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75-495: MMPA was signed into law on October 21, 1972, by President Richard Nixon and took effect 60 days later on December 21, 1972. It prohibits the "taking" of marine mammals , and enacts a moratorium on the import, export, and sale of any marine mammal, along with any marine mammal part or product within the United States . The Act defines "take" as "the act of hunting , killing, capture, and/or harassment of any marine mammal; or,

150-828: A basis for importing fish and fish products from nations engaged in harvesting yellowfin tuna with purse seines and other commercial fishing technology, as well as authorized appropriations for agency activities through FY 1988. Amended in 1988 Amended in 1994 Under the MMPA amended in 1994, in Section 119, NMFS and FWS was authorized to form the cooperative agreements ( co-management plan) with Alaska Native Organizations (ANOs) . This allows indigenous tribal government can engage in their territorial marine mammal protection and subsistence taking issues through individual co-management agreements which can be established with NOAA, USFWS, MMC, or other MMPA-affiliated agencies. Co-management

225-405: A blunt snout and reduced dentition rely on suction feeding . Though carnivorous, they house gut flora similar to that of terrestrial herbivores, probably a remnant of their herbivorous ancestry. Baleen whales use their baleen plates to sieve plankton, among others, out of the water; there are two types of methods: lunge-feeding and gulp-feeding. Lunge-feeders expand the volume of their jaw to

300-627: A divergence of the Monachinae (monk seals) and Phocinae lineages 22 mya. Fossil evidence indicates the sea otter ( Enhydra ) lineage became isolated in the North Pacific approximately two mya, giving rise to the now-extinct † Enhydra macrodonta and the modern sea otter, Enhydra lutris . The sea otter evolved initially in northern Hokkaidō and Russia, and then spread east to the Aleutian Islands , mainland Alaska , and down

375-471: A few are specialists. They typically hunt non-schooling fish, slow-moving or immobile invertebrates or endothermic prey when in groups. Solitary foraging species usually exploit coastal waters, bays and rivers. When large schools of fish or squid are available, pinnipeds hunt cooperatively in large groups, locating and herding their prey. Some species, such as California and South American sea lions, may forage with cetaceans and sea birds. The polar bear

450-501: A few eat other mammals. While the number of marine mammals is small compared to those found on land, their roles in various ecosystems are large, especially concerning the maintenance of marine ecosystems, through processes including the regulation of prey populations. This role in maintaining ecosystems makes them of particular concern as 23% of marine mammal species are currently threatened. Marine mammals were first hunted by aboriginal peoples for food and other resources. Many were also

525-698: A number of features for efficient locomotion such as torpedo-shaped bodies to reduce drag; modified limbs for propulsion and steering ; tail flukes and dorsal fins for propulsion and balance. Marine mammals are adept at thermoregulation using dense fur or blubber , circulatory adjustments ( counter-current heat exchange ); and reduced appendages, and large size to prevent heat loss. Marine mammals are able to dive for long periods. Both pinnipeds and cetaceans have large and complex blood vessel systems pushing large volumes of blood rich in myoglobin and hemoglobin , which serve to store greater quantities of oxygen . Other important reservoirs include muscles and

600-438: A number of terrestrial habitats, both continental and island. In temperate and tropical areas, they haul-out on to sandy and pebble beaches, rocky shores , shoals , mud flats , tide pools and in sea caves . Some species also rest on man-made structures, like piers , jetties , buoys and oil platforms . Seals may move further inland and rest in sand dunes or vegetation, and may even climb cliffs. Most cetaceans live in

675-629: A period of glaciation in the Pleistocene or from the eastern part of Siberia , (from Kamchatka and the Kolym Peninsula). The oldest known polar bear fossil is a 130,000-to-110,000-year-old jaw bone, found on Prince Charles Foreland in 2004. The mitochondrial DNA (mtDNA) of the polar bear diverged from the brown bear roughly 150,000 years ago. Further, some clades of brown bear, as assessed by their mtDNA, are more closely related to polar bears than to other brown bears, meaning that

