56 



FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



SOURCES OF DATA 



Each summer since 1955, a commercial fishing 

 vessel has been chartered to otter trawl for samples 

 at predesignated stations 20 miles apart. The sta- 

 tions sampled by year are represented in figure 2. 



The gear used each year was similar to that de- 

 scribed by Greenwood ( 1958) . This trawl is com- 

 monly called a "400 eastern type." 



At each station all crabs caught were measured 

 to the nearest millimeter, shell conditions were 

 noted, and males were tagged and released. Two 

 measurements were taken. Length of carapace 

 was measured from the posterior margin of the 

 orbit of the right eye to the midpoint of the pos- 

 terior margin of the carapace. Greatest width of 

 the carapace between spines was also measured as 

 a check on accuracy of length measurement since 

 a definite relationship exists between length and 

 width. 



We recorded four shell conditions, soft, new, 

 old, and very old, which are subjective classifica- 

 tions of the lengtJi of time since molt. The prin- 

 cipal basis of classification are scratches and dis- 

 colorations of the ventral basal segments of the 

 appendages. A soft exoskeleton is indicative of a 

 crab which has just molted, since after approxi- 

 mately 1 week the shell becomes firm and resists 

 Hexing. New-shell crabs have hard exoskeletons, 

 the ventral surfaces of which are white and un- 

 scratched, and are presumed to have molted dur- 

 ing the winter or spring immediately preceding 

 the sampling period. Crabs with yellowish ven- 

 tral exoskeletons and multiple darkly stained 

 scratches are classified as old-shells and are judged 

 not to have molted for one or more years. The 

 very-old-shell condition is an extension of the old- 

 shell and is characterized by an almost black ven- 

 tral exoskeleton and dense growth of fouling or- 

 ganisms. The time since last molting is not well 



BERING SEA 



Q-O— 



ji. 



ML 



PACIFIC OCEAN 



1955 - 1956 



BERING SEA 



BERING SEA 



• •••• •••• 



(A- 



PACIFIC OCEAN 



..IfL 



1958 1959 



Figure 2. — King crab sampling stations for the years 1955 tlirough 1959. 



