Endangered Species Marine Animals

Short answer

• "Endangered" has two different meanings that are often mixed up. On the IUCN Red List, Endangered is one of three "threatened" categories, sitting between Critically Endangered and Vulnerable. Under the United States Endangered Species Act, "endangered" means a species is in danger of extinction throughout all or a significant portion of its range, while "threatened" means it is likely to become endangered in the foreseeable future.
• NOAA Fisheries has jurisdiction over 165 endangered and threatened marine species under the Endangered Species Act: 80 listed as endangered and 85 as threatened, including 66 foreign species. The U.S. Fish and Wildlife Service handles some marine species too, including sea otters, manatees, walruses, and polar bears.
• The best known examples include the North Atlantic right whale, with an estimated 384 animals alive at the start of 2024; the vaquita, a small porpoise found only in the Upper Gulf of California, with about ten animals thought to remain; all six sea turtle species found in U.S. waters; the whale shark; and reef building corals, of which 44 percent of assessed species are now threatened with extinction.
• The main threats are accidental capture in fishing gear, ship strikes, habitat loss, pollution and plastic, overfishing, and warming seas. Climate change is the main driver behind the worsening status of reef building corals.
• Protection works through laws, recovery plans, protected habitat, fishing gear rules, rescue and research programs, and international trade controls. Listing alone does not save a species: recovery depends on reducing the specific threats that caused the decline, and that work often takes decades.

What “Endangered” Means

The word endangered sounds simple, but it is a technical term with more than one definition, and the definition matters. A species called endangered in a news report may be endangered on the IUCN Red List, endangered under United States law, or both. Those are different systems, run by different bodies, with different rules and different consequences.

The IUCN Red List of Threatened Species is the global system. IUCN stands for the International Union for Conservation of Nature. Its Red List assesses species against quantitative criteria, including population size, rate of decline, geographic range, and probability of extinction. Each assessed species is placed in one of nine categories: Extinct, Extinct in the Wild, Critically Endangered, Endangered, Vulnerable, Near Threatened, Least Concern, Data Deficient, and Not Evaluated.

The three threatened categories are Critically Endangered, Endangered, and Vulnerable. Critically Endangered means an extremely high risk of extinction in the wild. Endangered means a very high risk. Vulnerable means a high risk. A species needs to meet only one of the criteria for its category to qualify. Near Threatened means a species is close to qualifying for a threatened category. Least Concern means it has been evaluated and does not qualify for any higher risk category. Data Deficient means there is not enough information to assess the risk, which is not the same as being safe.

The United States system is legal rather than purely scientific. The Endangered Species Act was passed by Congress in 1973. Under the Act, an endangered species is one in danger of extinction throughout all or a significant portion of its range. A threatened species is one likely to become endangered within the foreseeable future. Listing decisions must be based on the best available science, and the Act requires the responsible agency to prepare a recovery plan for each listed species and to designate critical habitat where appropriate.

The two systems often agree, but they do not always match. The Hawaiian monk seal is listed as endangered under the Endangered Species Act, while its current IUCN Red List category is Vulnerable. The green sea turtle is listed as endangered for some populations and threatened for others under the Endangered Species Act, while its global IUCN assessment has changed over time. When an article gives a status, the honest question is always: status under which system, for which population, and assessed when?

A third point confuses readers. The Endangered Species Act can list a distinct population segment separately from the rest of the species. The North Atlantic right whale, the Cook Inlet beluga whale, and the western population of Steller sea lions are all listed as distinct units, because their situation differs from other populations of the same or a closely related species. A single species can therefore be endangered in one place and less at risk somewhere else.

How a Marine Species Gets Listed and Protected

In the United States, responsibility for marine species under the Endangered Species Act is split. NOAA Fisheries, formally the National Marine Fisheries Service, handles most marine fish, whales, dolphins, porpoises, seals, sea lions, sea turtles in the marine environment, and corals. The U.S. Fish and Wildlife Service handles sea otters, manatees, dugongs, walruses, polar bears, and sea turtles on land, including nesting beaches. The two agencies share responsibility for sea turtles, with NOAA Fisheries leading in the water and the Fish and Wildlife Service leading on shore.

A listing can start in two ways. The agencies can review a species on their own initiative, or any person or organization can petition them to list it. The agencies then review the best available science, including population data, trends, habitat condition, and threats, and decide whether the species meets the legal definition of endangered or threatened. Economic effects do not decide the listing. Once listed, a species receives legal protection. For endangered species, it is illegal to kill, harass, harm, or capture the animal without special permission. Threatened species may receive many of the same protections through species specific rules.