750-442: A seal to appear. When the seal exhales, the bear smells its breath, reaches into the hole with a forepaw, and drags it out onto the ice. The polar bear also hunts by stalking seals resting on the ice. Upon spotting a seal, it walks to within 100 yards (90 m), and then crouches. If the seal does not notice, the bear creeps to within 30 to 40 feet (9 to 10 m) of the seal and then suddenly rushes to attack. A third hunting method

825-806: A specified geographic area. Directed permits are required for any proposed marine mammal scientific research activity that involves taking marine mammals. Applications for such permits are reviewed and issued the Service's Division of Management Authority, through the International Affairs office. This office also houses the Division of International Conservation, which is directly responsible for coordinating international activities for marine mammal species found in both U.S. and International waters, or are absent from U.S. waters. Marine mammal species inhabiting both U.S. and International waters include

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900-477: A third time. Japan is the most recent member to depart, in January 2019, so as to resume commercial whaling. There have been consistent disagreement over the scope of the convention. The 1946 Convention does not define a 'whale'. Some members of IWC claim that it has the legal competence to regulate catches of only great whales (the baleen whales and the sperm whale). Others believe that all cetaceans, including

975-430: A volume bigger than the original volume of the whale itself by inflating their mouth. This causes grooves on their throat to expand, increasing the amount of water the mouth can store. They ram a baitball at high speeds in order to feed, but this is only energy-effective when used against a large baitball. Gulp-feeders swim with an open mouth, filling it with water and prey. Prey must occur in sufficient numbers to trigger

1050-1091: Is developed with a team involving representatives from fishing industry, management councils, governmental agencies, scientific community, and conservation organization. The consensus from the representatives is then submitted to NOAA for review then through the public comment. As the Plan is finalized, NOAA has the duty to monitor its implementation with the team. Yet, the Plans are uneven or unstandardized in practice to meet its statutory requirement. Successful plans are often based upon mandated, quantitative metrics, and consistent monitoring programs. Congress found that: all species and population stocks of marine mammals are, or may be, in danger of extinction or depletion due to human activities; these mammals should not be permitted to diminish below their optimum sustainable population; measures should be taken immediately to replenish any of these mammals that have diminished below that level, and efforts should be made to protect essential habitats; there

1125-530: Is herding, where a pod squeezes a school of fish into a small volume, known as a bait ball . Individual members then take turns plowing through the ball, feeding on the stunned fish. Coralling is a method where dolphins chase fish into shallow water to catch them more easily. Killer whales and bottlenose dolphins have also been known to drive their prey onto a beach to feed on it. Killer whales have been known to paralyze great white sharks and other sharks and rays by flipping them upside down. Other whales with

1200-536: Is inadequate knowledge of the ecology and population dynamics of these mammals; negotiations should be undertaken immediately to encourage international arrangements for research and conservation of these mammals. Congress declared that marine mammals are resources of great international significance (aesthetic, recreational and economic), and should be protected and encouraged to develop to the greatest extent feasible commensurate with sound policies of resource management. The primary management objective should be to maintain

1275-748: Is responsible for the management and conservation of polar bears , Pacific walruses , and northern sea otters in Alaska. Northern sea otters present in Washington state are managed by the Western Washington Field Office, while southern sea otters residing in California are managed by the Ventura Field Office. West Indian manatee populations extend from Texas to Rhode Island , and are also present in

1350-418: Is scarce. West Indian manatees eat up to 60 different species of plants, as well as fish and small invertebrates to a lesser extent. Sea otters are a classic example of a keystone species; their presence affects the ecosystem more profoundly than their size and numbers would suggest. They keep the population of certain benthic (sea floor) herbivores, particularly sea urchins , in check. Sea urchins graze on

