Funded
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- Objectives
- To use presence-only catch data to develop habitat models for all bycatch species caught in EPO tuna fisheries to facilitate mapping of their geographic range.
- To make distribution maps available in a format suitable for use as base maps for ecological risk assessment models (PSA, EASI-Fish)
- Background
- Many bycatch species caught in EPO tuna fisheries lack sufficient biological and catch data to undertake traditional stock assessment to determine their vulnerability to fishing.
- Data-limited Ecological Risk Assessment (ERA) methods are now increasingly used to determine the most vulnerable species to fishing, which have a strong reliance on estimating impacts using the overlap of fishing effort with a species’ distribution.
- Given the success of using the EASI-Fish approach for assessing the vulnerability of data-poor bycatch species in the EPO (e.g. sharks, devil rays, leatherback turtles), further development of SDMs for other species is required.
- Relevance for management
- Developing habitat models for bycatch species will improve the fishing mortality estimates using ERAs, from which their status can be determined and guide managers.
- Duration
- 24 months
- Workplan and status
- Jun-Dec 18: model development using data-rich species
- Jan-Feb 19: apply habitat model to bycatch species
- Mar-April 19: Finalize habitat maps for bycatch species
- May 19: present final model and assessment results at SAC-10.
- Jun 21-Sept 22: use Pacific-wide datasets to explore the use of a range of alternative SDMs in isolation or as ensembles for shark species caught in EPO pelagic fisheries
- External collaborators
- CPCs, SPC
- Deliverables
- Presentations at SAC-10, SAC-13 and at WCPFC, if required.
- Procedure, if successful, to be used annually within ERA models to assess the vulnerability of bycatch species in the EPO.
- Updated date: 01 May 2022
- Progress summary for the reporting period
- Initial models were developed using Integrated Nested Laplace Approximation (INLA) and Generalized Additive Models (GAMs) for one species of mobulid, and the leatherback turtle, which formed the basis of EASI-Fish assessments for these species.
- Subsequent explorations of SDMs were undertaken in 2021-2022 for 32 shark species caught in the EPO, in collaboration with SPC staff.
- Challenges and key lessons learnt
- Even highly sophisticated models in data-rich settings can predict habitat poorly, depending on the environmental data used for the prediction.
- It is likely that many more presence points occur within the EEZ of coastal nations in the EPO, however, obtaining high resolution data from domestic fisheries is a major challenge.
- Five manuscripts that use the habitat models have been published in scientific journals or given as IATTC presentations:
- Griffiths, S.P., Lezama-Ochoa, N., 2021. A 40-year chronology of spinetail devil ray (Mobula mobular) vulnerability to eastern Pacific tuna fisheries and options for future conservation and management. Aquatic Conservation: Marine and Freshwater Ecosystems 31, 2910–2925.Griffiths, S.P., Lezama-Ochoa, N., Román, M.H., 2019. Moving towards quantitative ecological risk assessment for data-limited tuna fishery bycatch: application of “EASI-Fish” to the spinetail devil ray (Mobula mobular) in the eastern Pacific Ocean. 9th Meeting of the IATTC Working Group on Bycatch, 11 May 2019, San Diego, California, USA. Document BYC-09-01.
- Griffiths, S.P., Kesner-Reyes, K., Garilao, C., Duffy, L.M., Román, M.H., 2019. Ecological Assessment of the Sustainable Impacts of Fisheries (EASI-Fish): a flexible vulnerability assessment approach to quantify the cumulative impacts of fishing in data-limited settings. Marine Ecology Progress Series 625, 89-113.
- Griffiths, S.P., Wallace, B., Swimmer, Y., Alfaro-Shigueto, J., Mangel, J.C., Oliveros-Ramos, R., 2020. Vulnerability status and efficacy of potential conservation measures for the east Pacific leatherback turtle (Dermochelys coriacea) stock using the EASI-Fish approach. 10th Meeting of the IATTC Working Group on Bycatch, 10 September 2020, La Jolla, California, USA. Document BYC-10-01.
- Griffiths, S.P., Fuller, L.M., Potts, J., Nicol, S., 2022. Vulnerability assessment of sharks caught in eastern Pacific Ocean pelagic fisheries using the EASI-Fish approach. 13th Meeting of the Scientific Advisory Committee of the IATTC, 16-20 May 2022, La Jolla, California, USA. Document SAC-13-11, 80.