SPERM WHALE DIVES TRACKED BY RADIO TAG TELEMETRY

Dives of a 12-m sperm whale ( Physeter catodon Linnaeus, 1758) were tracked in the southeast Caribbean by long range, 30 MHz radio tag with dive-profile telemetry over 4.6 d, 26 April-1 May 1995. Over the 295-km track, average speed was 0.7 m/sec (2.6 km/h). Of 158 dives (defined as submergences longer than 3 min), 65 were shallow (<200 m). The 93 deep dives averaged 990 m (range 420–1,330 m) in depth, and 44.4 min in duration (range 18.2–65.3 min). Water depth was at least 200 m deeper than the whale dive depth. The whale was engaged in activities at or near the surface, shallow dives, and deep dives during 22.6%, 23.4%, and 54% of the time, respectively. Depth and duration of dives were correlated, but there was little relationship between the length or depth of dives with the duration of surfacings either before or after dives. Deep dives occurred day and night. In 44.4% of the deep dives, the vertical movement of descents and ascents was interrupted at intermediate depths, lengthening these dives by an average of 10.8 min. During dives without stops at intermediate depths, descents averaged 11 min at 1.52 m/sec, and ascents averaged 11.8 min at 1.4 m/sec.     

SPERM WHALE SURFACE ACTIVITY FROM TRACKING BY RADIO AND SATELLITE TAGS1

Three 12-m sperm whales (Physeter catodon) were tagged and tracked west of Dominica in the southeast Caribbean to follow the surfacing patterns and movements of these presumed subadult males. Whale N was tagged in April 1993 with a 30-MHz radio tag and tracked for two days. Whale H was tagged in April 1995 with a 30-MHz radio tag and tracked for 4.6 d. Whale A was tagged in April 1995 with a satellite-monitored tag tracked by ARGOS for 21.5 d, the first four of which were concurrent with the tracking of Whale H, an associate. The tagged whales remained west of Dominica for at least 2, 5, and 13 d, respectively. Whales N and A then moved southward to waters off Martinique. There were no apparent effects on the whales by tagging or the presence of the tags. The whales averaged speeds of 2.6-3.5 km/h. Surfacings, indicated by tag signals, were of two types: short surfacings apparently primarily for respiration, averaging 7-10.5 min between repeated longer dives, occurring day and night; and extended surfacings seemingly for rest and social interactions with conspecifics, occurring mostly in daylight. Whales were near the surface for 20.4%–22.6% of the total time (26.6%–27.1% during the day and 14.9%–17.1% at night). Delayed blowing was observed as Whale N surfaced for 8.3 min between 47- and 45-min dives but delayed the first of its 31 blows for 1.5 min after surfacing.