Blue
Whales evolved from the Indohyus, about 50 million years ago. The closest
relative today is the hippopotamus. Up until the early 20th century
their numbers would have been fairly stable. The largest population was in the
Antarctic, numbering approximately 240,000 (range 202,000 to 311,000).
With the advent of ‘mechanized’ whaling, they were hunted
almost to extinction until protected by the international community in 1966. A
2002 report estimated there were only 5,000 to 12,000 Blue Whales worldwide.
Blue Whales tend to live alone or with one other
individual but it is not known how long these associations last. Larger feeding
groups of 30-50 may form when food is abundant but there does not seem to be
the communication typical of a true pod.
Blue Whale hunting was banned in 1966 but continued
illegally in the USSR
until the 1970’s. By that time 330,000 Blue Whales had been killed in the
Antarctic, 33,000 in the rest of the Southern Hemisphere, 8,200 in the North
Pacific, and 7,000 in the North Atlantic . By
the time the killing stopped, only about 1 out of every 1000 Blue Whales (0.15%)
survived.
Ships carrying whalers are no longer a threat to the Blue
Whale but ships carrying cargo are. This summer four were run down by ships further
depleting a population that is on the edge of extinction. Ship collisions
result from whales and cargo using the same sea lanes for their journeys.
Whale migration:
Blue Whales do a lot of traveling
and to better understand how their migrations conflict with shipping, a new
generation of scientists is taking to the seas.
Today’s ‘hunters’ attach GPS tags to
the Blue Whales to track their positions and record data as they travel. The
high-tech devices are attached to the whale in the form of a small harpoon that
is imbedded in the blubber.
The GPS tag will only transmit its
data above the water when the whale surfaces to take another breath. They spend
only about 10% of their time at the surface when they expel a rush of air and
spray that can be seen two km away; there
she blows!
National Geographic photo used for educational purposes.
Interested in swimming with dolphins? Check out some of the other posts in this blog.
http://youngmarinescientist.blogspot.com/
http://geraldgoeden.blogspot.com/
http://goedensnews.blogspot.com/
http://underwaterinternet.blogspot.com/
http://goedenquotes.blogspot.com/
http://gerrygoeden.blogspot.com/
http://goedenscience.blogspot.com/
http://goedenmarineecology.blogspot.com/
http://goedenshark.blogspot.com/
http://gerryquotes.blogspot.com/
http://einsteinsnature.blogspot.com/
http://youngmarinescientist.blogspot.com/
http://geraldgoeden.blogspot.com/
http://goedensnews.blogspot.com/
http://underwaterinternet.blogspot.com/
http://goedenquotes.blogspot.com/
http://gerrygoeden.blogspot.com/
http://goedenscience.blogspot.com/
http://goedenmarineecology.blogspot.com/
http://goedenshark.blogspot.com/
http://gerryquotes.blogspot.com/
http://einsteinsnature.blogspot.com/
No comments:
Post a Comment