1425-408: Is the development of echolocation in whales and dolphins. Toothed whales emit a focused beam of high-frequency clicks in the direction that their head is pointing. Sounds are generated by passing air from the bony nares through the phonic lips. These sounds are reflected by the dense concave bone of the cranium and an air sac at its base. The focused beam is modulated by a large fatty organ known as

1500-428: Is the most carnivorous species of bear, and its diet primarily consists of ringed ( Pusa hispida ) and bearded ( Erignathus barbatus ) seals. Polar bears hunt primarily at the interface between ice, water, and air; they only rarely catch seals on land or in open water. The polar bear's most common hunting method is still-hunting: The bear locates a seal breathing hole using its sense of smell, and crouches nearby for

1575-720: Is the only marine mammal that catches fish with its forepaws rather than with its teeth. Under each foreleg, sea otters have a loose pouch of skin that extends across the chest which they use to store collected food to bring to the surface. This pouch also holds a rock that is used to break open shellfish and clams, an example of tool use . The sea otters eat while floating on their backs, using their forepaws to tear food apart and bring to their mouths. Marine otters mainly feed on crustaceans and fish. Pinnipeds mostly feed on fish and cephalopods , followed by crustaceans and bivalves , and then zooplankton and warm-blooded prey (like sea birds ). Most species are generalist feeders, but

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1650-437: Is to raid the birth lairs that female seals create in the snow. They may also feed on fish. Sirenians are referred to as "sea cows" because their diet consists mainly of seagrass. When eating, they ingest the whole plant, including the roots, although when this is impossible they feed on just the leaves. A wide variety of seagrass has been found in dugong stomach contents, and evidence exists they will eat algae when seagrass

1725-408: Is viewed as the practice of indigenous sovereignty and self-determination.  Co-management under Section 119 includes the following activities: Alaska Nanuuq Commission (ANC) represents tribes for polar bears management with USFWS. In this partnership, the subsistence take of polar bear is legal according to MMPA, yet the prohibition is placed on taking females with cubs and harassment. Along with

1800-773: The Caribbean Sea ; however, this species is most prevalent near Florida (the Florida subspecies) and Puerto Rico (the Antillean subspecies). The Service's Jacksonville Field Office manages the Florida manatee , while the Boqueron Field Office manages the Antillean manatee . The polar bear, southern sea otter, marine otter, all three species of manatees, and the dugong are also concurrently listed under

1875-586: The Endangered Species Act (ESA). Amendments enacted in 1981 established conditions for permits to be granted to take marine mammals "incidentally" in the course of commercial fishing. In addition, the amendments provided additional conditions and procedures for transferring management authority to the States, and authorized appropriations through FY 1984. Policies created in 1982 The 1984 amendments established conditions to be satisfied as

1950-642: The Endangered Species Act of 1973 , and provisions that may need to be made to the MMPA.   The U.S. Fish and Wildlife Services are responsible for managing the take through the use of permits and other authorization as well as financially supporting efforts to help marine mammals that fall victim to stranding and relevant research efforts. Similar to the NOAA , the U.S. Fish and Wildlife Services conduct stock assessments of marine mammal populations under their jurisdiction which include walrus , manatees , sea otters , and polar bears . They are also responsible for

2025-572: The Eocene . Their evolutionary link to terrestrial mammals was unknown until the 2007 discovery of † Puijila darwini in early Miocene deposits in Nunavut , Canada. Like a modern otter, † Puijila had a long tail, short limbs and webbed feet instead of flippers. The lineages of Otariidae (eared seals) and Odobenidae (walrus) split almost 28 mya. Phocids (earless seals) are known to have existed for at least 15 mya, and molecular evidence supports

2100-486: The Indian Ocean . The variation observed in range size is a result of the different ecological requirements of each species and their ability to cope with a broad range of environmental conditions. The high degree of overlap between marine mammal species richness and areas of human impact on the environment is of concern. Most marine mammals, such as seals and sea otters, inhabit the coast. Seals, however, also use

