A Degradable Escape Panel Specification for Fish Traps: A Cotton-Twine Fastener That Ends Ghost Fishing Within Thirty Days

A lost fish trap does not stop fishing. Its bait draws a first catch, the catch itself becomes bait for the next, and the trap can go on taking fish long after its owner has written it off. This study first models that process: with a first cycle of 14 fish, six-day cycles, and each cycle retaining 0.78 of the previous cycle's catch as self-bait, a lost trap fishes for 97.2 days and takes 62.5 fish before its per-cycle catch fades below a quarter of a fish. The study then originates a specification for a degradable escape panel intended to stop a lost trap within a chosen deadline of 30 days: a buoyant 200 mm by 200 mm panel held shut by four ties of untreated cotton twine, sized so that seawater decay brings the twine's strength down to the panel's steady opening load at the right time, neither during normal service nor long after the deadline. The computed fastener rule accepts twine diameters from 2.35 to 2.75 mm; the nominal 2.5 mm tie, with an initial breaking strength of 12.5 kgf and a strength half-life of 8.75 days, opens the panel at 24.5 days, still shows a safety factor of 1.77 against the greatest service load after the longest permitted 10-day service interval, and cuts the lost trap's fishing life by 74.8 percent, preventing 21.9 of the 62.5 fish (35.1 percent) the unprotected trap would have taken. This study is simulated, not measured.