Final Technical Report: - Southwest Fisheries Science Center - NOAA

the genera Ziphius and Mesoplodon. Constant line-transect densities for two additional coastal
species that are present year-round were derived from published values: harbor porpoise
(Phocoena phocoena; Carretta et al., in press), and coastal bottlenose dolphins (Dudzik et al.
2006, Carretta et al. 2007).
Geographically stratified density estimates for the three unmodeled ETP cetacean species
(killer whale, sperm whale, and coastal spotted dolphin) were taken from Ferguson and Barlow
(2003) without further combining or splitting of strata (Fig. 8, Table 7).
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Figure 8. Stratum numbers for ETP
line-transect density estimates for
coastal spotted dolphin, killer whale,
and sperm whale (from Ferguson and
Barlow 2003).
Estimates of abundance and density for Hawaiian cetaceans (Table 8) were largely
derived from a 2002 shipboard line-transect survey (Barlow 2006). Although Barlow defined
two geographic strata for the analysis (Main Hawaiian Islands and Outer EEZ), variance
estimates were only provided for the combined Hawaiian EEZ area. For most species, density
estimates were similar in the two geographic strata (with wide, overlapping confidence
intervals), so a single EEZ-wide density and associated variance were considered appropriate.
Three species, however, exhibited markedly higher densities within the Main Hawaiian Islands
stratum. In these cases, stratum-specific density estimates were retained (to increase accuracy),
and variance was approximated by assuming the coefficient of variation (CV) was equal to that
estimated for the overall study area (likely underestimating the true variance). Lastly, Barlow
and Rankin (2007) provided updated estimates of false killer whale abundance in Hawaiian
waters, based on additional sighting data obtained during a 2005 Pacific Islands Survey.