698 



Fishery Bulletin 89(4), 1991 



0.20 

 0.15 

 0.10 

 0.05 

 0.00 



PERIOD 1 



1 



a 



i 



fi 



D 

 XJ 

 \ 



E 

 E 



o 

 o 



_Ll 



-0.05 

 -0.10 



0.20 



0.15 



0.10- 



0.05 



0.00 

 -0.05 

 -0.10 



0.20 



0.15 



0.10 



0.05 



0.00 

 -0.05 

 -0.10 J C3 

 SAND 



C3 N1 W1 L3 C1 C2 L1 L2 



PERIOD 2 



a 



C3 Nl W1 L3 C1 C2 L1 L2 



PERIOD 3 



In I 



It] t±l 



N1 W1 L3 CI C2 L1 L2 



LOW MODERATE HIGH 



STATIONS 



Figure 4 



Growth rates for juvenile queen conch at eight transplant 

 sites during three growth periods. Values are mean ± 

 standard deviation. Black bars represent growth rates 

 at sites with resident conch populations. Period 1 = 35 

 days, Period 2 = 40 days, Period 3 = 45 days. 



Ll, and L2 were low and not different P>0.05). 

 Growth rates at all other sites were different, and 

 strongly negative growth rates occurred at station C3 

 and L3. There were no significant cage differences at 

 any of the sites during this period (P>0.05). 



High growth rates at sites C2 and Cl were associated 

 with high body condition (Table 3). Predictably, condi- 

 tion was low in the bare-sand habitat and other sites 

 where survivorship was low (e.g., L3, Wl), and there 

 were various site differences (Kruskal-Wallis test, 

 H adj . 57.38, P<0.001) (Table 3). Despite high mortal- 

 ity and low growth rate at the high-biomass site (L2), 

 condition factor at that site was not significantly dif- 

 ferent from site Nl, a natural conch habitat. 



Comparing rates of mortality and growth, a pattern 

 emerges: low growth occurred with high mortality at 

 sites C3 and L2. Accelerating mortality and rapidly 

 declining growth rates were found at Wl and L3, while 

 mortality remained low and growth rates high at Cl, 

 C2, and Nl. At Ll, mortality was low but growth 

 declined from a high rate in the first period. 



Discussion 



Growth rates found in the natural conch habitats (Cl 

 and Nl), between 0.1 and 0.2 mm/day, were similar to 

 those determined for free-ranging juveniles at C 1 dur- 

 ing summer 1985 (0.12mm/day)(Wicklund et al. 1988), 

 and summer 1987 (0.10-0.15mm/day)(Stoner 1989a). 

 The rates reported here are also similar to those 

 reported from Los Roques, Venezuela, where growth 

 curves give mean growth rates of 0.16 mm/day for 

 tagged conch between 85 and 105 mm in shell length 

 (Laughlin and Weil 1982), and 0.14 mm/day for 90mm 

 conch (Brownell 1977). These results suggest that 

 enclosures used in this experiment did not inhibit 

 growth in the test animals. 



So that the numbers of conch in the enclosures re- 

 mained constant, dead conch were replaced with new 

 individuals which, in the less optimal sites, grew at a 

 rate slightly higher than conch enclosed earlier. 

 Replacement, therefore, results in overestimation of 

 growth rate (and probably survivorship) in the poor- 

 quality habitats and conservative separation of sites. 

 Differences in shell length among the experimental 

 sites by the second and third growth periods, and slight 

 differences in growth rates of conch between 90 and 

 120mm (Brownell 1977) would have only a minor in- 