2175-551: The North Atlantic right whale , are critically endangered . Other than being hunted, marine mammals can be killed as bycatch from fisheries, where for example they can become entangled in nets and drown or starve. Increased ocean traffic causes collisions between fast ocean vessels and large marine mammals. Habitat degradation also threatens marine mammals and their ability to find and catch food. Noise pollution , for example, may adversely affect echolocating mammals, and

2250-551: The North Ronaldsay sheep ( Ovis aries ) which normally eats seaweed outside the lambing season, the Eurasian otter ( Lutra lutra ) which is usually found in freshwater but can be found along coastal Scotland , and others. Marine mammals form a diverse group of 129 species that rely on the ocean for their existence. They are an informal group unified only by their reliance on marine environments for feeding. Despite

2325-574: The Old World (such as cetaceans ). The first known quadrupedal sirenian was † Pezosiren from the early middle Eocene. The earliest known sea cows, of the families † Prorastomidae and † Protosirenidae , were both confined to the Eocene, and were pig-sized, four-legged, amphibious creatures. The first members of Dugongidae appeared by the middle Eocene. At this point, sea cows were fully aquatic. Pinnipeds split from other caniforms 50 mya during

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2400-838: The West Indian manatee , sea otter , polar bear , and Pacific walrus . Species not present in U.S. waters include the West African and Amazonian manatee , dugong , Atlantic walrus , and marine otter . In efforts to conserve and manage marine mammal species, the Service has appointed field staff dedicated to working with partners to conduct population censuses, assess population health, develop and implement conservation plans, promulgate regulations, and create cooperative relationships internationally. Various Marine Mammal Management offices are located on either coast. The Service's Marine Mammal Management office in Anchorage, Alaska

2475-522: The hippopotamuses . Sirenians, the sea cows, became aquatic around 40 million years ago. The first appearance of sirenians in the fossil record was during the early Eocene, and by the late Eocene, sirenians had significantly diversified. Inhabitants of rivers, estuaries, and nearshore marine waters, they were able to spread rapidly. The most primitive sirenian, † Prorastomus , was found in Jamaica, unlike other marine mammals which originated from

2550-643: The spleen which all have the capacity to hold a high concentration of oxygen. They are also capable of bradycardia (reduced heart rate), and vasoconstriction (shunting most of the oxygen to vital organs such as the brain and heart) to allow extended diving times and cope with oxygen deprivation. If oxygen is depleted ( hypoxia ), marine mammals can access substantial reservoirs of glycogen that support anaerobic glycolysis . Sound travels differently through water, and therefore marine mammals have developed adaptations to ensure effective communication, prey capture, and predator detection. The most notable adaptation

2625-430: The 'melon'. This acts like an acoustic lens because it is composed of lipids of differing densities. Marine mammals have evolved a wide variety of features for feeding, which are mainly seen in their dentition. For example, the cheek teeth of pinnipeds and odontocetes are specifically adapted to capture fish and squid. In contrast, baleen whales have evolved baleen plates to filter feed plankton and small fish from

2700-656: The 1931 Geneva Convention for Regulation of Whaling and the 1937 International Agreement for the Regulation of Whaling, established in response to the overexploitation of whales in the post-World War I period. Neither instrument was effective, but each provided the framework for the International Convention for the Regulation of Whaling, which was spearheaded by the United States and signed by 15 countries in Washington, D.C. , on 3 December 1946;

2775-502: The MMPA to serve as an organization that provides oversight over conservation policies, regulations and programs being carried out to ensure they are carried out effectively by the federal agencies responsible for them. Their responsibilities also include ensuring the United States adhere to international agreements that relate to marine mammal conservation “including, but not limited to, the International Convention for

