Presentation Abstract

An estimated 12,193 pots become derelict each year in Puget Sound accounting for the annual mortality of 178,874 legal sized male Dungeness crab.1 Washington State law requires that all crab pots be equipped with biodegradable escape cord that will disintegrate over a period of time, disabling the pot by providing entrapped crab an egress route previously held closed by the escape cord. However, field observations during the Northwest Straits Foundation’s removals of over 5,000 derelict crab pots from Puget Sound have shown that disabling mechanisms for derelict crab pots do not always guarantee escapement. A 2007 study on Dungeness crab mortality in Washington’s Salish Sea documented crabs entering and dying in crab pots which had been disabled. A laboratory experiment simulating derelict crab pots was conducted to analyze the escapement effectiveness of 13 pot designs, and to test simple modifications. Crab pots equipped with an escapement route requiring crab to push open a door on the topside of the pot were least effective. Pots which provided an unobstructed escapement route either on the side wall or the topside edge of the pot were most effective, resulting in 1.00 escapee per crab tested. A simple modification of removing one escape ring and reattaching it on crab pots without unobstructed escape routes produced the desired escapement rate of 1.00 escapee per crab tested.

Session Title

Posters: Habitat Restoration & Protection

Keywords

Derelict gear, ghost gear, marine debris, crab pots, crab traps, Dungeness crab

Conference Track

SSE18: Posters

Conference Name

Salish Sea Ecosystem Conference (Seattle, WA : 2018)

Document Type

Event

SSEC Identifier

SSE18-85

Start Date

5-4-2018 11:30 AM

End Date

5-4-2018 1:30 PM

Type of Presentation

Poster

Contributing Repository

Digital content made available by University Archives, Heritage Resources, Western Libraries, Western Washington University.

Geographic Coverage

Salish Sea (B.C. and Wash.)

Rights

This resource is displayed for educational purposes only and may be subject to U.S. and international copyright laws. For more information about rights or obtaining copies of this resource, please contact University Archives, Heritage Resources, Western Libraries, Western Washington University, Bellingham, WA 98225-9103, USA (360-650-7534; heritage.resources@wwu.edu) and refer to the collection name and identifier. Any materials cited must be attributed to the Salish Sea Ecosystem Conference Records, University Archives, Heritage Resources, Western Libraries, Western Washington University.

Type

text

Language

English

Format

application/pdf

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Apr 5th, 11:30 AM Apr 5th, 1:30 PM

Testing the effectiveness of escapement mechanisms in derelict crab pots

An estimated 12,193 pots become derelict each year in Puget Sound accounting for the annual mortality of 178,874 legal sized male Dungeness crab.1 Washington State law requires that all crab pots be equipped with biodegradable escape cord that will disintegrate over a period of time, disabling the pot by providing entrapped crab an egress route previously held closed by the escape cord. However, field observations during the Northwest Straits Foundation’s removals of over 5,000 derelict crab pots from Puget Sound have shown that disabling mechanisms for derelict crab pots do not always guarantee escapement. A 2007 study on Dungeness crab mortality in Washington’s Salish Sea documented crabs entering and dying in crab pots which had been disabled. A laboratory experiment simulating derelict crab pots was conducted to analyze the escapement effectiveness of 13 pot designs, and to test simple modifications. Crab pots equipped with an escapement route requiring crab to push open a door on the topside of the pot were least effective. Pots which provided an unobstructed escapement route either on the side wall or the topside edge of the pot were most effective, resulting in 1.00 escapee per crab tested. A simple modification of removing one escape ring and reattaching it on crab pots without unobstructed escape routes produced the desired escapement rate of 1.00 escapee per crab tested.