Bradford et al.: Abundance estimates of cetaceans within the U.S. Hawaiian islands EEZ 
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Sightings (Ngys in Table 1; n=211) of cetacean species and taxonomic categories made by 
observers on systematic survey effort (fine lines) in Beaufort sea states 0-6 within the U.S. 
Hawaiian Islands Exclusive Economic Zone (thick black outline) during the Hawaiian Is¬ 
lands Cetacean and Ecosystem Assessment Survey in 2010. Sightings are grouped by detec¬ 
tion function species pool (Table 2): (A) pantropical spotted dolphin, (B) species pool 1, (C) 
species pool 2, (D) species pool 3, (E) species pool 4, (F) species pool 5, (G) species pool 6, 
(H) unidentified rorqual, (I) unidentified dolphin, and (J) unidentified cetacean. The main 
Hawaiian Islands are shown in gray with a thin black outline. 
results and, therefore, was not used in the abundance 
estimation. 
Estimation of abundance 
The mean group size and ESW of the sightings used in 
the estimation of abundance are shown in Table 3 for 
each species and taxonomic category. Mean group sizes 
range from 1.0 to 283.3 individuals and are highest for 
the small delphinids and lowest for the rorquals and 
beaked whales. One exception is the mean group size 
for the 3 sightings of Longman’s beaked whales. At 59.8 
individuals (range: 30.0-100.0 individuals), this mean 
group size is unexpectedly high given the mean group 
