Climate Change Projected to Shift Tuna Fisheries in Tonga Waters: Urgent Measures Needed

A new study led by The University of the South Pacific (USP) PEUMP Candidate Siosaia Vaihola, reveals that climate change will significantly impact the distribution and abundance of tuna species in Tonga’s Exclusive Economic Zone (EEZ).

The research, titled Climate Change Potential Impacts on the Tuna Fisheries in the Exclusive Economic Zones of Tonga is funded by the European Union and the Government of Sweden through the Pacific-European Union Marine Partnership (PEUMP) programme.

It has crucial implications for the sustainable management and conservation of Tonga’s most valuable commercial fisheries.

Key Findings:

• Species Impacted: The study focuses on four economically vital tuna species—albacore (Thunnus alalunga), bigeye (Thunnus obesus), skipjack (Katsuwonus pelamis), and yellowfin (Thunnus albacares).
• Climate Scenarios: The researcher used species distribution modelling to predict the impact of four climate change scenarios (RCP 2.6, RCP 4.5, RCP 6.0, and RCP 8.5) on these species.
• Future Projections: The models indicate a likely expansion and southward shift of productive tuna areas within Tonga’s EEZ by the year 2100, especially under the RCP 8.5 scenario.
• Environmental Variables: Predictions were based on a comprehensive set of environmental data and Catch Per Unit Effort (CPUE) datasets.

Implications:

The findings suggest that future climate conditions might create favourable habitats for these tuna species in the southern regions of Tonga’s EEZ. However, the study cautions that changes in ocean currents, chemistry, and trophic layers could alter these projections.

Lead author Siosaia Vaihola explains, “While our models predict an increase in suitable areas for tuna, the actual outcomes will depend on complex environmental interactions. This research underscores the need for adaptive management strategies to ensure the sustainability of tuna fisheries.”

Recommendations:

Sustainable Management: The study advocates for the implementation of adaptive management practices to sustainably harvest tuna populations under changing climatic conditions.

Further Research: It calls for more extensive studies incorporating additional environmental variables like dissolved oxygen, mixed layer depth, sea surface height, and chlorophyll-a concentration to refine predictions and aid in effective conservation planning.

This study is a critical reminder of the far-reaching impacts of climate change on marine resources and livelihoods.

“This groundbreaking research provides a vital foundation for the future conservation and management of tuna fisheries in Tonga” said Lavenie Tawake, USP PEUMP Team Leader.

“By anticipating the impacts of climate change, Tonga can better prepare for and mitigate potential disruptions to its crucial tuna industry.”

USP is one of four key implementing partners of the PEUMP Programme. The EUR 45 million programme promotes sustainable management and sound ocean governance for food security and economic growth while addressing climate change resilience and conservation of marine biodiversity.

It follows a comprehensive approach, integrating issues related to oceanic fisheries, coastal fisheries, community development, marine conservation and capacity building under one single regional action.

The PEUMP programme is housed within the Institute of Marine Resources within the USP School of Agriculture, Geography, Environment, Ocean and Natural Sciences (SAGEONS).

Click here to access the journal: https://www.mdpi.com/1424-2818/15/7/844