Evaluating potential biodegradable twines for use in the tropical tuna FAD fishery

Abstract

Despite several ecological and environmental concerns (e.g. increasing marine debris, stranding events), thousands of man-made drifting Fish Aggregating Devices (FADs) are deployed annually by the industrial tuna purse seiners worldwide. Yet, the use of biodegradable materials to construct the underwater part of the FAD has not been explored in detail to date. In this study, scientists, industry, and twine manufacturers collaborate to test and evaluate different potential biodegradable materials and twine designs that can be used in the FAD fishery. Results showed that different materials and designs degrade differently over the study period and that they play an important role in the lifetime of the twines. Results showed that the estimated time to failure (i.e. when breaking strength reaches 0 kgf) ranged between 193 and 557 days for the tested twines. Because twine performance may vary in real fishing tropical conditions, we recommend further experiments in which a new specific twine should be developed and tested: a twisted and bulked cotton, sisal and linen twine. The use of new biodegradable materials and designs are discussed under a global perspective, as well as its implications for conservation, management and relevant future lines of investigation.