The sutures and "tynes" previously used for smaller tags appeared to be 

 inadequate during blubber tests for the larger sized satellite-monitored tags. Thus, we 

 considered alternatives such as: 1) sutures which had spiral shapes or formed large arcs 

 to increase their surface area; 2) temple toggles (traditional-type harpoon heads) and 

 folding barbs; and 3) devices which penetrated and then expanded, such as "molley bolts" 

 and "catheters." 



Eight prototypic designs for subdermal attachment of surface-mounted tags were 

 considered. Each was developed in concert with appropriate delivery systems (Task "C"). 

 The question of power to deliver and deploy tags was one of the most serious. A 1982 

 tag design for humpback whales (Mate, 1983) utilized a Holex pressure cartridge to 

 hydraulically push stainless steel needles through curved forming fixtures. Similar designs 

 which required bending materials were avoided because of the need for high power 

 sources. We preferred pre-formed attachments, such as the modifications to the original 

 barnacle tag design (Mate, et al., 1983) made by K. Frost (pers. comm.) for application 

 to beluga whales. This design used pre-curved sutures which locked into place upon 

 deployment. We experimented with three versions of these sutures, including some with 

 fixed or folding barbs, to increase their surface area and resist outward migration. 



The relatively large size of the tag resulted in significant hydrodynamic drag and 

 exposed the tag to additional risk from rubbing on the bottom or against other animals. 

 Thus, we felt a substantial subdermal anchoring system was required and settled on a 

 spring-actuated system which deployed two curved stainless steel sutures to a depth of 10 

 cm - 12 cm. Ultimately, a Hat piece of stainless steel 3 mm thick and 1.8 cm wide was 

 added to the upper surface of the curved suture to increase the surface area and 

 additionally resist the outward migration of the suture through what appeared to be very 

 soft blubber. A spring (0.6 cm in diameter) was wound around the transmitter housing 

 with a suture attached to each end (Figures 3a and 3b). The cylinder was mounted to a 

 square base-plate with a foam rubber pad beneath it to protect the animal from abrasion. 

 A "trigger" button in the center of the base was used to trigger the attachment when the 

 base rested on a flat surface. The trigger released the energy of the coiled spring and 

 installed the subdermal sutures in the skin and blubber. The tag was designed to be 

 deployed either in a two stage process using a projectile dart and deployment vehicle, or 

 from the end of a 5.2 m pole (as a backup system). 



Deployment 



The primary deployment system used a dart fired from a crossbow (Figure 4). A 

 trailing line went through a pulley on the dart. One end of the line was attached to the 

 crossbow, while the other end was attached to a "tag deployment vehicle." The 

 deployment vehicle consisted of two 20 cm-diameter plastic net floats which had 

 sufficient flotation for recovery of the tag if the line broke. Pulling the line drew the tag 

 deployment vehicle to the dart on the whale. The tag could not attach until it reached 

 the dart which "armed" the tag's trigger. The tag attached only when the tag was at the 

 dart and the tag was tlat enough on the whale's back to depress the trigger. Once the 



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