Blue whales are thought to be among the most endangered of the great whales. Scientists estimate that the whaling industry destroyed 97 percent of the world's population. The largest remnant group in the world may feed off the California coast during the summer. However, scientists do not know where this population breeds and how these whales migrate there. Because this species is, quite literally, on the brink of extinction, we desperately need to manage the remaining whales carefully. The OSU Marine Mammal Program is at the forefront of this work, providing critical information about the habitat and movements of these whales. Between 1993 and 1995, OSU researchers placed satellite tags on blue whales and traced their southbound migration through Mexican waters to a previously unknown possible winter breeding and calving area 500 miles off the coast of Costa Rica. Seven blue whales were tagged off Southern California in 1998. Dr. Mate reports, "As during the El Niño of 1997, we saw very few whales and krill-eating birds, suggesting food might be hard to find. Half of the whales were 'skinny.' Many tagged whales did not stay in one place very long, but were moving around over large areas as if they were looking for food."

In January 2004, five tags were placed on blue whales in the fjords of southern Chile. All five worked perfectly, giving us the first information ever developed for a Southern Hemisphere blue whale population in winter.

The whales stayed in the feeding areas longer than was expected. For the most part they hugged the nearshore areas, making occasional forays out of the fjords into the open ocean, then returning. Two of the whales went north and offshore to the Nazca Ridge, an area where colliding tectonic plates are building up an underwater ridge. The upwelling is excellent in this area, and where there’s upwelling, there are usually good food resources. It may be that the Nazca Ridge (located at 25 degrees south, approximately 500 miles from shore) is a winter feeding area for this population, a possibility that we’ll be exploring more fully as we continue to evaluate our data.

Our field season in 2004 was part of the TOPP program (Tagging of Pacific Pelagics), co-funded by the Sloan, Packard and Gordon Moore Foundations. We used our new research boat, the R/V Pacific Storm, to travel from Oregon to the waters off central California in search of blue and humpback whales. This season was extremely successful: in four weeks we tagged 29 animals, eight of them with new depth tags. Within two months of tagging, the blue whales were ranging from the north end of Vancouver Island, Canada to Magdalena Bay, Mexico, a distance of over 2,000 miles. Of the 12 blue whales carrying location tags, four were briefly clustered in a five-mile area of water off Coos Bay, Oregon. Overall, the blue whales showed a strong affinity for the outer edge of cold, upwelled water (also known as salmon water), where they feed on krill.

In the summer of 2005 we again returned to the waters off central California for another field season of tagging blue and humpback whales as part of the TOPP program.

If you’d like to read more about blue whale research, check out:

The Movements of North Pacific Blue Whales During the Feeding Season off Southern California and their Southern Fall Migration

Bruce R. Mate, Barbara A. Lagerquist and John Calambokidis,

Abstract: The satellite-acquired locations of 10 blue whales (Balaenoptera musculus) tagged off southern California with Argos radio tags were used to identify: 1) their movements during the late summer feeding season; 2) the routes and rate of travel for individuals on their southern fall migration; and 3) a possible winter calving/breeding area. Whales were tracked from 5.1 to 78.1 d and from 393 to 8,668 km. While in the Southern California Bight, most of the locations for individual whales were either clumped or zigzagged in pattern, suggesting feeding or foraging (searching for prey). Average speeds ranged from 2.4 to 7.2 km/h. One whale moved north to Cape Mendocino, and four migrated south along the Baja California, Mexico, coast, two passing south of Cabo San Lucas on the same day. One of the latter whales traveled an additional 2,959 km south in 30.5 d to within 450 km of the Costa Rican Dome (CRD), an upwelling feature. The timing of this migration suggests the CRD may be a calving/breeding area for North Pacific blue whales. Although blue whales have previously been sighted in the Eastern Tropical Pacific (ETP), this is the first evidence that whales from the feeding aggregation off California range that far south. The productivity of the CRD may allow blue whales to feed during their winter calving/breeding season, unlike gray whales (Eschrichtius robustus) and humpbacks (Megaptera novaeangliae) which fast.

Marine Mammal Science 15(4):1246-1257 (1999)

Dive Characteristics of Satellite-Monitored Blue Whales (Balaenoptera musculus) off the Central California coast

B. A. Lagerquist, K. M. Stafford, and B. R. Mate Abstract: Dive habits of four Northeast Pacific blue whales (Balaenoptera musculus) were studied using satellite-monitored radio tags. Tags summarized dive-duration data into eight 3-h periods daily. One tag additionally summarized dive depth and time-at-depth information for these same periods. Tracking periods ranged from 0.6 to 12.7 days and provided data for 17 three-hour summary periods, representing 2,007 dives (788 of which provided depth information). Total number of dives during a 3-h summary period ranged from 83 to 128 dives. Seventy-two percent of dives were <1 min long. All whales spent >94 % of their time submerged. Average duration of true dives (dives >1 min) ranged from 4.2 to 7.2 min. Seventy-five percent of depth-monitored dives were to <16 m, accounting for 78 percent of that animal's time. Average depth of dives to >16 m was 105 + 13 m.

Marine Mammal Science 16(2):375-391 (2000)

Blue whale habitat and prey in the California Channel Islands

Paul C. Fiedler, Stephen B. Reilly, Roger P. Hewitt, David Demer, Valerie A. Philbrick, Susan Smith, Wesley Armstrong, Donald A. Croll, Bernie R. Tershy and Bruce R. Mate

Abstract: Whale Habitat and Prey Studies were conducted off southern California during August 1995 (WHAPS95) and July 1996 (WHAPS96) to (1) study the distribution and activities of blue whales and other large whales, (2) survey the distribution of prey organisms (krill), and (3) measure physical and biological habitat variables that influence the distribution of whales and prey. A total of 1307 cetacean sightings included 460 blue whale, 78 fin whale and 101 humpback whale sightings. Most blue whales were found in cold, well-mixed and productive water that had upwelled along the coast north of Point Conception and then advected south. They were aggregated in this water near San Miguel and Santa Rosa Islands, where they fed on dense, subsurface layers of euphausiids both on the shelf and extending off the shelf edge. Two species of euphausiids were consumed by blue whales, Thysanoessa spinifera and Euphausia pacifica, with evidence of preference for the former, a larger and more coastal species. These krill patches on the Channel Island feeding grounds are a resource exploited during summer-fall by the world’s largest stock of blue whales.

Deep-Sea Research II 45:1781-1801 (1998)