440 



Fishery Bulletin 103(2) 



50 



45 

 25 



20 



15 



10 



5 







- 75 



Clupeidae 



]• 



Synodontidae 



• • • . " » 



90- 



80. 

 50 



40 



30 - 



20 



10 

 



Engraulidae 



• • • • 



25 n 

 20 

 15 

 10 



5 







Scombridae 



*%•_-. 1* 



*^- 



+■ 



-T- 



10 20 30 40 50 60 70 80 90 10 20 30 40 50 60 70 80 90 



Mean water current speed (cm/sec) 



Figure 2 



Mean CPUE per sampling set (from within- and off-platform light traps) in relation to the mean cur- 

 rent speed per sampling set for each of the dominant families collected. Data from all platforms were 

 combined. Note changes in the scale of the .y-axis. 



CPUEs were mostly <5 fish per 10 min at these speeds. 

 There was a significant linear relationship between log- 

 transformed mean total CPUE data and mean current 

 speed (log 10 (y+l) = -0.013.T + 1.302, r 2 =0.23; F=49.61, 

 P<0.0001). 



Each of the dominant families collected by light traps 

 showed a similar pattern of highest mean CPUEs at 

 current speeds <30 cm/sec and relatively low mean 

 CPUEs at higher current speeds (Fig. 2). Clupeidae, 

 Engraulidae, and Blenniidae showed a slight trend of 

 highest CPUEs at intermediate current speeds (10-30 

 cm/sec), whereas the other families generally had high- 

 est CPUEs at the lowest speeds (<10 cm/sec). Synodon- 

 tidae and Blenniidae were rarely collected at current 

 speeds >40 cm/sec, and small numbers of Clupeidae, 



Engraulidae, Carangidae, and Scombridae were col- 

 lected at speeds up to 80 cm/sec. 



As current speeds increased, light trap collections 

 became limited to smaller size classes offish (Fig. 3). 

 For the first three current intervals, i.e., 0-9, 10-19, 

 and 20-29 cm/sec, a broad range of sizes were collected 

 and the distributions had median lengths of 15-19 

 mm. However, beginning at the fourth current interval, 

 30-39 cm/sec, the size distributions shifted toward an 

 increasingly greater proportion of the catch <10 mm 

 in length. This trend was most pronounced at the two 

 highest current intervals, 40-49 and >49 cm/sec, both 

 of which had distributions with median lengths of 5 

 mm. The size distributions from the two highest cur- 

 rent intervals were the only distributions that were not 



