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New Jersey Endangered and Threatened Species Field Guide
Species Group: Mammal
The sperm whale is the largest toothed whale with adult males reaching a length of up to 60 feet. Adult males are significantly larger than adult females which may grow to a length of 36 feet. The sperm whale's huge head extends a quarter to a third of its entire length. Its single blowhole, well left of the center and far forward on the head, emits a distinctive spout that is small, bushy and angled sharply forward. The sperm whale's skin, a dark brownish gray, looks corrugated.
Occasionally its belly and front of the head are grayish, and the mouth area white. The blunt, square snout extends far beyond the tip of the lower jaw, which has a row of large teeth on either side; smaller teeth are embedded in the upper jaw. They do not have a dorsal fin. Two-thirds of the way back from the snout the whale has a distinguishing dorsal hump and behind that are a number of bumps. The sperm whale’s flukes, or sides of the flat tail, are broad, triangular and heavily notched at their back edges.
Distribution and Habitat
Sperm whales live within the Atlantic, Indian, and Pacific Oceans from the equator to the edge of the polar pack ice. They are primarily observed in subtropical, temperate and subpolar waters. Male sperm whales have a wider distribution than females. They may range much closer towards the north and south poles than the females. Their migratory patterns are not well known and some populations may not migrate seasonally.
Sperm whales are usually observed in deep waters, far from most coastlines. They are not usually encountered within New Jersey’s coastal waters. According to the New Jersey Endangered and Nongame Species Program, there are no sightings currently documented within New Jersey waters for this species.
The sperm whale’s primary prey is squid (including giant squid), and fish, including some sharks. These whales are known for their deep and long dives in pursuit of their prey. They have been known to dive for over an hour for each dive and to a depth of 3,280 feet. There is no light at such depths, so sperm whales rely on echolocation to find their food. A fully grown adult male may eat almost 2 tons of food each day.
Female sperm whales will give birth approximately once every 5 years beginning when they are around 9 years old. Pregnancy lasts for 14-16 months. Calves are approximately 12-14 feet in length when born. They will nurse on their mother’s milk for several years, although they will begin to eat some solid food before they are a year old. Females form very close bonds with their young and are very protective of them. Male sperm whales reach sexual maturity when they are between 10–20 years old, but they may not breed for several more years, until they have reached a larger size. Males play no role in raising their young.
A typical family unit is comprised of about a dozen females and their young. Once a male sperm whale is between 4 and 21 years old, it will leave the family unit. Young male sperm whales will form “bachelor pods”, comprised of other young males. Once a male has become fully grown, it may travel alone. Adult males will only return to the female-led family groups once they are ready to breed.
Predators of the sperm whale, aside from humans, are sharks and the killer whale (Orchinus orca), which will only prey upon females and young individuals. When confronted by a pod of killer whales, a sperm whale family unit may adopt a defensive posture, placing the calves inside a circle surrounded by the adult females.
Current Threats, Status, and Conservation
All of the large whale species have been at risk of extinction due to a long history of whaling. The principal attraction of whaling was the whale's blubber, which yielded oil ideal for lamp oil and, much later, in the production of margarine. Whalebones were also used in the manufacture of glue, gelatin and manure. Besides being eaten by humans, the meat has also been used in dog food and, when dried and crushed, cattle feed. Sperm whales were also targeted for the spermaceti oil found within their head.
Commercial whaling of sperm whales ended in the late 1980’s due to the decline of the species. It was listed by the federal government as endangered in 1970 and, as a result of that federal status, was automatically added to the New Jersey endangered species list following enactment of the New Jersey Endangered and Nongame Species Conservation Act in 1973. Sperm whales are provided with additional protection with the Marine Mammal Protection Act of 1972. Sperm whales are currently considered the most abundant of the large whale species. The global population is currently thought to be between approximately 200,000 and 1,500,000.
Sperm whales face a number of threats, all of which are caused by humans. The greatest threats to sperm whales are those of habitat impacts including noise pollution and climate change. Other threats include entanglement in fishing gear, collisions with ships, and proposals to allow for a commercial hunt once again.
Negative impacts to whale habitat may take the form of offshore development, pollution, noise, overfishing, and climate change. Offshore energy development may destroy whale habitat or displace whales which would normally use the area. Oil spills and other chemical pollutants are also a threat to whales and the prey which they feed on.
Another form of pollution is noise pollution. Whales’ primary means of communication, navigation, locating food, locating mates, and avoiding predators and other threats is through their sense of hearing, which is much more highly developed than that of humans. Noise pollution created by ship traffic or offshore construction may negatively impact whales by disrupting otherwise normal behaviors associated with migration, feeding, alluding predators, rest, breeding, etc. Any changes to these behaviors may decrease survival, simply by increasing efforts directed at avoidance of the noise and the perceived threat. Active sonar, such as that used by the Navy, also threatens marine mammals by disrupting navigation, foraging and communication abilities. There have been instances of whale stranding and death caused by acoustic trauma. This may be due to a fatal injury within the structure of the ear, or may result from the distressed animal surfacing too rapidly and developing nitrogen bubbles within their blood (decompression sickness). In addition to the direct threat posed by active sonar, it may indirectly harm marine species by causing changes in behavior.
Overfishing of the fish and squid which sperm whales feed upon is another potential cause for concern as well as the potential impacts of global climate change. This issue may be the greatest long-term threat to the marine habitat and its species. Climate change may significantly alter the chemical balance of the seas, off-shore currents, and plankton distribution and abundance, thereby affecting migration routes of marine species and impacting the entire food web.
Entanglement in fishing gear is a potential threat to sperm whales. Individuals may become wrapped-up in nets and/or fishing line around their tail, mouth, or other body part. Discarded nets and lines may float at sea for decades or become snagged on rocks or debris at the ocean bottom. Once entangled in fishing gear, the whale may face an agonizing death, pulling the gear along while it swims for many days, months, or even years, as the gear slowly cuts through their body and causes swimming to become more difficult. Scars on whale bodies are often an indication of a previous entanglement from which they escaped.
Collisions with ships are an increasing threat to sperm whales. The increasing number of large and fast ships results in whales and ships being in close proximity more often. Unfortunately, whales do not always know or have time to react to the approach of large ships and they get hit, usually resulting in their death.
There is still no commercial hunt for sperm whales although several countries are interested in hunting them commercially again. Several countries currently allow hunting for this species and they are also hunted illegally. Japan currently hunts the species, claiming it does so for “scientific” purposes. The population today, however, remains endangered and such hunts may be setting back decades of recovery.
Although sperm whales are large animals, we don’t currently know a great deal about their habitat use off the coast of New Jersey. It is likely, in fact, that they may not occur within New Jersey’s waters which only extend 3 nautical miles off the coastline. It is likely, however, that they do occur within the ocean waters beyond 3-nautical miles. It is unknown whether they may be using those offshore waters as a migratory pathway between their summer feeding grounds in the north and their winter breeding grounds in the south. Surveys are currently being conducted off the New Jersey coastline in order to determine where whales are located, how many individuals are there, and during what time of year. Based on these findings, further knowledge regarding their habitat use in New Jersey waters may be gained and attention may then focus on protecting important habitats.
Text derived from the book, Endangered and Threatened Wildlife of New Jersey. 2003. Originally edited by Bruce E. Beans and Larry Niles. Edited and updated Michael J. Davenport in 2010.
Species: P. macrocephalus
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