Recovering Underwater Wonder: The Blue Whale

Underside of Blue Whale. Photo found http://tinyurl.com/pyjxf3v

Recovering Underwater Wonder: The Blue Whale

Blog post by Tenney Rizzo

Description and Ecology of the Blue Whale  (Balaenoptera musculus)

Blue Whale Feeding. Photo found http://tinyurl.com/p9j4hb9

The blue whale is a marine mammal belonging to the baleen whales. It is the largest animal known to have lived with the longest recorded whale measuring at 110 ft and the heaviest recorded whale weighing approximately 210 short tons. It has a long tapered body that appears stretched and slender in comparison with stockier builds of other whales. A blue whale’s body can be various shades of grey that appear blue in the water. There are at least three distinct subspecies: B. m. musculus of the North Atlantic and North Pacific, B. m. intermedia of the Southern Ocean and B. m. brevicauda, known as the pygmy blue whale, found in the Indian Ocean and South Pacific Ocean. Its diet is almost exclusively krill, though when feeding, it may subsequently take in small fish and squid as well.

Geographic and Population Changes

Present Blue Whale Geographic Concentrations.
Photo found http://tinyurl.com/p4t6ym7 

Until the beginning of the 20th century and the advent of bigger whaling ships and more mechanized and efficient methods of whale hunting, blue whales were abundant in nearly all oceans. The largest population was in the Antarctic with numbers of whales ranging from 202,00 to 311,00. Due largely to whaling, the number has declined to around 2,000 whales in each of the eastern North Pacific, Antarctic, and Indian Ocean groups. In 2002, there was estimated to be 5,000 to 12,000 blue whales worldwide, however as of 2014, the Californian blue whale population has come back to numbers near its pre-hunting with the help of conservation and protection efforts.

Listing Date and Type of Listing

The entire blue whale species was listed as endangered under the Endangered Species Act in July of 1998. The blue whale recovery plan is being implemented and listed as finalized with the goal of delisting though there is currently no criteria for delisting or downlisting recovering blue whale populations.

Cause of listing and Main threats to its continued existence

Whaling or whale hunting has historically been the major threat and cause of near extinction of blue whale populations. However, there are several other human impacts that continue to threaten populations. Collision with ships, disturbance from vessels, disturbance from military operations, sonar, and other sounds, entrapment and entanglement in fishing gear, and the habitat degradation of their primary food source are all threats to the blue whale’s continued existence.  

Description of Recovery Plan

Photo found http://tinyurl.com/nwhqeew

The goal of the Blue Whale Recovery Plan is to recover populations to such levels that it becomes appropriate to down list them from endangered to threatened, and eventually to such levels that they will be removed from the list of Endangered and Threatened Wildlife. The purpose of the plan is to identify a set of actions that will minimize or eliminate effects of human activities that are detrimental to the recovery of blue whale populations.

The key recommended actions of the plan are as listed:

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. Determine and minimize any detrimental effects of directed vessel and aircraft interactions

6. Maximize efforts to acquire scientific information from dead, stranded, and entangled  

animals

7. Coordinate state, federal, and international actions to implement recovery efforts

8. Establish criteria for delisting or downlisting

Photo found http://tinyurl.com/ooud9ec

References

Reeves, Randall R., Phillip J. Clapham, Robert L. Brownell, Jr., and Gregory K. Silber. "RECOVERY PLAN FOR THE BLUE WHALE." (1998): n. pag. U.S Fish and Wildlife Service. U.S Fish and Wildlife Service. Web. 6 June 2014. <http://ecos.fws.gov/docs/recovery_plan/whale_blue.pdf>.