738 



Fishery Bulletin 88(4), 1990 



T3 

 (0 



I 



cc 1 



^H NO INJURY 



HH BODY ONLY 



cm LEGS ONLY 



^ BODY a LEGS 



1004 



2276 



27 367 24 



KING CRABS 



TANNER CRABS 



Figure 7 



Effects of body and leg injuries on immediate survival odds (ratio 

 of number surviving to number of deaths) of king and Tanner crabs. 

 Sample size indicated above bars. Only injury-assessed crabs were 

 used. 



only six tows with tliis gear type, three of which had 

 large sampling factors and mostly dead Tanner crabs. 

 Delayed mortality was not compared between nets due 

 to limited data. 



Effects of injuries 



A weighted number of 3368 king crabs and 1421 Tan- 

 ner crabs were assessed for injuries. Figure 7 shows 

 the survival odds (ratio of number alive to number 

 dead) within each of four combinations of injury types: 

 (1) none, (2) legs only, (3) body only, and (4) legs and 

 body, calculated only for injury-assessed crabs. The ma- 

 jority of crabs suffered no detectable injuries, and had 

 the best survival odds of 1.8 for king crabs and 4.2 for 

 Tanner crabs. The most common type of injury for all 

 crabs was leg injuries, which resulted in survival odds 

 of 1.14 and 0.63 for king and Tanner crabs, respective- 

 ly. Injuries to the body and combined body and leg in- 

 juries were less frequent, resulting in survival odds of 

 0.98 and 0.44, respectively, for king crabs, and 0.59 

 and 0.71 for Tanner crabs. Body injuries were more 

 frequent but less serious among king crabs than Tan- 

 ner crabs and were predominantly broken spines, which 

 are more abundant and prominent on king crabs and 

 thus more likely to be damaged. Body injuries of Tan- 