Listing is the start of the work, not the end of it. The responsible agency must prepare a recovery plan that sets out what needs to happen for the species to recover enough to be removed from the list. Federal agencies must also consult with NOAA Fisheries or the Fish and Wildlife Service before carrying out, funding, or permitting actions that could affect a listed species or its critical habitat. Critical habitat is the specific area considered essential to the conservation of the species, and it can include feeding grounds, breeding areas, and migration routes.

A second law protects all marine mammals in U.S. waters, whether or not they are listed under the Endangered Species Act. The Marine Mammal Protection Act of 1972 places a moratorium on the taking of marine mammals, where taking means harassing, hunting, capturing, collecting, or killing, or attempting to do so. NOAA Fisheries manages whales, dolphins, porpoises, seals, and sea lions under this law, while the Fish and Wildlife Service manages polar bears, walruses, sea otters, manatees, and dugongs. Permits can allow limited taking for scientific research or public display, and separate rules govern accidental taking during commercial fishing.

International trade is controlled separately. The Convention on International Trade in Endangered Species of Wild Fauna and Flora, known as CITES, regulates trade in listed species and their parts. Species on Appendix I face the strictest controls, with commercial trade generally prohibited. Species on Appendix II can be traded only with permits. Many endangered marine animals, including whale sharks and most sea turtles, are listed on one of the CITES appendices. Trade controls matter because demand for shark fins, turtle shells, and other products can drive hunting far from where the animals live.

None of these systems works by itself. A whale protected from hunting can still die in a fishing net. A turtle protected on its nesting beach can still drown in a trawl. A coral protected from collection can still bleach in warm water. That is why recovery plans usually combine several tools at once: gear rules, speed limits for ships, habitat protection, pollution control, rescue programs, and research.

Whales, Dolphins, and Porpoises

Whales attract the most attention among endangered marine animals, because their declines were dramatic and well documented, and because some recoveries show that protection can work. Commercial whaling reduced many great whale populations to a small fraction of their former numbers before international controls took effect. Several large whale species remain listed as endangered under the Endangered Species Act today, including the blue whale, the fin whale, the sei whale, and the sperm whale. Their recovery is slow, because whales reproduce slowly, with long intervals between calves, so a population that lost most of its breeding adults needs decades to rebuild.

The North Atlantic right whale is the most closely watched case in U.S. waters. It has been listed as endangered under the Endangered Species Act since 1970, and it is listed as Critically Endangered on the IUCN Red List. NOAA Fisheries estimated that 384 North Atlantic right whales were alive at the start of 2024, with a 95 percent credible interval of 375 to 394. That estimate was about 20 animals higher than the estimate for 2020, and it marked the third consecutive year in which the population showed signs of increasing. Even so, NOAA Fisheries estimates that only about 70 reproductively active females remain, which limits how fast the population can grow.

The two main causes of death for North Atlantic right whales are entanglement in fishing gear and collisions with ships. NOAA Fisheries has described both as the primary threats to the species. Entanglement can kill a whale outright, or it can leave lines wrapped around the animal that cause injury, infection, and starvation over months. Ship strikes kill whales that spend time near the surface in busy shipping lanes along the east coast of the United States. Protection measures include seasonal speed restrictions for vessels in certain areas, fishing gear modifications, weak links designed to break under a whale’s weight, and disentanglement teams that respond when an entangled whale is reported.

The vaquita is a different kind of case: a species that declined so fast that it may now be too late to save. The vaquita is the smallest cetacean, a porpoise found only in the Upper Gulf of California in Mexico. It is listed as endangered under the Endangered Species Act and as Critically Endangered on the IUCN Red List. A survey in 1997 estimated about 567 vaquitas. Surveys in 2024 sighted only six to eight animals, and recent estimates put the total at about ten. The main cause of the decline is drowning in gillnets set illegally for totoaba, a large fish whose swim bladder is trafficked for high prices. Vaquitas are not the target of those nets; they die as bycatch. Mexico has restricted gillnet fishing in parts of the vaquita’s range, and patrols remove illegal nets, but enforcement has been uneven, and in October 2026 Mexico reduced the area where gillnets are prohibited, a change that conservation groups warned would increase the risk to the species.

Smaller cetaceans face similar pressures in other regions. The Maui dolphin, a subspecies of Hector’s dolphin found only off New Zealand, is listed as endangered under the Endangered Species Act. The Cook Inlet beluga whale, a distinct population segment in Alaska, is listed as endangered. The main Hawaiian Islands insular population of false killer whales is also listed as endangered. In each case, the population is small, geographically restricted, and exposed to fishing gear, noise, pollution, or loss of prey, and recovery depends on reducing those specific pressures.

