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Volume i (Issue #3), 1993 <br />30 <br />20 <br />c <br />~ 10 <br />0 <br />0 <br />"- 0 <br />c~ <br />~ 30 <br />0 <br />c 20 <br />a~ <br />U <br />10 <br />0~ <br />JANUARY <br />X-RADIOGRAPHY IN FEEDING AND GROWTH STUDIES <br />APRIL <br /> <br />0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 <br />M ('~ (~') C~ C~ M M (~ ('~ C7 ('~ ('~ C7 C'~3 Q7 M C'7 C~ <br />*- ~t 1~ OC")(iDONT-r ~ f~O ChCOONr <br />OO O rT~-r NOO O Or rTrNO <br />Time of day <br />FlGURE 2. Percentage of total daily (24 h) feed intake consumed by hatchery-reared "Hammerfest <br />strain" Arctic chart during successive 3-h periods. Measurements were made at different times of the <br />year under simulated natural daylength conditions. Horizontal bars indicate the light:dark cycle. <br />weight during the course of the experiment, whereas fish restricted to feeding in the <br />water column consumed only sufficient feed to maintain body weight (J~rgensen <br />and jobling, 1990). <br />Vll. INVEST/GATION OF FEED-GROWTH RELAT/ONSH/PS <br />The ~-radiographic method permits repeated estimations of feed intake to be made <br />both on groups of fish and, if tagged fish are used, on known individuals within a <br />rearing group. The inclusion of the estimation of feed intake as a routine procedure <br />in growth experiments provides data required for the detailed examination of the <br />effects of a variety of biotic and abiotic factors on feed-growth relationships and <br />bioenergetics. <br />Repeated measurements of feed intake made on individual fish result in the <br />collection of data relating to both intra- and interindividual variability, and informa- <br />231 <br />JUNE <br />