Evaluation of dFAD construction materials in the WCPO

Citation
Escalle L, Brouwer S, Pilling G (2018) Evaluation of dFAD construction materials in the WCPO. In: WCPFC Scientific Committee 14th Regular Session. WCPFC-SC14-2018/EB-IP-01, Busan, Republic of Korea, p 14
Abstract

Drifting Fish Aggregating Devices (dFADs) are widely used in the WCPO purse seine fishery, and have the potential to lead to ecosystems impacts such as ghost fishing, tuna school fragmentation, marine pollution and damage to coral reef or coastal areas. To mitigate these impacts, through CMM 2017-01 the WCPFC encourages the use of biodegradable and non-entangling dFAD materials. This paper reviewed the materials used to construct dFADs, as recorded by observers over the last 8 years. DFAD design was divided into i) the raft itself, including some components to ensure buoyancy and often covered by old nets or sacking to reduce detection by other vessels and ii) submerged appendages. For these two parts of dFADs, the use of natural (e.g. bamboos, trees, branches, natural debris, coconut fronds, planks, pallets, timbers) and artificial (e.g. floats, metal or plastic drums, pipes, cords, ropes, sacks, bags) materials was investigated.
Over the period 2011 to 2018, less than 2% of dFADs were made of completely natural materials and between 20–35% of dFADs investigated annually (observers record during deployment, fishing, servicing or visiting a dFAD) were made of completely artificial materials. No temporal trend in material use was detected. All fleets primarily used rafts that were either i) completely artificial or ii) a mix of artificial and natural materials, with artificial submerged appendages, to construct their dFADs. Fleets using rafts with mostly natural materials (although only in 8–14% of their dFADs) were Indonesia, Philippines, and Solomon Islands, using bamboo, planks or logs in the raft, with either no appendages or artificial appendages. However, even for those fleets, the occurrence of natural rafts remained occasional, with the majority of their rafts made of floats. Some specific dFAD designs include: i) bamboo rafts used by EU Spain, Ecuador and El Salvador; and ii) Philippines design drum rafts. Appendages were, however, almost always artificial, with a combination of cord, net, sacking or sheeting and weights.
The presence of nets used as appendages on dFADs was specifically investigated as an indication of the entangling potential of dFADs. Less than 12% of the dFADs had no netting, with no trend over time. However, the analysis detected a slight increase in the use of nets in both appendages and rafts over time. Philippines (42%), Tuvalu (31%) and Indonesia (26%) were fleets using the least netting within their dFADs construction.
Overall, natural and non-entangling dFAD materials appear seldom used in the WCPO. Non-entangling dFAD designs are well known and biodegradable dFAD designs are currently on trial at sea in other oceans (see Appendices for review of non-entangling and biodegradable dFADs). However, appropriateness of these dFAD designs (e.g. cost, material availability and effectiveness) for the WCPO still needs to be investigated.
We invite WCPFC-SC14 to:
- Note the materials currently used in dFADs in the region. In particular, the limited use of non-entangling and biodegradable materials, as well as the variability among fleets.
- Note the review of biodegradable materials and non-entangling dFAD designs from research projects in other oceans.
- Consider potential research activities and at-sea trials of biodegradable and non-entangling design options in the WCPO and provide corresponding advice to the FAD Management Options Intersessional Working Group.