Animal of the Month
August 2017

Name: Sei Whale

Class: Mammalia
Infraclass: Cetartiodactyla
Order: Cetacea
Family: Balaenopteridae
Genus: Balaenoptera

Number of Species: 2
Balaenoptera borealis borealis (Northern Hemisphere Sei)
Balaenoptera borealis schlegellii (Southern Hemisphere Sei)

Size: 40-60 feet long
Weight: Up to 100,000 lbs

Characteristics: Long body baleen bristle teeth, large tale, small fins
Color(s): Dark bluish-gray to black
Behavior: Social
Preferred Habitat: They prefer subtropical to sub-polar waters, especially deep waters away from the coastline. Migratory.
Range: Can be found in the Pacific, Atlantic and Indian oceans.
Diet: Plankton, small fish and cephalopods
Lifespan: 50-70 years

Status: Endangered

Not as well-known as it's larger cousins, the sei whale (pronounced "say" whale or "sigh" whale) just as important to the oceans. Sei whales get their names from the Norwegian word "seje". "Seje" is the Norwegian word for Norway pollock (Theragra finnmarchica), a fish native to Norwegian waters. Sei whales are often found with this type of fish, thus the name "sei" is derived. Sei whales can reach 40-60 feet long and weigh a whopping 100,000 lbs! Females tend to be slightly longer than males. They usually are solitary or live in pods of 2-5 individuals. Seis can dive underwater for up to twenty minutes.

Seis are baleen whales, meaning they have bristle-like teeth rather than sharp teeth in other carnivores. Like other baleen whales, seis eat plankton, small fish and other small sea creatures. A sei whale will eat as much as 2,000 lbs of food per day! Seis are also unique as they are the fastest known cetacean, reaching a top speed of 34.5 mph!

Sei whales migrate across the ocean and can be found in the Atlantic, Pacific or Indian oceans. The migratory patterns of this animal are not well known. Sei whales have been known to randomly appear in one area of the ocean and then not return there for years. They appear to be most common around the Gulf of Maine, on Georges Bank and Stellwagen bank in the summer. Seis begin to reproduce when they are about 45 feet long, or about 6-12 years old. Mating takes place in lower latitudes during the winter. A female will carry her calf for 11-13 months! The calf will nurse for 6-9 months before switching to plankton.

In the 19th and 20th centuries, sei whales were heavily whaled for their meat and blubber. Whaling is officially on a global moratorium, so in theory they are protected. However, there are those who would overturn the moratorium and legalize whaling once again. As seis and many other whale species are badly endangered, commercial whaling must remain out of the oceans in order to allow these majestic creatures to recover. In addition to the looming threat of whaling, seis still experience collisions with ships and fishing traps.

Learn more about sei whales:

New York State Department of Environmental Conservation

NOAA Fisheries

To protect sei whales and other cetaceans, look up these awesome organizations!

World Wildlife Fund, Sei Whale Page-What the WWF is doing to preserve the sei whale

Ocean Alliance-Protecting whales through education and research!

American Cetacean Society-Dedicated to protecting all cetaceans, including the sei whale


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