The carcasses of more than 120 bottlenose dolphins washed up along the shores of the Florida Panhandle last month, the victims of what scientists suspect was a red tide outbreak and environmentalists blame on run-off from development.
From pollution to hunting and fishing, marine mammals in the wild die by the thousands from contact with humans.
Scientists suspect the recent dolphin die-off in the Panhandle resulted from high levels of a toxin associated with red tide, but they disagree about what causes the deadly algal blooms. Some say red tide is naturally occurring; others agree with environmental groups that pollution can trigger it.
Wastewater run-off, rich in phosphorus and nitrogen, feeds phytoplankton in the water and sets off explosive growth, they say. The Natural Resources Defense Council wants a halt to discharges into the Gulf of Mexico by industry, farms and residential neighborhoods.
In a sweeping and critical report last month, the U.S. Commission on Ocean Policy, which Congress set up in 2000, called for immediate action to end gross pollution of the oceans from shoreline development, the use of offshore oil and gas, coastal tourism and marine transportation.
Fishing
Fishermen netting tuna kill 1,500 to 2,000 dolphins a year. International agreements that include measures allowing observers to accompany fishing crews have reduced the mortality, which reached 400,000 a year in the early 1970s. However, dolphin populations are not rebounding as scientists expected.
Researchers in Britain say 800 whales and dolphins die daily around the world because of fishing. Europe recently limited the use of nets and began requiring pingers, which emit sonic signals, to warn dolphins away.
Two months ago, rescuers chased up the East Coast after a young North Atlantic right whale – a rare, endangered species – was found off St. Augustine badly entangled in a fishing net. Nicknamed Kingfisher, the 34-foot-long whale was seen with lines wrapped around his blowhole and mid-body, fishing buoys and gear slapping his sides.
The lines could embed in his flesh and set off an infection. Rescuers attached a tracking device and figured they could trail and eventually free him, but a ship along the New Jersey shore cut off the tracking device and Kingfisher’s whereabouts and health are unknown.
Boating
Marine mammals caught in the paths of boats and ships die by the hundreds every year. Manatees are common victims of boating throughout Florida, but other animals affected include the endangered right whale. Ships struck and killed at least 12 of the estimated 300 left in the 1990s.
Hunting
Despite a global moratorium on whaling, Norway still hunts and kills about 700 minke whales a year. Japan kills a similar number for what it describes as research. The United States banned whaling in 1972. The year before, U.S. hunters killed 132 whales.
Canada has gradually increased a quota on harp seal hunts, allowing up to 350,000 a year to be killed. Their skins are turned into suede and other leather goods. Protests stopped what many considered the inhumane practice of clubbing newborns to death. Now, hunters in trawlers are allowed to shoot animals that are at least 12 days old.
Military
Some scientists have concluded that military use of sonar in the world’s oceans may be responsible for dozens of whale and dolphin deaths in recent years. The U.S. Navy initially denied a connection to its sonar in the beaching and deaths of eight whales following a training exercise in 2000 in the Bahamas but later ruled out all other causes. Researchers found bleeding around the whales’ brains and ears, likely from exposure to loud noise.
Marine mammals depend on sound to communicate.
Sonic waves can shake and tear the animals’ organs, cause them to become disoriented and even kill them, some scientists believe. The noises also may cause marine mammals to panic and ascend too rapidly. Researchers found gas bubbles in whales that beached themselves and died after a 2002 international naval exercise in the Canary Islands, leading the researchers to conclude the animals may have suffered decompression sickness akin to the bends, which afflicts scuba divers.
Last fall, in a settlement of a lawsuit filed by environmentalists, the Navy agreed to limit use of a new sonar system to detect enemy submarines. However, the Navy’s use of dolphins for detection continues, with dolphins on assignment in oceans near Iraq.
By Sally Kestin, The South Florida Sun-Sentinel
