Threats Due to the difficulty to survey populations, 38% of marine mammals are
data deficient, especially around the
Antarctic Polar Front. In particular, declines in the populations of completely marine mammals tend to go unnoticed 70% of the time.
Exploitation s on
Saint Paul Island, Alaska, in the 1890s|alt=A group of seal hunters surround a small group of sea lions with their clubs in the air Marine mammals were hunted by
coastal aboriginal humans historically for food and other resources. These subsistence hunts still occur in Canada,
Greenland, Indonesia, Russia, the United States, and several nations in the
Caribbean. The effects of these are only localized, as hunting efforts were on a relatively small scale. Because whales generally have slow growth rates, are slow to reach
sexual maturity, and have a low reproductive output, population recovery has been very slow. A number of whales are still subject to direct hunting, despite the 1986
moratorium on commercial whaling set under the terms of the
International Whaling Commission (IWC). There are only two nations remaining which sanction commercial whaling:
Norway, where several hundred
common minke whales are harvested each year; and
Iceland, where quotas of 150
fin whales and 100
minke whales per year are set.
Japan also harvests several hundred Antarctic and North Pacific minke whales each year, ostensibly for scientific research in accordance with the moratorium. The most profitable furs in the
fur trade were those of sea otters, especially the northern sea otter which inhabited the coastal waters between the
Columbia River to the south and
Cook Inlet to the north. The fur of the Californian southern sea otter was less highly prized and thus less profitable. After the northern sea otter was hunted to
local extinction, maritime fur traders shifted to California until the southern sea otter was likewise nearly extinct. The British and American maritime fur traders took their furs to the Chinese port of
Guangzhou (Canton), where they worked within the established
Canton System. Furs from
Russian America were mostly sold to China via the Mongolian trading town of
Kyakhta, which had been opened to Russian trade by the 1727
Treaty of Kyakhta. Commercial sealing was historically just as important as the whaling industry. Exploited species included harp seals, hooded seals, Caspian seals, elephant seals, walruses and all species of fur seal. The scale of seal harvesting decreased substantially after the 1960s, after the Canadian government reduced the length of the hunting season and implemented measures to protect adult females. Several species that were commercially exploited have rebounded in numbers; for example, Antarctic fur seals may be as numerous as they were prior to harvesting. The northern elephant seal was hunted to near extinction in the late 19th century, with only a small population remaining on
Guadalupe Island. It has since recolonized much of its historic range, but has a
population bottleneck. Polar bears can be
hunted for sport in Canada with a special permit and accompaniment by a
local guide. This can be an important source of income for small communities, as guided hunts bring in more income than selling the polar bear hide on markets. The United States, Russia, Norway, Greenland, and Canada allow subsistence hunting, and Canada distributes hunting permits to indigenous communities. The selling of these permits is a main source of income for many of these communities. Their hides can be used for subsistence purposes, kept as hunting trophies, or can be bought in markets.
Ocean traffic and fisheries after it collided with a ship
propeller|alt=A right whale sliced on both sides after colliding with a boat. A large amount of its flesh is visible as well as the intestines floating in the water
By-catch is the incidental capture of non-target species in
fisheries. Fixed and drift
gill nets cause the highest
mortality levels for both cetaceans and pinnipeds, however, entanglements in long lines, mid-water trawls, and both trap and pot lines are also common.
Tuna seines are particularly problematic for entanglement by dolphins. By-catch affects all cetaceans, both small and big, in all habitat types. However, smaller cetaceans and pinnipeds are most vulnerable as their size means that escape once they are entangled is highly unlikely and they frequently drown. Marine mammals also get entangled in
aquaculture nets, however, these are rare events and not prevalent enough to impact populations. Vessel strikes cause death for a number of marine mammals, especially whales.
