SCIENTIFIC NAME: Balaenoptera borealis -- From the Latin borealis (northern).

COMMON NAME: Sei Whale

DISCOVERED: Lesson, 1828

EXTERNAL ANATOMY:

Longitudinal ridge on head
Ventral grooves -- vary in number between 38 and 60
Dark gray on back, paler pigmentation on ventral surface
Ovoid grayish-white scars
Slim, streamlined body
Well defined and slightly hooked dorsal fin about two-thirds of way along back
Size: 17.1 (male), 18.6 (female)

GEOGRAPHICAL DISTRIBUTION:

Found in both the Northern and Southern hemisphere. Those in southern tend to be larger than ones in the northern hemisphere.
Distributed worldwide
Unpredictable, sporadic presence, irregular.
Generally migrate long distances between warm water winter breeding grounds and cold water summer feeding

NATURAL HISTORY:

HABITAT:

Deep temperate waters (offshore)
Pelagic species
Not generally found in inshore or coastal waters
Tends to follow temperature gradients and current lines in the ocean
Preferred surface temperature: 8-25 degrees C°

FOOD & FEEDING:

Copepods, krill, squid or octopus, other fish and crustaceans
Skim feed -- whatever is in abundance locally

LIFE CYCLE:

May live up to 70 years
2 year reproductive cycle
Gestation lasts about 11.5 months
Single calf born during winter- suckled 6 to 7 months
Sexually mature between 6-12 years
Physical maturity 25-30 years

BEHAVIOR

Stay consistently along surface for long periods of time
Rarely dive deep
Quietly slip below surface
Swim in small pods of 3-5
Appears to be some segregation by age, sex, and reproductive status
Adult animals predominate in high latitude
Schools consist mainly of juveniles and lactating females

WORLD POPULATION

World Population 40,000 - 60,000

200 in Icelandic survey
1,400-2,200 in Nova Scotia
13,000 in North Pacific
24,000 in Antarctic

HUMAN INFLUENCES

Traditionally not prime target of whaling
Heavily exploited around the mid 1960's
Many populations are severely depleted or have disappeared, especially during the 1960's and early 1970's