Endangered Species Research Project – Blue Whale
Physical description
Blue Whale “ Balaenoptera Musculus”, is the largest animal inhabiting earth and it can weigh up to 330,000 pounds (National Oceanic & Atmospheric Organization [NOAA] Fisheries). It is an aquatic mammal, with spinal cord, that belongs to the order Mysticeti i.e. it lacks teeth, and posses flexible comb like structure called baleen in the jaws, to filter and feed on small fishes and plankton from water (Osis, Synder, Gross, Haslie and Bradhurst, 7). Blue whales have a streamlined body with horizontal tail fins called flukes, a broad snout or rostrum, and paddle like limbs in front called flippers (Osis et al., 5). Blue whales in the North Atlantic and Pacific grow up to 90 feet length, while in the Antarctic they can grow up to 110 feet (NOAA Fisheries). They have a mottled grey color skin, that appears blue when seen through water, and the underside of flippers are white or in lighter color. Usually, microbes called diatoms colonize the flipper bottoms, and impart a characteristic yellow shade, which is termed as “sulfur bottom” (Simmonds, 49).
Blue whales have certain unique adaptations that enable them survive well in Oceans. Their large body size helps in heat retention, and the body’s stored fat “blubber” provides sufficient energy for whales during long periods of migration without food (Osis et al., 16). If the blue whales were on land, they would crush under their own weight due to lack of strong supporting bone structure (American Cetacean Society). But, as they inhabit the sea, water’s buoyancy help whales support their bodies without heavy bones. Further, the streamlined bodies enable blue whales to move faster by reducing the drag. The front flippers and boneless flukes help in swimming, and travelling long distances.
Description of Habitat
Blue whales are found in all Oceans of the world, and they are found more frequently in the Arctic and Antarctic waters, towards the poles with high concentration of krill fishes. Typical Blue whale aquatic habitats include cold polar areas, continental shelves hat are shallower than open oceans and upwelling areas (Osis et al., 23-24). The cold Polar Regions have a long summer and sufficient sunlight needed for plant growth. Cold water also has more dissolved oxygen, and sufficient stirring caused by storms that bring deep water to surface often (Osis et al., 23-24). All these conditions are favorable for phytoplankton and zooplankton growth, which are fed on by small fishes and krill. Krill fishes in turn attract large number of Blue whales to the aquatic habitat. Continental shelves are shallow and have sufficient sunlight, and the stir caused by winds make them ideal whale habitats (Osis et al., 23-24). Similarly regions with upwelling such as the Gulf of Mexico, have frequent eddy currents or surface winds that bring deep waters to the surface, and become favorite feeding grounds for blue whales (Osis et al., 23-24).
Blue Whales move pole ward during feeding season due to abundance of zooplanktons in the cold waters that attract more krill fishes, and return to warmer tropical waters during the mating season. Blue whales can be sighted year around in some regions, and they also migrate between summer and winter. Most reproductive activity occurs in winter, and summer migration is driven by food requirement. But, the migration routes are not exactly known and there are several resident clusters such as in Northern Indian Ocean that does not migrate at all. Blue whales store energy in the form of blubber or body fat, which they can use during migration time that might last up to 4 months (WhaleFacts.org). During migration they swim only at 3-6 mile/hour speeds to conserve energy, however they can swim at high speeds if needed i.e. up to 30 miles/hour (WhaleFacts.org).
Blue Whale Niche
Blue whales feed exclusively on krill (euphausiids), and krill fishes are found in regions rich in phytoplankton and zooplankton i.e. waters with sufficient light penetration. Blue whales share their ecological niche with other cetaceans, and young blue whales fall prey to Pods of Orcas or killer sharks (Osis et al., 85). Blue whales eat around 2 tons of food per day during the feeding season (Osis et al., 21). This is used to build the body’s fat layer blubber, which acts as an energy reserve. Blue whale’s baleens are structures similar to hair or nails and they grow throughout the whale’s lifetime. As blue whales lack teeth, they are gulpers i.e. their throat grooves expand during feeding, food and water is gulped, and the baleens allow only small fishes and krill of about 6.2cm size to enter (Osis et al., 17). This is a characteristic feeding adaptation that allows such huge blue whales to feed efficiently despite the fact that they are toothless.
Reproduction
Blue whales are sexually mature around 5-15 years and calving interval is 2-3 years. Females are usually larger than males, and typical mating and births happen in winter (NOAA Fisheries). Gestation period is around a year, and the newborn calves are 6-7 meters in length, weighing around 3 pounds (Simmonds, 50). Blue whale mating grounds are not usually rich in food supply. Being mammals blue whales nurse their calves for 6-7 months i.e. till the calves reach a weight of 23 tons and a length of about 52 feet. During the nursing period calves consume up to 100 gallons of mothers milk that contains 50% fat (Osis et al). Blue whales may live up to 90 years (Simmonds, 50), and give birth to only one calf at a time.