Sea Turtles

Sea turtles are among the oldest marine animals still alive, and they are also among the most threatened. There are seven species of sea turtle in the world: the green, hawksbill, Kemp’s ridley, leatherback, loggerhead, olive ridley, and flatback. Six of them occur in U.S. waters, and all six are protected under the Endangered Species Act. The flatback occurs only in the waters around Australia, Papua New Guinea, and Indonesia.

NOAA Fisheries states that the hawksbill, Kemp’s ridley, and leatherback sea turtles are listed as endangered under the Endangered Species Act. The loggerhead, green, and olive ridley sea turtles are listed as threatened, with some populations listed as endangered, including green turtle populations in Florida and on the Pacific coast of Mexico, and olive ridley breeding populations on the Pacific coast of Mexico. On the IUCN Red List, the hawksbill and Kemp’s ridley are Critically Endangered, the loggerhead and olive ridley are Vulnerable, and the green turtle’s global status has been revised over time as new data became available.

Sea turtles face threats at every stage of life. Females must return to beaches to lay eggs, so coastal development, artificial lighting, beach armoring, and loss of nesting habitat all reduce reproduction. Lighting disorients hatchlings, drawing them away from the sea and toward roads and buildings. In the water, turtles are caught accidentally in fishing gear, struck by boats, and killed by ingestion of plastic and marine debris, which they can mistake for food. Warming sand temperatures affect the sex of hatchlings, because the temperature of the nest determines whether an egg develops into a male or a female, and warmer nests produce more females. That shift may already be changing the balance of some populations.

The Kemp’s ridley is the most seriously imperiled of the sea turtles in U.S. waters. It nests mainly on a small stretch of beach in Mexico, with a smaller nesting population in Texas, and it was listed as endangered under the Endangered Species Act in 1970. Intensive protection of nests and hatchlings, including relocation of eggs to protected corrals and restrictions on shrimp trawling through turtle excluder devices, helped the population grow from its low point, but it remains far below historical numbers and vulnerable to a single bad nesting season or a single oil spill in the Gulf of Mexico.

Protection for sea turtles shows how several tools fit together. Turtle excluder devices in shrimp trawls let turtles escape nets that would otherwise drown them. Seasonal closures protect nesting beaches during the laying season. Lighting rules near nesting beaches reduce hatchling deaths. International agreements protect turtles on the high seas and in the waters of other countries, where U.S. law does not reach. And long term monitoring of nesting beaches gives scientists the trend data that listing decisions depend on.

Sharks and Rays

Sharks and rays are often left out of public discussion of endangered marine animals, partly because they are feared rather than loved, and partly because their declines are harder to see. But a large share of shark and ray species is now threatened. Unlike whales, which were hunted openly and then protected, many sharks declined quietly, through targeted fishing for fins and meat and through bycatch in fisheries aimed at other species.

The whale shark is the largest fish in the ocean, and it is listed as Endangered on the IUCN Red List, assessed in 2016. The assessment found that the global population had declined by more than 50 percent over the previous 75 years, with a decline of about 63 percent in the Indo-Pacific and more than 30 percent in the Atlantic. The main causes were targeted fishing, bycatch, and collisions with large ships. Whale sharks are filter feeders that eat plankton, krill, and small fish, and they pose no danger to people. They are listed on Appendix II of CITES, which regulates international trade in the species.

The scalloped hammerhead shows how listing can vary by population. NOAA Fisheries lists some scalloped hammerhead populations as endangered and others as threatened under the Endangered Species Act, depending on the population segment. Hammerheads are vulnerable because they gather in large schools, which makes them easy to catch in large numbers, and because they grow slowly and produce relatively few young. The oceanic whitetip shark is listed as threatened under the Endangered Species Act and as Critically Endangered on the IUCN Red List. The giant manta ray, the largest ray in the ocean, is listed as threatened under the Endangered Species Act. Manta rays are slow to reproduce, with females producing a single pup at a time after a long pregnancy, so even low levels of fishing can reduce a population faster than it can recover.

Shark protection faces a practical problem that whale protection does not. Many sharks are caught as bycatch, not as the target species, so a ban on targeting them does not stop the deaths. Reducing bycatch requires changes in fishing gear and practice, such as circle hooks, limits on longline soak time, and release practices that give a caught shark a chance to survive. It also requires catch limits and trade controls that apply across borders, because sharks migrate through the waters of many countries. CITES listings help, because they require permits and documentation for international trade in shark fins and other products, which makes illegal catch harder to sell.

