Originally designed to live on land, marine mammals are a diverse, charismatic group of animals that include more than 120 species. The animals share key characteristics of land mammals. They have hair, breathe air, give birth to live young, which feed off mother's milk when young. They have warm bodies and usually thick blubber to keep their body temperatures high. The bottlenose dolphin is probably the most widely recognized marine mammal, easily spotted just offshore from beaches around the world. Small groups of 20 or less can live in close proximity to shorelines, but groups living more offshore can reach several hundred. Bottlenose dolphin calves stay with their mothers for up to six years, learning how to hunt and become good dolphin citizens. Full-grown dolphins reach eight to 12 feet in length and can weigh up to 1,430 pounds. The bottlenose dolphin is protected in U.S. waters.
What makes them "marine" depends on the animal. They either live mostly in the sea or, like polar bears, depend on the ocean for food. The largest in the group are whales -- including humpback whales. These massive animals reach up to 50 feet in length and weigh up to 79,000 pounds. To maintain their weight, the animals feed on tons of krill and fish. They neared extinction due to whaling, but have recovered somewhat since a 1966 moratorium on whaling was introduced.
While polar bears live mostly on land or ice, they are excellent swimmers and have been known to swim up to 45 miles a day. The massive animals, weighing up to 1,500 pounds, hunt mostly seals. In recent years, biologists have observed that the bears are swimming now more than ever as melting stretches the distances between Arctic ice flows. Because they depend on sea ice to hunt seals, the polar bear is considered threatened as global warming melts and thins ice in this region.
This member of the weasel family is also the smallest marine mammal, with females weighing about 60 pounds and males weighing up to 90 pounds. They may be small, but they're also clever. They're the only marine mammals known to use tools. They use stones to break open clams and store food they gather in the folds of their armpits! Another feature that sets them apart is their lack of blubber. These marine mammals depend mostly on their fur to stay warm. That feature makes them particularly vulnerable to oil spills, which can compromise their fur's insulating effect.
Immediately recognizable by its long tusks and whiskers, the sea walrus is a hefty, flippered member of the Odobenidae family and is, in fact, the last living member of this group. Since both the males and females have big tusks and not much for teeth, the animals feed by sucking up shellfish from the ocean floor. So, just what are those tusks for? The longer they are (they grow to be up to four feet long in males), the higher an animal is ranked in the group. Males attack each other with their tusks to establish dominance. The ivory appendages are also handy for poking holes in the winter ice and for helping the animals pull themselves out of the water.
Manatees, also known as sea cows, are gentle herbivores that live in marshy areas in tropical and subtropical waters. The average adult manatee can weigh up 1,200 pounds and is around 10 feet long. Because of their slow metabolism, these animals can only survive in warm waters. Due to the unusually long, cold winter this year in part of the southeastern United States, populations of manatees throughout Florida were devastated. During the day, manatees usually like to stay close to the surface. At night, manatees will often sleep about three to 10 feet below sea level. This is why these gentle animals are so often accidentally injured, maimed or killed by passing boats.
Found up and down the North American coastlines, these marine mammals spend half of their lives swimming. Although they can reach up to six feet in length and weigh around 180 pounds, when on land and in plain sight harbor seals may not be easy to spot. Their spotted brown or tan fur allows harbor seals to blend in with sand and rocks. Unlike their very vocal relatives -- sea lions and elephant seals -- harbor seals are quiet creatures that make little noise. They like to hang out on beaches, sand bars and rocks during low tide to bask in the sun and sleep, but they never go far from the water. At the slightest sign of danger, they will quickly slip back under the waves. These expert swimmers have been known to plunge to depths of more than 1,600 feet and stay underwater up to 28 minutes.
This weekend, fisherman herded approximately 250 bottlenose dolphins into Japan's Taiji Cove and selected about a dozen, including an extremely rare albino dolphin, for possible sale to marine parks and aquariums.