Geographic Range
Blue whales concentrate in the upper and lower northern and southern hemispheres during feeding season, and migrate towards warmer tropical regions such as Gulf of Mexico and Costa Rica during mating season (WhaleFacts.org). However, different stocks inhabit the northern and southern hemispheres, where the seasons are opposite. Both stocks might come towards equator, but at different reasons, and hence they might not meet at all (Osis et al., 24). Presently the Blue whales are “highly endangered” and there is less evidence suggesting immediate recovery (Osis et al., 85). The major reason for the extreme reduction in Blue whale population is the excessive whaling operations carried out prior to the II world war. Some populations such as the Antarctic Blue whales are growing. Presently there are 1700 Antarctic Blue whales and they are growing at the rate of 7.3% annually. There are 5000 in Indian Ocean, 1,930 in the US west coast, 100-560 in the North Atlantic (Gillespie, 23-24). But, in many regions the count is uncertain especially due to illegal whaling. The International Whaling Commission has estimated in 2007 abundance of Blue whales in the major Ocean basins before and after the whaling era, and the data is presented in Table 1.
Life Expectancy and Social Interactions
Blue whale’s life expectancy is 70 – 90 years under normal circumstances (WhaleFacts.org). But, changing climatic conditions, Ocean currents, marine pollution, Ocean acidification and other anthropogenic activities, weather they live up to the expected time is a question. Whales are usually solitary animals that migrate only in small herds (WhaleFacts.org). They make low frequency sound ranging from185 – 190 decibels, i.e. below normal human hearing range that can travel long distances in water medium to communicate with other whales, or find migratory routes (Simmonds, 50). However, blue whales gather during mating or feeding.
Why is Blue Whale endangered?
Blue whales were hunted and processed to derive several useful products in the past. Fat from the blubber was used as a clean fuel and in leather tanning in the past (Osis et al., 31). Whale oil is still being hydrogenated and used in soap, nitroglycerine and margarine manufacture, and muscles are canned and used in pet foods as well as fertilizers (Osis et al., 31). Whaling industry has destroyed 97% of world’s blue whales. During the initial 15 years between 1910 and 1925, 47,200 blue whales were caught in Antarctic alone (Gillespie, 24-25). This number was exceeded in just the next 4 years, and 29,400 whales were hunted in 1year i.e.1931 alone. On the whole 118,300 blue whales were hunted just in 8 years preceding World War II (Gillespie, 24-25). The war slowed down the killing, but it resumed due to high demand for fuel i.e. blubber oil during the war.
Further, in 1925 there was tremendous advancement in stern slipway and onboard processing facilities (Osis et al., 28-30). This greatly reduced the time taken for processing the catch, and the need to come onshore. Hence, longer time could be spent in whaling offshore. In 1946, the International Whaling Commission (IWC) was convened, to formalize and develop whaling industry in an orderly fashion (Osis et al., 28-30). But, IWC initially advocated a self-regulatory mechanism, which was not successful in saving the dwindling whale population (Osis et al., 28-30). Most countries chose their own limits on whaling until a more stringent regulation, the Marine Mammal Protection Act (MMPA) was introduced in US (Osis et al., 28-30). World wide ban on blue whale killing was enforced in 1978, only when the blue whale population had reduced to less than 1% of its initial value that existed at the beginning of the centaury (Gillespie, 24).
Conclusion
Though commercial whaling is banned and restricted in most waters, illegal hunting is still being practiced due to lack of awareness or disregard for the long-term impacts. Presently climate change and global warming is causing Ocean temperatures to rise, and due to excessive green house gas emission, oceans are becoming acidified. This would have deleterious effects on blue whale population, as water temperature is a major driving factor during migration. Additionally, seismic and oil and gas explorations disturb natural habitats of whales, and the noise might also affect their interactions. Industrial pollution leads to accumulation of toxins, affects light penetration, destroys the habitat of planktons and other aquatic life forms. Thus, the ecological imbalance can eventually affect the already endangered blue whales. Hence, in addition to ban on commercial whaling, efforts to minimize marine pollution, and climate change impacts are essential to rejuvenate blue whales and save them from extinction.
Works Cited
American Cetacean Society. "Blue Whale." Web. 15 Mar. 2016. <http://acsonline.org/fact
sheets/blue-whale-2/>.
Gillespie, Alexander. Whaling Diplomacy: Defining Issues in International Environmental
Law. Cheltenham, UK: Edward Elgar, 2005. Web. 15 Mar. 2016. <https://books.
google.co.in/books?id=NzJmAwAAQBAJ&pg=PA23&redir_esc=y#v=onepage&q&f=false>.
NOAA Fisheries. "Blue Whale (Balaenoptera Musculus)." 10 Feb. 2016. Web. 15 Mar. 2016. <http://www.fisheries.noaa.gov/pr/species/mammals/whales/blue-whale.html>.
Osis, Vicki, Susan Leach Synder, Rachel Gross, Bill Hastie, and Beth Broadherst. The Great
Whales. Oregon State U Marine Mammal Institute, 2008. Web. 15 Mar. 2016. <http://
mmi.oregonstate.edu/sites/default/files/Great_Whales_6-30-08.pdf>.
Simmonds, Mark P. Whales & Dolphins of the World. Cambridge, MA: MIT, 2007. Web. 15
Mar. 2016. <https://books.google.co.in/books?id=TQxyo8O5KD8C&printsec=
frontcover&dq=whales&hl=en&sa=X&ved=0ahUKEwjQ3Ni6ysLLAhVN1I4KHUcFBm8Q6AEIIDAB#v=onepage&q=whales&f=false>.
WhaleFacts.org. "Whale Facts." 2016. Web. 15 Mar. 2016. <http://www.whalefacts.org/blue-whale-facts/>.