2850-573: The MMPA, they are responsible for effectively communicating with federal officials such as the Secretaries of State , Commerce or the Interior the recommended measures needed to be taken to ensure the effectiveness of the MMPA and the protection of marine mammals under this act. These recommendations can come in the form of implementation of international agreements, revisions to the endangered and threatened species list as deemed appropriate under

2925-576: The MMPA. The specific information that is included in all stock assessments are the geographic range of the stock being studied, current trends and productivity rates for the stock, potential biological removal levels which is defined under the MMPA as “the maximum number of animals, not including natural mortalities, that may be removed from a marine mammal stock while allowing that stock to reach or maintain its optimum sustainable population”, an estimation of mortality and injury rate caused by humans, potential threats to conservation efforts and current status of

3000-893: The Marine Mammal Protection Act through the implementation and enforcement of various policies and regulations to properly manage marine mammal populations. The NOAA does this through the identification of violations of the MMPA, coordinating efforts to aid stranded and entangled mammals, and conduct proper rehabilitation and release of injured marine mammals. The NOAA is also responsible for providing stock assessment reports on marine mammals under their jurisdiction which includes whales , dolphins , porpoises , seals , and sea lions . Stock assessment reports serve to identify trends in marine mammal populations, identify potential threats to said population, and whether current conservation efforts are effective and if adjustments need to be made to ensure effective enforcement of

3075-528: The North American coast. In comparison to cetaceans, sirenians, and pinnipeds, which entered the water approximately 50, 40, and 20 mya, respectively, the sea otter is a relative newcomer to marine life. In some respects though, the sea otter is more fully adapted to water than pinnipeds, which must haul out on land or ice to give birth. Polar bears are thought to have diverged from a population of brown bears , Ursus arctos , that became isolated during

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3150-404: The Regulation of Whaling The International Convention for the Regulation of Whaling is an international environmental agreement aimed at the "proper conservation of whale stocks and thus make possible the orderly development of the whaling industry". It governs the commercial, scientific, and aboriginal subsistence whaling practices of 88 member states. The convention is a successor to

3225-800: The Regulation of Whaling , the Whaling Convention Act of 1949, the Interim Convention on the Conservation of North Pacific Fur Seals, and the Fur Seal Act of 1966.” The MMC is also responsible for the review of the research programs conducted for the purpose of the MMPA as well as authorizing permits for the purpose of research, conservation or public display. If the MMC finds that the current conservation efforts are shown to be ineffective in protecting species identified under

3300-585: The Service and the NOAA better implement the MMPA. Coordination between these three federal agencies is necessary in order to provide the best management practices for marine mammals. Under the MMPA, the Service is responsible for ensuring the protection of sea otters and marine otters, walruses , polar bears , three species of manatees , and dugongs . NOAA was given responsibility to conserve and manage pinnipeds including seals and sea lions and cetaceans such as whales and dolphins . The NOAA enforces

3375-490: The Service that the issuance is consistent with the MMPA's regulations. The two types of permits issued by the National Marine Fisheries Service 's Office of Protected Resources are incidental and directed. Incidental permits, which allow for some unintentional taking of small numbers of marine mammal, are granted to U.S. citizens who engage in a specified activity other than commercial fishing in

3450-594: The US domestic standards. Yet it is difficult to expect this comparability from all exporting countries due to lack of fisheries records on bycatches and standardized protective measures which is causing unintentional harms. The Act emphasizes the recovery and prevention of the depletion of strategic marine mammal stocks. Under Section 118, Take Reduction Plan aims within six months of implementation to reduce incidental mortality and severe injury from fishery and approach zero mortality rate in five years. The Plan includes: The plan

3525-412: The attempt at such." The MMPA defines harassment as "any act of pursuit, torment or annoyance which has the potential to either: a. injure a marine mammal in the wild, or b. disturb a marine mammal by causing disruption of behavioral patterns, which includes, but is not limited to, migration, breathing, nursing, breeding, feeding, or sheltering." The MMPA provides for enforcement of its prohibitions, and for

