Davis, M. W.. NOAA/NMFS/AFSC, michael.davis@hmsc.orst.edu
, . W.. ,

 
DOES TURBULENCE ENHANCE FEEDING IN LARVAL AND JUVENILE FISHES: THEORETICAL AND EXPERIMENTAL ARTIFACT OR IS IT REAL?
 
Experimental designs that impose constant levels of turbulence may produce results that do not reflect behavioral capabilities of fishes. Gradients of turbulent water movement originating from surface or bottom water were generated in laboratory tanks. Larval walleye pollock (7-7.5 mm SL) and juvenile walleye pollock (60-70 mm FL) and sablefish (30-100 mm FL) were tested for responses to gradients of light intensity, turbulence and food. Walleye pollock larvae swam to depths with intermediate light intensities and turbulence less than a threshold intensity that inhibited orientation, swimming or feeding. Juvenile walleye pollock and sablefish swam to intermediate depths lacking turbulence and possible effects of surface or bottom turbulence could not be ascertained from mean depth distributions. Shallowest swimming depths showed that 60-70 mm sablefish and walleye pollock avoided surface turbulence, while smaller and larger sablefish swam into turbulent layers while maintaining orientation and swimming ability. All sizes of sablefish swam into bottom turbulence, while walleye pollock avoided it. Sablefish swam downward into food that was resuspended by bottom turbulence, while walleye pollock remained out of turbulence to feed. In our experiments, fish responded to laboratory conditions according to their observed field distributions, suggesting that the results were realistic.
 
Day: Tuesday, Feb. 2
Time: 02:00 - 02:15pm
Location: Hilton of Santa Fe
 
Code: SS01TU0200H