© Ishara S. Kodikara/AFP/Getty Images
Fifty right whales a year are now becoming trapped in fishing gear and death rates fro entanglement have more than doubled.
Fifty right whales a year are now becoming trapped in fishing gear and death rates fro entanglement have more than doubled.
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.
Comment: Also noteworthy is the fact that at least 69 individual birds have recently been recorded across Wisconsin. Additionally, it's perhaps interesting that the standard interpretation for these influxes doesn't seem to be holding true in recent years - that these invasions occur in 4 year cycles because of successful breeding fueled by periodic high numbers of lemming prey in the Arctic. This cyclic pattern looks to have disappeared this decade, see : SOTT Exclusive: Snowy owls flee northern latitudes for unprecedented fourth consecutive year - Sign of impending Ice Age?