Sei Whale

Balaenoptera borealis

Pronounced "Sigh" Whale

Photograph of Sei Whale off the coast of New Hampshire by Leonard Medlock.

Fast, Sleek, Enigmatic
This is the way Pieter Folkens (2) introduces the Sei Whale. Fast because the Fin Whale and the Sei Whale are the fastest of the great whales. The body is described as sleek and resembles that of the Blue Whale and the Fin Whale.

Enigmatic describe a person, thing or situation that is mysterious, puzzling, or ambiguous. In the case of the Sei Whale elusive might be a better description because the Sei Whale is unpredictable in distribution. For a number of years it may appear regularly in an area then be absent for years. So no wonder we are so excited that seven Sei Whales took up residence off the coast of New Hampshire in August of 2010. Leonard Medlock and Joe Besada obtained some excellent photographs. No trip or whale watch can promise you a Sei Whale. You just have to get out there and get very lucky.

The Sei Whale is a baleen whale, smaller than the Fin Whale and larger than the Minke Whale.

Description
Look for the very tall, sickle shaped dorsal fin to separate the Sei Whale from the similar Fin Whale. As you can see in the photograph to the right, the dorsal fin and the blow hole can be above the water at the same time.

The larger Fin Whale has a dorsal fin that is wider at the base than it is tall and usually the blow holes are under water when the dorsal fin is above water. See the photographs below.

The Minke Whale is much smaller and has white markings on the flippers and behind the head. (1) Dorsal fin seen simultaneously with the blow.

Also may be confused with Bryde's Whale which is further south.

The Sei Whale has throat groves and two blow holes like all Baleen Whales.

Like the Fin and Minke Whales, the Sei Whales is not much of a performer on the surface and it is probably frequently overlooked.

Photograph of Sei Whale by Leonard Medlock on Jeffreys Ledge off the coast of NH and used with his permission.

Notice the double blow hole and the tall sickle shaped dorsal fin visible at the same time as the blow hole is above water. The blow is usually over by the time the dorsal fin appears.

Photograph of Sei Whale by Jim Besada. Notice that the blow hole is still visible when the dorsal fin is above the water. The blow is puffy . In this picture the blow has been blown backward by the wind.

Fin Whale dorsal fin tends to be wider than it is tall. Both of these photographs by Leonard Medlock. Good job Len.

Sei Whale dorsal fin is taller and more sickle shaped.

Behavior
The Sei Whale seldom breaches and does not raise flukes on dive. It swims almost as fast as the Fin Whale and avoids ships.

Range
The Sei Whale is worldwide in distribution including tropical, subtropical, and arctic waters. It may be found on the continental shelf and in open water. Recently it has been photographed in the Gulf of Maine off the coast of New Hampshire.

Makes seasonal migrations to warmer waters in winter. Breeding grounds are unknown.

Food
Mostly copepods, krill and small fish. (1)

References:

2001 Kinze, Carl Christian Marine Mammals of the North Atlantic ; Princeton University Press (1)

2002 Folkens, Pieter The Guide to Marine Mammals of the World ; Alfred A. Knopf NY (2)