Alaska Department of Fish and Game Tests Twine for Crab Pots Using ADMET eXpert System
The Alaska Department of Fish and Game (ADF&G) has broad responsibilities including oversight of the crab fisheries in Alaskan waters. A consequence of the pot gear used by the industry is a phenomenon called “ghost fishing,” which happens when functional pots are lost but continue to trap and kill crabs and other organisms. In response, regulations were enacted that require one sidewall of all crab pots have an opening that is secured with a biodegradable 100% cotton twine that would break down over time, fail and allow the trapped organisms to escape.
The twine, which is expected to secure the pots for approximately 30 days, degrades over time due to biological activity that breaks down the cellulose in the twine. At the end of 30 days, the twine should degrade to the point that it fails so the crabs and other organisms can escape. “Soak time” is the primary determinant of twine failure.
The ADF&G staff determined that tensile testing the twine under controlled conditions would provide necessary empirical data. The study will measure how quickly the twine loses tensile strength and/or elasticity with increased soak times.
The ADF&G staff considered field-testing twine using actual crab pots, but it would have required a large vessel, been labor intensive, and expensive. Ultimately, they decided to use a controlled study and eliminate as many variables as possible.
David Barnard, the Biometrician for the program, prepared a project proposal and then researched universal testing machine providers. ADMET offered the lowest price and was able to satisfy all of ADF&G’s requirements with a simple and easy to use system.
Barnard ordered an eXpert 5601 tabletop machine equipped with an eP2 Digital Controller, a standalone touch panel controller that offers a balance between performance and simplicity, GaugeSafe data exchange software and a set of grips.
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