Why It Matters
A Congressional Research Service (CRS) report on the Marine Mammal Protection Act reveals mounting tensions between conservation and competing ocean uses, with climate change emerging as a challenge the 1972 law was never designed to address. The statute, last comprehensively updated in 1994, faces pressure from multiple directions: offshore wind expansion, international trade disputes over seafood standards, fishing industry conflicts over bycatch limits, and warming oceans that threaten marine mammal prey and habitats.
The Big Picture
The Marine Mammal Protection Act (MMPA) of 1972 established a moratorium on taking and importing marine mammals, with exemptions and permits issued by federal agencies for limited takes. Three agencies share implementation responsibility: NOAA's National Marine Fisheries Service (NMFS) handles cetaceans and most pinnipeds, the U.S. Fish and Wildlife Service (FWS) oversees walruses, sirenians, sea otters, and polar bears, and the Marine Mammal Commission (MMC) provides independent, science-based oversight. The MMPA emphasizes maintaining marine mammals as "significant functioning elements in the ecosystem" at "optimum sustainable populations."
Despite some conservation wins, the act's reach has limits. As of June 2026, 56 domestic and foreign marine mammal stocks remain listed as depleted. Meanwhile, approximately 75 percent of the 108 Atlantic marine mammal stocks examined by NMFS were assessed as having high or very high vulnerability to climate change, yet the MMPA as written does not explicitly address climate as a threat. Some species have rebounded, including western North Atlantic bottlenose dolphins, west Arctic bowhead whales, and several seal and sea otter populations, but Alaska has seen increases in strategic stocks, potentially reflecting climate and environmental stressors disproportionately affecting that region.
The act has also become a flashpoint for competing interests. Gear restrictions, fishing closures, and emergency regulations designed to protect species like the North Atlantic right whale have generated significant economic and legal conflict with commercial fishers. In September 2025, NMFS published marine mammal comparability findings for over 100 nations, with import restrictions taking effect January 1, triggering litigation over swimming crab fisheries. The rapid expansion of offshore wind energy in U.S. waters has raised new questions about incidental take authorizations and the adequacy of environmental review under the MMPA.
The Bottom Line
Congressional action appears imminent. H.R. 8509 would extend provisions managing lobster and crab fishery interactions with North Atlantic right whales through December 2035, while H.R. 8496 proposes explicitly amending the MMPA to require agencies to list species at risk from climate change and develop climate impact management plans.
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