1058 



Ultrasonic telemetry: Its application to coral 

 reef fisheries research 



Dirk C. Zeller 



School of Marine Biology and Aquaculture 



James Cook University 



Townsvllle, ^1 1, Australia 



E-mail address: DirkZelleraicueduau 



The importance to fisheries re- 

 search of understanding movement 

 patterns of fishes is increasingly 

 being recognized (Hilborn and 

 Walters, 1992 ). Traditionally, mark- 

 recapture studies with external 

 tags constituted the major method 

 of examining movements in fishes 

 (Shepherd, 1988). However, exter- 

 nal tagging techniques are known 

 to have several limitations (re- 

 viewed by Kearney, 1989) that often 

 cannot be addressed adequately. In 

 particular, data obtained through 

 conventional tagging studies are 

 usually limited to knowledge of a 

 single point of capture, point of re- 

 capture, and the straight line dis- 

 tance and time interval between 

 these two events. Such data can be 

 misleading because the exact dis- 

 tance traveled and the patterns of 

 movement are unknown. However, 

 such patterns are of major impor- 

 tance to current research efforts in 

 tropical reef fisheries, including 

 investigations of spawning aggrega- 

 tion events (Samoilys and Squire, 

 1994: Zeller, 1998), and to the assess- 

 ment of movements in relation to 

 marine reserves (e.g. Russ and 

 Alcala, 1996). 



Ultrasonic telemetry is an ideal 

 tool to address questions of move- 

 ment and activity patterns of 

 fishes. It can be used effectively 

 under circumstances that limit the 

 use of more traditional methods, 

 yet its suitability for fisheries re- 

 search is only slowly being realized 

 (Nelson, 1990). Reviews of tele- 

 metry in the aquatic environment 



are provided by Harden-Jones and 

 Arnold ( 1982), Hawkins and Urqu- 

 hart (1983) and Nelson (1990). 



Ultrasonic telemetry has been 

 little used on coral reef fishes (e.g. 

 Holland et al., 1993; Tulevech and 

 Recksiek, 1994); most studies have 

 concentrated on sharks (Nelson, 

 1990). Recent studies, however, 

 have successfully applied the 

 present techniques to the serranid 

 Plectropomus leopardus (Zeller, 

 1997, 1998; Zeller and Russ, 1998), 

 the primary target species of line 

 fisheries on the Great Barrier Reef, 

 Australia (Kailola et al., 1993). 



The aims of this study were the 

 assessment of ultrasonic telemetry 

 in the coral reef environment and 

 the application of the technique to 

 P. leopardus. The first objective was 

 the determination of a suitable 

 transmitter placement technique 

 and anesthetic. The second objec- 

 tive consisted of a field evaluation 

 of ultrasonic telemetry. The final 

 objective comprised tracking trials 

 of P. leopardus. 



Materials and methods 



Study location and ultrasonic 

 telemetry equipment 



The study was conducted during 

 1993 at Lizard Island Research Sta- 

 tion, northern Great Barrier Reef, 

 Australia (lat. 14°40'S; long. 145° 

 28'E). The telemetry equipment 

 consisted of V8-2L transmitters and 

 a VR60 receiver linked to a direc- 



tional 50-80 kHz hydrophone ( Vemco 

 Ltd, Halifax, Canada). 



Evaluation of fish anesthetics and 

 transmitter placement techniques 



Fish (size range: 34.0 cm-52.5 cm 

 fork length [FL]) were caught on 

 hand lines. Aquarium facilities in- 

 cluded 500-, 1000-, and 2000-L tanks 

 with continuous flow-through water 

 supply. Stocking densities did not 

 exceed 2 fish/500 liters. Specimens 

 were retained for an acclimation pe- 

 riod ( 1-3 days), and were not fed for 

 24 hours prior to the experiments. 



The first concern was that of pro- 

 curing a successful, deep anesthe- 

 sia that allowed a gentle recovery 

 in the fish. Three anesthetics were 

 tested: 1) Hypnodil'^'" (Janssen 

 Pharmaceutica, active ingredient: 

 metomidate) was used at a concen- 

 tration of 7 mg/L (Mattson and 

 Riple, 1989); 2) phenoxyethanol 

 was used at a concentration of 0.5 

 nil/L (Mattson and Riple, 1989); and 

 3) MS-222 (tricaine methanesul- 

 fonate) was used at a concentration 

 of 80 mg/L (Thomas and Robertson, 

 1991). 



Three methods were used to at- 

 tach telemetry units to the animals: 

 1) stomach placement (force feed- 

 ing) by means of oral insertion of 

 the transmitter into the stomach 

 (e.g. Holland et al., 1992)— the least 

 intrusive method, neither resulting 

 in external protrusion of the unit, 

 nor requiring surgery; 2) external 

 placement by attaching transmit- 

 ters directly to the dorsal muscula- 

 ture (Holland et al., 1996); and 3) 

 internal placement by inserting 

 transmitters into the body cavity as 

 described by Hart and Summerfelt 

 (1975) and Holland et al. (1993). 

 Surgical implements were disin- 

 fected in ethanol and soaked in 

 Tamodine"", a fish-antiseptic solu- 

 tion (Vetark Professional, Winches- 



Manu.script accepted 13 October 1998. 

 Fish. Bull. 97(41:1058-106.5 ( 1999). 