Corals and Reef Animals

Corals are animals, not plants, and reef building corals are among the most threatened groups in the ocean. A global reassessment published by the IUCN in October 2026 found that 44 percent of reef building coral species are threatened with extinction. Of the 774 species with enough data to assess, 340 were classified as threatened: 33 Critically Endangered, 251 Endangered, and 56 Vulnerable. The first global assessment, completed in 2008, had found about one third of species threatened. The new assessment used data up to 2020, before the fourth global coral bleaching event of 2023 to 2025, and its authors cautioned that the true share at risk is likely higher than 44 percent.

Coral bleaching is the main mechanism. Corals live in partnership with tiny algae that live inside their tissues and provide food through photosynthesis. When water becomes too warm, corals expel the algae, lose their color, and can starve if the warm water persists. A bleached coral is not dead, and it can recover if temperatures fall quickly, but repeated or prolonged bleaching kills whole reefs. Warming seas, driven by climate change, are the main cause of the recent bleaching events, and the IUCN reassessment identified warming as the main driver of the worsening coral status. Local pressures make bleaching worse: pollution, sediment from coastal development, and overfishing of the herbivorous fish that keep algae from smothering corals.

Some corals are listed individually under the Endangered Species Act. Elkhorn coral and staghorn coral, two Caribbean species that build the framework of reefs in Florida and the Caribbean, are listed as threatened, having been listed in 2006. Boulder star coral is also listed as threatened. Pillar coral was listed as threatened in 2014 and its status was changed to endangered in 2025. These listings bring legal protection against collection and harm, and they require federal agencies to consider the corals when permitting coastal work.

Corals matter beyond themselves, because reefs support a large share of marine life. The animals that live on reefs include many of the fish, turtles, and invertebrates discussed in this article, and the reef itself protects coastlines by breaking wave energy. Readers who want a closer look at reef wildlife can start with our guide to animals on the coral reef, which covers the animals that depend on reef habitat, and our guide to Great Barrier Reef animals, which covers the wildlife of the world’s largest reef system. The physical conditions that shape reef life, including light, temperature, and water movement, are covered in our companion article on coral reef abiotic factors, and the weather patterns that affect the Great Barrier Reef are covered in our companion article on the weather of the Great Barrier Reef.

Seals, Sea Lions, and Other Marine Mammals

Seals and sea lions are protected by both the Endangered Species Act and the Marine Mammal Protection Act, and several populations are listed as endangered or threatened. The Hawaiian monk seal is one of the best documented cases. It is listed as endangered under the Endangered Species Act, and NOAA Fisheries estimates the total population at about 1,600 animals, with roughly 1,200 in the Northwestern Hawaiian Islands and about 400 in the main Hawaiian Islands. The population has increased since 2013, with significant growth in the main Hawaiian Islands, but it remains small, and individual animals are vulnerable to entanglement in marine debris, disease, and disturbance on beaches.

The western population of Steller sea lions is listed as endangered under the Endangered Species Act. Bearded seals and most ringed seal subspecies are listed as threatened; the Ladoga and Saimaa ringed seal subspecies are listed as endangered. The Mediterranean monk seal, found in the Mediterranean Sea and the eastern Atlantic, is listed as endangered under the Endangered Species Act as a foreign species. These listings show that the Act reaches beyond U.S. waters for foreign species, although the protections that apply inside the United States, such as the ban on taking, are the main practical effect for animals that rarely enter U.S. waters.

Manatees and dugongs are also marine mammals at risk, although their stories differ. The West Indian manatee, which includes the Florida manatee, was reclassified from endangered to threatened under the Endangered Species Act in 2017, a decision that reflected population growth but remained controversial among conservation groups. Manatees are managed by the U.S. Fish and Wildlife Service rather than NOAA Fisheries, and their main threats are boat strikes, loss of warm water refuges, and loss of seagrass. Dugongs, found in the Indian and Pacific Oceans, are listed as endangered under the Endangered Species Act as a foreign species.

Sea otters illustrate a recovery that is real but incomplete. Southern sea otters, found along the California coast, are listed as threatened under the Endangered Species Act and are managed by the Fish and Wildlife Service. Their population grew from a small remnant after hunting for fur nearly wiped them out, but growth has slowed, and the population remains vulnerable to oil spills, disease, and shark bites. Sea otters matter to their ecosystem because they eat sea urchins, which would otherwise overgraze kelp forests, so their recovery affects the whole coastal habitat.

The Main Threats, Grouped

The threats to endangered marine animals fall into a small number of groups, and most species face more than one at the same time. Understanding the groups helps explain why a single fix rarely solves the problem.

