Humpback and blue whale photographic identification research off California, Oregon, and Washington in 1999

Publications >> Humpback and blue whale photographic identification research off California, Oregon, and Washington in 1999

Citation

Calambokidis, J., T. Chandler, K. Rasmussen, G.H. Steiger, and L. Schlender. 2000. Humpback and blue whale photographic identification research off California, Oregon, and Washington in 1999. Final report to Southwest Fisheries Science Center, Olympic Coast National Marine Sanctuaries, and Channel Islands National Marine Sanctuary. Cascadia Research, 218½ W Fourth Ave., Olympia, WA 98501. 39pp

Executive summary

Surveys were conducted in 1999 to continue long-term research studies of humpback and blue whales off California, Oregon, and Washington. Primary objectives of this work have included examining the abundance of these two species, trends in population size, movement and migration patterns, and reproduction and mortality rates. In 1999 several other objectives were undertaken including deployment of an underwater video/instrument package on blue whales and testing a new method for measuring the sizes of whales. Support for this research in 1999 came from Southwest Fisheries Science Center, Olympic Coast National Marine Sanctuary, the Channel Islands National Marine Sanctuary, and several individual contributors.

Photographic identification studies of humpback and blue whales were conducted off California, Oregon, and Washington during dedicated surveys by Cascadia personnel on 64 days between 20 May and 3 November 1999. These were conducted using Cascadia’s 5.3m RHIBs and on a few occasions other boats. Collaborating researchers and work from opportunistic platforms provided additional effort and identification photographs especially in Monterey Bay. Identification photographs were taken using standard procedures employed in past research (Calambokidis et al. 1990a, 1990b, 1999a, 2000).  Both the right and left sides of blue whales in the vicinity of the dorsal fin were photographed as well as the ventral surface of the flukes. For humpback whales, photographs were taken of the ventral surface of the flukes.

There were 449 sightings of 1,018 humpback whales approached in 1999 off California, Oregon, and Washington with an estimated 646 identifications made which yielded 348 unique individuals. Photographic identification of blue whales conducted in 1999 yielded 414 identifications of 178 unique individuals out of 361 sightings of 540 whales. Locations of sightings in 1999 were more clumped than in past years with most blue whale identifications made in the Santa Barbara Channel and more than half the humpback whale identifications coming from the Monterey Bay area.

Abundance estimates for humpback whales show that the population has continued to increase, the estimates using 1998 and 1999 samples is 1,024 (CV 0.097). These are the highest estimates we have obtained to date. Inexplicably, sightings of humpback whales calves remained low, likely indicating a bias in our observations. Long-range movement patterns of blue whales were examined in 1999 with the help of comparisons to identification photographs gathered by Cascadia in a 1999 cruise to the Costa Rican Dome and identification photographs from Mexico gathered by Diane Gendron (CICIMAR). These comparisons have revealed extensive movements of blue whales from California down to Mexico and the Costa Rica Dome in winter and spring.

Several other components of the research proved promising in 1999. We successfully attached a CRITTERCAM underwater camera (including a hydrophone and pressure and temperature sensor) to a blue whale in collaboration with National Geographic. This yielded excellent images of blue whale swimming behavior and contributed to an analysis of marine mammal diving strategies. We documented an anomalously pigmented white blue whale. Estimated sizes of humpback whales were determined using a laser range-finder and calibrated camera system. We also obtained biopsy samples of humpback and blue whales for determination of gender and genetic patterns.

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