SEI WHALE

~JESS BERNAL~

(Balaenoptera borealis)

Date Listed: 06/02/1970

ENDANGERED

SEI WHALE

Sei whales ( "sigh") are a part of the rorqual family and are the fourth largest whales after the blue, fin, and humpback whale. They are considered a cosmopolitan species, which means that their existence extends over most of the ocean, particularly the Northern Hemisphere. Their scientific name, means "winged whale" (Balaenoptera) and "Northern" (Borealis). They are considered the fastest swimming cetaceans. They are observed singly, or in small groups of 2-5. Sei whales become sexually mature around 6-12 years old and mate and give birth in winter and lower latitudes.

They like to feed at dawn and exhibit odd and unpredictable behavior while feeding and foraging on prey and fish.

The similarity between other whale species, such as Bryde's whale, has caused difficulties in making distinguishes between population stock and dynamics. The fine bristles of the

Sei whale's baleen (filter-feeder system) 

is the best way of distinguishing them from their relatives.

GEOGRAPHIC AND POPULATION CHANGES

The Sei whale's range extends from the North Atlantic Ocean to the North Pacific Ocean, as well as down into the Southern Hemisphere. They have seasonal North/South movements where they spend the winters in low latitudes, and summers in high latitudes. They tend to stay away from enclosed bodies of water.

HABITAT REQUIREMENTS AND LIMITING FACTORS

Sei whales occur in tropical, temperate, and subpolar waters all around the world.

Their migratory movements and distributions are not well known, and vary unpredictably (accounting for the difficulty in determining their population stock). They are usually found in deep waters, away from the coastline.

CAUSE OF LISTING AND MAIN THREATS

• Primarily: extensive commercial whaling- beginning in the 1950s, after the larger whales had already been considerably decreased. 
• Secondary: collisions with vessels, entanglement in fishing gear, reduced or displaced prey due to climate change.

Of all commercially exploited "great whales", the Sei whale is one of the least studied due to current status of stocks being poorly known. 

RECOVERY PLAN AND STRATEGIES

The population of Sei whales is structured and organized by three sections of the ocean basin in order to understand the genetic differences and better determine the stocks between the populations.

The population status is unknown, so the strategy for recovery is to create a way to research and obtain the data that leads to finding out the population trends, structure, and to discover the factors that may be preventing the Sei whale recovery; as well as figuring out the natural threats to the species.

The National Marine Fisheries Service has divided the required management techniques into three Tiers.

1. Continual international regulation of whaling
2. A combination of monitoring and data to determine the population size, trends, and structure.
3. Continued stranding response and associated data collection.

The Goal= to recover the Sei whale so they can be downlisted from Endangered, to Threatened, and eventually removed from the ESA list all together.

Awareness is the first step in making an effort to save the Sei Whale. It is not that well known, and there are a variety of other whales that are endangered and getting attention as well. The best hope for the Sei whale is to get enough notice to be able to monitor and track their population stocks in order to provide a safer and more habitable ocean for them to live in. 

Sources:

http://ecos.fws.gov/docs/recovery_plan/FINAL%20Sei%20Whale%20Recovery%20Plan.24July.pdf

http://en.wikipedia.org/wiki/Cosmopolitan_distribution

http://www.nmfs.noaa.gov/pr/species/mammals/cetaceans/seiwhale.htm