Breaking strength evaluation of biodegradable twines to reduce ghost fishing in the pot and trap fisheries of Chile
Passive fishing gears such as pots and traps can be constructed with a section of netting made from natural fibers. In the event the fishing gear is lost or abandoned, these fibers deteriorate which effectively disables the fishing gear and allows organisms which accidentally enter the gear, an opportunity to escape without harm. This study evaluated several twines manufactured from natural fibers for their suitability to reduce ghost fishing in pots and traps. Nine cotton and jute twines of different diameters and construction were selected from Valparaiso local market, Chile. The twines were submerged for 56 days in seawater under laboratory conditions. Measurements of breaking strength were performed every 14 days. A decrease in the mean breaking strength was observed after 56 days for all twines, ranging from 0.5 to 29.6% for jute twines and 12.8 to 71.7% for cotton twines. The time until total degradation was predicted to be 113-230 days for the twisted jute twines, 68-234 for the twisted cotton twines, and 108-205 for the braided cotton twines. Our results suggest that cotton twines are a more suitable and feasible option to be implemented. The need to perform trials of biodegradable devices under commercial fishing conditions is warranted.