environmental science , geography , biology , archaeology , meteorology
The loss of Dungeness crabs Cancer magister to ghost fishing (mortality caused by lost traps) was estimated from catches and mortalities in 10 simulated lost traps. Traps were originally baited and then left in place for 1 year at a 10‐m depth in Departure Bay, British Columbia. Divers examined the traps at intervals and tagged all the crabs caught. In a year, the traps caught 169 Dungeness crabs, which were nearly all males, and about half of which died. Mortality rates of legal and sublegal size crabs were nearly the same. At the end of the study, the traps were all in good condition and continued to catch crabs. I also estimated an annual trap loss rate of 11% from a questionnaire survey of crab fishermen in the Fraser River estuary. From the estimated number of traps fished, loss rate, mortality rate per trap, and other values, I estimated that loss to ghost fishing might be equivalent in weight to 7% of the reported catch in the Fraser River District. This estimate is not directly applicable to other areas, but it is recommended that crab fishery management agencies develop and test inexpensive techniques, as well as regulations, that will prevent crab mortality from lost traps.