Gray Whale Relocation Records 



Enlargement 

 Of ThiB Area 



Figure 7. — Map of California coastline showing 

 (Gigl) 13 March-5 May 1972. 



conducted following the release of the 

 whale using a similar data transmitter 

 with one-third the power of the system 

 used on the test animal and a modified 

 antenna have yielded data acquisition 

 ranges up to 40 nautical miles. 



RESULTS 



During the initial 2 hours after re- 

 lease of the test animal, signals were 

 very intermittent and seldom longer 

 than 2 seconds in duration. Ohserva- 

 tions lead us to believe this was a 

 behavioral problem since the animal 

 frequently broke the surface of the 

 water showing onl\ her blow hole and 

 mid-portion of her back as illustrated 

 in Figure 6. Since the data transmitter 

 was mounted on the dorsal ridge (on 

 the last half of the body) the antenna 

 either did not break the surface of the 

 water, thus no transmission, or only 

 the tip of the antenna broke the sur- 

 face, resulting in a very short duration 

 transmission. 



locations o( the Sea World yearling gray whale 



This resulted in limited data recep- 

 tion during the first 2 hours after re- 

 lease and subsequent loss of the ani- 

 mal's location and movement pattern. 

 Those signals over 2 seconds in dura- 

 tion that were received during this 

 time period did indicate temperature- 

 at-depth values reasonable for the lo- 

 cation and time of year (e.g.. above 

 20 meters temperatures of 13°-I4°C 

 and below 20 meters a temperature 

 of 7.4C'). A 20-meter isothermal layer 

 is not uncommon at this location. 

 Since the quality of radio signal ac- 

 quisition was quite poor, the search 

 from the RV Cupc was abandoned in 

 favor of an aerial search. The animal 

 was relocated on i.^i March between 

 1300 and 1500 hours on a bearing of 

 320°T south of Oceanside. The animal 

 was relocated again on 16 March 

 close inshore off San C'lemente. Calif., 

 working slowly north. The photograph 

 shown in Figure 6 was taken at this 

 time. On this flight and those that 

 followed, although the animal could 



be easily located, acquisition of use- 

 able temperature-at-depth data was 

 limited I) by the long time interval 

 between adequate exposure of the an- 

 tenna, and 2) by the apparent short 

 range of the transmissions received. 

 Areas of visual relocation and radio 

 contact from 16 March 1972 to 5 May 

 1972. are illustrated in Figure 7. 



After a period of 5 to 6 days, the 

 animal's swimming pattern changed 

 and longer and more frequent trans- 

 missions were being received. In order 

 to verify these observations and. if 

 possible, to collect temperature-at- 

 depth data over a 24-hour period, the 

 RV Ciipc left San Diego at approxi- 

 mately 1600 hours on 20 March 1972 

 for the Dana Point-San Clemente, 

 Calif, area. At IS4() hours. 3.'^ nautical 

 miles from San Clemente. Calif., we 

 acquired weak signals from the animal 

 bearing 340°T. At 2300 hours, signal 

 level had increased and we were re- 

 ceiving bearing and temperature-at- 

 depth data. Initial data indicated tem- 

 peratures of 12°-I4°C at depths of 

 l.'^-20 meters. At 2350 hours the 

 animals diving behavior changed and 

 indicated some dives to depths of 170 

 meters. Triangulation placed the ani- 

 mal at a location approximately on the 

 100 fathom curve. 1.7 nautical miles 

 off Laguna Beach. Calif. (Aliso Can- 

 yon). Although the depths recorded 

 at this location were realistic if the 

 animal was diving to the bottom, the 

 water temperatures at those depths 

 appeared to be anomalous. At this 



HktlMUM DOWH TIME - 16 m 



Figure 8. — Mean down times and depths of dive 

 as a function ol time of day recorded 20-21 

 IVIarch 1972. 



56 