3600-461: The cetaceans genetically and morphologically fall firmly within the Artiodactyla (even-toed ungulates). The term "Cetartiodactyla" reflects the idea that whales evolved within the ungulates. The term was coined by merging the name for the two orders, Cetacea and Artiodactyla, into a single word. Under this definition, the closest living land relative of the whales and dolphins is thought to be

3675-502: The co-management, Alaska Scientific Review Group is set up, with indigenous entities involved, to advise stock assessment and revise method for assessment. Alaska Beluga Whale Committee (ABWC) was founded in 1988 to manage beluga subsistence hunting in Alaska. After the MMPA amended, ABWC starts to develop a co-management plan with National Marine Fisheries Service (NMFS) aiming to become an "umbrella organization  concerned  with statewide, national and international affairs." With

3750-555: The convention since its ratification: Canada, Egypt , Guatemala , Greece , Jamaica , Mauritius , Philippines , the Seychelles and Venezuela . Belize , Brazil , Dominica , Ecuador , Iceland , Japan, New Zealand , and Panama have all withdrawn from the convention temporarily but ratified it second time; the Netherlands , Norway , and Sweden have each withdrawn from the convention twice, only to have accepted it

3825-443: The convention took effect on 10 November 1948. A protocol broadening the scope of the convention's enforcement was signed on 19 November 1956. The objectives of the International Convention for the Regulation of Whaling are to protect all whale species from overhunting ; establish a system of international regulation for whale fisheries to ensure proper conservation and development of whale stocks; and safeguard for future generations

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3900-537: The convention. The initial signatories were Argentina , Australia, Brazil , Canada, Chile , Denmark , France, the Netherlands , New Zealand , Norway , Peru , South Africa, the Soviet Union , the United Kingdom and the United States. Although Norway is party to the convention, it maintains an objection to the 1986 IWC global moratorium and it does not apply to it. Nine states have withdrawn from

3975-479: The creation and implementation of conservation plans which often occur in collaboration with industries which can potentially impact marine mammal populations of particular concern. The MMPA prohibits the take and exploitation of any marine mammal without appropriate authorization, which may only be given by the Service. Permits may be issued for scientific research, public display, and the importation/exportation of marine mammal parts and products upon determination by

4050-521: The diversity in anatomy seen between groups, improved foraging efficiency has been the main driver in their evolution . The level of dependence on the marine environment varies considerably with species. For example, dolphins and whales are completely dependent on the marine environment for all stages of their life; seals feed in the ocean but breed on land; and polar bears must feed on land. The cetaceans became aquatic around 50 million years ago (mya). Based on molecular and morphological research,

4125-812: The floor or to stay submerged. Surface-living animals (such as sea otters) need the opposite, and free-swimming animals living in open waters (such as dolphins) need to be neutrally buoyant in order to be able to swim up and down the water column. Typically, thick and dense bone is found in bottom feeders and low bone density is associated with mammals living in deep water. Some marine mammals, such as polar bears and otters, have retained four weight-bearing limbs and can walk on land like fully terrestrial animals. All cetaceans are carnivorous and predatory . Toothed whales mostly feed on fish and cephalopods , followed by crustaceans and bivalves . Some may forage with other kinds of animals, such as other species of whales or certain species of pinnipeds . One common feeding method

4200-525: The founding from NMFS, ABWC focus on facilitating scientific communication for the public, harvest monitoring, beluga tracking, aerial survey, genetics-based stock studies. The regional groups of ABWC are designate to "develop  local management  plans,  hunting guide-lines and means of enforcement." The Marine Mammal Protection Act has conservation benefits beyond US boundaries. The Act requires imported fisheries products to minimize incidental mortality and severe injury of marine mammals aligning to

4275-454: The globe, but their distribution is patchy and coincides with the productivity of the oceans. Species richness peaks at around 40° latitude, both north and south. This corresponds to the highest levels of primary production around North and South America , Africa , Asia and Australia . Total species range is highly variable for marine mammal species. On average most marine mammals have ranges which are equivalent or smaller than one-fifth of

