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Cetacean Assessment & Ecology Program

Gray Whale Census in 2006/07

Figure 1, gray whale sighting rates
Figure 1.  Gray whale sighting rates throughout the southbound migration past Granite Canyon in central California, 12 December 2006 to 22 February 2007.
 

Gray whales (Eschrichtius robustus) have a phenomenally routine migration along the western coast of North America. The southbound migration was documented by Cetacean Assessment and Ecology Program (CAEP) observers from 12 December 2006 to 22 February 2007 (Fig. 1) in a manner comparable to previous surveys (see below). Lone observers independently recorded sighting and environmental data during three 3-hour watches each day in small sheds on the edge of a 22-m sea cliff at Granite Canyon in central California.

The counting system and observer performance were tested through paired, independent observational effort, as has been done each census since 1985/86. In addition, the Southwest Fisheries Science Center (SWFSC) conducted an independent effort in a nearby trailer, using a team of two observers (one dedicated to searching, the other both searching and typing in data) that rotated through 1.5-hour (h) watches for 9 h each day from 2 to 27 January. These counts will serve as a comparison to the standard effort by CAEP observers because the SWFSC will be conducting the gray whale census in the future.

A fix-mounted, high-powered (25X) binocular provided an index of the offshore distribution of migrating whales passing within the sighting range of the observers. The timing of the 2006/07 southbound migration seemed to be 1 week later than in previous years, with the median date close to 21 January instead of 15 January. Most (80%) of the sightings occurred in January, 17% were in February, and only 3% were in December.

There were 1,770 pods of whales counted during the 73 days (651.6 h) of the standard census during fair to excellent visibility conditions. This summary count compares favorably with similar counts from 2000/01 (1,684 pods in 599.4 h) and 2001/02 (1,712 pods in 531.5 h). Population abundance calculations from the observer counts will follow the same analytical approach applied in previous studies.

These methods account for  1) whales passing during periods when there is no observational effort (prior to and after the census season, at night, or when visibility is poor);  2) whales missed within the viewing range during on-effort periods;  3) differential sightability by observer, pod size, distance offshore, and various environmental conditions;  4) errors in pod-size estimation;  5) covariance within the corrections due to variable sightability by pod size; and  6) differential diel travel rates of whales.

By David Rugh


Beluga Conference in Valencia, Spain

With many institutions across the world displaying live beluga whales for research and educational purposes, and six polar countries managing wild beluga populations, there is an increasing need for communication and information sharing to further beluga whale conservation. In order to foster collaborations in research and husbandry practices, L’Oceanogràfic of Valencia, Spain, hosted the First International Workshop on Beluga Whale Research, Husbandry, and Management in Wild and Captive Environments, from 9 to 11 March 2007.

The workshop was the first directed effort at bringing people together who work with beluga whales, either in captivity or in the wild, to review the current state of knowledge, determine research needs, and build a coordinated effort to better conserve and understand these charismatic animals. Participants in the workshop identified topics for research in aquaria that would be advantageous for conservation of belugas in their natural habitats and discussed how research results from wild beluga populations could enhance the well-being of captive belugas.

NMML representatives at the conference presented posters on:  1) “Habitat use of beluga whales in Cook Inlet Alaska,” detailing the last 3 years of habitat analyses by applying advanced ecological modeling techniques as a means to better understand beluga distribution and habitat preferences;  2) “Using advanced techniques to determine age categories of belugas”, which applied digital imagery to better differentiate calves, juveniles, and adults in aerial photographs and video;  and 3) “Cook Inlet beluga population: failure to thrive?”, which presented a review of recent research and discussed future research needs and interests, including studying comparable wild populations and captive animals.

Overall, this workshop was a huge first step towards beluga conservation. Not only are belugas an important component of the arctic ecosystem, but they also are an ideal species for learning about climate change and ecosystem fragility. This workshop was a catalyst to promoting cross-cultural understanding and collaboration among stakeholders around the world.

By Kimberly Goetz and Rod Hobbs
 

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