The Endangered Species Act and the Cost of Instability

In the early 1970s, scientists began sounding a clear warning after months of population observations: species across the United States were disappearing at a rate unseen in modern history. From birds and terrestrial mammals, to fish, plants, and marine life, population declines were glaring. Habitat destruction, industrial expansion and practices, pollution, and overexploitation were driving these population declines. And while existing wildlife laws regulated specific threats, such as hunting, they did not require the federal government to act when species were nearing extinction.

In overwhelming bipartisan support, Congress passed the Endangered Species Act (ESA) in 1973, establishing a national commitment to prevent at-risk species from endangerment and eventually extinction. The ESA emerged during a period of overlapping environmental legislation. It followed the Clean Air Act, the Clean Water Act, and, just one year earlier, the Marine Mammal Protection Act (MMPA). Together, these laws reflected a growing recognition that environmental and wildlife decline required proactive, science-based policy rather than reactive intervention after damage was done.

To date, the ESA has had over a 99% success rate in preventing listed species from going extinct. However, in November 2025, the Trump administration and Department of the Interior proposed changes that would revise ESA regulations, including how species are listed, how critical habitat is designated, and how agencies assess population risk. Experts agree that these changes would loosen how strictly the ESA is enforced, prioritizing flexibility for commercial, industrial, and economic expansion over wildlife protections.

For many Americans, the Endangered Species Act is most closely associated with historic recovery stories, like the Bald Eagle. But the legislation spans far beyond iconic terrestrial species, playing an important role in the protection and recovery of marine mammals, whose threats and declines are often far less visible to the public.

By the time the ESA was enacted in 1973, many whale, seal, and sirenian populations had been reduced by decades of commercial exploitation. Despite the Marine Mammal Protection Act sharply limiting hunting, capture, and harassment of marine mammals in U.S. waters in 1972, scientists recognized that some marine mammal populations remained at critically low numbers. Emerging threats such as habitat degradation, vessel traffic, prey depletion, and pollution would continue to keep these species at risk unless addressed.

The ESA provided a legal framework to recognize these risks more formally. “Listing” under the Act acknowledged that certain marine mammal populations were vulnerable to extinction without sustained and coordinated intervention. For species such as the North Atlantic right whale, Hawaiian monk seal, and Florida manatee, ESA listing triggered recovery planning, habitat protections, and federal oversight that extended beyond reducing direct mortality.

Over time, additional marine mammals were listed as new threats emerged or populations failed to recover as expected. Some species, including Southern Resident Killer Whales and Cook Inlet beluga whales, were listed decades after the ESA’s passage, reflecting the law’s flexible nature and its ability to respond to evolving scientific evidence. These listings recognized that modern threats can be just as limiting as historical exploitation.

Today, over 30 marine mammal species and populations are listed as endangered and threatened under the Endangered Species Act.

Taken together, these listings reflect the span of marine mammals that depend on the Endangered Species Act for protection. While the specific populations and the specific threats facing each mammal vary, their inclusion under the ESA signals a shared vulnerability: slow recovery rates, dependence on intact habitats, and sensitivity to human impacts. As regulatory changes to the ESA are once again under consideration, the consequences for these marine mammals hinge on its current level of protections remaining intact.

The proposed changes to the Act presented in late 2025 are not the first attempt at narrowing its scope, but rather a continuation and revision of changes advanced by the Trump administration’s first term. Those earlier revisions were widely criticized by conservation scientists, who found no evidence that weakened ESA implementation improved species recovery and warned that reduced protections could increase extinction risk over time. For marine mammals already dependent on strong, precautionary safeguards, these renewed changes raise concerns about whether the ESA will continue to function as a tool for recovery or shift toward a more limited role focused on minimal compliance.

For decades, the ESA’s blanket rule has extended many of the same protections afforded to endangered species to those listed as threatened, preventing populations from declining further toward extinction. Removing this rule would mean that threatened species would no longer automatically receive protections against harm unless specific regulations are written for each species.