Bycatch, meaning accidental capture in fishing gear, is the leading threat for many of the animals in this article. Gillnets drown vaquitas, turtles, and seals. Longlines hook sharks, turtles, and seabirds. Trawls sweep up turtles and other animals along with the target catch. Pot and trap lines entangle right whales and other large whales. Bycatch is hard to eliminate, because fishing gear is designed to catch animals, and the same gear that catches fish will catch other animals that share the water. Solutions include gear that lets non target animals escape, such as turtle excluder devices, seasonal closures in areas where endangered animals gather, and limits on the riskiest gear in the riskiest places.

Ship strikes kill whales, manatees, and sea turtles. Large ships cannot easily avoid a whale at the surface, and fast ships kill more often than slow ones. Speed restrictions in areas where right whales gather, and rerouting of shipping lanes away from whale habitat, are the main tools. The same logic applies to boat strikes on manatees in Florida, where speed zones in shallow water reduce deaths.

Habitat loss affects animals that depend on specific places. Sea turtles need undisturbed nesting beaches. Seals need beaches where they can rest and raise pups without disturbance. Corals need clear, warm, shallow water with the right chemistry. Coastal development, dredging, beach armoring, and pollution all shrink or degrade those places. Critical habitat designation under the Endangered Species Act is meant to protect the most important of these areas, but designation alone does not stop every harmful activity, and habitat outside the designated area can still matter.

Pollution takes several forms. Plastic debris entangles seals, turtles, and seabirds, and ingested plastic can block a turtle’s gut or make it feel full when it is starving. Chemical pollution, including oil spills, pesticides, and runoff, poisons animals directly and degrades their habitat. Noise pollution from shipping, seismic surveys, and construction interferes with whales and dolphins, which depend on sound to communicate, navigate, and find food. Light pollution on nesting beaches disorients turtle hatchlings.

Overfishing harms endangered marine animals in two ways. It removes the animals themselves, when they are the target or the bycatch, and it removes their food. When prey fish decline, predators that depend on them, including whales, seals, and sharks, have less to eat and reproduce less successfully. Overfishing of herbivorous fish on reefs also allows algae to overgrow corals, which weakens the reef that many other animals depend on.

Climate change is the threat that cuts across all the others. Warming water causes coral bleaching, shifts the distribution of prey, and changes the sex ratio of turtle hatchlings. Ocean acidification, caused by the ocean absorbing carbon dioxide from the atmosphere, makes it harder for corals, shellfish, and other animals to build shells and skeletons. Sea level rise erodes nesting beaches and floods low lying coastal habitat. Unlike a fishing net, climate change cannot be fixed by a rule about one gear type in one place, which is why scientists describe it as the main long term threat to many marine species.

How Protection Works in Practice

Protection works best when it targets the specific threat that is killing the animals. The recovery of some species shows the pattern clearly. Humpback whales, which were heavily hunted, recovered in many areas after commercial whaling ended and international protection took effect. Gray whales in the eastern North Pacific recovered enough to be removed from the endangered list in 1994, although the western population remains at risk. These recoveries took decades, and they depended on removing the main cause of decline, not on a single action.

Recovery plans are the central tool under the Endangered Species Act. A recovery plan sets out the criteria for removing a species from the list, the actions needed to meet those criteria, and the estimated cost and time. Plans are not self executing: they depend on funding, on cooperation from states, tribes, industry, and other countries, and on monitoring that shows whether the population is actually responding. NOAA Fisheries publishes recovery plans for the marine species under its jurisdiction, and the Fish and Wildlife Service does the same for the species it manages.

Marine protected areas help by reducing several threats at once in a defined area. A protected area can restrict fishing, shipping, and development, giving animals a place to feed and breed with less disturbance. Protected areas work best when they cover the places animals actually use, when the rules are enforced, and when they are large enough to matter for animals that range widely. A small protected area does little for a whale that migrates thousands of kilometers, but it can matter a great deal for a coral reef or a seal breeding beach.

Rescue and rehabilitation programs handle individual animals. Entangled whales are disentangled by trained teams. Stranded seals and sea lions are treated and released. Injured turtles are rehabilitated. These programs save individual animals, and for a species with only a few hundred individuals, each animal matters. They also provide data on what is killing animals, which feeds back into policy. A rescued seal with a plastic ring around its neck is evidence, not just a sad story.

Research and monitoring are the foundation of all of it. Population estimates, such as the North Atlantic right whale estimate of 384 animals at the start of 2024, come from long term photo identification catalogs, in which individual whales are recognized by markings and tracked over years. Nesting beach surveys give the trend data for sea turtles. Acoustic monitoring tracks vaquitas that are almost never seen. Without that monitoring, listing decisions would be guesses, and recovery would be unverifiable.

