Pacific Coast Feeding Group Gray Whales

During the northbound migration, a small number of individually identified gray whales (n=14) divert from the migratory path to enter the Strait of Juan de Fuca, travelling >100 miles to northern Puget Sound (NPS), where they feed on dense patches of ghost shrimp. Efforts to photographically identify these whales began in 1990, and most of these whales (71%) have been sighted in NPS in at least ten of the past 24 years. These whales arrive in NPS in the spring and feed for 2-3 months.

The majority of eastern North Pacific gray whales feed in the Bering, Chukchi, and Beaufort Seas. Photo-ID and genetics have shown that a subset of this population, the Pacific Coast Feeding Group (PCFG), is a somewhat distinct group of about 200 individuals known to feed through the summer and fall from N California to SE Alaska. Recruitment to this group is an important consideration in understanding its status and management. A large scale collaborative effort was initiated in 1998 to monitor PCFG whales.

Despite extensive use of implant tags for more than 30 years in large whales, long-term consequences have generally only been examined on short-term, anecdotal basis or in generalized terms. We evaluated the physical condition of the tag site and healing characteristics in 35 gray whale tagging events from 2009 to 2013 and 83 blue whale tagging events that took place in the eastern North Pacific from 1993 to 2008.

Deployment of tags on whales using approaches that either embed or anchor the tag into the blubber and muscle layer have been commonly used for many decades. Follow up studies on the potential impact of these tags have relied mostly on limited or short term observations of tagged animals.

Gray whale (Eschrichtius robustus) populations in the eastern North Pacific have increased at an annual rate of close to 3% since cessation of commercial exploitation and now number over 20,000 (Buckland et al. 1993, Reilly 1992), which is close to their historical population size.

This report summarizes the research conducted by Cascadia Research on gray whales in Washington State up to 1994. This included boat surveys that yielded sighting information, photographic identification of individual animals, sighting reports from the public, and examination of stranded animals. The report also includes our photographic catalog of individual animals identified through 1993.

Cascadia Research has been studying gray whales in Washington waters since the mid-1980s. The goals of this overall research effort have been to characterize the different ways gray whales use Washington waters and to determine the number of individuals engaged in feeding and other critical activities.