The short-term (daily) movements of bonefish 

 were monitored by an ultrasonic tracking sys- 

 tem. Fish were captured by angling and gill nets. 

 Bonefish were only minimally injured by the 

 netting procedure, since the mesh size of 6.25 cm 

 was chosen to restrain the fish without injury to 

 the gills. Captured fish were removed by hand 

 from the gill net and were held in a hand net for 

 further treatment. Individuals, selected accord- 

 ing to size (>2 kg) and physical condition, were 

 equipped with ultrasonic transmitters. In track- 

 ing studies prior to 1981, the transmitter was 

 placed in the stomach with a glass plunger 

 (Henderson et al. 1966; Yuen 1970). During 1980, 

 this technique often resulted, 3 out of 5 times, in 

 disgorgement of the transmitter. Therefore, 

 surgical implantation of the transmitter in the 

 body cavity was used during 1981. Here, the fish 

 was restrained ventral side up. Several scales 

 were removed posterior to the pelvic fins and 

 lateral to the midline, and an incision of 3-4 cm 

 was made with a surgical scalpel. The trans- 

 mitter was then inserted, and the incision 

 sutured. This procedure is similar to that used by 

 Hart and Summerfelt (1975). To aid in recovery, 

 the fish was slowly worked forward and back in 

 the water by hand to aerate the gills. The 

 majority of the fish appeared to survive the 

 implant and recovered without noticeable effect, 

 provided predators of the bonefish were not in 

 the immediate vicinity at time of release. Several 

 individuals held in a saltwater holding tank for 

 periods of 24-96 h showed no noticeable ill 

 effects. Conclusions drawn from the observed 

 movements of fish immediately after release are 

 of questionable value, since behavior and 

 movements may be strongly influenced by the 

 process of capture and handling. Thus, only 

 tracks initiated 24 h or more after release were 

 considered to reflect normal behavior. 



The transmitters were 58 mm long and 15 mm 

 in diameter, weighed 3-4 g in water, and oper- 

 ated at a frequency range of 74-77 kHz. They 

 were manufactured by either Smith Root Inc. or 

 Sonotronics, 2 and were pulsed at different inter- 

 vals (1-2 pulses/s), so that individual fish could be 

 distinguished when several transmitters were 

 operating in the same general area. Power for 

 the pulse intervals was supplied by mercury 

 batteries with a useful life of about 7-14 mo. 



Reference to trade names does not imply endorsement by 

 the National Marine Fisheries Service, NOAA. 



Range was as wide as 0.5 km at times, but much 

 narrower when the water was turbulent. 



A Smith Root TA-50 and a Sonotronics digital 

 (pulse/frequency display) receiver, with their 

 respective hydrophones, were used to receive the 

 signals. All tracking was conducted from a 4.5 m 

 skiff equipped with two foot-controlled variable- 

 speed electric motors. The hydrophones were 

 mounted off the bow about 0.5 m below the sur- 

 face, allowing the direction of a transmitting fish 

 to be ascertained by pointing the bow in the di- 

 rection of the strongest signal. Data recorded 

 during tracking included location, water depth 

 and temperature, tide state, time, and wind 

 speed and direction. This information was gen- 

 erally recorded at about 30-min intervals, but 

 more frequently when a tracked fish was moving 

 rapidly. Location was accurately recorded on 

 Bahamian land survey maps by using chartered 

 landmarks in conjunction with depth. 



To investigate long-term movements, a con- 

 ventional tag and release program was initiated 

 in February 1980. At the outset, Monel metal 

 strap tags were crimped into the lower jaw. This 

 method was replaced (January 1981) by the use 

 of dart tags (FD 68B PVC) inserted adjacent to 

 the dorsal fin, a procedure requiring less time 

 and handlingof the fish. These tags were of much 

 heavier construction than those used by Bruger 

 (1974). Tagging was concentrated in areas 

 frequently fished and/or areas in which schools 

 of bonefish were consistently seen. 



Monthly collections of 20-30 bonefish were 

 obtained from the study areas by nets and 

 angling from June 1980 through December 

 1981, except September 1980. These data pro- 

 vided information on size distribution of cap- 

 tured individuals over the yearly cycle. Collec- 

 tions were obtained each month from the same 

 general areas (indicated in Fig. 1). 



Results 



Between August 1980 and November 1981, 13 

 bonefish were implanted with ultrasonic trans- 

 mitters and released. Of these, only three fish 

 were relocated more than 24 h from time of re- 

 lease. Two of these fish, from McLean's Town 

 Creek (50.5 and 53.5 cm FL (fork length)), were 

 tracked for a period of 5 d each, with total track- 

 ing times of 16 and 30 h, respectively. The fish 

 from Big Creek Lake (61.0 cm FL) was followed 

 over a 100-d period for a total tracking time of 32 

 h (Fig. 2). Water depths in these areas ranged 



150 



