and relates them to the local time (EDT), sunrise and sunset. The optimum PTT 

 initialization time to maximize data recovery was calculated (Figure 7), and resulted in 

 initiating the tlrst transmission sequence of the day at 05:15 (GMT). Because the 

 transmission schedule was fixed at two hours out of every six, the number of possible 

 messages received throughout the day was different from 1989. 



In 1990, the discrete information included the duration of the last dive, number of 

 surfacings between transmissions and the internal temperature of the transmitter 

 (Appendix B). Due to funding limitations, there was no pressure transducer for depth 

 information. The temperature sensor was inside the transmitter and provided only an 

 amorphous average of the animal's recent temperature environment. Nonetheless, deep 

 dives into temperature-stratified water were detected when the PTT reported long dives 

 associated with colder temperatures. Short dives near the surface reported warmer 

 temperatures. Summary information included the number of dives and average duration 

 of all dives during a 6-hour summary period. 



Attachment 



A stainless steel shaft, 6 mm in diameter and 14 cm long was mounted in each 

 endcap. Since clean cuts heal faster than jagged cuts, a double-honed blade was used at 

 the end of each shaft. Two pairs of folding barbs were mounted behind the blade 

 (Figure 8). The cutting action of the blade reduced resistance to penetration allowing 

 application with less power. One pair of barbs was in the plane of the entry blade and 

 one pair was perpendicular. 



Deployment 



PTT performance was optimized when 1) the antenna was vertically oriented, and 

 2) the tag was well out of the water during each whale surfacing. Thus, we attempted to 

 place the tag high on the back, approximately 1 m behind the blowhole. Close 

 approaches were, therefore, required by our small boat to achieve proper antenna 

 orientation and tag location. A modified Barnett 68 kg (150 pound) compound crossbow 

 was used to accurately apply tags at distances up to 15 m. An aluminum shaft with a 

 "C"-shaped tag holder fell away after tagging (Figure 8). Attention was devoted to 

 velocity to avoid excessive impact and bruising by the tag. A bobbin-wound, 9 kg (20 lb) 

 test line was used to recover the pushrod and tag if it missed its mark. 



Ballistic Tests 



Both the 1989 and the 1990 attachment systems were extensively tested on foam 

 targets and gray whale skin and blubber to control accuracy, impact and antenna 

 orientation. The gray whale samples were obtained from fresh carcasses found along the 

 Washington and Oregon coasts. In both cases, testing determined necessary changes to 

 the system and assured that the electronics and batteries would survive the application 

 process. 



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