International cooperation matters because the ocean has no fences. Whales, turtles, sharks, and tuna cross the waters of many countries, and a species protected in one country can be caught in another. Treaties and agreements, including CITES, the Convention on Migratory Species, and regional fisheries management organizations, set shared rules. Their effectiveness depends on enforcement, which varies widely, and on the willingness of countries to accept catch limits and gear rules that cost their fishing industries money in the short term.

Reading Population Numbers Honestly

Population numbers for endangered marine animals are often reported as single figures, such as 384 right whales or about ten vaquitas, but a single figure hides a great deal. The honest way to read these numbers is to ask four questions: when was the estimate made, how was it made, what is the uncertainty, and what is the trend?

The date matters because populations change, and because an old estimate can mislead. The North Atlantic right whale estimate of 384 refers to the start of 2024, based on sightings data through 2024 and published in 2025. A reader who sees 384 in 2026 should not treat it as a live headcount. The vaquita estimate of about ten is based on surveys in 2024 and 2025, and the animals are hard to find, so the true number could be slightly higher or lower. The coral figure of 44 percent threatened is based on data up to 2020, and the authors themselves caution that the true figure is likely higher after the bleaching event of 2023 to 2025.

The method matters because some animals are counted directly and others are estimated from models. Right whales are identified individually from photographs, which gives a relatively precise estimate with a stated credible interval of 375 to 394. Vaquitas are counted from visual sightings and acoustic detections in a small area, which gives a range rather than a precise total. Coral assessments are based on expert judgment applied to data on distribution, trends, and threats, which is a different kind of estimate again. None of these methods is wrong, but they are not interchangeable.

Uncertainty matters because a small population is hard to count. When only a few hundred animals remain, missing a few matters. When only about ten remain, missing one or two changes the total by a large share. Scientists report ranges and intervals for this reason, and responsible reporting keeps the range visible rather than rounding it away.

The trend matters most of all. A population of 384 that is growing slowly is in a different position from a population of 384 that is falling fast. The right whale population declined sharply from 2015 to 2020, and the decline has slowed since then, with three consecutive years of small increases. That is encouraging, but the population remains far below its peak of about 483 in 2010, and mortality remains above the level the population can sustain. A single good year does not mean recovery, and a single bad year does not mean extinction. The trend over a decade is the meaningful measure.

What Travelers and Readers Can Do

This article is a neutral explainer, not a call to action, and it makes no fundraising appeal. But readers often ask what responsible behavior looks like around endangered marine animals, and the rules are simple enough to state plainly.

Keep your distance from marine mammals, sea turtles, and seals. In the United States, federal rules prohibit approaching or remaining within 500 yards of a right whale, and NOAA Fisheries advises keeping a distance from all marine mammals and reporting stranded or entangled animals to the authorities rather than trying to help directly. A seal resting on a beach is usually not in trouble; it is resting, and approaching it can cause it to abandon the beach or its pup.

Choose seafood with care, and be aware that fishing gear matters as much as the species on the plate. Bycatch is the main threat to many of the animals in this article, and fisheries that use turtle excluder devices, circle hooks, and other bycatch reduction measures kill fewer non target animals. Seafood guides published by aquariums and conservation organizations can help a reader identify lower impact choices, although no guide is a substitute for regulation.

Reduce plastic use and dispose of fishing gear properly, because debris in the water entangles and kills marine animals. Support the protection of nesting beaches and reef areas by following local rules about lighting, access, and anchoring. And when visiting reefs, avoid touching or standing on corals, which are living animals that are easily damaged and slow to recover.

None of these actions, by itself, saves a species. Species are saved, when they are saved, by laws, by enforcement, by changes in fishing and shipping practice, and by long term monitoring and research. Individual behavior helps at the margins, and it matters most when it supports the larger systems that do the heavy work.

FAQ

What is the most endangered marine animal?

There is no single answer, because “most endangered” can mean the smallest population, the highest risk category, or the fastest decline. The vaquita is often described as the most endangered marine mammal, with about ten animals thought to remain, and it is listed as Critically Endangered on the IUCN Red List. The North Atlantic right whale, with 384 animals estimated at the start of 2024, is also Critically Endangered on the IUCN Red List. Both are in serious trouble, but for different reasons and in different places.

How many marine species are endangered?

NOAA Fisheries has jurisdiction over 165 endangered and threatened marine species under the Endangered Species Act: 80 listed as endangered and 85 as threatened, including 66 foreign species. That count covers only the species under NOAA Fisheries jurisdiction. The IUCN Red List assesses many more marine species globally, including species that are not listed under United States law. The two counts measure different things, so they should not be combined into a single total.

What is the difference between endangered and threatened?

