SOMERTON and OTTO: DISTRIBUTION AND REPRODUCTION OF GOLDEN KING CRAB 



BIOLOGICAL VARIATION WITH 

 DEPTH AND LATITUDE 



Mean Size 



Size-frequency distributions of golden king crab, 

 based on the combined 1981 and 1982 observer data, 

 are shown by sex, area, and depth strata in Figure 

 2. Linear trends in mean size with depth and latitude 

 were examined statistically using multiple regres- 

 sion. For each sex in each year, when carapace 

 length was regressed against latitude and depth 

 simultaneously, ignoring interaction, both the 

 latitude coefficient and the depth coefficient were 

 negative and highly significant (P < 0.001). Aver- 



aged over both years, mean size decreased by 6.2 

 mm for males and by 4.6 mm for females for each 

 1 degree increase in latitude, and mean size de- 

 creased by 7.9 mm for males and by 6.2 mm for 

 females with each 100 m increase in depth. 



The latitudinal decrease in size probably reflects 

 a latitudinal decrease in growth rate. Two shallow- 

 water Bering Sea crabs, Chionoecetes bairdi and C. 

 opilio, also show a latitudinal decrease in size, and 

 this decrease was correlated with a latitudinal 

 decrease in maximum summer water temperature 

 (Somerton 1981a). Although we lack sufficient tem- 

 perature data from the depths inhabited by golden 

 king crab to allow a statistical test, it is likely that 

 mean annual bottom temperature also decreases 



0.25 -I 



MALES NORTHERN AREA 



.35 FEMALES NORTHERN AREA 



0.00 



25 50 75 100 125 150 175 200 



0.00 



25 50 75 100 125 150 175 200 



0.25 MALES CENTRAL AREA 



0.00 



25 50 75 100 125 150 175 200 

 CARAPACE LENGTH (MM) 



0.35 FEMALES CENTRAL AREA 



0-30 - 

 0.25 - 



< 

 o 



0.20 



o 



I 



UJ 

 CL 



x 0.15- 

 o 



0. 10 



0.05 - 



0.00 



<500 M 

 >500 M 



CARAPACE LENGTH (MM) 



Figure 2.— Size-frequency histograms for males and females of golden king crab, by depth strata and subarea. Due to differences 

 in the sampling intensity with depth (Table 2), frequencies have been standardized to catch per hour of trawling. 



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