The following new publication is available as a pdf from http://www.cascadiaresearch.org/robin/hawaii.htm Baird, R.W., and A.M. Gorgone. 2005. False killer whale dorsal fin disfigurements as a possible indicator of long-line fisherey interactions in Hawaiian waters. Pacific Science 59:593-601. Abstract: Scarring resulting from entanglement in fishing gear can be used to examine cetacean fishery interactions. False killer whales (Pseudorca crassidens) are known to interact with the Hawai'i-based tuna and swordfish long-line fishery in offshore Hawaiian waters. We examine the rate of major dorsal fin disfigurements of false killer whales from near-shore waters around the main Hawaiian Islands to assess the likelihood that individuals around the main islands are part of the same population that interacts with the fishery. False killer whales were encountered on 11 occasions between 2000-2004, and 80 distinctive individuals were photographically documented. Three of these (3.75%) had major dorsal fin disfigurements (two with the fins completely bent over and one missing the fin). Information from other research suggests that the rate of such disfigurements for our study population may be more than four times greater than for other odontocete populations. We suggest the most likely cause of such disfigurements are interactions with long-lines, and that false killer whales found in nearshore waters around the main Hawaiian Islands are part of the same population that interacts with the fishery. Two of the animals documented with disfigurements had infants in close attendance and were thought to be adult females. This implies that even with such injuries, at least some females may be able to produce offspring, despite the importance of the dorsal fin in reproductive thermoregulation. In addition for those interested in false killer whales, there is a report on the same site examining inter-island movements and estimating population size of false killer whales around the main Hawaiian islands (abstract below). This research is on-going, and I would be interested in hearing from anyone working with this species in the wild. Robin Baird ------------------- Baird, R.W., A.M. Gorgone, D.L. Webster, D.J. McSweeney, J.W. Durban, A.D. Ligon, D.R. Salden, and M.H. Deakos. 2005. False killer whales around the main Hawaiian islands: an assessment of inter-island movements and population size using individual photo-identification. Report prepared under Order No. JJ133F04SE0120 from the Pacific Islands Fisheries Science Center, National Marine Fisheries Service. The current best estimate of population size for false killer whales within Hawaiian waters is only 268 individuals (Barlow 2003), though the estimate is not very precise (CV = 1.08). False killer whales are considered a "strategic" stock by the National Marine Fisheries Service, as "takes" in the Hawai'i-based swordfish and tuna long-line fishery exceed the "Potential Biological Removal" (PBR) level. We studied false killer whales as part of small-boat based surveys for odontocetes around the main Hawaiian islands from 2000 through 2004, and in this report we assess inter-island movements, examine "mark" change over time on individual animals, estimate the proportion of marked individuals within the population, and provide a mark-recapture population estimate. Dedicated surveys for odontocetes were undertaken around all the main Hawaiian islands, and all groups of false killer whales encountered were approached and attempts made to photographically identify all individuals present. False killer whales were encountered on 14 occasions in directed surveys (2.9% of all odontocete sightings), in eight of the 10 months of the year surveyed, and in three of the four island-areas surveyed. Encounters were in a wide range of water depths (37 to 3,950 m). Photographs from seven opportunistic encounters were also available. Seventy-seven percent of individuals photographed were considered to have markings that could be recognized in the long-term (between-years). Seventy-six individuals with such long-term markings were documented, 47 of which were seen on two or more occasions. Ten individuals were documented with mark changes, though the rate of mark change was low (approximately one change every six years). Re-sighting analysis suggest that there are considerable inter-island movements of individuals (for example, 19 of 21 individuals identified off O'ahu have been recorded off the island of Hawai'i or around the "4-islands"). A multi-site mark-recapture analysis, taking into the proportion of marked individuals in the population, resulted in an estimate of 123 individuals in the population (CV = 0.72). This estimate applies to a population of false killer whales that used the study area; however the geographic range of that population is not known. Also, we assumed population closure and homogenous capture probabilities among individuals. The degree to which these assumptions may have been violated and the resulting estimate biased remain unclear. ============================================ Robin W. Baird, Ph.D. Research Biologist Cascadia Research Collective 218 1/2 W. 4th Avenue, Olympia, WA 98501 USA http://www.cascadiaresearch.org/Robin/robin.htm Phone 1-360-943-7325 Fax 1-360-943-7026 E-mail rwbaird@cascadiaresearch.org or rwbaird@dal.ca