In tonnes, tuna and tuna-like species were the third-largest seafood catch to be transshipped at sea, according to recent data published in a 2020 Food and Agriculture Organization of the United Nations (FAO) report.

Tuna Regional Fisheries Management Organizations (RFMOs) regulate transshipment in their regions. With some exceptions, purse seiners are required to transship in port. Other gears, such as longline, may engage in transshipment at sea under certain regulatory conditions. Tuna RFMOs also mandate observer coverage — either on the carrier vessel or on the fishing vessel — and require the submission of transshipment data.

But gaps persist — particularly in the regulation of at-sea transshipment, including the types of data collected, the level of monitoring, and data-reporting recipients and timelines. These gaps can increase the likelihood of illegal, unreported, and unregulated (IUU) fishing activities, including mis-reporting of catches and overfishing, which undermine fisheries management.

At ISSF, we are helping to improve tuna transshipment policies, practices, monitoring, and compliance — through our conservation measures for seafood companies and vessels, best practices research, RFMO benchmarking analysis, and advocacy outreach.

If flag States and RFMOs do not comprehensively regulate and monitor transshipment in their regions, vessels have more opportunity to engage in illegal, unreported, or unregulated (IUU) fishing activities when catches are transferred in the middle of the ocean, and thereby evade detection.

Rigorous government and RFMO management measures — that is, rules that address fishing activity, data collection, observer coverage, vessel monitoring systems, port state inspections, authorized vessel lists, and much more — are critical for preventing illegally caught fish from entering the global supply chain.

In addition, if fishing vessels are not compelled to document their transshipments properly, important data for fisheries monitoring and management are lost or compromised — including, most fundamentally, the type, size, and location of their catch. 

Requiring vessels to collect and provide accurate transshipment data ensures “product traceability” in the seafood supply chain. Robust data also allows scientists to assess stock health — and enables authorities to track vessel compliance.

At worst, at-sea transshipment can be exploited by unscrupulous fishers to hide illicit activities. IUU fishing, which can take these and other forms, is more likely when transshipment is poorly regulated:

• Fishing without authorization and/or license(s)
• Exceeding fishing quotas
• Underreporting catches
• Fishing in closed, restricted areas
• Failing to follow bycatch mitigation measures to protect at-risk marine species

Given these risks, tuna transshipment must be well regulated and well monitored by Regional Fisheries Management Organizations (RFMOs) and national governments.

Each of the four tropical-tuna RFMOs, for example, prohibits purse seiners — and other vessels under certain conditions — from transshipping at sea.

But at-sea transshipment overall has increased in recent years. In 2017 alone, approximately 94,780 tonnes of tuna and tuna-like species were transshipped at sea, as noted by the Food and Agriculture Organization (FAO) of the United Nations in a recent report.

As an exception to that trend, the number of reported transshipment events decreased in 2020-2021 due to the pandemic and overall reductions in fishing activities and port calls. At that time, however, in the Western and Central Pacific 83% of transshipments were unobserved.

As the number of at-sea transshipments has increased over time, it has become even more imperative for RFMOs to better oversee and regulate vessel activity in their regions. 

To support tuna RFMOs in that effort, ISSF has identified opportunities for improvement in their current transshipment measures.

While these best practices are focused on at-sea transshipment, a number of these practices can also improve transshipment when it takes place in port.

Tuna RFMO Measures Regulating Transshipment

Benchmarking of certain current tuna RFMO requirements regulating at-sea transshipment against best-practice recommendations

Priority reform in place

Partial reform in place

Does not have priority reform in place

To strengthen their at-sea transshipment policies to prevent IUU activities and overfishing, RFMOs should follow these best practices, which are detailed in ISSF reports and other resources:

In these and other ways, seafood companies, food retailers, NGOs, and other sustainable-fishing stakeholders can join ISSF in pushing for better oversight of tuna transshipment:

	Collect key data elements on transshipped tuna in your supply chain. Talk to suppliers about practices of source vessels and request they follow best practices.
	Advocate to RFMO member governments, including where you have business interests or source tuna, and participate in national RFMO advisory bodies
	Publicly support ISSF position statements and NGO Tuna Forum advocacy

ISSF researches and analyzes RFMO and government policies and regulations on transshipment and many other issues in sustainable fishing.

Visit the ISSF site to explore our scientific and advocacy publications, blogs, infographics, and more.

RFMO Best Practices Snapshot

See how tuna RFMOs are performing on best practices in transshipment regulation

RFMO Best Practices Report

Read our detailed review of RFMO transshipment measures

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