420 



Fishery Bulletin 105(3) 



The batch fecundity (number of eggs in one batch) of 

 50 female P. cygnus with early-stage eggs that ranged 

 in carapace length (CL) from 67.1 to 96.2 mm was de- 

 termined. Twenty-three females had either one or two 

 damaged appendages and 27 had no damaged append- 

 ages; females with early-stage eggs and more than two 

 damaged appendages were seldom caught and therefore 

 were not assessed. The endopodites with eggs were 

 removed from the lobsters and dried in an oven for 24 

 hours. The eggs were then separated from the setae and 

 weighed to the nearest 0.0001 g. Three subsamples of 

 each brood (each of -0.05 g) were taken and weighed. 

 The number of eggs in each subsample was counted to 

 determine the mean number of eggs per gram of dry 

 egg weight, and the mean of these values was used to 

 estimate the total number of eggs in the brood. The 

 mean fecundity per spawning season was compared 

 for females with and without appendage damage after 

 standardizing for carapace length with ANCOVA. 



The total number of eggs produced by all mature fe- 

 male P. cygnus caught during the 2002 survey in each 

 of the three commercial fishing zones was estimated 

 by using an equation that incorporates the number of 

 broods of eggs produced each spawning season and the 

 effects of appendage damage on the likelihood of spawn- 

 ing once or twice. 



{TF = NB xF xPOi)^), 



where TF = the total fecundity (number of eggs pro- 

 duced) by mature females; 

 NB = the probability of a female producing one 

 or two broods each spawning season, on 

 the basis of their CL; 

 F = s the relationship of fecundity to carapace 

 length; and 

 PO = the probability that females with damaged 

 appendages DA will produce eggs. 



Pi=(l/l-i-exp(-ln(19)x(CL-SB5„)/(SB9g-SjB5o))), 



P2=(l/l-i-exp(-ln(19)x(CL-Z)B5o)/(DB95-DS5o))). 



where Sfigg and SBgg = the CLs at which 50 and 95%, 



respectively, of the population 

 at each location produced one 

 brood of eggs (Pj); and 



DBgo and DSgg = the CLs at which 50 and 95%, 

 respectively, of the population 

 at each location produced two 

 broods of eggs (P._,) per spawn- 

 ing season (de Lestang and 

 Melville-Smith, 2006). 



Results 



Frequency of appendage damage in 2001—05 surveys 



The percentage of western rock lobster with damaged 

 appendages in the 2001-05 survey catches decreased as 



Table 1 



Percentage of all female and male western rock lob- 

 ster (Panulirus cygnus) with old damage, or regener- 

 ated appendages, in the three management zones of the 

 fishery. Data are from the 2001-05 fishery-independent 

 breeding stock survey. 



Fishing zone 



Sex 



Zone A 



Zone B 



ZoneC 



Female 

 Male 



17.8% 

 18.9% 



12.4% 

 8.7% 



20.9% 

 17.2% 



the number of damaged appendages increased (Fig. 2, 

 A-C). For example, in zone A, about 82% of all female 

 and male P. cygnus in the catches had no appendage 

 damage, whereas about 9%, 4%, and 2% of both sexes 

 had one, two, and three damaged appendages, respec- 

 tively. Only 1% of the catch of each sex had four damaged 

 appendages and less than 0.5% of all lobsters had more 

 than five damaged appendages. 



The incidence of appendage damage was significantly 

 different between zones (P<0.001) and both zones A 

 and C had higher incidences than zone B (Table 1) . In 

 addition, within zones B and C, significantly (P<0.001) 

 more females than males were caught with appendage 

 damage. There was no significant difference (P=0.14) 

 in the incidence of appendage damage for females and 

 males caught at the Abrolhos Islands. 



Relationship between appendage damage and 

 carapace length 



The incidence of new appendage loss differed signifi- 

 cantly (P<0.001) between the two sexes in the various 

 size classes (Fig. 3A). New appendage loss in females 

 remained at about 17% in all the size classes, whereas 

 in males this loss decreased from 15% to 8% in the first 

 four size classes, then increased substantially to 28% 

 and 20% in the larger size classes (110-119 and 120- 

 129 mm CL, respectively). 



The incidence of old appendage loss also differed sig- 

 nificantly (P<0.001) between sexes in different size 

 classes (Fig. 3B). Old appendage damage was slightly 

 more common as females increased in size, i.e., from 

 7% to 11% between the 60-69 and 100-109 mm CL size 

 classes. This increase also occurred for males but to a 

 much greater extent, i.e., from 4% to 23% between the 

 60-69 and 100-109 mm CL size classes. The incidence 

 of old appendage damage in males then declined slightly 

 over the two largest size classes (110-119 and 120-129 

 mm CL) 22 and 16%, respectively (Fig. 3B). 



Regenerated appendages in the catches of lobster 

 differed significantly (P<0.001) between sex and size 

 classes (Fig. 3C). Regenerated appendages were more 

 commonly recorded for females than for males, but re- 

 generated appendages for each sex remained relatively 



