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New Jersey Endangered and Threatened Species Field Guide


Image of Humpback whales feeding.Zoom+ Humpback whales feeding. © Mike Davenport

Humpback whale

Megaptera novaeangliae

Species Group: Mammal

Conservation Status

State: Endangered

 


Identification

The humpback whale is a large baleen whale. It may reach a length of up to 60 feet with adult females being larger than adult males. It has a broad, rapidly tapering body that is primarily dark gray. Their bellies may be dark gray, white, or a combination and they have large white flippers or pectoral fins which have scalloped leading edges. The long flippers are the most distinctive feature of this whale. At one-third the whale’s body length, the flippers are larger than those of any other species of whale.

The top of the humpback’s head and lower jaw is dotted with randomly placed fleshy knobs. The lower jaw also has a rounded projection on its tip. Instead of teeth, it’s mouth has great plates of horny baleen which extend from the upper jaw. These are used to strain food from large mouthfuls of water. It has two blowholes on the top of it’s head and grooves on the throat and chest. The humpback's blow is often wide and balloon-shaped, although it can be tall and columnar in larger animals

The dorsal fin is highly variable in shape and size. It may be almost absent, a mere knob, or high and almost dolphin-like. The dorsal fin is located on a small hump a little more than two-thirds of the way back on the upper body. Their concave, deeply notched tail or flukes have scalloped rear edges. The pattern on the underside of the tail varies from all white to all black. The pattern of color under the tail is individually distinctive, similar to a human’s fingerprint, allowing researchers to identify and track individual whales.

Image of Range of the Humback whale off the coast of New Jersey.Zoom+ Range of the Humback whale off the coast of New Jersey.

Distribution and Habitat

Humpback whales live within all of the major oceans of the world, from the equator to sub-polar regions. Within the western North Atlantic Ocean, humpbacks feed during spring, summer, and fall near western Greenland, eastern Canada, and the northeastern U.S. (including New Jersey). During the winter, many humpbacks from this population can be found in the West Indies, their breeding and calving grounds. Some humpbacks, however, may remain at their northern feeding grounds during the winter.

Summer feeding habitat is within cold waters where prey is abundant. This is typically within relatively shallow waters. Winter breeding and calving habitat is within warm shallow waters. Prey is largely absent from these waters and humpbacks will typically go without any food during the months spent at the breeding grounds. Calving areas are usually near islands, offshore reefs, or continental shores. During migration, humpback whales stay near the surface of the ocean.

Diet

Humpback whales primarily feed on tiny crustaceans known as krill as well as small fish. They may consume up to 3,000 pounds of food each day. They feed by filter feeding with their mouthful of baleen. They do so by taking a large mouthful of both prey and water, closing their mouth, and then pushing the water out of their mouth using their enormous tongue. The prey items are then left within the mouth, trapped by the strips of baleen, and ready to be swallowed.

Humpback whales may use several hunting methods involving the use of bubbles to herd or disorient fish. One such method is unique to humpback whales and is known as “bubble netting”. This technique is often performed with a group of whales with specific roles for individuals. The whales begin by diving below a school of fish and then blowing bubbles out of their blowhole in a circular pattern. As the bubbles rise, they form a “cage” around the fish, which causes the fish to school within a tighter formation within the bubble net. Finally, the whales swim upward through the bubble net with their mouths wide open, capturing a large mouthful of fish.

Image of A group of humpback whales feeding.A group of humpback whales feeding. http://www.flickr.com/photos/mistermoss/ / CC BY 2.0

Life Cycle

During the summer, humpback whales will spend most of their time feeding and building-up fat in the cold waters of the North Atlantic. These fat stores will be necessary for the long migration to their winter breeding and calving grounds, located in warmer subtropical or tropical waters, where no feeding will take place for the entire winter. Humpback whales have one of the longest migrations of any animal. They have been known to travel up to 5,160 miles between summer feeding grounds and winter breeding grounds. Humpbacks have been known to travel 3,000 miles in as few as 36 days.

At their winter breeding and calving grounds, humpbacks form small loose groups. These groups usually consist of a single adult female and several adult males. The males compete for the female, trying to swim closer to her than the other males and often shoving other males out of the way. Males, and only males, are also known to sing while at the wintering grounds. While it is not known what the exact function of the singing is, it is believed that it may play a role in attracting females or warning off other males. Males may sing for hours and each song may last 20 minutes and be heard 20 miles away.

Adult females also give birth during the winter, after a pregnancy which lasts for 11 months. Newborn calves are 13-16 feet long and grow quickly feeding on the milk of their mother. They will feed on the mother’s milk for up to 10 months after birth. Only one calf is born and an adult female may reproduce every second or third year. Mothers are extremely protective of their calves and the mother and calf will stay close together. Males play no role in raising their young.

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. Baleen was also of value. 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.

In 1966, the International Whaling Commission prohibited commercial whaling of humpbacks 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. Humpbacks are provided with additional protection with the Marine Mammal Protection Act of 1972.

Despite the ban on hunting, humpback whales face a number of threats, all of which are caused by humans. These threats include entanglement in fishing gear, collisions with ships, harassment by whale watchers, habitat impacts, and proposals to allow for a commercial hunt once again.

Image of Humpback whale.Humpback whale. © Mike Davenport

One of the greatest threats to humpback whales is entanglement in fishing gear. Humpback whales often 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 humpback whales. The increasing number of large and fast ships, especially near busy ports such as the port of New York/New Jersey, 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.

Whale watching vessels may stress or accidently strike whales. There are whale watching guidelines in place which restrict ships’ approach distance and direction to whales and it is against the law to violate these. Unfortunately, some countries throughout the world do not impose such regulations on whale watching, resulting in the whales being harassed by too many vessels at too short a distance from the whale.

Negative impacts to whale habitat may take the form of development, pollution, noise, overfishing, and climate change. Shipping channels, aquaculture, offshore energy development, and recreational use of marine areas 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 small fish which humpbacks 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.

Humpback whales are increasing in abundance throughout much of their range. Ship strikes and entanglements may be slowing their recovery however. There is still no commercial hunt for humpback whales although several countries are interested in hunting them again. Japan and Denmark have proposed hunts for this species.

In 2016, nine of the fourteen humpback whale populations around the world were removed from the Federal Endangered Species List, including the population which occurs within the Northwest Atlantic Ocean. However, the species is still listed as Endangered by the state of New Jersey.

Although humpback whales are large animals, we don’t currently know a great deal about their habitat use off the coast of New Jersey. It has long been thought that humpbacks may only be using New Jersey waters as a migratory pathway between their summer feeding grounds in the north and their winter breeding grounds in the south. Feeding has been documented in New Jersey waters and individuals have been observed close to the shoreline, including within Delaware Bay. 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 & 2016.


Scientific Classification

Kingdom: Animalia
    Phylum: Chordata
       Class: Mammalia
          Order: Cetacea
             Family: Balaenopteridae
                Genus: Megaptera
                   Species: M. novaeangliae

Find Related Info: Endangered, Mammals

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