Vol. 53 - Alaska Resources Library and Information Services

stomach contents but soft-bodied polychaete worms are the major food of
juvenile king crab.
The results of correction for differential gut residence were
sensitive to the values determined for gut residence time. Note the rise
in the dietary importance of the miscellaneous category of food items in
August (Table 32). An increase in their frequency of occurrence in August
coupled with low gut residence times means a high corrected percentage of
all occurrences. Whereas frequency of occurrence after correction was
high, dietary importance by dry weight was quite low. These results
suggest two alternative explanations. In August a greater number of crabs
could have been consuming a greater number of miscellaneous items but only
in small amounts. Alternatively, the gut residence times for these
miscellaneous items could have been underestimated. More experimental
effort in determining stomach clearance rates for a larger set of
potential prey items would have been desirable.
Less dramatic than changes brought through correction for gut
residence time were changes in relative ranking in the diet after
estimation of soft tissue dry weights from the dry weights of hard parts
in stomachs and soft tissue/hard tissue ratios. Floc increases in the
overall diet from 54% of the dry weight of stomach contents to 91% of the
estimated dry weight of soft tissue (Table 33). Correction for gut
residence time increases floc contribution to 92% of the total corrected
dry weight of soft tissue. Excluding floc, only polychaetes increase in
relative ranking after estimation of soft tissue dry weight but not
dramatically so. It is after correction for gut residence times that
polychaetes come to dominate the dietary composition based on tissue dry
weight.
Comparing the corrected dietary compositions determined by frequency
of occurrence,soft tissue dry weight and caloric intake (columns 3, 6, and
7 in Tables 31 and 32) clearly indicates two things: First, a substantial
proportion of the bulk of the food ingested resides in the floc and,
secondly, soft-bodied polychaete worms are a substantially more important
dietary component than previously supposed. Every stomach examined
contained floc, which constituted 54% of the overall dry weight of stomach
contents. In terms of corrected soft tissue dry weight and caloric
intake, over 90% of the diet of juvenile king crab derives from whatever
prey items contribute to the floc found in the stomachs.
Polychaetes are the dominant prey taxa in the crab diet by frequency
of occurrence, soft tissue dry weight and caloric intake. Except for
echinoderms, dietary composition by soft tissue dry weight parallels
dietary composition by caloric intake. The caloric values of the prey
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