By: Nir Barnea, Pacific Northwest Regional Coordinator for the NOAA Marine Debris Program
Every year, about 12,000 crab pots are lost in the Puget Sound, mostly from recreational fishing. These lost pots can continue to capture marine life, a process called “ghostfishing.” Recreational crab pots may come in different models and designs, but all have an escape mechanism to allow trapped crabs to escape from the pot if it is lost. But— are all escape mechanisms equally effective? If not, can simple modifications make them more effective and decrease the ghostfishing problem?
An elegantly designed and collaborative study tested these questions. Thirty crab pots, representing ten commonly-designed recreational Dungeness crab pot models, were placed in water tanks at NOAA’s National Marine Fisheries Service facility in Mukilteo, near Seattle. Dungeness crabs were individually tagged (a total of 350 crabs were used!) and were placed in the pots. Food for the crabs was placed outside the pots, adding extra incentive for the crabs to escape. The escape mechanism was then activated (by cutting an escape cord which would disintegrate if left in the water for a period of time) and the number of crabs escaping from the pots was tracked daily for two weeks. The study was repeated three times.
The results were remarkable. In two models, nearly 100% of the crabs trapped in the pots escaped after the escape mechanism was activated. Another model allowed nearly 90% of the crabs to escape. But in the other three models, only 10% or less of the crabs escaped. Even two weeks after the escape mechanism was activated, 90% of the crabs remained trapped in those models. The study then explored modifications to increase escapement rates. The great news is that after implementing simple modifications and repeating the escape experiment, all pots achieved the desired nearly 100% escapement rate.
The study, a Fishing for Energy Partnership grant managed by the National Fish and Wildlife Foundation with funding from the NOAA Marine Debris Program, was led by the Northwest Straits Foundation, in partnership with Natural Resource Consultants, NOAA Fisheries, and the Washington Department of Fish and Wildlife. The results were shared with state agencies, and hopefully will contribute to gear modification and improvements of crab pot design and their escape mechanisms, and in a larger sense, reduce the mortality of crabs and other species associated with the loss of crab pots in the Puget Sound and elsewhere.
For more information on this project, visit the project profile page on our website.