FORD ET AL.: POPULATION OF WESTERN ROCK LOBSTERS 



The data from reef I, the secondary control reef, 

 were only sufficient for an examination of the single 

 molt increments of 3-yr-olds. Within this age class 

 there was no significant difference in mean molt in- 

 crement between the two sexes and the data for the 

 whole age class were pooled. There were no signif- 

 icant differences between the mean single molt in- 

 crement for 3-yr-olds from reef I and the mean 

 single molt increment for this age class on either 

 reefs III or V (t-test, P > 0.05). 



Annual and Seasonal Growth 



The mark-recapture data from reefs I, III, and V 

 are considered within four time periods: From Janu- 

 ary 1981 to May 1981 (the "summer-autumn" 

 period), from May 1981 to September 1981 (the 

 "winter" period), from September 1981 to Febru- 

 ary 1982 (the "spring-summer" period) and from 

 January 1981 to January-February 1982 (the "an- 

 nual" growth period). As described in Methods sec- 

 tion above, average relative growth rates (ARGRs) 

 of males and females were not significantly differ- 

 ent and therefore the data were pooled. Because of 

 the small number of ^5-yr-old lobsters, their growth 

 data were combined with the data for the 4-yr-old 

 individuals. The ARGRs of the different age groups 



from all three reefs over each of the four time 

 periods are given in Figure 6. 



Comparison of growth data for the test reefs for 

 each age group and recapture interval were made 

 using Wilcoxon rank sum tests. The primary pur- 

 pose was to evaluate whether growth data for the 

 three reefs could be pooled for later analysis. The 

 comparisons are of interest in their own right, but 

 caution is required in interpreting some of the dif- 

 ferences established because of small sample sizes 

 in some cells. 



The results showed no significant differences in 

 ARGRs of any age group between reefs III and V 

 (P > 0.05), the treatment and the principal control 

 reefs respectively in the density manipulation ex- 

 periment. There were significant differences in 

 ARGRs between reefs I and III for individuals 3 

 years of age in January-May 1981, May-September 

 1981, and January 1981 -January 1982 and for in- 

 dividuals >4 years of age in January-May 1981. 

 There also were significant differences in ARGRs 

 between reefs I and V for individuals 3 years of age 

 in January-May 1981 and May-September 1981, 

 and for individuals >A years of age in January-May 

 1981 (P < 0.05). The significant differences all 

 showed consistently higher ARGRs on reef I than 

 on reefs III and V. 



> 

 2 



0) 



k- 



(U 

 Ol 

 (0 



4) 



> 



10 



c 



15 

 4) 



JAN -MAY 81 



Reef I III V 



0.20 r 



0.18 

 0.16 

 0.14 

 0.12 

 0.10 

 0.08 

 0.06 

 0.04 

 0.02 



_Ll 



I I I I I I I I I I I 



MAY -SEPT. 81 

 I III V 



i. 



1 1 1 1 1 1 1 



SEPT-JAN. 82 JAN. 81 -JAN. 82 

 I III V I III V 



I I I ] I 



I I I I I I I 



2 3?4 2 3?4 2 3*4 2 3*4 2 3?4 2 3*4 23*4 2 3*4 2 3*4 2 3*4 2 3*4 2 3*4 



Age ( Years ) 



Figure 6.— Average relative growth rates (ARGRs) of juvenile Panulirus cygmis 

 on test reefs at Seven Mile Beach, Western Australia. 



783 



