Stoner et aL; Reproduction and larval abundance in queen conch 



167 



LOCATIONS 



Bermuda 

 Florida Keys 



Bahamas 



Turks and Caicos 



Mexico — — - 



Jamaica 



Puerto Rico — 



U.S. Virgin Islands 



St. Kitts / Nevis 

 Venezuela 



REFERENCES 



Berg ec al. (in press) 



D'Asaro(l965) 

 Glazer (pers. comm.) 



This study 



Davis etal. (1987) 



Cruz (1986) 



Corral and Ogawa ( 1 987) 



Salley (1986) 



Appeldoom etal. (1987) 



Randall (1964) 

 Coulston etal. (1987) 



Willdns etal. (1987) 



Brownell (1977) 



Weil and Uughlin ( 1 984) 



MONTHS 



F M A M J 



H 1 1 1 1 — 



A S O N D 



I 1 1 1 1 1 



* no data prior to July 



Figure 6 



Reproductive seasons reported for Stromkis gigas in the Caribbean region. Seasonality 

 refers to any observations of reproductive behavior (copulating or egg-laying), and does 

 not include histological results (see text). Locations are arranged in order of latitude 

 from north (top) to south (bottom). Data for Mexico are for Banco Chinchorro on the 

 Caribbean coast. 



density was 0.82/10 m^ (Table 2) 

 and surface-water temperature 

 was 31 °C. Highest density at 

 this site (1.35 larvae/lOm^) oc- 

 curred on 28 July, when numbers 

 of copulating and spawning 

 females were highest at the Re- 

 productive Site. On 12 August, 

 larval density declined to 0.77 

 larvae/lOm^, concurrent with 

 declines in reproductive activity. 

 Larvae were last collected over 

 the nursery area on 14 Septem- 

 ber at a density of 0.17 larvae/ 

 10 m^; at this time, surface- 

 water temperature on the Exu- 

 ma Bank was 30 °C and repro- 

 ductive activity was near zero. 

 During the reproductive sea- 

 son, all but three of the conch 

 veligers collected were between 

 340 and 600 pim in shell length (x 

 384Mm, SD 64, n 394) (Fig. 5). 

 The largest three larvae (1350 

 ^m) were removed alive from 

 samples collected at the bank site 

 in mid-July. Metamorphosis oc- 

 curred within 24 hours in all 

 three larvae. 



of 29.8°C and 28.1°C, respectively. Larvae continued 

 to be found at the pass sites until the end of September, 

 but were not present at the Reproductive Site after 23 

 August. No veligers were collected at any of the sites 

 in October, concurrent with observation of the last egg 

 mass. At this time, surface-water temperature had de- 

 clined to 27.2°C and bottom temperature was 27.5°C. 



Density of larvae at the Adderley Cay cut site showed 

 a direct correlation with the percentage of females 

 copulating (r 0.952, F 68.312, jo<0.0001) and egg- 

 laying (r 0.860, F 19.889, p 0.003). Densities of larvae 

 at the Reproductive Site and the Rat Cay cut site were 

 not correlated with copulation or egg-laying (p>0.05). 

 Maxima in larval abundance occurred during months 

 with highest water temperature, but there was no 

 significant correlation between abundance of larvae 

 and surface-water temperature at Adderley Cay cut (F 

 5.232, p 0.056) or Rat Cay cut (F 0.514, p 0.494) dur- 

 ing the reproductive season (June-October). Log- 

 transformation of the data did not improve the correla- 

 tion coefficients. 



Plankton collections over the nursery area, west of 

 Children's Bay Cay, were begun on 13 July 1988; larval 



Discussion 



At Lee Stocking Island, the reproductive season for 

 queen conch began in April and ended in early October. 

 Although differences by a few months were found in 

 the occurrence of reproductive behavior, there was no 

 apparent trend related to latitude in beginning, end, 

 or length of reproductive season in queen conch from 

 Bermuda to Venezuela (Fig. 6).* The longest reproduc- 

 tive season was reported for the Caribbean coast of 

 Mexico (Banco Chinchorro) (Cruz 1986, Corral and 

 Ogawa 1987), where egg masses were found year- 

 round. One of the shortest reproductive seasons was 

 reported by D'Asaro (1965) for the Florida Keys, but 

 more recent, intensive observations have shown that 

 queen conch may spawn over at least a 9-month period 

 in Florida (R. Glazer, Dep. Nat. Resour., Marathon, FL 

 33050, pers. commun., Sept. 1990). 



*For geographic comparison, "reproductive seasonality" refers to 

 any reported observation of pairing, copulation, or egg-laying in 

 queen conch, except where noted in the text. Histological data are 

 not included. 



