© Ishara S. Kodikara/AFP/Getty ImagesFifty right whales a year are now becoming trapped in fishing gear and death rates fro entanglement have more than doubled.
One of the more hopeful ecological stories of recent years - the slow restoration of numbers of the North Atlantic right whale - has taken a disastrous turn for the worse. Marine biologists have found their population has plunged abruptly in the past few years and that there may now only be around 100 reproductively mature females left in the sea.
Many scientists fear the species could soon become the first great whale to become extinct in modern times.The principal cause for the North Atlantic right whale's precipitous decline has been the use of increasingly heavy commercial fishing gear dropped on to the sea bed to catch lobsters, snow crabs and hogfish off the east coast of North America. Whales swim into the rope lines attached to these sea-bed traps and their buoys and become entangled. In some cases hundreds of metres of heavy rope, tied to traps weighing more than 60kg, have been found wrapped around whales.
"We have records of animals carrying these huge loads - which they cannot shake off - for months and months," said Julie van der Hoop, of Aarhus University in Denmark.
"In some cases they have to burn more than 25,000 calories a day to carry these great weights around with them. Some whales die. In other cases, divers have been able to free them but the whales are often left very thin and undernourished. As a result, they cannot reproduce."
The North Atlantic right whale,
Eubalaena glacialis, derives its name from the fact that early whalers considered them to be the "right" whales to hunt - they are slow swimmers, linger in coastal waters and float after being killed. Vast numbers were slaughtered across the Atlantic, with only a few pods surviving along the east coast of the United States and Canada. Numbers dropped - possibly to a population as low as 100 - until in 1935 it was declared illegal to hunt them.
