Eastern Pacific Tunas Poised for Significant Progress on Sustainability

After months of scientific progress and cooperation among nations that fish in the eastern Pacific Ocean – one of the most productive marine areas in the world – the Inter-American Tropical Tuna Commission (IATTC) is poised to advance long-term protections for five tuna stocks: four in the eastern Pacific – bigeye, skipjack, and two yellowfin – and Pacific bluefin.

IATTC oversees fishing in the region for tuna species that are worth a combined $5.14 billion at the final point of sale. At its annual meeting in Lisbon, Portugal, from 31 August to 4 September, managers must seize the chance to secure lasting protections for these important fisheries.

Multi-stock management procedure can benefit tropical tunas

The tropical tunas of the eastern Pacific—bigeye, skipjack and yellowfin—support livelihoods throughout the region and are linked by their ecology and the fisheries that target them. Tropical tuna management has long been challenging because vessels fishing for one species also catch others that inhabit the same areas. This overlap means that to be effective, rules need to consider the interconnectedness of the stocks, and that scientists and managers must prioritize the health of the most compromised fish population over the more robust ones, given the risk of overfishing the weaker stock.

Protect Marine Life A Short History of Pacific Bluefin

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This is why, when IATTC meets later this month, it should urgently adopt a management procedure (MP) that considers the effects of fishing for eastern Pacific bigeye, not only on that population but also on skipjack and two stocks of yellowfin in the region. MPs are long-term, science-based approaches to fisheries management in which commission members agree in advance on benchmarks to determine future changes in allowable catch. If a fish population is healthy, catch levels can stay the same or even increase over time. But if the population declines, catch levels automatically decrease based on those pre-agreed targets.

To its credit, IATTC has already made strides over the past year to better manage these species, based on the latest stock assessment of bigeye, which clarified the health of the tropical tuna populations. Previously, scientists thought bigeye was the most vulnerable species in the region, but the new data shows that the southwest yellowfin stock is probably the “weakest” stock and requires the most restrictive management.

With this new understanding, IATTC scientists have devised a mechanism to improve the proposed bigeye MP by incorporating the safety and status of the yellowfin and skipjack fisheries into prospective fishing rules. Such a multi-stock MP would better protect all IATTC-managed tropical tunas and minimize the chance of overfishing skipjack or yellowfin.

Prioritize long-term protections for Pacific bluefin tuna

Another top agenda item for the IATTC meeting will be adoption of management measures for Pacific bluefin tuna. Because Pacific bluefin has only one population that spans the Pacific Ocean, it is managed jointly by IATTC and the Western and Central Pacific Fisheries Commission (WCPFC). Managers from the two commissions failed at a July meeting to endorse an MP for the stock, despite a prior tentative agreement, largely because of disputes of catch allocations. But the upcoming IATTC meeting will give members the opportunity to restart those negotiations and adopt a precautionary MP for Pacific bluefin that could then be complemented by a similar measure at the WCPFC meeting in November.

In Lisbon, IATTC has a chance that doesn’t present itself often: to modernize the management of not one stock, but five at once. If members seize this moment, it will mark a historic milestone for eastern Pacific tropical tunas and for fisheries management – the first multi-species MP adopted by any of the five regional organizations that oversee tuna fishing in the global ocean.

Dave Gershman leads The Pew Charitable Trusts’ conservation advocacy with Pacific regional fisheries management organizations.