AU and PERRYMAN: DOLPHIN HABITATS 



or 25 X 150 mm Fuji binoculars, mounted both port 

 and starboard either on or above the flying bridge 

 The sighting distance to the horizon was about 7.0 

 and 5.5 nmi for the David Starr Jordan and Town- 

 send Cromwell respectively. Both ships cruised at 

 about 10 kn (18.5 km/h). The cetacean search-day 

 generally started at 0600 and ended 1800, with two 

 teams, or watches, alternating. In 1976 and 1977 the 

 watches were each 2 or 3 h long, depending on the 

 ship. In 1979 and 1980 they were all standardized 

 to 3 h. There were two experienced persons on each 

 watch, who alternated each hour between the port 

 and starboard binoculars. A third person sometimes 

 helped in record keeping, obtaining supplementary 

 data, and temporarily relieving the other watch 

 members. The peripheral data collected included 

 bathythermograms, surface temperature and salin- 

 ity, weather observations, sighting condition 

 measurements, sighting effort, and observations on 

 fish and birds. 



When a cetacean school was sighted, its angle 

 relative to the ship's heading was measured and its 

 distance from the ship estimated. The ship then ap- 

 proached the school for closer observation. School 



size was estimated and the species identified. 



The reader is cautioned that the distributions to 

 be described are based upon relatively few sightings 

 of schools (Tkble 1) and that they pertain to the 

 January-March season specifically. Though the pat- 

 tern of sampling was widespread, the actual area 

 surveyed was a very small fraction of the huge area 



Table 1.— Summary of school sizes for spotted, spin- 

 ner, striped, and common doipfiins from the January- 

 March research cruises of 1976, 1977, 1979, and 1980. 



'Standard deviation factor for the geometric mean. 



zjotal spotted dolphin schools is 157 + 79 = 236. 



^Total spinner dolphin schools is 44 + 79 = 123. 



"Additionally, there were 838 school sightings of unidentified 

 and other species of dolphins (Delphinidae) and 543 school 

 sightings of whales (Balaenopteridae, Ziphiidae, and 

 Physeteridae). 



170 

 30' 



70" 

 30" 



Hawaiian Islands 



JANUARY-MARCH R/V CRUISE TRACKS 

 FOR 1976, 1977, 1979, 1980 



Christinas Island * 



30' 

 170 



J 



Figure 2.— Cruise tracks of the January-March cruises by RV David Starr Jordan and RV Townsend Cromwell. These cruises took place 



in 1976, 1977, 1979, and 1980. 



625 