4350-806: The health and stability of the marine ecosystem. The goal is to obtain an optimum sustainable population within the carrying capacity of the habitat. Marine mammal Marine mammals are mammals that rely on marine (saltwater) ecosystems for their existence. They include animals such as cetaceans ( whales , dolphins and porpoises ), pinnipeds ( seals , sea lions and walruses ), sirenians ( manatees and dugongs ), sea otters and polar bears . They are an informal group, unified only by their reliance on marine environments for feeding and survival. Marine mammal adaptation to an aquatic lifestyle varies considerably between species. Both cetaceans and sirenians are fully aquatic and therefore are obligate water dwellers. Pinnipeds are semiaquatic; they spend

4425-712: The health of coastal ecosystems, and similar changes have been observed as sea otter populations recovered in the Aleutian and Commander Islands and the Big Sur coast of California. However, some kelp forest ecosystems in California have also thrived without sea otters, with sea urchin populations apparently controlled by other factors. The role of sea otters in maintaining kelp forests has been observed to be more important in areas of open coast than in more protected bays and estuaries . International Convention for

4500-529: The ice further north that remains frozen year-round. Seals may also migrate to other environmental changes, such as El Niño , and traveling seals may use various features of their environment to reach their destination including geomagnetic fields, water and wind currents, the position of the sun and moon and the taste and temperature of the water. Baleen whales famously migrate very long distances into tropical waters to give birth and raise young, possibly to prevent predation by killer whales. The gray whale has

4575-546: The important natural resources represented by whale stocks. The primary instrument implementing these aims is the International Whaling Commission , established by the convention as its main decision-making body. The IWC meets annually and adopts a binding "schedule" that regulates catch limits, whaling methods, protected areas, and the right to carry out scientific research involving the killing of whales. As of January 2021, there are 88 parties to

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4650-720: The issuance of regulations to implement its legislative goals. Authority to manage the MMPA was divided between the Secretary of the Interior through the U.S. Fish and Wildlife Service (Service), and the Secretary of Commerce , which is delegated to the National Oceanic and Atmospheric Administration (NOAA). Subsequently, a third federal agency, the Marine Mammal Commission (MMC), was established to review existing policies and make recommendations to

4725-576: The longest recorded migration of any mammal, with one traveling 14,000 miles (23,000 km) from the Sea of Okhotsk to the Baja Peninsula . During the winter, manatees living at the northern end of their range migrate to warmer waters. Marine mammals have a number of physiological and anatomical features to overcome the unique challenges associated with aquatic living. Some of these features are very species-specific. Marine mammals have developed

4800-401: The lower stems of kelp , causing the kelp to drift away and die. Loss of the habitat and nutrients provided by kelp forests leads to profound cascade effects on the marine ecosystem. North Pacific areas that do not have sea otters often turn into urchin barrens , with abundant sea urchins and no kelp forest. Reintroduction of sea otters to British Columbia has led to a dramatic improvement in

4875-476: The majority of their time in the water but need to return to land for important activities such as mating , breeding and molting . Sea otters tend to live in kelp forests and estuaries. In contrast, the polar bear is mostly terrestrial and only go into the water on occasions of necessity, and are thus much less adapted to aquatic living. The diets of marine mammals vary considerably as well; some eat zooplankton , others eat fish, squid, shellfish, or seagrass, and

4950-541: The oceans, which have also evolved several specialized aquatic traits. In addition to the above, several other mammals have a great dependency on the sea without having become so anatomically specialized, otherwise known as "quasi-marine mammals". This term can include: the greater bulldog bat ( Noctilio leporinus ), the fish-eating bat ( Myotis vivesi ), the arctic fox ( Vulpes lagopus ) which often scavenges polar bear kills, coastal gray wolf ( Canis lupus ) populations which predominantly eat salmon and marine carcasses,