Tourism boats designed for whale and
dolphin watching can also negatively impact on marine mammals by interfering with their natural behavior. The fishery industry not only threatens marine mammals through by-catch, but also through competition for food. Large-scale fisheries have led to the depletion of
fish stocks that are important prey species for marine mammals. Pinnipeds have been especially affected by the direct loss of food supplies and in some cases the harvesting of fish has led to food shortages or dietary deficiencies, starvation of young, and reduced recruitment into the population. As the fish stocks have been depleted, the
competition between marine mammals and fisheries has sometimes led to conflict. Large-scale
culling of populations of marine mammals by commercial fishers has been initiated in a number of areas in order to protect fish stocks for human consumption. Shellfish aquaculture takes up space so in effect creates competition for space. However, there is little direct competition for aquaculture shellfish
harvest.
Noise pollution from anthropogenic activities is another major concern for marine mammals. This is a problem because underwater noise pollution interferes with the abilities of some marine mammals to communicate, and locate both predators and prey.
Underwater explosions are used for a variety of purposes including
military activities, construction and
oceanographic or
geophysical research. They can cause injuries such as hemorrhaging of the lungs, and contusion and ulceration of the
gastrointestinal tract. The second effect of
global climate change is
global warming due to increased
carbon dioxide levels in the atmosphere. Raised sea levels, rising sea temperatures and changed currents are expected to affect marine mammals by altering the distribution of important prey species, and changing the suitability of breeding sites and migratory routes. The Arctic food chain would be disrupted by the near extinction or migration of polar bears. Arctic sea ice is the polar bear's habitat. It has been declining at a rate of 13% per decade because the temperature is rising at twice the rate of the rest of the world. By the year 2050, up to two-thirds of the world's polar bears may vanish if the sea ice continues to melt at its current rate. A study by evolutionary biologists at the
University of Pittsburgh showed that the ancestors of many marine mammals stopped producing a certain enzyme that today protects against some neurotoxic chemicals called
organophosphates, including those found in the widely used pesticides chlorpyrifos and diazinon. Marine mammals may be increasingly exposed to these compounds due to agricultural runoff reaching the world's oceans.
Protection (IWC) The
Marine Mammal Protection Act of 1972 (MMPA) was passed on October 21, 1972, under president
Richard Nixon to prevent the further depletion and possible extinction of marine mammal stocks. The Act was updated on 1 January 2016 with a clause banning "the import of fish from fisheries that cannot prove they meet US standards for protecting marine mammals". The requirement to show that protection standards are met is hoped to compel countries exporting fish to the US to more strictly control their fisheries that no protected marine mammals are adversely affected by fishing. Of the
agreements made, three of them deal with the conservation of marine mammals:
ACCOBAMS,
ASCOBANS and the
Wadden Sea Agreement. In 1982, the
United Nations Convention on the Law of the Sea (UNCLOS) adopted a pollution prevention approach to conservation, which many other conventions at the time also adopted. There are 23 member states. The Agreement on the Conservation of Small Cetaceans of the Baltic and North Seas (ASCOBANS) was adopted alongside ACCOBAMS to establish a special protection area for Europe's increasingly threatened cetaceans. and an
environmental agreement (a type of
international law) the
International Convention for the Regulation of Whaling which controlled commercial, scientific and subsistence whaling. The Agreement on the Conservation of Seals in the
Wadden Sea, enforced in 1991, prohibits the killing or harassment of seals in the Wadden Sea, specifically targeting the harbor seal population. The 1973
Agreement on the Conservation of Polar Bears between Canada, Denmark (Greenland), Norway (
Svalbard), the United States and the Soviet Union outlawed the unregulated hunting of polar bears from aircraft and
icebreakers, as well as protecting migration, feeding and
hibernation sites. Various
non-governmental organizations participate in
marine conservation activism, wherein they draw attention to and aid in various problems in marine conservation, such as pollution, whaling, bycatch, and so forth. Notable organizations include the
Greenpeace who focus on overfishing and whaling among other things, and
Sea Shepherd Conservation Society who are known for taking direct-action tactics to expose illegal activity.
