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Project O.2.a - Develop and implement analytical tools for understanding the trophic ecology of apex predators

01 Jun 2018 - 01 Apr 2019

Program(s) in charge: Ecosystem & Bycatch Program
  • To further develop and validate statistical tools for the analysis of complex datasets in trophic studies of apex predators.
  • To enhance external collaborations and professional development through the analysis of Atlantic bluefin tuna diets in relation to biological and environmental variables.
  • IATTC staff have developed an innovative approach for analyzing complex diet data using classification trees. The approach has been used for regional diet studies of yellowfin tuna in the EPO and for a broad-scale global comparison of yellowfin, bigeye and albacore diets.
  • To facilitate more widespread adoption of the method, it requires validation of regional studies in other ocean basins, given the importance of spatio-temporal differences in available prey taxa.
  • Collaboration with other scientists studying the trophic ecology of apex predators can assist with validating the approach, while also enhancing collaborative relationships.
Relevance for management
  • Optimizing statistical tools to analyse trophic data is crucial for understanding the trophodynamics of apex predators in the EPO and whether predator-prey relationships may be impacted by fishing.
  • Diet analyses are fundamental for the identification of ecological functional groups, which are required in the development of ecosystem models to understand the potential ecological impacts of fishing.
  • Integrating environmental factors into analyses of regional studies provides managers with information on effects of climate change on variation in forage communities to verify observed global patterns.
9 months
Workplan and status
  • Jun 2018: data analyses
  • Aug – Nov 2018: Discuss preliminary outputs with collaborators and implement necessary collaborator inputs into method development
  • Nov 2018-Mar 2019: Manuscript preparation
External collaborators
Massachusetts Division of Marine Fisheries; numerous other universities and government agencies
Manuscript summarizing the revised approach, using an Atlantic-wide analysis of bluefin trophic ecology as a case study.
Updated date: 01 May 2023
Progress summary for the reporting period
Improvements have been made to a statistical tool for analyzing complex diet data, developed in collaboration with scientists at CSIRO (Australia), used to represent trophic interactions in ecosystem models
Challenges and key lessons learnt
  • The project has previously been stalled pending provision of data by external collaborators and then by COVID-19. Data assembly and quality checking of the various datasets by external collaborators is expected to occur in 2022.
  • Exploratory analyses and initial classification trees commenced in late 2022, and results were sent to the Principal Investigator at the Massachusetts Division of Marine Fisheries. Collaborative discussions and initial manuscript drafts are expected to occur in 2023.
The statistical tool is being used by various organizations, including IRD (France) and SPC.