"Cook Inlet Beluga Whale"

The National Marine Fisheries Service (NMFS) conducted aerial surveys of the beluga whale (Delphinapterus leucas) population in Cook Inlet, Alaska, almost monthly between June 2001 and June 2002. The surveys were flown in a twin-engine, high-wing aircraft at an altitude of 244 m (800 ft) and speed of 185 km/hour (100 kt). Tracklines were approximately 1.4 km offshore, and systematic transects were made across the inlet, covering much of upper Cook Inlet. These methods were consistent with NMFS= abundance surveys conducted each June or July since 1993, except that only in June were there multiple surveys (repeat samplings) within a block of days. During the 2001­ 02 monthly surveys, aerial counts of belugas (median counts when more than one observer was counting) generally stayed high from June through October (n = 211 in June, 39 and 152 in July, 205 in August, 185 in September, 162 in October, respectively), but counts dropped from November to April (n = 24 in November, 15 in January, 0 in February, 18 in April, respectively) before rising again the following June (n = 192). Low counts in winter were probably due to ice in the inlet, making it hard to see the white whales. This study provides evidence of the presence of belugas in upper Cook Inlet in nearly every month of the year, but it is not clear what proportion of the population remains in the upper inlet year-round.

The stock of beluga whales in Cook Inlet, Alaska, declined by greater than 50 percent between 1994 and 1999 resulting in a depleted determination under the Marine Mammal Protection Act. The NOAA Fisheries believes that the subsistence harvest of these whales was the principal factor in the decline.

In this study, scientists present the first assessment of killer whale predation on belugas in Cook Inlet.

Assessment of Cook Inlet noise and potential impacts to the Cook Inlet beluga whale population.

A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Environmental Science at the Alaska Pacific University–Anchorage, Alaska.

Beluga whales (Delphinapterus leucas) in Cook Inlet are the most geographically and genetically isolated of the five stocks recognized around Alaska (OCorry-Crowe et al. 1997, Laidre et al. 2000). Their isolation, in combination with high site fidelity in summer (Rugh et al. 2000, 2005, 2010), makes them particularly vulnerable to both environmental (Moore et al. 2000) and anthropogenic impacts (Hill 1996). The population of Cook Inlet belugas declined by nearly 50% between 1994 and 1998 to an estimated 347 whales (Hobbs et al. 2000). Despite cessation of the Alaska Native subsistence hunt in 1999 of approximately 70 animals per year (Mahoney and Shelden 2000), the abundance estimates of belugas in Cook Inlet have remained low (321 and 340 animals in 2009 and 2010 compared to 653 in 1994) with no notable signs of recovery (Hobbs and Shelden 2008). In recognition of the low numbers of belugas remaining in Cook Inlet, the U.S. government listed this isolated population as endangered under the U.S. Endangered Species Act in October 2008.

This poster contains information about the creation of a web-hosted database for Cook Inlet beluga whale stranding and harvest data.

A study, conducted during the 2003 aerial survey of Cook Inlet belugas (Delphinapterus leucas), developed a method to estimate the portion of calves in the population. Beluga calves were identified by their small relative size and dark gray coloring.

Beluga whales, Delphinapterus leucas, live year-round in arctic and subarctic seas of the Northern Hemisphere (Hazard 1988). In Alaska waters, belugas spend summer in different regions of Alaska (Frost and Lowry 1990) to the extent that genetic differentiation has occurred within the species (O’Corry-Crow et al. 1997). These summering populations are found in Cook Inlet, Bristol Bay, the eastern Bering Sea, the eastern Chukchi Sea, and the eastern Beaufort Sea (Fig. 1). For Cook Inlet, both geographic and genetic isolation from the other beluga populations in Alaska has resulted in evident genetic drift (O’Corry-Crowe et al. 1997, 2010). While some of these Alaska populations are migratory, covering 1,000s of kilometers between summering and wintering regions, most Cook Inlet belugas remain year-round within the boundaries of the inlet.