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Bycatch In Small-Scale Tuna Fisheries


Three studies of tuna fishery bycatch have been commissioned by FAO: investigations covering the purse seine, longline and small-scale fisheries. This document presents the results of the work on the small-scale tuna fishery bycatch and the associated issues.

Executive summary

It is intended to summarise on a national level catch information of small-scale tuna fisheries and those small-scale fisheries that catch tuna. The document also aims to identify on a global scale data gaps, major issues and management concerns associated with these fisheries and their bycatch.


Bycatch from purse seining and longlining has been the subject of a considerable amount of research. Small-scale tuna fishing and the associated bycatch have received relatively little attention, and no work has been carried out to obtain a global overview. In addition, several recent studies link small-scale fisheries to bycatch of threatened species.

The various uses of the term bycatch cause considerable confusion, especially for a global study that encompasses several areas that use the term differently. Many fisheries specialists in the various regions of the world believe that their definitions of bycatch are universal (or at least should be).

The concept of bycatch may have limited relevance to small-scale fisheries in developing countries, where almost everything in the catch has economic value and can become a target.

This document attempts to avoid using the term bycatch when estimating national catches. It is replaced by the term non-tuna species. When bycatch is used, it is synonymous with non-target species, regardless of whether retained or discarded.

Small-scale fisheries

In this document, small-scale fisheries is defined as those fisheries that use vessels that are open or partially undecked, or vessels that use outboard engines or sails, or vessels that fish with handlines, rod-and-reel gear, harpoons or similar non-industrial gear.

Catch estimates

The study made estimates of tuna and non-tuna catches in the small-scale fisheries of 181 country ocean areas. The total amount of tuna produced by these fisheries was about 681 000 tonnes per year in the mid-2000s. About 753 000 tonnes of non-tuna was produced by those same fisheries.

Important production areas

The East and Southeast Asia region produces about 72 percent of the worlds tuna catches by small-scale fishing. The Indian Ocean produces about 21 percent. Comparisons between the non-tuna catches of the various regions are not very meaningful much of the non-tuna catch is made by fisheries in which tuna is a minor component and should not be construed to be the bycatch of the small-scale tuna fisheries of a region.

Indonesias small-scale pelagic fisheries appear to produce about 390 000 tonnes of tuna and 519 000 tonnes of non-tuna. These estimates rely heavily on a recent World Wide Fund for Nature (WWF) report. Because this indicates that Indonesia is responsible for over half of the tuna caught by small-scale pelagic fishing in the world, efforts should be made to confirm the validity of that study.

Although some fisheries specialists contend that there are no small-scale fisheries that target tuna (i.e. there are only small-scale fisheries that take tuna as part of a catch), the study identified 15 small-scale fisheries that target tuna. These fisheries catch more than half of all tuna taken by small-scale fisheries.


Discarding in small-scale pelagic fisheries appears to be so low that it should not be considered a major problem or a priority for receiving management attention.

Bycatch reduction

Most small-scale fisheries that catch tuna are true multispecies fisheries in which there are no discards and perhaps no sensitive species in the composition of the catch. In these situations, the general thrust of reducing/eliminating bycatch may not be appropriate. What is required in many small-scale pelagic fisheries is attention to any components of the catch that are over-exploited, threatened, or protected.

Sensitive species

One of the most important issues in the bycatch of small-scale pelagic fishing is the capture of sensitive species, especially sea turtles and marine mammals. The targeted tuna fisheries are generally not problematic; most difficulties appear to occur with small-scale gillnets, a type of gear that rarely targets tuna, but that takes relatively large amounts of turtles and mammals.

There are a number of technical measures to decrease turtle bycatch in small-scale longline and gillnet fisheries. An important principle is that the development, design and implementation of turtle bycatch reduction measures should take into account the socio-economic aspects of fishers and fishing communities.

Information on techniques for reducing the incidental catch of marine mammals in small-scale pelagic fisheries is not as common as that for turtles. Much of the current work consists of developing appropriate strategies, such as better documenting the extent of the threat, capacity building for national fishery officers and generating national political will to take action.

Priorities for improving information

The major priorities for improving understanding of bycatch in small-scale pelagic fisheries are improved coverage of bycatch by the regional fisheries management organizations (RFMOs) that collect such information, increased involvement of the other tuna RFMOs in small-scale fisheries, additional information on the catch from small-scale pelagic fisheries in Indonesia, and greater technical details on the small-scale pelagic fisheries that are likely to be taking substantial quantities of sensitive species.

August 2011