By Pita Ligaiula in Manila, Philippines
The scientific advisory body for the Tuna Commission has raised alarms about the escalating impacts of climate change on the Western and Central Pacific region, highlighting how it is reshaping ocean ecosystems and tuna stocks. During the recent WCPFC22 meeting, the Secretariat of the Pacific Community (SPC) presented a comprehensive update on climate and ecosystem indicators, revealing a discernible trend of increasing ocean temperatures, expanding warm conditions, and rising ocean heat content alongside more frequent marine heatwaves.
These findings, presented in accordance with the Commission’s 2019 Climate Change Resolution, suggest that tuna fisheries are likely to face mounting pressures as the Pacific Ocean continues to warm. The SPC added that ongoing efforts are underway to establish a set of relevant climate and ecosystem indicators for annual reporting.
SPC noted that the El Niño-Southern Oscillation (ENSO), a significant climate driver in the Pacific, continues to influence fishing patterns. From 2020 to 2023, the Western and Central Pacific Ocean (WCPO) saw extended La Niña conditions followed by a brief and intense El Niño. Current conditions are now shifting towards neutral, with forecasts indicating that another El Niño event may start to develop by mid-2026. This dynamic is likely to influence the purse-seine fishing effort and may lead to increased catch rates of bigeye tuna by 2026.
Data on sea surface temperatures illustrate a persistent warming trend in various regions of the WCPO. The SPC reported that since 2010, all ten of the hottest years on record in specific regions have occurred, with 2024 noted as an anomalously warm year.
Region-specific analyses depict a warming of up to 1°C in some areas since the 1980s, while others demonstrate short-term temperature fluctuations linked to the movement of warm pools. Worryingly, the warm pool itself is becoming not only hotter but also has shifted its spatial distribution. Since 2014, waters exceeding 30°C have comprised an average of 30 percent of the warm pool area, with a peak of 55 percent recorded in August 2024—an indication of significant changes compared to previous decades.
The SPC’s report also highlighted rising ocean heat content (OHC) as a key indicator of long-term warming, showing consistent increases from 1993 to 2023, particularly near Papua New Guinea and the Solomon Islands.
In a striking assessment, SPC revealed that the region has not experienced a single day in the past decade without some portion being affected by marine heatwave (MHW) events. The frequency, duration, and intensity of these marine heatwaves have risen significantly, jeopardizing both ecosystems and the behavior of tuna species.
The indicators discussed aim to guide decisions related to WCPFC’s climate resolution and are expected to be refined ahead of SC22 in 2026. These advancements will assist in better understanding recent climate trends and their implications for management decisions in relation to tuna fisheries.
Amidst the ongoing discussions on harvest strategies and fish stock management, it’s clear from the SPC’s presentation that the effects of climate change are not merely hypothetical; they are pressing realities that are actively altering the structure of the world’s largest tuna fishery. As the fishing community grapples with these challenges, the hope remains that concerted efforts in climate-aware management strategies can help mitigate the impacts on marine ecosystems and ensure sustainable tuna fisheries for future generations.
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