Completed
Funded
Click to see projects by theme, goal or target:
- Objectives
- Evaluate the performance of shallow non-entangling versus normal depth FADs in the EPO purse-seine fishery, with an emphasis on the tuna and non-tuna species catch composition; seeking a practical solution to reduce fishing mortality on small undesirable sizes of bigeye
- Background
- The fishing mortality of small bigeye caught in sets on FADs should be reduced, to increase the maximum sustainable yield from the bigeye fisheries in the EPO
- Bigeye tuna associated with FADs in the EPO exhibit deeper depth distributions than skipjack or yellowfin tunas
- The presence of bigeye in the EPO purse seine catch was reported to be more likely with deeper floating objects
- Relevance for management
- A potential solution for reducing fishing mortality on small undesirable sizes of bigeye and/or reducing fishing mortality on bycatch species associated with FADs, including sharks and turtles
- Duration
- 2015-2018
- Workplan and status
- 2015-2017: ISSF arranged for experiments to be undertaken at sea in collaboration with NIRSA, a seafood company located in Posorja, Ecuador, with a fleet of 11 purse-seine tuna vessels.
- The first experiment began in June-July 2015 with deployments of 50 shallow and 50 normal depth FADs and concluded on 31 October 2016. The second experiment began in March-May 2017 with deployments of 100 shallow and 100 normal depth FADs and concluded on 31 December 2017.
- 2018: The catch data collected by observers aboard NIRSA vessels from sets on the experimental FADs from the two experiments is being examined to confirm FAD types
- 2018: A statistical evaluation of the performance of the shallow non-entangling versus normal depth FADs, including the tuna and non-tuna species catch compositions, will be conducted
- External collaborators
- ISSF, NIRSA
- Deliverables
- Relevant information on performance of shallow non-entangling FADs versus normal FADs based on field experiments
- Full resolution FAD data was provided to the data team working on the POSEIDON model project
- Manuscript for peer review and publication in a scientific journal
- Updated date: 01 Jun 2019
- Progress summary for the reporting period
- Analyses of the catch-per-set data for tunas and non-tuna species, coupled with corresponding effort and environmental data, were completed.
- Manuscript in final stages of preparation for submission to a peer-reviewed scientific journal in 2019
- Analyses complete and manuscript accepted for publication.
- Challenges and key lessons learnt
- There is no significant difference in the catch by tuna species, or the catch of total tunas between shallow (5m depth) non-entangling dFADs and a traditional dFAD design (40m depth) in the EPO.
- Drift speeds between shallow (5m depth) non-entangling dFADs and a traditional dFAD design (40m depth) were not significantly different.
- Satellite buoy echo-sounder data was compared to total tuna catch to evaluate whether echo-sounder biomass estimates were accurate. Results from the evaluation of 67 sets indicated that there is no correlation between biomass reported under the buoy and what the vessel captured. Eighty-five percent of the buoy estimates over estimated biomass by a considerable margin.
- Schaefer, K.M., Fuller, D.W. and Chaloupka, M., 2021. Performance evaluation of a shallow prototype versus a standard depth traditional design drifting fish-aggregating device in the equatorial eastern Pacific tuna purse-seine fishery. Fisheries Research, 233, p.105763.