Cook Inlet Beluga Whales Still Declining

Written by on October 22, 2009 in Marine Life, Policy & Ocean Law
Beluga whale - NOAA Alaska Fisheries

Beluga whale – NOAA Alaska Fisheries

Earlier this month NOAA Fisheries Service’s published a survey showing the declining trend of beluga whale population in the Cook Inlet.  The endangered beluga whale is not showing the hoped for recovery, but rather a continued trend of gradual population decline.

Scientists conducted aerial surveys in early June during fish migrations, when belugas concentrate near river mouths.  They flew over Cook Inlet counting the beluga whales while also taking photographs and video, which after careful examination provided a more accurate estimate of the beluga whale population — 321 animals.

These whales are generally found in shallow coastal waters, often in water barely deep enough to cover their bodies, but have also been seen in deep waters.  They seem well adapted to both a cold ocean habitat and a warmer freshwater habitat.  Belugas can be found swimming among icebergs and ice floes in the waters of the Arctic and subarctic, where water temperatures may be as low as 32° F (0° C).

The Beluga or White whale is unmistakable when adult – it is all white or whitish grey.  Unlike many dolphins and whales, the vertebrae in the neck are not fused together, allowing the animal flexibility to turn its head laterally.  Males can reach 18 feet (5.5 meters) long and weigh between 2,400 and 3,500 pounds (1,100 and 1,600 kilograms), while females grow to as much as 13 feet (4.1 meters) and weigh between 21,500 and 2,600 pounds (700 and 1,200 kilograms).  This is larger than all but the largest dolphins but smaller than most other toothed whales.

Human-caused mortality, primarily legal subsistence harvest by Alaska Natives, has been the most significant source of mortality of this species during recent times.  Subsistence harvest is the only factor that can be identified as influencing the decline of the Cook Inlet population from 1994 to 1998, when 67 whales per year were harvested, prompting the “depleted” designation under the MMPA.

"Beluga or White Whale." In: "An account of the Arctic regions with a history and description of the northern whale-fishery", by W. Scoresby. 1820. P. 588, Vol. II. Plate XIV. Library Call Number G742.S42 1820.

“Beluga or White Whale.” In: “An account of the Arctic regions with a history and description of the northern whale-fishery”, by W. Scoresby. 1820. P. 588, Vol. II. Plate XIV. Library Call Number G742.S42 1820.

The Cook Inlet stock of beluga whales is designated as depleted under the Marine Mammal Protection Act (MMPA) and was listed as endangered under the Endangered Species Act (ESA) in October 2008.

Following the depleted determination in May 2000, NMFS proposed regulations limiting the harvest of beluga whales in Cook Inlet, Alaska.  In April 2004 NMFS published interim harvest regulations to govern the taking of Cook Inlet beluga whales by Alaska Natives for subsistence purposes from 2001-2004.  NMFS published final harvest regulations in October 2008, to implement a long-term plan to manage subsistence harvests of Cook Inlet belugas, from 2008 until recovery.

The Cook Inlet beluga population estimates since 1994 are:

The rate of decline since 1999 when the hunting quota was established, has been -1.49% per year.

The rate of decline since 1999 when the hunting quota was established, has been -1.49% per year.

Listen to their songs at the University of Rhode Island’s Office of Marine Programs.

Beluga whale stocks in Alaska - Courtesy of NOAA's Alaska Fisheries

Beluga whale stocks in Alaska – Courtesy of NOAA’s Alaska Fisheries

Cook Inlet belugas are one of five beluga populations recognized within U.S. waters.  The other populations summer in Bristol Bay, the eastern Bering Sea, the eastern Chukchi Sea and the Beaufort Sea.  The Cook Inlet population is considered the most isolated, based on the degree of genetic differentiation and the geographic distance between the Cook Inlet population and the four other beluga populations, which are not listed as endangered or threatened.

Population size estimates from the most recent Stock Assessment Reports are (approximately):

  1. Bristol Bay: 1,600 individuals
  2. Eastern Bering Sea: 18,000 individuals
  3. Eastern Chukchi Sea: 3,700 individuals
  4. Beaufort Sea: 40,000 individuals

NOAA Fisheries Service is scheduled to propose designating areas of critical habitat for Cook Inlet beluga whales later this month.

Includes information from NOAA Fisheries Services materials.

Beluga whale - Photo by Ansgar Walk

Beluga whale – Photo by Ansgar Walk

Copyright ©  2009 by Marine Science Today, a publication of OceanLines LLC

About the Author

About the Author: Celia is Director of Business Operations for OceanLines LLC and is a frequent contributor to both OceanLines and Marine Science Today. She is a certified diver and her favorite topic is marine biology, especially stories about whales. .

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