Vital Activity Parameters as Related to the Early Life History of Larval and Post-Larval Lake Whitefish (Coregonus clupeaformis)

Abstract

Larval lake whitefish hatched in nature were transported to constant environmental conditions and experimented on over fish sizes of 12.6 to 24.9 mm. Swimming speed whiel feeding on live plankton was 1.5 cm/sec and did not increase proportional to size. Sustained swimming ability increased from 3.7 to 11.4 cm/sec and maximum short distance speed increased from 6.7 to 22.6 cm/sec proportionally with size. Body lengths per second averaged 3.7 times the body length. Young whitefish were non-schooling and fed independently at an effective feeding rate of 37.8% of all encounters with copepods. Feeding cased during absolute darkness. Food intake and activity was continuous, enabling larvae to search between 8.1 h and 14.5 1/h. Temperature preference was 12-17 C when acclimation temperatures were 6, 11, and 14.5 C. Avoidance temperatures were 20-23C with heat narcosis and death above 24 C. Temperature preference did not change with size. Light gradients from 2475-1 lux had no concentrating effects except on the smallest sizes. Vertical distributions in the laboratory were epilagic. (See also W77-04524) (Chilton-ORNL)