Defenders of the drive-hunt method say that the roundup is part of a cultural tradition, but demand for these animals also comes from aquariums and marine parks, which are part of a billion-dollar industry worldwide. Discovery News investigated where US marine park facilities get their dolphins and if any of them have come from Taiji Cove.
Among the dolphins housed at marine parks and aquariums in the United States, 100 were caught in the wild and are on display at 23 facilities nationwide, according to Ceta-Base, a database of captive-held cetaceans around the world.
The Alliance of Marine Mammal Parks and Aquariums says that approximately 64 percent of the dolphins in its member facilities are not wild, but were born in a park or aquarium.
Some of those dolphins live for decades, such as Toad, who has been with the U.S. Navy for 45 years, and Nellie, who is at Augustine, FL-based Marineland Dolphin Adventure and has lived in captivity for 60 years.
But others do not survive that long. In the 2009 study The Case Against Marine Mammals in Captivity, co-published by The Humane Society of the United States and the World Society for the Protection of Animals, the authors write:
Fierce debate continues over the issue of mortality rates and longevity, especially of whales and dolphins. The mortality data related to live captures are more straightforward -- capture is undeniably stressful and, in dolphins, results in a six-fold increase in mortality risk during and immediately after capture.
Despite this, the Marine Mammal Protection Act (MMPA), enacted in 1972, makes it legal to capture dolphins from the wild for entertainment purposes, although no permits to do so have been issued since 1989. One explanation, notes the World Society for the Protection of Animals, is the unprecedented number of dolphin strandings over the last couple of decades that have made it unnecessary to take these marine mammals from the wild.
Two dolphins jump through hoops at a traveling dolphin circus in Indonesia. Over 72 bottlenose and stenella dolphins are frequently hauled out of their plastic performing pools and loaded into the back of trucks as the circuses move from town to town.Arief Priyono/LightRocket via Getty Images
Another reason that US-based facilities may not need to capture wild dolphins is that it's legal to import them from other countries, as long as those dolphins were caught according to US regulations.
“A provision in the MMPA requires that imports cannot come from inhumane capture methods or unsustainable populations,” David Phillips, executive director at Earth Island Institute and director of the International Marine Mammal Project, told Discovery News. But, he said, record keeping is not very good, making it possible for other countries to justify their methods even if they may not be meeting our standards.
Even the phrase “unsustainable population” is loaded when applied to animals such as bottlenose dolphins. These marine mammals are not listed as threatened or endangered under the Endangered Species Act.
“But bottlenose dolphins are classified as ‘data deficient’ on the International Union for Conservation of Nature's Red List and population trends for U.S. stocks are currently unknown,” Ric O’Barry, campaign director of the Dolphin Project, told Discovery News while monitoring the weekend's dolphin roundup at Taiji Cove.
Captain Paul Watson of the Sea Shepherd Conservation Society and his team were also observing the Taiji event. Their team reports that, based on information from previous years, many of the Taiji dolphins get shipped to Mexico, Turkey, Dubai, China, Hong Kong, Taiwan, Korea and other parts of Japan.
But aquariums in the United States still attempt to import dolphins from places like Japan and Russia, where reports of inhumane treatment of animals are common. In 2012, for example, SeaWorld attempted to obtain a permit to import a Pacific white-sided dolphin from Japan that was identified to have been born in captivity.
It can't be confirmed whether or not this dolphin or others being imported from Japan come directly Taiji Cove. Lisa Agabian, a Sea Shepherd spokesperson, said to Discovery News, however, "Documents in other countries can be falsified as to the marine mammal's true source of origin. It is then difficult for anyone to prove otherwise."
The increased publicity of the drive-hunt methods such as those used at Taiji Cove is increasing awareness of the plight of dolphins taken from the wild to serve in the entertainment industry. Even the US ambassador to Japan, Caroline Kennedy, sent a tweet over the weekend about her concern at the Japanese dolphin hunt.
For now, the billion-dollar-per-year marine park industry seems to have the upper hand.