Jacuna tuna fish landing. Puerto Princessa, Philippines.  © Jürgen Freund/WWF Canon

Project

BESTTuna: Monitoring tunas in the Pacific

Across the world’s oceans float thousands of rafts, placed there by fishermen to increase their catches of tunas including yellowfin, bigeye and skipjack. These rafts, known as Fish Aggregating Devices (FADs), can be simply floating tree logs, shelters under which fish tend to congregate, or bamboo rafts with ropes anchored to the sea soil. Large companies often create rafts from steel and foam constructions. The use of FADs has dramatically improved the tuna catches. However, NGOs and governments worry about overfishing of (juvenile) tuna and other fish species, and until now there is little monitoring and regulation of the FADs.

Across the world’s oceans float thousands of rafts, placed there by fishermen to increase their catches of tunas including yellowfin, bigeye and skipjack. These rafts, known as Fish Aggregating Devices (FADs), can be simply floating tree logs, shelters under which fish tend to congregate, or bamboo rafts with ropes anchored to the sea soil. Large companies often create rafts from steel and foam constructions. The use of FADs has dramatically improved the tuna catches. However, NGOs and governments worry about overfishing of (juvenile) tuna and other fish species, and until now there is little monitoring and regulation of the FADs.

To help quantify the effects on the ecosystem, two PhD candidates from AFI investigated how fishermen are using these rafts in Indonesia and the Philippines. According to their field work, fishermen do not seem to use signals from nature (such as sea currents or the prevalence of birds) to put their rafts on specific, tuna-rich places. So the distribution of the rafts seems random and not restricted to specific places. This means that possible regulations to reduce pressure could be restricting the number of FADs per hectare or per fisher.

The two PhDs, Widhya Nugroho Satrioajie and Edison Macusi, are part of the interdisciplinary programme BestTuna, in which AFI collaborates with the Wageningen chair Environmental Policy, three other chairgroups, four Asia-Pacific universities and WWF. Using acoustic radio tags and sensors to monitor (juvenile) tuna’s biomass build-up and movements below FADs is one of the steps that will be taken coming months. The cordon of FADs around the islands are moving further and further away from the coast lines, in the Philippines already up to 400 kilometres. This worsens the situation for poor fishermen, who often have to work at a vessel or a bamboo raft for months. The BestTuna team wants to know, among other things, if tuna species can re-colonize the sea near the coast by bypassing the rafts.



BESTTuna projectproposal

More information

IFITT is an other colaboration between AFI and BESTTuna. For more information about, please see link