Ultra High Molecular Weight Polyethylene (UHMWPE): New generation netting material for energy and resource conservation in fisheries

Abstract

Invention of synthetic fibre was a major development which revolutionized the fishing industry. By mid-20th century, synthetic fibres have replaced natural fibres in fish netting and ropes. Ultra-high Molecular Weight Polyethylene (UHMWPE) fibre available under the trade names Dyneema / Spectra is a recent introduction in the fishing sector. Dyneema, the strongest manmade fibre, was invented by DSM, Netherlands in 1974 and commercialized in 1990. Among many applications, due to its excellent strength, this fibre is best suited for ropes, trawls, purse seines and lines. UHMWPE fibre has a low weight/strength ratio, by which, a thinner material (1/3rd of nylon) can be used for fishing purpose thereby considerably reducing drag. Though manufacturers claim upto 40% savings on fuel, it was not tested in India. For the first time in India, ICAR-CIFT took up a study in collaboration with DSM India and Garware Wall Ropes Ltd., and proved that use of UHMWPE trawls reduced drag by 15% reduction and a 10% saving on fuel in comparison to PE trawls. Since the material has low elongation (<5%) and do not shrink in water, mesh size remain intact allowing better filtration and reduction in bycatch. In purse seining, UHMWPE fibre facilitates good water filtering, reduced drag and faster sinking of the net. Designs with substantial weight reduction and faster sinking speed by substituting certain portions of nylon mini purse seine with UHMWPE were developed by ICAR-CIFT. Although empirical results show better performance, trials are to be carried out to get real time results. As the material is highly bite resistant, depredation problem by puffer fish and dolphin can also be prevented. UHMWPE ropes can be used in trawling to substitute wire ropes which helps in weight reduction, drag reduction, fuel saving and a clean catch devoid of oil and grease contamination. Fishing trials conducted by ICAR-CIFT using UHMWPE rope of 12 mm dia. for the past five years, proved it as a very good substitute to steel wire rope. UHMWPE webbing is a very good choice for cages by providing better water exchange and low resistance. Thus UHMWPE is a ‘green fibre’ for the fisheries industry of the Country for energy saving and resource conservation.