BAILEY ET AL.: ZOOPLANKTON ABUNDANCE AND FEEDING HABITS OF FRY 

 Table 5.-Continued. 



Stomach Evacuation 



The time required for satiated fry in the 

 aquarium to evacuate food in their stomachs was 

 inversely related to temperature. In tests at 

 12.8°C, the stomachs of two of five pink salmon 

 were empty after 2 h without food. However, 6 h 

 elapsed before successive samples of five fish con- 

 tained no food, and 6 h was therefore accepted as 

 the time required for pink salmon to evacuate 

 their stomachs at a temperature of 12.8°C (Table 

 6). For chum salmon, the first empty stomach was 

 observed after 1 h without food at 12.8°C. Only 

 after 10 h did successive samples of five chum salm- 

 on have empty stomachs. This longer evacuation 

 time for chum salmon probably resulted from the 

 larger and different kinds of organisms eaten. 

 Using the same criterion for time of evacuation as 

 described above for 12.8°C, pink salmon fry 



Table 6.— Time required for pink and chum salmon fry to 

 evacuate food from their stomachs at various temperatures. 



Temperature 

 (°C) 



Pink salmon 

 (hours) 



Chum salmon 

 (hours) 



8.5 

 10.0 

 12.8 



16 

 9 

 6 



10 



confined without food had empty stomachs after 9 

 h at 10°C and after 16 h at 8.5°C. We did not test 

 chum salmon at the lower temperatures. 



ZOOPLANKTON ABUNDANCE AND 

 DISTRIBUTION 



The abundance of zooplankton in the near-sur- 

 face waters was determined from the samples we 

 collected in the inner and outer bays of Traitors 



853 