Under the Endangered Species Act, endangered means a species is in danger of extinction throughout all or a significant portion of its range. Threatened means it is likely to become endangered in the foreseeable future. On the IUCN Red List, Endangered is one of three threatened categories, between Critically Endangered and Vulnerable, and “threatened” is the collective term for all three. The same species can be endangered under one system and threatened or vulnerable under the other.

Are all sea turtles endangered?

All six sea turtle species found in U.S. waters are protected under the Endangered Species Act. The hawksbill, Kemp’s ridley, and leatherback are listed as endangered. The loggerhead, green, and olive ridley are listed as threatened, with some populations listed as endangered. The seventh species, the flatback, occurs only around Australia, Papua New Guinea, and Indonesia and is not found in U.S. waters.

Why are coral reefs dying?

The main cause is warming water, which causes coral bleaching. When water becomes too warm, corals expel the algae that live in their tissues and provide food, and they can starve if the warm water persists. Local pressures, including pollution, sediment, and overfishing of herbivorous fish, make bleaching worse. A global reassessment published by the IUCN in October 2026 found that 44 percent of reef building coral species are threatened with extinction, based on data up to 2020, before the bleaching event of 2023 to 2025.

What is the Endangered Species Act?

The Endangered Species Act is a United States law passed by Congress in 1973. It provides a means to conserve the ecosystems on which endangered and threatened species depend, and a program for the conservation of those species. NOAA Fisheries is responsible for most marine species under the Act, and the U.S. Fish and Wildlife Service is responsible for land and freshwater species and for some marine mammals. Listing decisions must be based on the best available science.

What is the Marine Mammal Protection Act?

The Marine Mammal Protection Act of 1972 places a moratorium on the taking of marine mammals in U.S. waters, where taking means harassing, hunting, capturing, collecting, or killing, or attempting to do so. It protects all marine mammals, not only those listed under the Endangered Species Act. NOAA Fisheries manages whales, dolphins, porpoises, seals, and sea lions under the Act, and the Fish and Wildlife Service manages polar bears, walruses, sea otters, manatees, and dugongs.

Can endangered marine animals recover?

Yes, sometimes, but recovery is slow and depends on removing the cause of the decline. Humpback whales recovered in many areas after commercial whaling ended. Eastern North Pacific gray whales recovered enough to be removed from the endangered list in 1994. The North Atlantic right whale population has shown small increases in recent years, and the Hawaiian monk seal population has grown since 2013. Recovery takes decades for animals that reproduce slowly, and it requires sustained protection rather than a single action.

How do scientists count animals as rare as the vaquita?

Vaquitas are almost never seen, so scientists use a combination of visual surveys from boats and acoustic monitoring, which detects the clicks vaquitas use to navigate and find food. A survey in 2024 sighted six to eight vaquitas, and recent estimates put the total at about ten. The number is an estimate with uncertainty, not a precise headcount, because the animals are few, the water is murky, and the survey area is limited.

Where can I check the current status of a marine species?

The IUCN Red List of Threatened Species (iucnredlist.org) gives the global conservation status of assessed species. NOAA Fisheries Species Directory gives the Endangered Species Act status of marine species under its jurisdiction. The U.S. Fish and Wildlife Service Environmental Conservation Online System gives the status of species under its jurisdiction. Statuses change as new assessments are completed, so check the date of the assessment as well as the category.

