False killer whale (Pseudorca crassidens)

Species >> False killer whale (Pseudorca crassidens)

The false killer whale (Pseudorca crassidens) is regarded as Data Deficient globally and in Australia. In most parts of its range, there is little information on its social behaviour, dispersal or ecology. The present study is the first assessment of its movement patterns in Australian waters, on the basis of satellite tracking of four individuals, in the Arafura and Timor Seas from late March to early July 2014. When initially tagged, the four individuals occurred in a single group; they then showed generally similar movement patterns and regularly re-associated.

In May 2002, the U.S. Geological Survey and Geological Survey of Canada conducted seismic surveys in the coastal waters of northern Washington and southern British Columbia. As a part of this project, Cascadia Research was contracted by the USGS and GSC to monitor marine mammals from the survey platform J. P. Tully, and provide mitigation on impacts on marine mammals by requesting shutdown of the sound sources when marine mammals were close to the operations.

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.

Recent management and conservation issues have arisen concerning false killer whales in Hawaiian waters. Two demographically isolated populations have been identified, a small (estimated 123 individuals) island-associated population around the main Hawaiian Islands (hereafter Hawai‘i insular stock) and a larger (estimated 484 individuals) offshore population (hereafter Hawai‘i pelagic stock).

Chivers et al. (2007) found Hawai‘i insular false killer whales to be distinct from other strata within the Indo-Pacific Ocean using mitochondrial DNA (mtDNA) control region sequence data. Here, we add new samples and eight nuclear DNA (nDNA) microsatellite markers to that study. After extensive quality checking, some haplotypes and duplicate individuals were removed from the 2007 mtDNA data set.