Vol. 53 - Alaska Resources Library and Information Services

Regression analysis was used to relate carapace size to the maximum
stomach volume. As a measure of carapace size, carapace length was used
for king crab and carapace width for tanner crab.
STOMACH CLEARANCE RATES
Stomach clearance rates for juvenile king crab were determined for
several prey types. To determine how quickly the quantity of contents
naturally-present in the stomach decreased, juvenile king crabs from large
catches in June and August were used. A portion of these large catches
were frozen immediately, and the rest held without food in a live tank at
ambient seawater temperature (8-9 C). During holding in June, the live
tank was periodically siphoned to remove feces and regurgitated shell. In
August, the crabs were held in baskets that separated the crabs from any
regurgitated or defecated material. At selected time intervals after
capture, subsamples of the captive crabs were removed from the live tank
and frozen. Later the volume and dryweight of the gut contents of these
crabs were determined.
The volume of stomach contents was determined by subtracting the
displacement volume of the stomach wall alone, Vs, from that of the
intact, ligatured stomach with its contents, V[subscript] Dividing s the resulting
volume by the maximum stomach volume, V[subscript]max
, and'multiplying by 100, gave
the percentage stomach fullness, F, by volume. Thus,
V[subscript]s
c - s
F = -- 100.
Vmax
For June samples determination of clearance rates by plotting
percentage stomach fullness against time was confounded by the large
volumes of clear liquid that still occurred in stomachs after solid
material disappeared, and to avoid this confounding the dry weight of the
stomach contents and the volume of the solid material alone were
determined. After determining sex, wet weight, and carapace length, of
thawed crabs from August, the stomachs and their contents were transferred
to graduated and tared centrifuge tubes. After 1 h of settling, the total
volume of liquid and solids and the volume of solids alone were recorded.
Settling for 16 h did not change the volume noted after 1 h. After noting
the volumes and the occurrence of sand, floc, soft tissue, or hard parts,
the stomach contents were dried at 60 C to constant weight. The
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