5025-858: The ongoing effects of global warming degrade Arctic environments. Procaviidae Elephantidae Dugongidae (dugongs) Trichechus manatus (West Indian manatee) Trichechus senegalensis (African manatee) Trichechus inunguis (Amazonian manatee; freshwater species) Hippopotamidae Mysticeti (baleen whales) Odontoceti (toothed whales, except river dolphins ) Ruminantia Perissodactyla Pholidota Feliformia Canidae Ursus maritimus (polar bear) all other ursids Enhydra lutris (sea otter) Lontra felina (marine otter) † Neogale macrodon (sea mink) all other mustelids Otariidae (eared seals) Odobenidae (walruses) Phocidae (earless seals) The term "marine mammal" encompasses all mammals whose survival depends entirely or almost entirely on

5100-621: The open ocean, and species like the sperm whale may dive to depths of −1,000 to −2,500 feet (−300 to −760 m) in search of food. Sirenians live in shallow coastal waters, usually living 30 feet (9.1 m) below sea level. However, they have been known to dive to −120 feet (−37 m) to forage deep-water seagrasses . Sea otters live in protected areas, such as rocky shores, kelp forests , and barrier reefs , although they may reside among drift ice or in sandy, muddy, or silty areas. Many marine mammals seasonally migrate. Annual ice contains areas of water that appear and disappear throughout

5175-541: The polar bear might not be considered a species under some species concepts . In general, terrestrial amniote invasions of the sea have become more frequent in the Cenozoic than they were in the Mesozoic. Factors contributing to this trend include the increasing productivity of near-shore marine environments, and the role of endothermy in facilitating this transition. Marine mammals are widely distributed throughout

5250-624: The smaller dolphins and porpoises, fall within IWC jurisdiction. An analysis by the Carnegie Council determined that while the International Convention for the Regulation of Whaling has had "ambiguous success" owing to its internal divisions, it has nonetheless "successfully managed the historical transition from open whale hunting to highly restricted hunting. It has stopped all but the most highly motivated whale-hunting countries. This success has made its life more difficult, since it has left

5325-478: The stock and a minimum population estimation. These stock assessments are created through research conducted by programs at NOAA research science centers which are located in Hawaii, Massachusetts, Alaska, Florida, Washington, and California. Research contributions are also made by researchers not affiliated with the previously mentioned programs as well. The Marine Mammal Commission (MMC) was created in 1972 through

5400-474: The target for commercial industry, leading to a sharp decline in all populations of exploited species, such as whales and seals. Commercial hunting led to the extinction of the Steller's sea cow , sea mink , Japanese sea lion and Caribbean monk seal . After commercial hunting ended, some species, such as the gray whale and northern elephant seal , have rebounded in numbers; conversely, other species, such as

5475-459: The water. Polar bears, otters, and fur seals have long, oily, and waterproof fur in order to trap air to provide insulation. In contrast, other marine mammals—such as whales, dolphins, porpoises, manatees, dugongs, and walruses—have lost long fur in favor of a thick, dense epidermis and a thickened fat layer (blubber) to prevent drag . Wading and bottom-feeding animals (such as manatees) need to be heavier than water in order to keep contact with

5550-409: The whale's interest, be within a certain size range so that the baleen plates can filter it, and be slow enough so that it cannot escape. Otters are the only marine animals that are capable of lifting and turning over rocks, which they often do with their front paws when searching for prey. The sea otter may pluck snails and other organisms from kelp and dig deep into underwater mud for clams . It

5625-483: The year as the weather changes, and seals migrate in response to these changes. In turn, polar bears must follow their prey. In Hudson Bay , James Bay , and some other areas, the ice melts completely each summer (an event often referred to as "ice-floe breakup"), forcing polar bears to go onto land and wait through the months until the next freeze-up. In the Chukchi and Beaufort seas, polar bears retreat each summer to

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