Sources & references

• NOAA Fisheries. Species Directory, ESA Threatened and Endangered. NOAA Fisheries has jurisdiction over 165 endangered and threatened marine species (80 endangered; 85 threatened), including 66 foreign species (40 endangered; 26 threatened). The directory lists the protected status of individual species, including blue whale (ESA Endangered), North Atlantic right whale (ESA Endangered), vaquita (ESA Endangered), elkhorn coral and staghorn coral (ESA Threatened, listed 2006), scalloped hammerhead (ESA Endangered and Threatened for different population segments), giant manta ray (ESA Threatened), and Hawaiian monk seal (ESA Endangered). https://www.fisheries.noaa.gov/species-directory/threatened-endangered
• NOAA Fisheries. Endangered Species Act. The purposes of the Act are to conserve the ecosystems on which endangered and threatened species depend and to provide a program for their conservation; "endangered species" means a species in danger of extinction throughout all or a significant portion of its range. https://www.fisheries.noaa.gov/national/endangered-species-conservation/endangered-species-act
• NOAA Fisheries. The Endangered Species Act at 50. The Act was passed by Congress and signed in 1973; a species is threatened if it is likely to become endangered within the foreseeable future, and endangered if it is in danger of extinction throughout all or a significant portion of its range; listing decisions are based on the best available science; listed species receive a recovery plan. https://www.fisheries.noaa.gov/node/155341
• NOAA Fisheries. Marine Mammal Protection Act. The Act places a moratorium on the taking of marine mammals and marine mammal products, where taking includes harassing, hunting, capturing, or killing; NOAA Fisheries manages cetaceans and most pinnipeds, and the U.S. Fish and Wildlife Service manages polar bears, walruses, sea otters, manatees, and dugongs. https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-protection-act
• NOAA Fisheries. North Atlantic Right Whale. The species has been listed as endangered under the Endangered Species Act since 1970; in October 2025 NOAA Fisheries estimated 384 (plus 10, minus 9) North Atlantic right whales alive at the start of 2024; there are only about 70 reproductively active females; entanglement and vessel strikes are the primary threats. https://www.fisheries.noaa.gov/species/north-atlantic-right-whale
• Linden, D. W. 2025. Population size estimation of North Atlantic right whales from 1990 to 2024. NOAA Technical Memorandum NMFS-NE-338. The estimated median population size at the start of 2024 was 384 whales, with a 95 percent credible interval of 375 to 394; the sharp decrease from 2015 to 2020 appears to have slowed, although mortality remains above recovery thresholds. https://repository.library.noaa.gov/view/noaa/72014/noaa_72014_DS1.pdf
• NOAA Fisheries. Fun Facts About Terrific Sea Turtles. All six species of sea turtles in the U.S. are protected under the Endangered Species Act: green, hawksbill, Kemp's ridley, leatherback, loggerhead, and olive ridley; the hawksbill, Kemp's ridley, and leatherback are listed as endangered; the loggerhead, green, and olive ridley are listed as threatened, with some populations listed as endangered. https://www.fisheries.noaa.gov/national/outreach-and-education/fun-facts-about-terrific-sea-turtles
• IUCN. Guidelines for the Appropriate Use of the IUCN Red List by Business, Version 1.1 (July 2022). The Red List categories are Extinct, Extinct in the Wild, Critically Endangered (extremely high risk of extinction in the wild), Endangered (high risk), Vulnerable (medium risk), Near Threatened, Least Concern, and Data Deficient; species in the three threatened categories are Critically Endangered, Endangered, and Vulnerable. https://nc.iucnredlist.org/redlist/content/attachment_files/Guidelines_for_Appropriate_Use_of_IUCN_Red_List_for_Business_ver_1_1.pdf
• IUCN Red List of Threatened Species. Rhincodon typus (Whale Shark). Assessed 18 March 2016; listed as Endangered under criteria A2bd+4bd; population trend decreasing. https://www.iucnredlist.org/species/19488/2365291
• IUCN. Nearly half of reef-building coral species face elevated relative risk of extinction. Press release, 15 October 2026. A global reassessment found 44 percent of reef-building coral species threatened with extinction; of 774 species with sufficient data, 340 were threatened (33 Critically Endangered, 251 Endangered, 56 Vulnerable); the assessment used data up to 2020, before the fourth global coral bleaching event of 2023 to 2025, and the authors caution the true share at risk is likely higher; the first assessment in 2008 found about one third threatened. https://iucn.org/press-release/202610/nearly-half-reef-building-coral-species-face-elevated-relative-risk-extinction
• NOAA Fisheries. Hawaiian Monk Seal. Species profile read 5 Nov 2026: "We estimate the population to be around 1,600 seals, nearly 1,200 seals in Papahanaumokuakea, and 400 seals in the main Hawaiian Islands"; the population began to increase gradually in 2013 in both areas and continues to grow at a slow, steady rate; the species is listed as endangered under the Endangered Species Act. https://www.fisheries.noaa.gov/species/hawaiian-monk-seal
• U.S. Fish and Wildlife Service and NOAA Fisheries, via NOAA Ocean Today. The Endangered Species Act. The Endangered Species Act of 1973 is described as having prevented the extinction of 99 percent of the species it protects, using science based management plans; the U.S. Fish and Wildlife Service is in charge of land and freshwater species and NOAA Fisheries is in charge of marine species. https://oceantoday.noaa.gov/endspeciesact/welcome.html
• eCFR. 50 CFR 224.103. Approaching a right whale within 500 yards (460 m) by vessel, aircraft, or any other means is unlawful; vessels and aircraft must leave the area if a right whale is approached within that distance. https://www.ecfr.gov/current/title-50/part-224/section-224.103
• U.S. Fish and Wildlife Service. West Indian Manatee Reclassified from Endangered to Threatened. Press release, 30 March 2017. The Service announced the downlisting of the West Indian manatee from endangered to threatened; the final rule was published 5 April 2017 (Federal Register Vol. 82 No. 64) and took effect 5 May 2017.