446 



MECHANICAL AND ACOUSTICAL SENSES 



However, various other sensor (transducer) types are available, 

 such as those that vary capacitance, inductance, or voltage output. To use 

 these in the CSULB shark transmitter would require additional circuitry. 

 Other UST circuits have been designed with a particular sensor of this type 

 in mind. Examples are the single-channel depth transmitters described by 

 Luke et al. (1973) and Pincock and Luke (1975), which use strain-gauge 

 (voltage output) pressure sensors. Many strain -gauge pressure transducers are 

 commercially available, some being very small and accurate but possessing 

 the disadvantages of relatively high cost and susceptibility to failure if ex- 

 posed to more than two or three times design pressure. 



Like transmitter circuits, sensors are often designed and built by the re- 

 searchers themselves to fit particular needs. Mackay (1970) discusses 

 methods of sensing various parameters of interest in biomedical telemetry. A 

 review of transducers used for measurement purposes, including principles of 

 operation, physical descriptions, and commercial suppliers, is given by 

 Aronson (1974). 



Application, Tracking, Recovery 



Attachment to Shark— Several methods can be used for fastening the 

 transmitter to the shark (Figure 17). The primary concern is to avoid exces- 

 sive capture and application trauma or long-term irritation, which might 

 affect data validity. The precise effects can only be surmised, but it would 

 seem that gross capture and application trauma would considerably affect a 

 shark's behavior immediately after release but that this effect would dimin- 

 ish with time and eventually disappear. Any irritation caused by the attached 

 transmitter itself, however, probably would persist. 



BACK 



(BARBED DART) 



FIN 

 (PINS OR SUTURES) 



frO 



STOMACH 



(SELF INGESTED 

 IN BAIT) 



BODY CAVITY 



(VIA INCISION) 



Figure 17 Transmitter application methods, external and internal. 

 Application via barbed dart or by self-ingestion is accomplished 

 without capturing the shark. The self-ingestion method is totally 

 atraumatic. 



