Non-Entangling & Biodegradable FADs Guide

ISSF’s Non-Entangling & Biodegradable FADs guide for tuna fishers, Regional Fisheries Management Organizations (RFMOs), governments, and vessel owners shows research-based best practices in Fish Aggregating Device (FAD) design — both to avoid bycatch and reduce marine pollution.

Four tuna RFMOs already require fleets in their regions that fish with FADs to use only non-entangling designs. Some RFMOs additionally encourage fleets to build those FADs with biodegradable materials. The guide, first published in 2012 and revised in 2019 to include the biodegradable recommendation, is available in several languages.

ISSF 2017-01: Computing a Global Rate of Non-Target Species Catch (Bycatch) in Tropical Tuna Purse Seine Fisheries*

Date Added: February 9, 2017
Downloaded: 558 times
Tags: Bycatch, Justel-Rubio, Purse Seine, Restrepo, science, Tuna
Authors: Justel-Rubio, Restrepo
Language: English
Author(s): Ana Justel-Rubio & Victor Restrepo
Featured: False
Report Type: Technical Report


We present estimates of bycatch rates for the tropical tuna purse seine fisheries using observer data for 2011-2015 from all oceans.

The term “bycatch” refers to the catch of anything that is not the main reason for which the skipper is fishing, irrespective of its fate (retain or discarded). The target tunas in this fishery are skipjack, yellowfin and bigeye. Note, however, that many of the incidental catches, such as small tuna species, are valuable and are retained and end up being marketed and consumed. Therefore, we also present estimates of bycatch rates excluding minor tunas.

We estimate the average 2011-2015 global bycatch rate to be 1.4% of the target tunas caught (0.92% if minor tunas and bonitos are excluded), which is low for a large industrial fishery. Some organizations and individuals give importance to such a single number as a proxy for measuring the environmental impact of a fishery. 

However, the magnitude of a bycatch rate does not necessarily imply a given level of concern (or lack of it) for any particular species. For example, a bycatch rate of 10% may be of no concern for one species that is highly productive, while one of 1% may be of concern for another, less productive one. 

The impact of fishing on individual species, target and non-target, needs to be assessed through adequate monitoring and research.