COOK INLET BELUGA WHALE } Delphinapterus leucas
FAMILY: Monodontidae

DESCRIPTION: Belugas are small whales, measuring up to 15 feet long with a maximum weight of 3,000 pounds. They are bigger than all but the largest dolphins and smaller than most other toothed whales. At birth, beluga whales are five feet long, roughly 100 pounds, and dark blue-gray in color. Unmistakable as adults, their color lightens to white, and they have a dorsal ridge rather than a fin. Belugas have ornately curved tail fins, broad, short flippers, and a soft, bulbous head.

HABITAT: These belugas live in the icy waters of Cook Inlet off the coast of Alaska.

RANGE: Belugas have a circumpolar distribution, with about 30 separate populations occurring throughout the Arctic region. Five distinct summer populations are currently recognized in Alaska: the Beaufort Sea, eastern Chukchi Sea, eastern Bering Sea, Bristol Bay, and Cook Inlet populations. The Cook Inlet population doesn’t migrate and is separated from the other four populations by the Alaska Peninsula.

MIGRATION: While some belugas are migratory, the Cook Inlet population remains in the same area all year.

BREEDING: Female beluga whales become sexually mature after age four and will give birth every two or three years. Breeding occurs in the spring, and after a gestation period of longer than a year, a single calf is born. The calf emerges tail first and is immediately guided to the surface to be attended to by its mother. Calf and mother will remain together for two years.

LIFE CYCLE: Belugas generally live 40 years.

FEEDING: Belugas mainly subsist on fish, but they also eat octopuses, squid, crabs, and snails, using echolocation to find prey. In the shallow waters off Alaska, feeding dives are to depths of 100 feet and generally last two to five minutes.

THREATS: Threats include industrial development, pollution, sewage discharge, oil and gas development, gillnets, ship traffic, sonar devices, global warming, and underwater seismic blasting.

POPULATION TREND: Numbering 1,300 individuals as recently as the 1980s, the geographically isolated and genetically distinct beluga whales in Cook Inlet, Alaska could be readily seen from shop windows and restaurants in downtown Anchorage. The population declined precipitously in the 1990s, and the National Marine Fisheries Service falsely predicted that the Cook Inlet beluga whale population would rebound once hunting was restricted. Three hundred to 400 whales likely remain today.

Photo © Martin Tiller