Table 2. — Estimated number of dead Dungeness crabs. Gray- 

 land to North Cove, Wash., 18 April 1979. 



2 ■*• Gray land 

 3 



Nahcot t a 



10 km 



Figure l. — Southern Washington coast and locations of num- 

 bered transects. 



Nearly all animals examined contained muscula- 

 ture in the appendages and thoracic region and 

 relatively few exuvia were found (Table 1). Be- 

 cause of decomposition and some bleaching of 

 shells, animals were judged to have been on the 

 beach 1-3 d and a relatively high percentage had 



'Average of two successive transects. 



been damaged by scavenging birds, thereby pre- 

 cluding identification of sex in those instances. 

 Still, all Dungeness crabs sexed were females 

 which, of the 42 measured, averaged 147 mm 

 carapace width (range 110-162 mm). 



Substantial numbers of dead crabs were found 

 with densities of up to 1.64 crabs/m of shoreline (in 

 the 8-10 m band of upper high tide) computed at 

 transect 3 (Table 1). Generally, the numbers of 

 dead crabs observed between transects seemed 

 consistent with the densities recorded along 

 transects. Estimation of the total number of dead 

 crabs on the beach between Grayland and North 

 Cove (7.9 km) was 6,461 animals (Table 2). 



Discussion 



Mass mortality of C. magister has not, to our 

 knowledge, been previously reported for any 

 locale within this species range from central 

 California to Alaska. At the time of the incidence 

 we describe for southern Washington, there were 

 no similar reports of mortality along Oregon 

 beaches according to Dale Snow.^ Furthermore, he 

 had never verified an occurrence of extensive crab 

 mortality in that state during 17 yr of fisheries 

 research. 



Does our report then, describe an isolated or 

 rare phenomenon of this species or does an event 

 such as mass mortality go undetected, observed 

 but not interpreted for what it is? Along the Wash- 



'Dale Snow, Oregon State Department of Fish and Wildlife, 

 Newport, Oreg., pers. commun. April 1979. 



Table l. — Dead Dungeness crabs along measured beach transects in southern Washington (shown in Figure 1). 



Dead crabs 



350 