As food meat (bottom), blubber (middle) and dried fish (left) with potatoes,
Faroe Islands|alt=The whale meat is dark purple and shredded like jerky, the blubber is a pale-pink color and in slices, the dried fish is a light-brown color and ripped into slices, and the potatoes are light-yellow and cut into thin slices. For thousands of years,
indigenous peoples of the Arctic have depended on
whale meat and
seal meat. The meat is harvested from legal, non-commercial hunts that occur twice a year in the spring and autumn. The meat is stored and eaten throughout the winter. The skin and blubber (
muktuk) taken from the
bowhead, beluga, or narwhal is also valued, and is eaten raw or cooked. Whaling has also been practiced in the
Faroe Islands in the North Atlantic since about the time of the first
Norse settlements on the islands. Around 1,000
long-finned pilot whales are still killed annually, mainly during the summer. Today, dolphin meat is consumed in a small number of countries worldwide, which include Japan and Peru (where it is referred to as
chancho marino, or "sea pork"). In some parts of the world, such as
Taiji (in Japan) and the Faroe Islands, dolphins are traditionally considered food, and are killed in
harpoon or
drive hunts. There have been human health concerns associated with the consumption of dolphin meat in Japan after tests showed that dolphin meat contained high levels of
methylmercury. Similar concerns exist with the consumption of dolphin meat in the Faroe Islands, where
prenatal exposure to methylmercury and
PCBs primarily from the consumption of pilot whale meat has resulted in
neuropsychological deficits amongst children. Ringed seals were once the main food staple for the
Inuit. They are still an important food source for the people of
Nunavut and are also hunted and eaten in Alaska.
Seal meat is an important source of food for residents of small coastal communities. The seal blubber is used to make
seal oil, which is marketed as a
fish oil supplement. In 2001, two percent of Canada's raw seal oil was processed and sold in Canadian health stores.
In captivity Aquariums Cetaceans , 2009|alt=A killer whale with a collapsed dorsal fin breaching out of a pool in front of an audience in stands Various species of dolphins are kept in captivity. These small cetaceans are more often than not kept in theme parks and
dolphinariums, such as
SeaWorld.
Bottlenose dolphins are the most common species of dolphin kept in dolphinariums as they are relatively easy to train and have a long lifespan in captivity. Hundreds of bottlenose dolphins live in captivity across the world, though exact numbers are hard to determine. The dolphin "smile" makes them popular attractions, as this is a welcoming
facial expression in humans; however, the smile is due to a lack of facial muscles and subsequent lack of facial expressions. Organizations such as
World Animal Protection and the
Whale and Dolphin Conservation campaign against the practice of keeping cetaceans, particularly killer whales, in captivity. In captivity, they often develop pathologies, such as the dorsal fin collapse seen in 60–90% of male killer whales. Captives have vastly reduced life expectancies, on average only living into their twenties. In the wild, females who survive infancy live 46 years on average, and up to 70–80 years in rare cases. Wild males who survive infancy live 31 years on average, and up to 50–60 years. Captivity usually bears little resemblance to wild habitat, and captive whales' social groups are foreign to those found in the wild. Captive life is also stressful due to the requirement to perform circus tricks that are not part of wild killer whale behavior, as well as restricting pool size. Wild killer whales may travel up to in a day, and critics say the animals are too big and intelligent to be suitable for captivity. Captives occasionally act aggressively towards themselves, their tankmates, or humans, which critics say is a result of
stress. Dolphins are often trained to do several
anthropomorphic behaviors, including waving and kissing—behaviors wild dolphins would rarely do.
