Ecology of the Blue Whale
The blue
whale, Balaenoptera muscukus, is a cosmopolitan species of baleen whale,
which means blue whales are all over the earth in many different oceans. It is
the biggest animal ever recorded on the surface of the earth, the females tend
to be larger than the males and blue whales that are found in the Northern
Hemisphere are generally larger than those found in the Southern Ocean. Blue
whales can range up to 92 feet! When blue whales feed their throat and chest
expand to allow space for all of the sea water and food that they intake
simultaneously. Although they do not largely compete with humans for their food
source of euphausiids, humans still pose a great threat to blue whales. They
still get caught in fishing gear, are lethally struck by vessels, bothered by
low-frequency noises, and are subject to habitat degradation.
Geographic and Population Changes
Blue whales are found in coastal
waters, but often more offshore. Occasionally blue whales have been spotted off
the coast of Cape Cod, Massachusetts in summer and in fall, also a bit further
north in Canadian waters blue whales have been seen on the Scotian Shelf. Blue
whales are very nomadic so they are seen almost everywhere around the world,
not because of their population size but because of their habits of traveling
from place to place. Humans have been the cause of the dramatic population
changes of the blue whale, with vessel interactions, entrapment in fishing
gear, habitat degradation, military, and hunting. Because of the large size of
the blue whales they have been a major target of hunters, who believe that
taking down an animal of the blue whales' stature is a big accomplishment. At
least 11,000 blue whales have been killed by hunters during the late 19th
century all the way to the middle of the 20th century.
Blue
whales where listed as endangered on June 2, 1970, by the National Marine
Fisheries Service. Although the recovery plan for blue whales was not enacted
until July, 28, 1998, a whole 28 years later. The recovery plan has a list of
seven objectives to address: "(1) determine population structure of blue
whales, (2) estimate population size and monitor trends in abundance, (3)
identify and protect essential habitats, (4) minimize or eliminate human-caused
injury and mortality, (5) coordinate state, federal, and international actions
to implement recovery efforts, (6) determine and minimize any detrimental
effects of directed vessel1 and aircraft interactions, and (7) maximize efforts to acquire
scientific information from dead, stranded, and entangled animals." (seven
steps are attributed to the writers of the recovery plan, go to the link
after this sentence to see, full recovery
plan). http://ecos.fws.gov/docs/recovery_plan/whale_blue.pdf If these
seven steps can be achieved the blue whales may someday be taken off the
endangered species list.
Cause of Listing and Main Threats to
its Continued Existence
The cause of the blue whale being listed is the
enormous amount of hunting done by humans and the various interactions and
pollution caused by humans. Their enormous size made them prize possessions of
hunters and it makes them a target to a lot of incidental harm from various
human activities. Humans are the main threat to the continued endangerment of
the blue whales. Humans must be more careful around the habitats of blue whales
to allow blue whale populations to reach the level that they once were at
before hunting them left their whole population depleted. Blue whales are a
very valuable component to the ecology of the sea and humans need to become more
conscious in their efforts to help the blue whales return to prominence.
Description of the Recovery Plan
As mentioned above the seven step
plan for recovery is centered around protection of the blue whales essential
habitats because without them the blue whale could go from endangered to
extinct. Humans play a major factor in the recovery plan of the blue whale, if
the effects of humans can be largely lessoned or even completely eliminated
blue whale populations would go up severely. Then last but certainly not least
scientist continue to gather information from dead, stranded, and entangled
blue whales in order to find out even more about what humans can do to
help blue whales out instead of harm them.
Sources:
http://www.montereybayaquarium.org/animal-guide/marine-mammals/blue-whale
http://imgur.com/gallery/HyfVJIu
https://www.pinterest.com/infooffspring/blue-whales/
http://animalstime.com/blue-whale-facts-kids-blue-whale-habitat-diet/
http://ecos.fws.gov/docs/recovery_plan/whale_blue.pdf
