1064 



Fishery Bulletin 97(4), 1999 



and should be selected for longer term studies, espe- 

 cially for bottom-associated reef fishes. Wound clo- 

 sure was observed within 14-21 days, and subse- 

 quent research (Zeller, 1997, 1998) illustrated that 

 secondary infections were reduced with the use of a 

 broad-spectrum bacteriacide (Myxazin'", Waterlife 

 Research Industries, Longford, UK) and oral antibi- 

 otic ( tertcacycline ). After the initial occurrence of gas- 

 bubble-trauma (Weitkamp and Katz, 1980), the 

 aquarium water was filtered through gravel prior to 

 use. No further incidents of gas-bubble-trauma oc- 

 curred (Zeller, 1997, 1998). 



Releasing the experimental tracking specimens 

 immediately after intrusive surgery meant releas- 

 ing an injured fish that became a prime target for 

 reef fish predators. All subsequent tracking speci- 

 mens were retained for a recovery period in aquaria 

 until the implant incision was healed (2-3 weeks). 

 This procedure proved to be successful during sub- 

 sequent studies and no further fatalities due to pre- 

 dation were observed (Zeller, 1997, 1998). 



This study demonstrated clearly that external at- 

 tachment of transmitters is not a viable option for P. 

 leopardus because fish are disturbed by the external 

 package and attempt to dislodge the devices. How- 

 ever, a study on a reef-associated carangid, a species 

 with a more pelagic lifestyle, reported successful use 

 of external transmitters (Holland et al., 1996). This 

 finding illustrates the necessity of evaluating trans- 

 mitter placement techniques in relation to species 

 and species-specific habits. 



Force feeding was demonstrated to be of use with 

 P. leopardus only for short-term duration not exceed- 

 ing a few days. Even the longest retention time re- 

 corded (216 hours) was considered unsatisfactory for 

 longer term tracking studies (Zeller, 1997, 1998). 



Tricaine methanesulfonate (MS-222) was the best 

 anesthetic because it induced a successful loss of sen- 

 sation and a gentle recovery, with the potential ad- 

 ditional benefit of improved recovery from physical 

 trauma because it elevated levels of the corticoster- 

 oid hormone (Thomas and Robertson, 1991 ). Further- 

 more, unlike with phenoxyethanol, Losey and Hugie 

 (1994) did not observe any negative effects with MS- 

 222 in regard to the olfactory sense. The present find- 

 ings suggest that MS-222 represents the most suitable 

 anesthetic for the surgical placement of transmitters. 



Ultrasonic tracking of coral reef fishes 



The following considerations' will improve position 

 estimation for tracking studies on coral reefs, and 

 have been applied successfully (Zeller, 1997, 1998; 

 Zeller and Russ, 1998): manual tracking with visual 

 triangulation should be conducted by taking bear- 



ings at approximately right angles (90°) to each other 

 and with approximate distances of 50-75 m between 

 vessel and transmitter. Bearings taken at angles less 

 than 90°, or taken at sharp angles to the prevailing 

 wind, should be avoided. These considerations will 

 result in minimal directional bias of bearings and 

 ensure maximum accuracy and precision of esti- 

 mates. If uncertainty about location or directional- 

 ity of signal exists, it is suggested that "ground-zero 

 tracking" (Nelson, 1990) be used to verify exact loca- 

 tion of tracking specimen. 



Acknowledgments 



I would like to thank G. Russ and the anonymous 

 referees for criticisms of the manuscript. This study 

 was funded by the Lizard Island Reef Research Foun- 

 dation. Logistic support was provided by the School 

 of Marine Biology and Aquaculture, James Cook 

 University. This is a contribution from the Lizard 

 Island Research Station, a facility of the Australian 

 Museum. 



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