Sperm Whale
Listing Date: December 10, 2010
Listing Type: Endangered
(Picture by: The Smithsonian Magazine)
The Sperm Whale is known worldwide and is seen as a charismatic mega fauna. Sperm Whales are thought to be the only other marine mammal (besides the killer whale) to exist in most parts of every ocean. The Sperm Whales' head makes up a large portion of its body (around 1/3rd of its total length) (Rice 1989). This is ideal to fit their large brain (after all they have the the largest heads compared to any animal on earth!) On the face are snouts which allows the whales to communicate with other whales by making the right nasal passage cross with the nasal acoustic pathway to the"Spermaceti" (a type of high quality oil) which creates a horn like sound (researchgate.net). The Sperm Whale also has a thin lower jaw, which creates an "under-bite." This large mouth also contains around 25 pairs of mandible teeth. Sperm Whales have small eyes. The whales are usually colored dark gray with white undertones on its mouth and stomach. And on its spine is a dorsal fin (US Fish and Wildlife Service Endangered Species List). Sperm whales can also grow up to 18 meters in length for men and 12.5 meters in length for females. At these lengths both males and females can weigh anywhere from 24 metric tons to 57 metric tons (US Fish and Wildlife Service Endangered Species List). The life span of a female Sperm Whale has the ability to live up to 80 years, while the male average is at least 60 years.
(Picture by: wikimedia.org)
Sperm Whales are found throughout all of the world’s waters, but interestingly enough, statistics show that only males swim through arctic waters during summer for feeding and return back to warmer waters during breeding season. It was found that this dispersal is caused by "possible developmental genetic differentiation" (Lyholm and Gyllensten 1998). Even with this, on the Pacific, both males and female Sperm Whales move back and fourth through US and Canada to the Bering Sea (US Fish and Wildlife Service Endangered Species Sperm Whale Recovery Plan). The sperm whale have two different common populations: the western North Atlantic stock, and the northern Gulf of Mexico stock. Genetic variation were also found between subdivisions of Mediterranean sea sperm whales, and the North Atlantic sea sperm whales due to isolation between the different ocean basins. The Sperm Whales population (worldwide) is estimated to be around 300,000 to 450,000, which is only about 32% of their population before they were endangered (Whitehead 2002). The western North Atlantic coast has an estimated 4,800 whales, Northern US Atlantic 2,700, while the Southern US Atlantic has around 2,200.
(Picture By: wildwhales.org)
There are many factors when it comes to threats for sperm whales. Interactions with fisheries is one of the main threats to sperm whales. Fishing gear set up by these fisheries often get caught or carried away by the whales, injuring them and limiting or limiting movement to do normal activities. Sperm whales have also become bycatch to tuna and swordfish fisheries, further causing imperilment to their population. A second threat to the sperm whales are anthropogenic noises created by boats, ships, and large vessels that affect the whales' ability to communicate and navigate, as well as affect their social patterns between other whales. The noises from each ship is usually caused by the vessels that carry out oil exploration and the testing of weapons/bombs underwater. All noise can affect the whales by causing hearing impairment or damage, masking other sounds made from predators, prey or friends; and masking each whales own personal responses to each of these factors. Ship strikes or blows are also a main cause of whale death and injury. Due to whales natural socializing patterns, whales float atop or near the surface of the ocean. This makes them extremely susceptible to ship strikes, then are injured by the vessels propellers. Whales become more likely to be injured this way when they swim among boating trade routes. Whale watching activities also are a detriment to the whales this way. Next is contaminants and pollutants. chlorinated pesticides like DDT, DDE, and dieldrin, as well as ingesting heavy metal pollutants that multiply greatly up the trophic levels to k-strategists such as whales (Kasuya 1998). Oil spills are also another leading cause of death to sperm whales. Last but not least to contribute to the death of hundreds and thousands of sperm whales over the years is whaling. Commercial whaling of these animals are have been historically done by hand-harpooning. From 1800 to 1900 an estimated 700,000 whales were harvested. From 1910-73 around 605,000 were harvested. This trend continued until the Sperm Whales were added to the US Fish and Wildlife Service Engendered Species List. Whaling has decreased since then due to the International Whaling Commission was implemented. Since then whaling has been on the decline but is still a harmful factor to the killing of whales.
Whaling started to skyrocket during the 19th century, taking a "disproportionately large number of sperm whales in the north Atlantic compared to other basins" (Best 1983). This luckily changed during the 20th century in both north Atlantic and southern ocean basins, and after WWII whaling in North Atlantic were in areas that mostly male. Females in the North Atlantic declined from 1905 to 1979. This means recovery for over exploitation would most likely be found in the north Atlantic (Avila de Melo and Martin 1985). Sperm whales were killed for longer than 2 centuries. Whaling continued to be unregulated until around 1970 when law introduced quotas. International Whaling Comission IWC complete protection from commercial whaling 1981-82. japan still takes whales for" research". Norway and Iceland objected the IWC and are still "free to whale sperm whales" but both coutries do not express need or want to kill them (US Fish and Wildlife Service Endangered Species Sperm Whale Recovery Plan).
The recovery strategy that the US Fish and Wildlife Service goal for recovery is to limit and minimize human activities that postpone the recovery of sperm whale populations. A step towards recovery for the sperm whales would be to determine the actual population size of the whales as a whole. After this goal is obtained US Fish and Wildlife Service can begin to measure sperm whale trends among the entire population and assess these trends. The recovery plan must also have the oceanic management help of many nations to complete this recovery due to the fact that the whales swim freely though all waters. But, the ultimate goal for the Sperm Whales recovery is to limit their "collisions with vessels, direct harvest, and possibly competition for resources, loss of prey base due to climate change, and disturbance from anthropogenic noise" (US Fish and Wildlife Service Sperm Whale Recovery Plan). After all it is most important to keep whale populations healthy. If the populations reach stability, they can help maintain a stable food chain and keep overpopulation of some animal species at bay (whalefacts.org). Success in all areas of the recovery plan would ,make it possible for the sperms whales recovery to be completed in by the years 2025-2035.
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