Biodegradable twine for trawl fishing: Seawater ageing and net modelling

Fishing gears are designed to catch marine species, but when lost at sea, they can continue to trap and kill aquatic life, a phenomenon known as ghost fishing. This study evaluated the use of a biodegradable twine made from poly(butylene succinate)/poly(butylene adipate terephthalate) (PBS/PBAT) in trawl fishing. The assessment included mechanical testing, trawl modelling, and seawater ageing simulations to explore potential loss scenarios. Mechanical tests indicated that the PBS/PBAT braid was about half as strong as high-density polyethylene (HDPE) but was suitable for braiding and netting. After 3 years in seawater, PBS/PBAT monofilaments showed biotic degradation, with strength losses of 20 % at 15 °C and 80 % at 25 °C. This suggests that gear made from this polymer would degrade faster than conventional gear if lost. Trawl modelling further demonstrated that trawl performance was only slightly affected by material change and ageing, highlighting the potential for reducing ghost fishing with less persistent twine.