HAWKES ET AL.: RHIZOCEPHALAN PARASITISM OF ALASKA KING CRAB 



Blue King Crab 



Glacier Bay and Lynn Canal blue king crab data 

 were pooled. The populations were considered to be 

 identical because the two groups were regarded as 

 having the same linear relationship (ANCOVA). 

 Smaller crabs (<134 mm in carapace length) not 

 common to data sets from both areas and skipmolts 

 were eliminated from this analysis. 



Significantly (chi-square test) more skipmolts were 

 found among the nonparasitized crabs (45/237) than 

 the parasitized crabs (9/131). Because skipmolts tend 

 to be heavier than new shell crabs (Somerton and 

 Macintosh 1983), skipmolting was analyzed as a 

 possible source of bias. In male blue king crabs the 

 new shell crabs had a higher mean weight than the 

 skipmolts at greater carapace lengths, while the 

 skipmolts had a higher mean weight at the smaller 

 lengths (Fig. 2). Although individual linear relation- 

 ships did not describe the data as well as a common 

 line, the skipmolts were eliminated from further 

 analyses of both blue and golden king crab data. 



Subsequently, in the length-weight relationships of 

 male blue king crabs pooled from both areas, with 

 small crabs represented in each group, the nonpara- 

 sitized crabs were heavier at a highly significant level 

 than the parasitized crabs (ANCOVA) (Fig. 3). Non- 



parasitized males were 8.7% heavier than parasitized 

 crabs. Nonparasitized male blue king crabs also had 

 a significantly (£-test) higher condition factor (8.5 ± 

 0.8) than parasitized crabs (7.2 + 0.6), indicating that 

 nonparasitized crabs were heavier for a given length. 

 Condition factor did not vary with size in non- 

 parasitized blue king crabs but the slope was sig- 

 nificant and negative for the parasitized crabs. This 

 indicates that the condition factor of parasitized blue 

 king crabs decreased with increased size 



Only five nonparasitized female blue king crabs 

 were available for length-weight relationships and 

 condition factor comparisons. More samples are 

 needed for further analysis of female blue king crabs. 



Golden King Crabs 



Males with carapace lengths common to both para- 

 sitized and nonparasitized crabs, 117 to 159 mm, pro- 

 vided linear relationships that were parallel and 

 significantly different (Fig. 4). Briarosaccus callosus 

 was not present in any of the large commercial-size 

 crabs sampled in 1983; therefore, these samples were 

 excluded from analysis. The percent weight dif- 

 ference between parasitized and nonparasitized male 

 golden king crabs was about 2.6%. Weight conver- 

 sion in parasitized male P. platypus of similar sizes 



4000- 

 3500 



O) 3000 



O) 2500 

 2000 J 



Old Shell 



log n Y = -5.04 + 2.60loghX 

 r*=0.70 



New Shell 



log n Y=-6.54 +2.89log n X 

 H =0.68 



n i 181 





130 



135 



140 



^45 150 15JF 



Length (mm) 



160 



Figure 2— Length-weight linear relationships of new shell and skipmolt nonparasitized male 



Paralithodes platypus. 



329 



