Figure 7 -Fishes associated with drifting objects in the offshore waters of Central America in 1963. A, a school of adult 

 Scclator ocyurus associated with an entire tree; the small fish in background were juvenile Selar cmmenophlhalmus. B an 

 aggregation of adult Canthidermis maculntus in the branches of the same tree; all but three had a dark coloration. C, a 

 group of juvenile Pscnes pacificus. Xaucmks duclor, and other carangids beneath a drifting plank; Psenes are m a dense 

 clump directly below the plank, Xaucrabs can be recognized by the presence of dark vertical bars. D, juvenile Canthi- 

 dermis maculatus, Xaucrates duclor, and various juvenile carangids beneath a drifting log. 



Divers made daily counts of the number of individu- 

 als of each species beneath each of the two logs. The 

 volumes of the two balsa logs calculated from their 

 measurements were 0.021 m.' (log A) and 0.065 m.' 

 (log B). 



Counts of the number of indi\nduals beneath logs 

 A and B were 20 and 96 for the second day and 121 

 and 80 for the third day. By the fourth day it was 

 not possible to make an accurate tabulation because 

 the number of fish under each log was well over 100. 

 On the fifth day 198 individuals were captured under 



log A and 349 under log B. Prior to being moored 

 log B was encountered 27 miles from shore and 236 

 fish representing 8 species were captured at that time. 

 Thus more fish were captured after the log was 

 moored 5 days than were collected when the log was 

 drifting 27 miles from shore. Fewer species were 

 represented, however. The larger number of indi- 

 viduals captured beneath log B may reflect the 

 difference in volume of the logs. 



Although logs A and B were moored only 100 m. 

 apart, their associated fish populations differed in 



rLOTS.\M IN' OFFSHORE WATERS 



21 



