FISHERY BULLETIN: VOL. 85, NO. 2 



domness test (Zar 1974). Conchs were especially 

 clumped at Cat Cay, all appearing within 10 m of 

 shore, effectively making their densities much 

 higher than were reported for 100 m transects 

 (Table 2). 



Queen conch densities reported for other areas in 

 the Caribbean were generally lower, ranging from 

 0.8-5.2 conchs/10 m^ in Cuba (Alcolado 1976), 0.01 

 conchs/10 m- in U.S. Virgin Islands (Wood and 

 Olsen 1983), 0.9 conchs/10 m^ in the Turks and 

 Caicos (Hesse 1979) to 0.1-21 conchs/10 m^ {X = 

 4.2 conchs/10 m-) in Los Roques, Venezuela (Weil 

 and Laughlin 1984). 



Growth of Queen Conch 

 by Season, Location, and Size 



Seasonal Growth 



Based on all data collected between February 1980 

 and June 1982, there was a significant (P < 0.001 

 ANOVA) seasonal difference in mean length of un- 

 tagged individuals. Queen conchs measured during 

 winter were smaller than those measured during 

 other seasons (Table 3). 



Nearly all growth of juvenile queen conchs in our 

 study took place during the warm summer months, 

 May-September. At Cat Cay, for example, mean 

 growth of tagged conchs ranged from 0.44 to 1.63 

 cm per month during the summer, and from 0.18 

 to 0.30 cm per month during the remainder of the 

 year. This is consistent with studies by Randall 

 (1964) on queen conch in St. Croix, U.S. Virgin 

 Islands; by Alcolado (1976) in Cuba; and by Appel- 

 doorn (1985) on small juveniles in Puerto Rico. Our 

 small caged conchs (2.4-3.6 cm at tagging), held for 

 1 year, increased 3.56 cm on the average; 92% of 

 this increase (3.27 cm) took place between April and 

 October. 



Growth by Location and Size 



To examine the effect of location and size on 

 growth, mean monthly growth of penned and un- 

 penned tagged queen conch was compared within 

 3 size groups (<9.6 cm, 9.7-15.3 cm, >15.4 cm) by 

 location. Densities of penned conchs (10-20 conchs/ 

 10 m-) were higher than densities of unpenned 

 conchs (2-20 conchs/10 m^, X = 8) measured in the 

 field. In every size class, unpenned conchs grew 

 significantly faster (P < 0.001, ANOVA). Among 

 unpenned conchs, there was a significant interaction 

 effect of location and size on mean monthly growth. 

 Large conchs (>15.4 cm) at Little Cockroach Cay, 



Table 2. — Average density of queen conchs by sampling 



sites. 



Table 3.— Mean length of untagged queen conchs collected in 

 each season between February 1980 and June 1982. 



' + 95% confidence interval. 



where density was lowest, grew faster than all other 

 sizes. Small conchs (<9.6 cm) grew the next fastest, 

 followed by intermediate-sized conchs (Table 4). 

 Queen conchs at Cat Cay and Vigilant Cay offshore 

 west, where densities were higher, grew slower as 



Table 4. — Comparison of mean monthly growth rates (cm) for un- 

 penned queen conchs. Underlined locations indicate significant 

 difference in monthly growth between locations as determined by 

 Student-Newman-Keuls test. 



Size class 



Tagging locations 



9.6 cm 



Vigilant Cay Little Whale Cat Cay 

 Offshore West Cay 



(0.40) + '0.3 (0.48) ± 0.03 (0.50) ± 0.04 

 A/ = 198 A/ = 13 N = 114 



9.6-15.3 cm Cat Cay 



(0.25) ± 0.02 

 N = 385 



Little Whale Little Cockroach 



Cay Cay 



(0.40) ± 0.03 (0.48) ± 0.02 

 A/ = 186 N = 248 



15.3 cm 



Little Whale Little Cockroach 



Cay Cay 



(0.31) ± 0.07 (0.50) ± 0.03 

 A/ = 23 A/ = 146 



'95% confidence interval. 



304 



