On January 1st, 2026, NOAA Fisheries implemented new import prohibitions under the Marine Mammal Protection Act (MMPA), banning seafood imports that failed a comparability finding. According to the findings, 240 fisheries from 46 countries failed to adequately protect marine mammals and were subsequently blocked from exporting their products to the U.S. Eight months later, this policy is noticeably affecting companies that produce the now-banned products. But the impact on the water is more difficult to measure and may not be going as NOAA intended.

I purchase seafood for a U.S.-based importing company that specializes in sushi ingredients. We recently visited a yellowfin tuna first receiver and processor near Tuy Hòa, Vietnam, and asked how operations have changed since the import ban on January 1st. This company processes yellowfin tuna for raw consumption, exporting “sashimi-grade” products to Europe, Japan, China, and its largest market, the U.S. Some of the raw material is handline-caught from a nearby fishery improvement project. This fishing method met the comparability study standards and has not been banned. But when handline fishing is slow, as it has been in recent years, fishers deploy gillnets to boost their catch. NOAA’s comparability findings determined that yellowfin tuna caught using gillnets do not meet MMPA standards and therefore can no longer be imported when caught in Vietnamese fisheries.

To adapt, the tuna company began diverting most of its locally caught tuna to markets that do not ban tuna caught by gillnets. This meant that most of the local tuna, whether handline or gillnet-caught, could not be sent to U.S. customers like me. Many of the local vessels deploy handline and gillnet gear during the same trip, mixing their catch upon landing. Mixing is a major traceability concern, so the tuna company we spoke with decided to withhold most of this local raw material from its U.S. customers going forward, to avoid any unintended overlap.

But this tuna company, and many others like it, cannot afford to lose its U.S. customers entirely. Those sales accounted for about 50% of their annual revenue in 2025. Instead, it began importing longline-caught, frozen, yellowfin tuna from Taiwan and Indonesia. Longline fisheries were mostly approved in the comparability finding, despite struggles with bycatch, traceability, and fair working conditions. NOAA determined that longline tuna fisheries in Indonesia and Taiwan adequately avoid marine mammals and would not require import blocks. Tuna processors in Vietnam decided to import frozen tuna from these foreign fisheries, thaw the tuna – whether whole fish or pre-cut loins – in their warehouse, process it into final product forms, and then re-freeze it before exporting.

Many tuna buyers in the U.S. market won’t care about the complicated traceability story created by this new, longer tuna supply chain. But all buyers will notice the difference in quality between a twice-frozen tuna and a once-frozen tuna. Color and texture are the most important characteristics of raw tuna. Both are severely compromised when frozen twice: