Threatened & Endangered Species

Until recently, humankind seemed to view the ocean as a source of infinite resources. Its vast size and depth and unexplored frontiers made the ocean appear invulnerable to overexploitation.

The truth is that the populations of many species are decreasing at an unsustainable rate, and the number of species listed as Endangered from marine life Families such as whales, dolphins, manatees and dugongs, salmon, seabirds, sea turtles, and sharks to name a few, are on the rise.

Read “The Sixth Extinction” by Elizabeth Kolbert:
Rodolfo Dirzo et al. “Defaunation in the Anthropocene”
Stuart Pimm et al. “Biodiversity of Species and Their Rates of Extinction”
Get to know an endangered species:
Half of world’s wildlife has died off in past 40 years:

Until recently, humankind seemed to view the ocean as a source of infinite resources. Its vast size and depth and unexplored frontiers made the ocean appear invulnerable to overexploitation. The truth is that the populations of many species are decreasing at an unsustainable rate, and the number of species listed as endangered from marine life families such as whalesdolphinsmanatees and dugongs, salmon, seabirds, sea turtles,and sharks to name a few, are on the rise. The threats to marine species are difficult to perceive because marine animals are not as visible as animals on land. But unfortunately, marine creatures are equally, if not more, vulnerable to problems such as habitat destruction and overexploitation. Shallow water animals that breathe air, like turtles, manatees, dugongs, and whales are often hit by boats and caught in fishing gear. Species such as turtles that lay their eggs on land often lose their nurseries due to coastal development. Animals that have taken millions of years to evolve, that are invaluable to all ecosystems, have and continue to vanish from places where they once flourished.


Marine Species are in serious trouble

  • CRCritically Endangered (222 species)
  • ENEndangered (329 species)
  • VUVulnerable (778 species)
  • NT or LR/ntNear Threatened (527 species)
  • DDData Deficient (3,648 species)

Note: Last updated: 7/29/23. All 19 Marine Regions selected, not included: LC or LR/lc (Least Concern (10,783 species)), subspecies and varieties (36) or subpopulations (153).

“More than 42,100 species are threatened with extinction. That is still 28% of all assessed species.”

Loss of habitats, the spread of disease, pollution, and unsustainable fishing practices are directly related to the actions of humans and recovery from these problems is rarely straightforward. Many marine species live in small, specific habitats while others require protection across their migration routes that cover vast areas and include breeding and feeding grounds. Marine protected areas (MPAs) have been designated in many places worldwide, which can help protect and restore threatened species, but MPAs are limited in size and therefore, limited to the marine life that inhabits those areas.

[December 9th, 2022] “The IUCN Red List now includes 150,388 species, of which 42,108 are threatened with extinction. Over 1,550 of the 17,903 marine animals and plants assessed are at risk of extinction, with climate change impacting at least 41% of threatened marine species.” Read more: IUCN Red List: Human activity devastating marine species from mammals to corals

Not Enough Data

Smaller corals, invertebrates, and fish are crucial components to ecosystems. There are about 11,000 species less than 1-2 mm and about 15% of those have highly specific niches. Data on populations of small invertebrates and marine fish is difficult to collect. There is data for larger species that indicates huge losses of parrotfish, humphead wrasse, and grouper. Spiny lobsters are now very hard to find in any coral reef and the coconut crab is now only located in protected areas and tiny islands. Genetic diversity, habitat diversity, and species diversity must work together for global ecosystems to function.


The definition of a threatened species is one that may become extinct if measures aren’t taken to protect it. An endangered species is one that has a very small population and at greater risk of becoming extinct. Many species that become extinct never make it to the endangered species list.

The Endangered Species Act

In 1969, the Departments of the Interior, Agriculture, and Defense passed the Endangered Species Conservation Act to prevent mass extinctions of certain species. The use of endangered species by humans for food, fur, and other commercial uses was outlawed by this act and by the Marine Mammal Protection Act of 1972. In 1973, the Convention on International Trade in Endangered Species (CITES) of Wild Fauna and Flora was implemented to cut back on the trade of plants and animals in trouble. The 1973 Endangered Species Act is one of the most significant environmental laws in America and defines endangered or threatened species, puts plants and invertebrates under protection, requires federal agencies to start programs to conserve important habitats, creates a wide umbrella of laws against hunting for endangered species, and matches contributions from individual states towards the project. The United States Fish and Wildlife Service (FWS) and the National Marine Fisheries Service (NMFS) are responsible for the enforcement of the Endangered Species Act.

Scientific Research

Scientists and the general population are also worried that if the destruction of biodiversity continues at the current rate, a mass extinction event will eventually take place. Many species go extinct before there is time to save them. Without protection, resources like global fisheries and future medicines may be lost forever unless adequate policy, scientific research, and individual actions can prevent further loss.

The North Atlantic right whale is one example of an animal researched at Wood’s Hole in response to the mysterious reduction in species number. Scientists think that a number of factors may contribute to the declining number of right whales in the North Atlantic including collisions with boats, entanglement with fishing gear, failure to reproduce, unprotected feeding grounds, and exposure to chemicals. Simply stating that an animal is on a protected list and banning hunting is not enough. There are many other human influences preventing survival.


There is great controversy surrounding the endangered species list related to when a species should be considered endangered, when should the species be removed from the list, whether governments can take land to protect habitats from development, and loopholes to the protection laws. Placing a species on the endangered list often causes the value to soar for poachers and collectors.

We simply can’t say it any better. » Visit the Species Alliance site

The Categories

The IUCN Red List of Threatened Species provides the conservation status for different species and indicates how many exist, an increase or decrease in numbers, how well they are reproducing and if their populations face potential threats.

Conservation categories include: extinct, extinct in the wild, critical or critically endangered, endangered, vulnerable and secure or low risk (see Figure 1). The Steller’s sea cow is listed as extinct and no one expects to ever see one again. Animals that have gone extinct in the wild but still exist in captivity are, for example, the dromedary camel and Przewalski’s horse.

Marine animals teetering above extinction on the critically endangered list are coelacanthssouthern bluefin tunahawksbills and leatherback sea turtles. Marine endangered animals include: loggerheadsgreen and olive ridley sea turtles, various species of sawfishes and blue whalesDugongshumphead wrasseswhale sharkshumpback whalesgrey nurse sharks, and great white sharks are examples of marine animals that will likely go extinct if little changes.

In the low-risk category are animals that do not meet the requirements to be considered on the endangered list. Threatened species are not protected as seriously as endangered species and include many species of whales and sharks. The last two categories are the “data deficient category” and the “not evaluated” category essentially meaning that more data needs to be collected or the species has not been considered yet. There are a great number of endangered species that still need to be put on the list and the definitions of what is considered endangered or threatened can vary greatly.

Listing a Species

Sometimes, the U.S. Fish and Wildlife Service or National Marine Fisheries Service will add a species to the list and other times citizens or groups will petition for the species to be added. Before a species can be placed on the Endangered Species list it must first be on the Federal list of endangered and threatened wildlife and plants. Due to political pressures or time frames, species are often placed on a candidate list before they can be officially considered endangered or threatened. Once on the official list, anyone who ignores the Endangered Species Act can be fined up to $50,000 and jailed for up to one year. A plan is also made detailing how important habitats will be protected and what will be done to assist recovery of the species. Most species placed under protection by the Endangered Species Act have avoided extinction. Another interesting fact about the Endangered Species Act is that it contains a citizen enforcement clause so that the public can “sue” the government to make sure a species with dwindling numbers is listed. The IUCN endangered species red list can be downloaded from:


Sometimes, the preservation of one endangered species can mean a lot more than preventing the extinction of an animal. In the 1970’s the Tellico dam in Tennessee not only threatened the survival of the perciform (snail) darter, but also the existence of one of the few remaining wild rivers in the state, sacred Native American land, important farmland, and recreational sport fishing. Using the Endangered Species Act, citizens in 1978 were able to get a Supreme Court ruling to prevent building of the Tellico dam in 1978. Politicians lobbied for a provision to the Environmental Species Act that would allow the dam and other projects to be completed if the benefits of building these structures would outweigh environmental problem caused. Even when it was determined that the dam was not economical, Congress allowed the dam to be built anyway. The snail was found in other places so it was moved down to the threatened list and the farmland, American Indian sites, and recreation on the wild river were lost.


The Convention on International Trade in Endangered Species (CITES) was formed to make sure trade of exotic animals and plants across nations does not put their survival into jeopardy. Over 30,000 species are protected by CITES and none have become extinct due to trading since initiation of the agreement between governments.

IUCN (International Union for Conservation of Nature)

The IUCN Red List does not yet give a complete picture of the number of marine species in trouble, even though they do list larger species like marine mammals, turtles, and seabirds that are considered threatened. The slowly changing lack of information about other species poses an obstacle to the protection of marine invertebrates and many types of fish. Only a few invertebrates exist on the list, including the giant clam. A campaign called “Shattering the Myth” was created to change things for marine species by the IUCN Species Survival Commission. Currently and recently added to the Red List are the swordfish, sawfishes, types of tunas, sharks, groupers, seahorses, manta rays, coelacanths, etc.

NMFS (National Marine Fisheries Service)

The NMFS defines an endangered species as “any species which is in danger of extinction throughout all of a significant portion of its range”. Mammals listed as endangered with the NMFS are blue whalesbowhead whalesfin whales, Western North Pacific gray whaleshumpback whalesnorthern right whalessei whalessouthern right whalessperm whalesChinese river dolphins in China, Indus river dolphins in Pakistan, dugongsWest Indian manatees, Gulf of California harbor porpoises, Western stock of Steller sea lionsCaribbean monk sealsHawaiian monk sealsMediterranean monk seals, and ringed seals in Finland.

Marine Mammals

Marine mammals close to becoming an endangered species are categorized under threatened. These include: the Eastern Stock of the Steller sea lionGuadalupe fur seals, and the California sea otters.

According to the Marine Mammal Protection Act (MMPA), species can also be called “depleted”. A depleted species is one whose numbers have dropped lower than the optimum sustainable population (OSP). The OSP is determined by whether the animals are reproducing in a healthy number that corresponds to the carrying capacity of the environment. When it is determined that a species has been depleted, the NMFS comes up with a plan to research factors involved and to bring the numbers back. Animals considered depleted are the North Atlantic Coastal bottlenose dolphins, Eastern spinner dolphinsNorth Pacific fur seals, the Northeastern Offshore and Coastal spotted dolphins, and Cook Inlet beluga whales. More information is being collected on “species of concern” which include Cook Inlet beluga whales and orcas (killer whales). Eastern Pacific gray whales has been recovered by the Endangered Species Act and were actually taken off the list. Steller’s Sea cows was lost forever shortly before the MMPA and ESA were implemented.

Pinnipeds are seals, sea lions or walruses but are taxonomically relatives of bears, dogs, raccoons, otters or weasels. The families under pinnipedia include PhocidaeOtariidae and Odobenidae which are earless seals, fur seals or sea lions, and walrus respectively. The main reason for the loss of many pinnipeds is the amount of commercial fishing that took place from the 1700’s up to the 1900’s. Other reasons include the development of coastline and lack of fish due to overfishing.

Another group of marine mammals affected by commercial hunting between the 1700’s and the 1900’s were the baleen whales. Populations of baleen whales are still low in numbers even though commercial hunting is now mostly illegal. Many whales are still being hit and killed by ships, particularly critically endangered northern right whales. Whales are also tangled in fishing gear or marine garbage. Sometimes something as small as a party balloon can kill a whale by cutting off its digestive tract.

Marine Invertebrates

Marine invertebrates and plants are currently listed under the “candidates or species of concern” category in the Endangered Species Act due to a lack of information or time. These include Brachiopods, Corals, Mollusks, and various plant life. Brachiopods are invertebrates that live on the seafloor and feed through a filter appendage. They are attached to objects in the ocean and resemble a clam. Brachiopods reached the peak of their numbers in the Paleozoic era and were reduced greatly during the Permo-Triassic mass extinction. The two classes or types of brachiopods are the Inarticulata and the Articulata. Reasons for decline in number of brachiopods include habitat destruction, overfishing, pollution and sediment accumulation, general vulnerability to stress, and small numbers.

Corals are made of invertebrate polyps and are either hard or soft. They have been around for 500 million years since the Cambrian period. Hard corals are composed of calcium carbonate and they live symbiotically with zooxanthellae, a type of phytoplankton. Soft corals have calcareous pieces of matter in their structure and are usually found independently in deeper waters. All corals are related to anemones, hydras or jellyfish. There is only one class of coral and that is Anthozoa. Subclasses include Alcyonaria, Ceriantipatharia, and Hexacorallia (Zoantharia). In consideration for endangered status are the elkhorn coral, staghorn, ivory-bush, and Hawaiian reef corals (Order Scleractinia). Corals have declined drastically in numbers due to disease epidemics since the 80’s, destruction of habitat, accumulation of sediment, a changing food chain resulting in increased predation, hurricanes, pollutants, alien species, invasive species like green algae, small numbers, fishing practices, and bleaching of corals due to temperature changes, to name a few.

