inverse relation to inshore water temperature 

 (Fig. 3). That this change represents a movement 

 of large fish rather than small fish from the flats 

 during summer is strongly supported by 

 numerous conversations with the guides, man- 

 agers, and avid anglers of the Deep Water Cay 

 Club. All of these persons made it clear that the 

 catching of large (>55.5 cm FL) bonefish on the 

 flats, although not common in winter months, is 

 extremely rare in summer. The measurement of 

 55.5 cm FL, used in this paper to distinguish 

 large from small fish, corresponds to the division 

 between the fifth and sixth age-class of bonefish 

 from the Florida Keys (Bruger 1974). 



Discussion 



Information gained from extended ultrasonic 

 tracking of three individuals in two different 

 areas suggests that bonefish display a regular 

 pattern in daily movements in response to tidal 

 changes. These movement patterns, although 

 monitored on individuals, are probably repre- 

 sentative of school movement because trans- 

 mitter-implanted fish generally returned and 

 remained with schools of bonefish (3-20 individ- 

 uals) within 24 h of release. The observed differ- 



ences in daily movements of bonefish in the two 

 different areas may indicate the effects of differ- 

 ences among the two locations in such factors as 

 bottom topography, food resource distribution, 

 and predation. However, this point is in need of 

 further research. 



Information derived from ultrasonic tracking, 

 conventional tagging, and repetitive collecting 

 effort in specific areas indicates that movements 

 of bonefish on a long-term basis are highly 

 variable and without apparent pattern. Ultra- 

 sonic tracking has indicated that individual fish 

 usually remain in a given localized area for less 

 than a week. The two fish tracked for 5 d 

 apparently left the McLean's Town area after 

 that time, since extensive searching on the sixth 

 day, up to 2 km from the area last observed, 

 resulted in no relocation of the fish or the trans- 

 mitter. Subsequent searches of the same area 

 weeks and months later also were unsuccessful. 

 Six other fish equipped with transmitters and 

 released in apparently good condition were never 

 relocated 24 h after release. 



Another strong indication of the transient 

 nature of bonefish movements is the lack of 

 return of conventionally tagged fish, although a 

 concentrated tag and recapture effort was made 



a. 



E 



sample sue ,Tau } A s 

 [no individuals] 34 25 



O 

 18 



N 



19 



'J 

 20 20 20 



25 22 



J 

 25 



A S O N D 



25 24 20 22 21 



O - temperature 

 • - /o individuals 



Summer 1980 



Summer 1981 



Months 



FIGURE 3. — Proportions of large individuals found in monthly collections of bonefish in the waters 

 around Deep Water Cay, Grand Bahama. Each data point represents the percent of individuals col- 

 lected each month exceeding 55.5 cm FL. No collection was obtained in September 1980. Open 

 circles = temperature, solid circles = percent individuals. 



152 



