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Fishery Bulletin 101(4) 



and treatment FADs were deployed on 24 September 1997. 

 FADs were monitored daily as described above, from 25 

 September through 3 October 1997 (sampling days=9). 

 Data were analyzed for experimental effects on total 

 assemblage size, species diversity (S and HB), number of 

 A. troschelii. number of £. hipinnulata, and total number 

 of fishes minus the number of A. troschelii. 



Recaiit-enriched vs. nonenriched FADs 



I tested the hypothesis that the presence of prior recruits 

 (juvenile sergeant major damsclhsh, Abudefduf troschelii) 

 would have a positive effect on subsequent recruitment to 

 a FAD. I used A. troschelii because these were the most 

 important species associated with FADs by frequency and 

 abundance (Table 1). It is possible that the selection of a 

 particular species as the prior recruit might affect the sub- 

 sequent recruitment of the same or different species (via 

 intra- or interspecific competition for example), but I had 

 no basis for predicting the direction of such effects. 



Given the strong day-to-day changes in assemblage sizes, 

 this test required frequent, short-interval observations of 

 the experimental FADs. I used drifting, rather than an- 

 chored, FADs to provide a more realistic (and conservative) 

 test of the effect. (Drifting objects should result in fewer 

 chance encounters by potential fish recruits carried by cur- 

 rents through a fixed FAD array, but anchored FADs are 

 much easier to track for longer experiments.) I deployed 

 four drifting FADs (constructed from 3 buoys — the "single" 

 size) in the stippled area indicated in Figure 3. Two of 

 these FADs were enriched with nine A. troschelii per FAD, 

 previously collected from anchored FADs and released in 

 close proximity to drifting FADs immediately after deploy- 

 ment. The two control FADs received no sergeant majors 

 to start. Both groups were checked immediately following 

 deployment to verify that the fish had associated with the 

 experimental FADs and to check against quick recruitment 

 to the control FADs. To minimize the potential transfer of 

 fish with the boat, I accelerated sharply when leaving a 

 FAD enriched with sergeant majors and when checking 



