autotomies occurred by chance alone, our data 

 could be similarly interpreted to suggest that 

 Dungeness crabs with injured appendages 

 showed little decrease in pot-entering ability and 

 that our estimate of injury was accurate. For this 

 interpretation of the chi-square results to be 

 valid, one must assume that all injuries occurred 

 before the crabs entered pots and that injury did 

 not occur within the pots. 



Appendage injury in Dungeness crabs was bi- 

 laterally symmetrical except for the 3d walking 

 leg. Interestingly, Easton (1972) demonstrated 

 that 3d walking legs of Hemigrapsus oregonensis 

 were the most easily autotomized. In other stud- 

 ies, both bilateral symmetry and asymmetry have 

 been reported for different species of crabs 

 (Durkin et al. 1984; Needham 1953). Asymmetri- 

 cal appendage loss has been associated with crabs 

 that move predominantly in one direction, while 

 symmetrical leg loss occurs in crabs that move 

 randomly (Needham 1953). 



The chelipeds, followed by the 1st and 4th 

 walking legs, were most vulnerable to injury. 

 Limb loss has been correlated in other studies 

 with degree of exposure of the limb; the outermost 

 limbs, the longest limbs and limbs with postures 

 that afford little protection are most frequently 

 lost (Needham 1953). Anterior limbs are lost 

 more frequently than posterior limbs (Needham 

 1953). The chelipeds are the most anterior and 

 one of the most exposed appendages on Dunge- 

 ness crabs and are frequently used in aggressive 

 threat postures. After loss of chelipeds, the 1st 

 walking legs remain as the most anterior, ex- 

 posed limbs and therefore, the most vulnerable. 

 The 4th walking legs are the most posterior and 

 also very exposed limbs on an intact crab. 



A significantly greater number of Dungeness 

 crabs with 2 or more missing legs was observed 

 than expected if multiple autotomies occurred by 

 chance, indicating an increased susceptibility to 

 subsequent appendage loss after initial injury 

 (Needham 1953; Easton 1972). 



The correlations between appendage injury and 

 date were significant but may not be biologically 

 important. Although these correlations were sig- 

 nificant, the r^ values (square of the coefficient of 

 variation) were low. Increased appendage injury 

 later in the year may be related to other factors. 

 Soak times, the length of time pots were left in 

 the water, were longer later in the year. Dunge- 

 ness crabs may cannibalize other crabs while con- 

 fined in pots (Waldron 1958). There may also be 

 delays between time of injury and subsequent au- 



totomy and regeneration. Regeneration of legs in 

 Dungeness crabs is usually completed after 2 or 3 

 molts (Cleaver 1949). 



Over the sampling period, only b^c of all crabs 

 had regenerating appendages while 187^ had 

 missing appendages. The discrepancy may be due 

 to increased mortality of the crabs following in- 

 jury (McVean and Findlay 1979), or by the effi- 

 cient, yearly removal of legal-sized, injured crabs 

 by the commercial fishery. 



When temporal incidence of appendage injury 

 was compared with the opening and closing of the 

 commerical Dungeness crab fishing season, con- 

 siderable appendage injury occurred when the 

 fishery was closed. Closure of the fishery tradi- 

 tionally occurs during the crabs' mating period, 

 when a high percentage of soft-shelled female 

 crabs are present in the population. There was, 

 however, some overlap in late July and early 

 August in fishing, molting, and mating. Exclud- 

 ing damage by humans, potential causes of ap- 

 pendage injury are aggression between males 

 competing for females, the cheliped-to-cheliped 

 mating embrace of Dungeness crabs that can last 

 up to a week, cannibalism, and the increased vul- 

 nerability of females which molt prior to mating 

 (Butler 1960; Durkin et al. 1984). Damage to 

 Dungeness crabs can also result from other fish- 

 ing gear such as trawls (Reilly 1983), but no other 

 commercial fisheries occurred in the study area 

 while the Dungeness crab fishery was closed. 



The results of our studies indicate that Dunge- 

 ness crabs in southeastern Alaska are in com- 

 parable condition to adult populations of Dunge- 

 ness crabs examined in Washington and Oregon, 

 in terms of appendage injury. Further studies are 

 needed to investigate the effect of appendage in- 

 jury on survival of Dungeness crabs and the con- 

 tribution of handling injury and mortality of 

 crabs in the commercial fishery. 



Acknowledgements 



T. Meyers and D. Erickson provided technical 

 assistance for which we are very appreciative. We 

 would like to thank T. Olsen, C. Kondzela, and 

 D. Sterritt for assistance in data collection. This 

 research was funded by Alaska Sea Grant project 

 R/06-20. 



Literature Cited 



Butler, T. H. 



1960. Maturity and breeding of the Pacific edible crab, 



159 



