Purves et a\: Distribution, demography, and discard mortality of crabs caught as bycatch in the South Atlantic 



881 



P spinosissima 



P. anamerae 



50 



60 



70 80 90 



Carapace width (mm) 



Figure 6 



Carapace-width frequency distribution for the three Paralomis species (mm). (A) P. 

 spinosissima, (B) P. formosa, (C) P. anamerae. The minimum legal size (102 mm for P. 

 spinosissima and 90 mm for P. formosa) is indicated with a vertical line and arrow. 



between the vitality indices of P. formosa and P. spinosis- 

 sima clearly showed that both species displayed signifi- 

 cantly lower vitality on the Argos Helena than on the Argos 

 Georgia (Table 7). 



The processing environment of the two vessels may ex- 

 plain these differences. On the Argos Helena crabs were 

 likely to sustain more damage as pots were emptied down 

 a vertical chute before entering the processing area below 

 deck. On the Argos Georgia pots were emptied on a hori- 

 zontal conveyer belt leading to the factory. Interestingly, 



there was no significant difference between the vitality 

 displayed by P. anamerae between the two vessels, al- 

 though this may be a result of the smaller sample size for 

 this species. For the Argos Georgia, the vitality of P. ana- 

 merae was significantly lower than for either P. formosa 

 or P. spinosissima. 



The results of the three survival experiments are shown 

 in Table 8. Experiment 1 re-immersed only lively crabs 

 and included a control set of animals retained on deck 

 in a large tank for the same length of time as the re-im- 



