Macy et al : Metabolic rate of Brevoortia tyrannus 



287 



70 

 60 

 50 

 40 

 30 

 20 

 10. 



70. 







60 



50-1 

 40 

 30 



20-1 

 10 

 



10°C 



13.0 cm/s 



ttx. 



1 r 



34.4 cm/s 



ft-n r 



59.8 cm/s 



a ^ 







25 



50 



i. 



75 



100 



15°C 



13.8 an/s 



k. 



1 r 



35.4 cm/s 



1^ 



60.8 cm/s 



25 



r^ 



T 



50 



t- 



75 



— r 

 100 



20°C 



 12.2 cm/s 



2 



qi_ 



1 1 r 



39.5 cm/s 



In. 



T r 



63.2 cm/s 



-f^ 



-r 

 25 50 75 100 



t- 



Swimming speed, cm/s 



Figure 3 



Frequency distribution of swimming speeds within a menhaden school swimming against 

 typical slow, intermediate, and fast flows, at 10", 15". and 20°C. The flow rate inside the 

 flume is indicated m each graph. Open bars indicate fish swimming against the current 

 faster than the flume speed; diagonally hatched bars indicate fish swimming against the 

 current, but slower than the flume; solid bars indicate fish actively swimming down current 

 (i.e. with the current). 



cal limit in the present experiments. Hettler (1976) 

 measured a high oxygen consumption rate of 0.82 

 mg O.ytg wet wt • h) during feeding by juvenile men- 

 haden at 27°C, but the full metabolic scope (Fry, 1957) 

 of menhaden remains unknown. Metabolic scope is 

 related to the surface area of the gills and to the ca- 

 pacity of fish to take up oxygen from the surround- 

 ing medium. The unusually large gill area in men- 



haden (Gray, 1954) suggests that metabolic scope is 

 also large. 



We were unable to determine either maximum or 

 critical swimming speeds for adult menhaden (Brett 

 and Glass, 1973) because sufficiently high currents 

 could not be produced in the flume respirometer 

 Current speeds ranged from 12 to 63 cm/s (0.5 to 2.5 

 BL/s), which spans the reported range of voluntary 



