Vol. 53 - Alaska Resources Library and Information Services

SHIPBOARD OBSERVATIONS OF FEEDING BEHAVIOR
On shipboard the feeding behavior of juvenile king crab was observed
during the clearance rate experiment and later filmed in a large
glass-fronted aquarium with flowing ambient seawater. Special note was
taken of how crabs handled prey items during ingestion.
DIEL FEEDING CHRONOLOGY
In areas of high crab density continuous trawling from 23 to 72 hours
was conducted to collect crabs for determination of diel feeding
chronologies. Generally, two or three trawls took place within 2 h, and
the samples taken within each 2-h period of the 24-h cycle were pooled.
Stomach fullness determined as described above was plotted against
time of day and the plot examined for periods of high fullness. Because
this method proved inadequate due to high volumes of liquid in otherwise
empty stomachs, preserved and frozen stomachs were analyzed as decribed
above to obtain the percentage of maximum stomach volume occupied by
solids and dry weight of stomach contents standardized by the wet weight
of the crab. Plots of these two variables against time of day were
examined for periods of high stomach contents.
DAILY RATION
Using the diel feeding chronologies and equations for the clearance
rates of all items naturally present in the king crab stomachs, daily
rations for June and August were calculated following a modification of
the technique of Elliott and Persson (1978). The diel feeding
chronologies gave the dry weight (mg/g crab wet weight) of stomach
contents for each 2 h period of the 24 h cycle. To determine the amount
of food consumed during each 2-hour interval, the following equation from
Elliott and Persson (1978) was used.
Ct = St - S[subscript]o
+ A
where
t = midpoint of the 2-h interval,
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