Pinnipeds The large size and playfulness of pinnipeds make them popular attractions. Some exhibits have rocky backgrounds with artificial haul-out sites and a pool, while others have pens with small rocky, elevated shelters where the animals can dive into their pools. More elaborate exhibits contain deep pools that can be viewed underwater with rock-mimicking cement as haul-out areas. The most common pinniped species kept in captivity is the California sea lion as it is abundant and easy to train. Other species popularly kept in captivity include the grey seal and harbor seal. Larger animals like walruses and Steller sea lions are much less common. Pinnipeds are popular attractions because they are "
disneyfied", and consequently, people often anthropomorphize them with a curious, funny, or playful nature. Some organizations, such as the
Humane Society of the United States and World Animal Protection, object to keeping pinnipeds and other marine mammals in captivity. They state that the exhibits could not be large enough to house animals that have evolved to be migratory, and a pool could never replace the size and biodiversity of the ocean. They also oppose using sea lions for entertainment, claiming the tricks performed are "exaggerated variations of their natural behaviors" and distract the audience from the animal's unnatural environment.
Sea otter Sea otters can do well in
captivity, and are featured in over 40 public
aquariums and
zoos. In 2007, a
YouTube video of two cute sea otters holding paws drew 1.5 million viewers in two weeks, and had over 20 million views . Filmed five years previously at the
Vancouver Aquarium, it was YouTube's most popular animal video at the time, although it has since been surpassed. Otters are often viewed as having a "happy family life", but this is an
anthropomorphism.
Sirenians The oldest manatee in captivity was
Snooty, at the
South Florida Museum's Parker Manatee Aquarium in
Bradenton, Florida. Born at the Miami Aquarium and Tackle Company on July 21, 1948, Snooty was one of the first recorded captive manatee births. He was raised entirely in captivity, and died at the age of 69. Manatees can also be viewed in a number of European zoos, such as the
Tierpark in
Berlin, the
Nuremberg Zoo, in
ZooParc de Beauval in France, and in the
Aquarium of Genoa in Italy. The
River Safari at
Singapore features seven of them.
Military |alt=A bottlenose dolphin jumping out of the water (the entire body is visible) in front of a trainer in camouflage. The dolphin is wearing a small, cylindrical camera on its right fin Bottlenose dolphins and California sea lions are used in the United States Navy Marine Mammal Program (NMMP) to detect mines, protect ships from enemy soldiers, and recover objects. The Navy has never trained attack dolphins, as they would not be able to discern allied soldiers from enemy soldiers. There were five marine mammal teams, each purposed for one of the three tasks: MK4 (dolphins), MK5 (sea lions), MK6 (dolphins and sea lions), MK7 (dolphins) and MK8 (dolphins); MK is short for mark. The dolphin teams were trained to detect and mark mines either attached to the seafloor or floating in the water column, because dolphins can use their echolocative abilities to detect mines. The sea lion team retrieved test equipment such as fake mines or bombs dropped from planes usually out of reach of divers who would have to make multiple dives. MK6 protects harbors and ships from enemy divers, and was operational in the
Gulf War and
Vietnam War. The dolphins would swim up behind enemy divers and attach a buoy to their air tank, so that they would float to the surface and alert nearby Navy personnel. Sea lions would hand-cuff the enemy, and try to outmaneuver their counter-attacks. The use of marine mammals by the Navy, even in accordance with the Navy's policy, continues to meet opposition. The Navy's policy says that only positive reinforcement is to be used while training the military dolphins, and that they be cared for in accordance with accepted standards in animal care. The inevitable stresses involved in training are topics of controversy, as their treatment is unlike the animals' natural lifestyle, especially towards their confined spaces when not training. There is also controversy over the use of
muzzles and other inhibitors, which prevent the dolphins from foraging for food while working. The Navy states that this is to prevent them from ingesting harmful objects, but conservation activists say this is done to reinforce the trainers' control over the dolphins, who hand out food rewards. The means of transportation is also an issue for conservation activists, since they are hauled in dry carriers, and switching tanks and introducing the dolphin to new dolphins is potentially dangerous as they are territorial. ==See also==