Baird, R.W., G.S. Schorr, D.L.
Webster, D.J. McSweeney, M.B. Hanson and R.D. Andrews. 2010. Movements and
habitat use of satellite-tagged false killer whales around the main Hawaiian
Islands. Endangered Species Research doi:10.3354/esr00258.
ABSTRACT: There are 2 recognized
stocks of false killer whales Pseudorca crassidens in the US Exclusive Economic
Zone surrounding Hawai‘i, a small demographically isolated population around the
main Hawaiian Islands and a larger offshore ('pelagic') population. Recent
evidence suggests the insular population may have declined precipitously over
the last 20 yr, and one possible contributing factor is interactions with
offshore longline fisheries or other hook and line fisheries. To assess
movements and habitat use, satellite tags were remotely deployed on individuals
in 3 groups from the insular population and one from the offshore population.
Although tagged off the leeward side of the island of Hawai‘i, individuals from
the insular population regularly moved to the windward sides of the islands.
Some insular individuals moved extensively and rapidly among islands, while
other individuals remained associated with the island of Hawai‘i for extended
periods before moving among the islands. Comparisons of distances between tagged
individuals indicated that individuals within groups disassociated and
re-associated over periods of days, occasionally moving more than 100 km apart
before re-associating. The offshore individual, tagged 123.8 km offshore,
approached to within 62 km of land, inshore of the longline fishery exclusion
boundary. The 3 insular groups moved a maximum of 83, 87 and 96 km offshore,
indicating that the distance from shore cannot be used as a strict boundary
between the populations, and that individuals from the insular population may
overlap with the longline fishery. Combined with photo-identification the
results suggest that boundaries between these 2 stocks should be
revised.