Dire straits of yellowfin tuna
Kristina Heidrich et al. | December 2023
New publication
Highlights
Multiple lines of evidence confirm that Indian Ocean yellowfin tuna are in dire straits
IUCN classifies Indian Ocean yellowfin tuna as ‘Vulnerable’ and biomass trajectories estimate a decline of ∼70% since 1950.
Ecological data from baited remote underwater video systems (BRUVS) indicate that Indian Ocean yellowfin tuna are least common, least abundant, and smallest across all oceans, the first application of BRUVS as a fisheries independent methodology.
This approach opens up additional avenues to understanding the conservation status of other large pelagic species such as oceanic sharks.
Abstract: Yellowfin tuna (Thunnus albacares) are highly valued pelagic fisheries target species. Regional fisheries management organizations (RFMOs) are the principal mechanism that manage yellowfin tuna fisheries. Determining changes in population abundances is crucial for effective conservation and management. We use a range of alternative methods for monitoring biomass trends and evaluating the status of yellowfin tuna in each ocean basin and show how additional, multiple lines of evidence can enhance our understanding of the conservation and exploitation status of this species. Our analysis of regional biomass trajectories and Catch-MSY++ assessments corroborate the findings of the most recent RFMO stock assessments suggesting yellowfin tuna in the Indian Ocean are in critical condition, while the Eastern Pacific yellowfin tuna population shows the lowest levels of overexploitation. These results are supported by fisheries-independent data from baited remote underwater video systems (BRUVS), showing that the Indian Ocean yellowfin tuna population is the least common, least abundant, and smallest across all oceans. Our findings support previous claims of systematic and widespread overfishing of yellowfin tuna in the Indian Ocean and thus confirm calls to reduce current fishing levels to ensure the long-term viability of the species.
A yellowfin tuna having a scratch as observed on a BRUVS