Proposed Abstract Title

Determining Effectiveness of Dungeness Crab Escapement in Derelict Traps Commonly used in the Washington Waters of the Salish Sea

Type of Presentation

Oral

Session Title

Plastic in the Salish Sea

Location

2016SSEC

Description

The prevalence and impacts of derelict crab traps in the Washington waters of the Salish Sea have been well documented by partnering organizations and agencies within the region. Several efforts have been made to reduce trap loss, extract accumulated traps and reduce the impacts (i.e., Dungeness crab mortality, habitat degradation) of traps that become derelict. When properly equipped with legally compliant biodegradable escape cord, a derelict trap becomes “disabled” upon escape cord degradation, allowing an egress route for entrapped crab to escape. However, among the multiple trap designs commonly used in the region, the effectiveness of escapement varies. A laboratory experiment simulating derelict traps was conducted to analyze the escapement effectiveness of 13 trap designs, some equipped with simple modifications. The least successful trap designs in allowing crab escapement were those with escape routes that require crab to push open a door situated on the topside of the trap, offset from the edge. Escapement effectiveness in these traps improved when equipped with a bungee, designed to spring the door open upon escape cord degradation, but escape rates still did not reach the desired 1.00 escapee per crab tested. The traps most successful at allowing crab escapement were those that provided an unobstructed escape panel either on the wall of the trap or along the edge of the topside of the trap. Traps that are not initially designed with this feature can be easily modified by detaching one escape ring, and re-attaching it with escape cord. The opening in the trap following escape cord degradation from the ring falling to the seafloor provides crab the ability to freely escape. This was the first reporting of escapement effectiveness from derelict crab traps of the region, and results can assist in resource management and gear manufacturing decisions.

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Determining Effectiveness of Dungeness Crab Escapement in Derelict Traps Commonly used in the Washington Waters of the Salish Sea

2016SSEC

The prevalence and impacts of derelict crab traps in the Washington waters of the Salish Sea have been well documented by partnering organizations and agencies within the region. Several efforts have been made to reduce trap loss, extract accumulated traps and reduce the impacts (i.e., Dungeness crab mortality, habitat degradation) of traps that become derelict. When properly equipped with legally compliant biodegradable escape cord, a derelict trap becomes “disabled” upon escape cord degradation, allowing an egress route for entrapped crab to escape. However, among the multiple trap designs commonly used in the region, the effectiveness of escapement varies. A laboratory experiment simulating derelict traps was conducted to analyze the escapement effectiveness of 13 trap designs, some equipped with simple modifications. The least successful trap designs in allowing crab escapement were those with escape routes that require crab to push open a door situated on the topside of the trap, offset from the edge. Escapement effectiveness in these traps improved when equipped with a bungee, designed to spring the door open upon escape cord degradation, but escape rates still did not reach the desired 1.00 escapee per crab tested. The traps most successful at allowing crab escapement were those that provided an unobstructed escape panel either on the wall of the trap or along the edge of the topside of the trap. Traps that are not initially designed with this feature can be easily modified by detaching one escape ring, and re-attaching it with escape cord. The opening in the trap following escape cord degradation from the ring falling to the seafloor provides crab the ability to freely escape. This was the first reporting of escapement effectiveness from derelict crab traps of the region, and results can assist in resource management and gear manufacturing decisions.