For marine mammals such as manatees and sea otters, this change could create gaps in protection during critical periods. Delays in establishing species-specific rules would leave populations exposed to threats such as vessel strikes, habitat disturbance, and coastal development, pressures that can quickly reverse recovery gains for slow-reproducing species.

The proposed changes would require agencies to place greater emphasis on economic costs when determining the degree of protections under the ESA. While economic impacts have long been considered during the Act’s implementation, prioritizing them more heavily could shift the balance away from precautionary conservation.

For marine mammals, this raises concerns in regions where conservation intersects with shipping, fisheries, offshore energy development, and coastal infrastructure. Species whose habitats overlap with economically valuable waters, such as right whales, beluga whales, and monk seals, could face weakened protections if conservation measures are seen as too costly or burdensome.

Under current ESA framework, federal agencies must consult with wildlife experts to ensure that proposed actions do not harm listed species or their habitats. The proposed revisions would narrow when and how these consultations are required.

For marine mammals, consultation has been a key mechanism for identifying risks that are not immediately obvious, including noise exposure, prey limitations, and repeated disturbances. Reducing the consultation requirements increases the likelihood that these incremental threats go unaddressed, particularly in offshore and coastal environments where activities often overlap.

Habitat loss remains the leading cause of extinction, affecting an estimated 90 percent of listed species. The proposed regulatory changes would make it more difficult to designate and protect critical habitat, particularly in areas where future development is anticipated.

Marine mammals depend on expansive, connected habitats for migration, feeding, breeding, and calving. Narrowing habitat protections could fragment these essential areas, reducing prey availability and increasing exposure to further human activity. For species already limited by habitat constraints, these changes could undermine long-term recovery even in the absence of direct harm.

The proposed changes, if implemented, would not eliminate the Endangered Species Act, but would alter how protections are applied. The effects of these decisions extend beyond individual species, influencing how the United States approaches marine conservation in an increasingly industrialized ocean. While the formal public comment period has now closed, the future of the ESA is still being shaped through oversight, enforcement, and continued public engagement.

Although the public comment period closed in December 2025, the Endangered Species Act’s impact is shaped by how regulations are finalized, interpreted, and enforced over time. Following updates from federal agencies, congressional oversight committees, and independent scientific organizations helps ensure that changes affecting endangered species remain visible and accountable is key to making sure that any changes impacting endangered species stay transparent and accountable. Many significant shifts in conservation policy occur through implementation decisions rather than legislation, making public awareness crucial.

Paying attention to habitat designation in your area is also critical. Habitat protection is often influenced by regional planning processes, coastal development decisions, and offshore permitting. Tracking how habitat considerations are applied locally can reveal how broader ESA changes play out.

Members of Congress play an ongoing role in shaping wildlife policy through oversight, funding, and future legislative action. Communicating support for strong, science-based implementation of the Endangered Species Act helps signal that endangered species protection remains a public priority.

Here is a short script you can share:

Research, monitoring, and response efforts form the foundation of ESA protections. Population surveys, habitat studies, and stranding response programs provide the data used to assess risk, designate habitat, and guide recovery planning. Supporting organizations that conduct marine mammal research or respond to strandings helps ensure that conservation decisions remain grounded in evidence rather than assumption.

Additionally, public understanding plays a powerful role in shaping conservation outcomes. Sharing clear, accurate information about how laws like the ESA function and why they matters for species recovery helps spread the word on factual information others may be missing.

The Endangered Species Act was created to prevent extinction before it becomes inevitable, and for more than five decades it has served as one of the strongest safeguards for species at risk across the United States. The strength of the ESA lies not only in its existence, but also in how consistently its protections are applied over time. For marine mammals whose threats are rarely witnessed by the public and whose recovery is dependent on decades of protections, even subtle shifts in how the Act is implemented can have lasting consequences for population stability and long-term survival.

Thumbnail: Mother manatee and calf swimming out of inlet, courtesy of NOAA Photo Library