Blue Whale (Balaenoptera Musculus) 

Alex Metzner

Description & Ecology 

The blue whale, which is a cosmopolitan species of baleen whale, is the largest animal known to man. Adult blue whales in the Southern Ocean can be as long as 108 feet and up to 330,693 pounds. It is in the Southern Ocean you will find the largest whales. The maximum length of a female blue whale in the Northern Hemisphere is about 88 feet. In general, females are larger than males2.

Blue whales are long and slender compared to other whales. The dorsal fin is also smaller and set further back than other balaenopterid whales. In the picture above, it is obvious that the blue whale has a flat rostrum. When the whale wants to eat, its chest area expands to accommodate the massive amounts of seafood and water that enter the whale. Over time, as the food and water is filtered, its chest returns back to the normal, slender like shape. The blue whale actually has a gray pattern on it which looks light blue through water, hence the name “blue whale.” There are three subspecies of the blue whale: B. m. musculus, B. m. intermedia, and B. m. brevicauda2.

Blue whales are thought to feed exclusively on euphausiids or krill. They usually eat at depths of 330 feet or sometimes deeper. They eat up to around 40 million krill a day. If blue whales, or whales in general, were extinct, the food population would become unbalanced, due to the excess of krill. Phytoplankton use nutrients in whale feces to thrive, while other marine life feeds off phytoplankton. People also pay money to whale watch, boosting local economies3.

Geographic & Population Changes 

Before the harpoon guns were invented, blue whales were not really threatened. They were quick and large enough to escape early whalers. After the invention and the realization that a single blue whale could yield an astonishing 120 barrels of oil, blue whales were killed in large amounts. The International Whaling Commission eventually put a ban on all blue whale hunting in 1966, but recovery is slow and only 5-1,000 remain in the Southern Hemisphere and around 3-4,000 in the Northern Hemisphere. Before the hunting of blue whales progressed, the blue whale population was estimated at 350,0005. Collisions with ships, pollution in the Gulf of St. Lawrence, entanglement, and hunting have all caused the whale population to decrease, but mainly hunting before 19602. 

Blue whales are found in oceans all around the world. During winter, they migrate to tropical waters to mate5. The range of blue whales in the North Atlantic ranges from north of Baffin Bay and the Greenland Sea. In the eastern United States, blue whales are rare, although there have been few sightings. They are present in the Gulf of St. Lawrence but leave during winter and return during spring when the ice breaks up. Over 320 blue whales have been photo-identified in the Gulf of St. Lawrence. Sighting off the west coast of Iceland have increased at about 5 percent each year. Blue whales have been found offshore Kamchatka and the Kuril Islands in summer and Japanese waters in summer. Another area of concentration is in the eastern tropical Pacific Ocean around the Costa Rican Dome, where sightings are recorded year round2.

Listing Date & Type 

In 1970, the blue whale was listed as endangered under the Endangered Species Act (ESA). When the ESA passed in 1973 the blue whale was listed as endangered in its range and also was listed as depleted under the Marine Mammal Protection Act7. 

Cause of Listing & Threats 

The blue whale was driven to the brink of extinction mainly by hunting after the harpoon gun was invented. Blue whales were in high demand due to their high yield of oil7. Currently, blue whales are threatened by chemical and sound pollution, habitat loss, overfishing of krill (their main feeding source), ship collisions, and entanglement. Climate change might also have an effect on krill and therefore blue whales8.

Recovery Plan 

North Atlantic and North Pacific blue whale populations are treated together. Currently, no whaling for blue whales is legal. Whale watching activities have decreased all around the world, which could benefit the whales do to prohibitions on harassment of marine animals. The ultimate goal of the recovery plan is to increase blue whale populations to the point of being able to remove them from the list of Endangered and Threatened Wildlife. Overall the main goal of the stepdown outline is to determine stock structure of the populations occurring around the world, estimate the size and trends in the abundance of populations, protect the blue whales’ habitat, reduce human-caused injury, minimize ship collisions, get information from dead whales, coordinate programs for recovery of blue whales and establish criteria for deciding whether to delist or down list blue whales2.

What Can You Do? 

To help, you can support efforts to improve fishing gear by only buying seafood that is MSC certified. This can help decrease bycatch. We also need to send our message to leaders that warming should be limited to under 2 degrees Celsius, as climate change is a threat to whales8.

Other Resources 

YouTube has a collection of eye opening whale videos. Watch here (https://www.google.com/search?q=whales+geopgrahics&espv=2&biw=944&bih=927&source=lnms&tbm=isch&sa=X&ved=0ahUKEwj6pd7Fos_QAhVhrVQKHVMWBCEQ_AUIBygC#tbm=isch&q=where+blue+whales+live&imgrc=hGI2Jw1owth89M%3A) as GoPro captures shots of blue whales in an in-depth short documentary for the search of the blue whale9. Here (https://www.google.com/search?q=whales+geopgrahics&espv=2&biw=944&bih=927&source=lnms&tbm=isch&sa=X&ved=0ahUKEwj6pd7Fos_QAhVhrVQKHVMWBCEQ_AUIBygC#tbm=isch&q=where+blue+whales+live&imgrc=hGI2Jw1owth89M%3A) displays blue whales feeding on krill10.

Resources 

[1] Retrieved November 30, 2016, from https://www.gentlegiants.is/media/8067/blue-whale-balaenoptera-musculus.jpg?width=1000&height=500
[2] Endangered Species. Retrieved November 30, 2016, from U.S. Fish & Wildlife Service, http://ecos.fws.gov/docs/recovery_plan/whale_blue.pdf
[3] Copyright, M., & Use, T. of. (1998). Spider-eye puffers, Canthigaster amboinensis. Retrieved November 30, 2016, from http://marinebio.org/species.asp?id=41
[4] Retrieved November 30, 2016, from http://www.berkeley.edu/news/media/releases/2007/11/images/whale-sequence.jpg
[5] Blue whale. (2003). Retrieved November 30, 2016, from http://acsonline.org/fact-sheets/blue-whale-2/
[6] Whales geopgrahics. Retrieved November 30, 2016, from https://www.google.com/search?q=whales+geopgrahics&espv=2&biw=944&bih=927&source=lnms&tbm=isch&sa=X&ved=0ahUKEwj6pd7Fos_QAhVhrVQKHVMWBCEQ_AUIBygC#tbm=isch&q=where+blue+whales+live&imgrc=hGI2Jw1owth89M%3A
[7] Blue whale: Federally endangered listing information, Alaska department of fish and game. (2016). Retrieved November 30, 2016, from http://www.adfg.alaska.gov/index.cfm?adfg=specialstatus.fedsummary&species=bluewhale
[8] naturepl. Blue whale. Retrieved November 30, 2016, from http://wwf.panda.org/what_we_do/endangered_species/cetaceans/about/blue_whale/
[9] GoPro (2015, November 26). GoPro: The search for the blue whale - A prelude to “racing extinction” Retrieved from https://www.youtube.com/watch?v=-AHbNMXhCF8
[10] BBC Earth (2010, July 26). Humpback whales feeding on krill - deep into the wild - BBCRetrieved from https://www.youtube.com/watch?v=1_BqC9IIuKU