Morphometric and Lipid-Based Measures of Condition for Sunshine Bass Fry

Lochmann, S. and G. Ludwig, Aquaculture and Fisheries Center, University of Arkansas at Pine Bluff, P.O. Box 4912, Pine Bluff, Arkansas 71603 slochmann@uaex.edu

Survival of sunshine bass during fingerling production varies considerably. The variability may be due to food limitation, predation, or other environmental factors. Assessment of condition of fry early in the production run might give an indication of probability of survival. To calibrate a morphometric and a lipid-based measure of condition in fry we reared sunshine bass in 260-L black cylindrical tanks. Stocking rate was 20 fry/L. Fish were fed natural zooplankton ( 65 microns < plankton < 150 microns) daily at a rate of 20 prey items/L. Beginning at age 9 days fry were offered 50% protein microencapsulated feed at a rate of 1g/2.4 h. On the first day of each week for three weeks, twenty fry were videotaped and preserved at –70 C. Approximately 200 fry denied food by placing them in 3.7 L glass jars with gentle aeration. On the second day of each week 15 fry from the cylindrical tank and 15 fry from the glass jar were videotaped and preserved. This was repeated as long as there were fry in the glass jars. Morphometric measurements taken from the video images including total length, head length, head height, eye diameter, body depth at the pectoral fin, body depth at the anus, and gut height. We examined ratios of body measurements previously shown to be useful in assessing condition in striped bass. We were fairly successful in discriminating relatively well-fed fry from food-deprived fry. Fry were processed for lipid analysis using an Iatroscan TLC-FID system. We also used the ratio of triacylglycerols to sterols as a measure of condition. This spring we will collect fry from outdoor ponds to look for a correlation between condition and survival during the 6-week production cycle.

Copyright © 1999
Texas Chapter of the American Fisheries Society
Last modified: 03/03/04 04:15:38 PM