Melville-Smith and de Lestang: Changes in egg production of Ponu/irus cygnus associated with appendage damage 



421 



100 

 90 

 80 

 70 



10 



A Zone A 



Females. n=20.092 

 Males, n=8358 



100 



90 



80 



10 



12 3 4 5 6 7 



B Zone B 



9 10 11 12 



-•— Females, n=1 7,984 

 ° Males, n=11, 206 



12 3 4 5 6 7 



9 10 11 12 



C Zone C 



-• — Females, n=7522 

 ° Males, n=5437 



100 

 90 

 80 

 10 



4 5 6 7 



Appendages damaged 



Figure 2 



Percentage of female and male western rock lobster {Panuliriis cygnus) 

 with 0-12 damaged appendages in the catch at three management zones: 

 (A) zone A, Abrolhos Islands; (B) zone B, northern coastal; and (C) zone 

 C, southern coastal,. Note that the _v-axis is not continuous. 



constant at about 4% and 3%, respectively, in all size 

 classes below 120 mm CL. Above this size class, the 

 incidence of regenerated appendages increased mark- 

 edly in females (10%) and declined to zero for males 

 (Fig. 3C). 



The influence of appendage damage on egg production 



The proportions of female P. cygnus (CL>65 mm) from 

 the Abrolhos Islands that were classified as having ovig- 

 erous setae, as being single breeders, and as being double 

 breeders, all declined with increasing appendage damage 

 (Fig. 4, A-C). A consistent trend existed between the 

 various reproductive states and the magnitude of their 

 appendage damage. For females at the Abrolhos Islands 

 above the size at maturity, the likelihood of developing 

 ovigerous setae declined with the number of appendages 



damaged: 98% likelihood (one appendage damaged), 95% 

 (two), 80% (five), and 58% (six). This likelihood contin- 

 ued to decline until it reached zero for all females with 

 either 11 or 12 damaged appendages (Fig. 4A). 



For ovigerous females with damaged appendages, 

 the likelihood of producing either one or two batches of 

 eggs each spawning season declined more rapidly than 

 the likelihood of developing ovigerous setae. Females 

 with one damaged appendage were 20% and 19% less 

 likely to produce one or two batches of eggs, respec- 

 tively, whereas those with five damaged appendages 

 were around 85% and 65% less likely to produce one or 

 two batches of eggs, respectively. Females with more 

 than seven damaged appendages did not produce eggs 

 (Fig. 4, B and C). Equations describing the relation- 

 ships between appendage damage and the likelihood of 

 spawning once for single breeders and twice for double 



