Goebel et al.: Diving patterns and foraging locations of female Callorhinus ursmus 



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T 



Figure 2 



Three-dimensional plots of diving records for nine female northern fur seals at St. Paul Island, Alaska, in July and August 1985. Each 

 plot represents the diving record (all dives >20m in depth) of one trip to sea for each female. 



in water 140 m to 1400 m deep. On the day she was 

 located, as well as on most days of her trip, she ex- 

 hibited the deep-diving pattern. For a 24-hour period 

 from 1200 on 4 August until 1200 on 5 August she 

 made 70 dives (50% during the day) with a mean depth 

 of 94.2m (SD 18.5). 



Two females (651 and 767) were located only once, 

 on their return to St. Paul from a foraging trip (Fig. 

 1, Table 1). Female 651 was located 2.5 hours before 

 she returned ashore and after she had completed 99% 

 of her foraging trip. Her last dive was 6.9 hours before 

 being located. Female 767 was located 8.2 hours before 

 she returned ashore and 2.5 hours after her last dive. 



Female 695 was located on three separate days, each 

 time she was 110-160km northwest of St. Paul Island, 

 diving to depths greater than 100 m over the continen- 

 tal shelf in water 1 10-140 m deep. This female ex- 

 hibited the deep-diving pattern every day of her 10-day 

 trip, but also made seven dive bouts which had mean 

 dive depths of less than 75 m, five of which occurred 

 during the night. 



Female 214 was located on the fifth day of a 12-day 

 feeding trip in approximately 3500 m of water. On that 

 day, as well as most other days, she exhibited the 

 shallow diving pattern and dived primarily at night 

 (Fig. 3). 



Female 713 was also located on three consecutive 

 days. She exhibited a foraging pattern of deep diving, 

 day and night, on the first and last days of a foraging 

 trip and shallow diving at night on other days. She was 

 located on 25 July, the fifth day of a 7-day trip, 80km 

 south of St. Paul Island at the continental shelf break 

 in approximately 200 m of water. On that day she dived 

 exclusively at night with a mean depth of dive of 46.7 m 

 (SD 17.1, n 171). This was the night following her loca- 

 tion at the shelf break. On the sixth day and on the last 

 day of her trip she was located over the shelf and dived 

 both during the day and night to much greater depths 

 (mean depth of dive 101.3m, SD 26.9, n 67 for the sixth 

 day, and 103.5m, SD 11.0, n 11 for the last day). 



Female 854 was located on the first day of a 4-day 

 trip over the continental shelf but within 18 km of the 

 200-m depth contour. From the time she left shore 

 (2208) until she was located 20.8 hours later she had 

 made 22 dives— all but three were greater than 75 m 

 (x 75.6, SD 7.6). Of these dives, 77% were made be- 

 fore dawn. Her second night at sea was spent actively 

 diving to depths of less than 35 m (n 70, x 22.8, SD 

 19.6). She began diving at 2353 and dived continuous- 

 ly until 0340. This female was in transit across the con- 

 tinental shelf during the night, making occasional dives 