Mollusks are invertebrates and most of them are in the Class Gastropoda which means “stomach foot” in Latin. They have a soft body and are often found with a shell, although they can also have an internal shell or no shell. Related to segmented worms and pogonophora, there are seven Classes of mollusks including: Aplacophora, Bivalvia, Cephalopoda, Gastropoda, Monoplacophora, Polyplacophora, and Scaphopoda. Animals qualifying as species of concern include: black abalone, green abalone, pink abalone, and pinto abalone. The white abalone is currently classified as endangered. The abalone has been overfished, numbers decreased, genetic diversity has been lost, it has been subjected to disease, poachers and changes in the food chain resulting in an increase in predation.

Marine Plants

Most marine plants include types of seagrass, types of mangroves and types of algae. Mangroves and seagrasses are flowering plants and use pollen to reproduce. They are often found close to the coast. Algae can be anything from tiny phytoplankton to huge seaweeds. So far, Johnson’s seagrass is listed as threatened, although many other plants should be on the list. Plants are mostly lost when humans change the habitat, natural events change the environment or oxygen is used up by organisms thriving in nutrient-enriched areas (also often caused by humans).

Sea Turtles

Sea turtles are another animal threatened by extinction in the oceans. With aerodynamic bodies, oversized flippers and the ability to breathe air, these unique animals live in tropical or subtropical oceans all over the planet. The United States is visited by six of the seven types of sea turtles including greenshawksbillsKemp’s ridleysleatherbacksloggerheads and olive ridleys. Sea turtles rely on undisturbed beaches to lay eggs and can travel huge distances to feed or nest.

Green sea turtles are endangered or threatened; hawksbill sea turtles are endangered; Kemp’s ridley sea turtles are endangered; leatherback sea turtles are critically endangered; loggerhead sea turtles are threatened; and olive ridley sea turtles are endangered or threatened. The National Oceanic and Atmospheric Administration (NOAA) fisheries are primarily in charge of the conservation and restoration of these species although the U.S. Fish and Wildlife Service shares jurisdiction.

The major reasons why sea turtles are declining in numbers include: development or destruction of nesting and foraging places, accidental tangling in nets or lines, tangling in marine garbage and being hit by boats or motor craft. Regulations on gillnets, longlines, pound nets and trawls have been established by the NOAA fisheries and certain areas crucial for sea turtles have been roped off at important times. It is also important to handle sea turtles in a certain way and there are now regulations for this as well. Comprehensive strategies, research and management efforts are in the process of being developed so that the sea turtle can recover. In addition to nation-wide programs, the NOAA also has national and international programs.

Marine and Anadromous (freshwater breeding) Fish

Marine and anadromous fish are also under protection by the NOAA. Anadromous fish start out in freshwater, go to saltwater and then return to freshwater to breed. Marine fish spend their entire lives in saltwater. Most fish listed under the Endangered Species Act are Pacific salmonids and have been listed as Evolutionary Significant Units. Other types of fish listed are Atlantic salmon, shortnose sturgeon, smalltooth sawfish and the Gulf sturgeon.

Additional Resources
WHOI : Oceanus : Whither the North Atlantic Right Whale?
Wikipedia Threatened species
Wikipedia: Endangered species
Wikipedia: Endangered Species Act
Wikipedia: Convention on the International Trade in Endangered Species of Wild Flora and Fauna
IUCN Red List – Categories & Criteria (version 3.1)
Endangered Species Information, U.S. Fish and Wildlife Service
Status of Marine Mammals Under the Law – NOAA – Office of Protected Resources
Marine Invertebrates and Plants – Office of Protected Resources – NOAA Fisheries
Marine Turtles – Office of Protected Resources – NOAA Fisheries
Pinnipeds – Seals, Sea Lions, and Walruses – Office of Protected Resources – NOAA Fisheries
Cetaceans – Whales, Dolphins, and Porpoises – Office of Protected Resources – NOAA Fisheries
Marine and Anadromous Fish – Office of Protected Resources – NOAA Fisheries

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