Endangered Species: The Blue Whale
Ellen Ray
Description and Ecology of the Blue Whale
Whales are listed as endangered primarily due to human caused impacts, although whaling was also a significant factor. According to Ecology Law Quarterly, "It is estimated that 380,000 blue whales were killed by whalers in the twentieth century—largely for the manufacture of soap and margarine—resulting in extirpation within some populations and reduction of others by more than 99 percent." Indirect factors that continue to threat the Blue Whales are the reduced amount of krill due to habitat degradation, distburbance due to noise pollution. A predominant direct factor are boat strikes and entanglement in fishing gear, especially off the coast of California and Mexico.
According to the WWF, the Blue Whale is the largest known mammal to have lived on Earth. They can grow up to 30 meters, although blue whales are recorded to be larger in the southern hemisphere. Compared to other whales, blue whales are relatively slim. However, when feeding, the throat and chest will expand drastically to account for the amount of water and plankton being filtered and consumed. Blue whales have a very large seasonal migration, although it is expected that their distribution is ultimately determined by the location of their food. They feed primarily in the North, then make their way South to reserve energy and reproduce in the subtropics.
 |
*Dark blue shows blue whale distribution
Photo courtesy of CCA
|
Geographic
and Population Changes
Geographic changes amongst the blue whale mirror their dietary needs and the distribution of their prey. There are three primary stocks of blue whales, and according to Randall R. Reeves, "the three geographical populations of blue whales, as
follows: Antarctic stock as "endangered," North Pacific stock as "low risk, conservation dependent,"
and North Atlantic stock as vulnerable (pg. 3)." Populations of blue whales are not showing significant recovery other than those off the coast of California, now listed at around 2,000.
Listing
Date
and Type of Listing
According to the Alaska Department of Fish and Game, The Blue Whale became nearly extinct in the late 1800's and early 1900's. In 1966 they became protected from commercial whaling, and were listed as endangered under the Endangered Species Act on 06/02/1970.
Cause
of listing and Main threats to its
continued existence
 |
| Blue Whale and Whaling Men, by Frank Hurley, National Library of Australia |
Recovery plan
According to the National Marine Fisheries Service, the recovery plan of Blue Whales begins with the assessment and estimation of the population through telemetry, then to monitor trends and the estimated population. Next, it is very important to protect the habitat to ensure the protection and survival of the whales. Eliminating injury or mortality caused by humans is a factor that can greatly impact the success of the whales considering that vessel strikes is one of the most. Another way to ensure the recovery of Blue Whales is to acquire as much information from stranded, entangled, or dead whales. Although all of these efforts may set the stage for an ideal recovery plan, the last steps are to ensure that maximum recovery efforts occur on a state, federal, and international levels. Once all these steps are complete, we can then determine whether or not blue whales can be delisted.
References:
http://wwf.panda.org/what_we_do/endangered_species/cetaceans/about/blue_whale/ http://www.adfg.alaska.gov/index.cfm?adfg=specialstatus.fedsummary&species=bluewhale http://www.ccaro.org/local-cetacean-blue-whale.phphttp://www.bluewhales.org/wordpress/wp-content/uploads/blue_whale.jpg
http://www.themonthly.com.au/issue/2013/july/1372600800/catherine-ford/savage-history-whaling-pacific-and-southern-oceans
http://elq.typepad.com/currents/2010/08/currents37-07-segee-2010-0816.html
http://ecos.fws.gov/docs/recovery_plan/whale_blue.pdf
No comments:
Post a Comment