extract was introduced into the pond, with the pump in operation, by 

 slowly siphoning it into the funnel over a 48-minute periods This es- 

 tablished a gradient of attractant from the outlet to beyond the attrac- 

 tion area. Timing, only^ was attempted and this consisted of the time 

 out of 3 minutes spent in the first 1/lOth of the pondp i„eo the area 

 between the seaward gates and the first string i^figo 4), not including 

 the shallows. The results are shown in figure 7, 



ISO 

 160 

 140 



2 '20 



z 



S 100 



(A 



80 



z 



60 



? 40 



20 







CONTROL 



3 LITERS STOCK EXTRACT 

 SIPHONED IN 



TEST PERIODS 



Fig. 7, --Time (seconds) out of successive 3-minute periods in pond experiment 

 No, 112, in which a gradient of stock extract of skipjack flesh was established 

 for 48 minutes. 



31 



