The early impacts of global warming are expected to appear first in the lives of the most common species. Tuna and swordfish are likely to be the most affected, with notable declines predicted in many climate scenarios. Researchers at AZTI, the technology center based in the Basque Country, project that by 2050 tuna stocks could suffer an average 36 percent drop in productivity and a 15 percent reduction in size. These changes will ripple through the fishery sector, influencing demand, prices, and the overall profitability of the fishery in the years ahead.
This study links the combined pressures of climate change and fishing activity to potential shifts in the productivity and size of major commercial tuna and swordfish populations. A team of researchers and modelers from Europe and Canada collaborated on the work, which was published in Global Planetary Change.
Maite Erauskin-Extramiana, an AZTI researcher who coordinated the study, commented that the goal was to understand how climate change and fishing pressure could affect some of the most commercially vital species. The aim is to inform decisions that help secure future resource levels and the stability of fisheries revenues.
The analysis indicates that climate change and fishing pressure could collectively lower the future productive potential of key tuna species and swordfish by an average of 36 percent by 2050, signaling meaningful shifts for stock management and market expectations.
The results also suggest that high‑trophic species will feel more pressure from climate impacts if they operate near current maximum sustainable yield levels or continue existing fishing pressures. Notably, Pacific bluefin tuna might show a slight uptick, while five other species — Atlantic and southern bluefin tuna, swordfish, albacore, and yellowfin tuna — are expected to experience declines in biomass and size at varying rates. Erauskin-Extramiana emphasized these differential trajectories across species, underscoring the need for nuanced management.
This will influence price and demand for the species.
Size projections show an overall 15 percent global decrease by 2050 due to climate change. Yet some stocks, such as yellowfin and Pacific skipjack, may witness modest size increases. The study points out that market prices and demand are partly tied to fish size, and thus climate change and fishing pressure can reduce industry income even when some stocks appear to gain in productivity.
The fishing sector is urged to adapt to these evolving conditions. Suggested responses include raising value through sustainability certifications, cutting fuel use, and shortening time at sea by embracing digital tools and smarter logistics. Lower fuel consumption is itself a climate action, since tuna fishing accounts for a portion of total fuel use in global fisheries and contributes to CO2 emissions reductions when managed efficiently.
Citation: AZTI study on tuna productivity and size under climate change.
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