Delgado et al.: Translocation of Strombus gigas as a strategy to rehabilitate the Florida Keys conch population 281 



ries of graded ethanols (one change of 60% ethanol and two 

 changes of 70% ethanol for two hours each) and loaded into 

 an automatic tissue processor (Shandon Hypercenter XP, 

 Shandon Scientific Ltd., Pittsburgh, PA) for dehydration, 

 clearing, and paraffin infiltration. Tissues were embedded 

 in Paraplast Plus (Fisher Scientific, Pittsburgh, PA) and 

 sectioned at 4 jim with a rotary microtome. Two serial 

 sections from each tissue sample were mounted on glass 

 slides, allowed to dry overnight, and stained with hema- 

 toxylin 1 and eosin Y (Richard Allen Inc., Richland, MI). 

 All laboratory procedures followed approved standard op- 

 erating procedures developed under the Good Laboratory 

 Practices guidelines (EPA and FDA guidelines). 



A detailed histological inspection of each sample was 

 made to assess the stage of gonadal maturity and the 

 percentage of gametogenic tissue. Each animal was given 

 a score from 1 to 8 to quantify gonadal maturity (Table 2). 

 This index was derived from a maturity scale developed 

 by Egan (1985). Because of the small number of animals 

 collected, gonadal maturity scores from 1 to 5 were com- 

 bined to group animals that would be capable of spawning 

 or had recently spawned (Table 2). Scores from 6 to 8 were 

 combined to group animals that would not spawn again in 

 a season or were not capable of spawning (Table 2). In ad- 

 dition, the percentage of gametogenic tissue present (i.e., 

 the percentage of ovarian or testicular tissue occupying 

 the available space of the section) was visually estimated 

 by using the following index: <25%, 25-50%, 51-75%, and 

 >75%. For statistical analyses, this index was reduced to 

 two categories: <50% and >50%. 



Statistical analyses 



We evaluated differences in reproductive behavior (mating 

 and spawning) between resident nearshore and translo- 

 cated nearshore conch for each season by using Fisher's 

 exact test because it is not sensitive to small sample sizes 

 (Zar, 1996). We also examined differences in gonadal 

 condition (i.e., gonadal maturity and the percentage of 

 gametogenic tissue) between resident nearshore and 

 resident offshore conch for each season by using Fisher's 

 exact test. Males and females were analyzed separately. 

 In order to assess the effectiveness of the translocations to 

 the offshore region, we used Fisher's exact test to compare 

 the gonadal condition of translocated nearshore conch 

 with the gonadal condition of resident nearshore conch 

 in summer and in fall. Again, the sexes were analyzed 

 separately. All tests were run on SPSS 9.0 (SPSS Inc., 

 Chicago, ID for Windows. Results were considered sig- 

 nificant if P<0.05. 



Results 



Reproductive behavior: mating 



Approximately 84% of the tagged resident nearshore conch. 

 69% of the tagged translocated nearshore conch, and 88% 

 of the tagged resident offshore conch were observed at 

 least once during monitoring. Resident nearshore conch 



Table 3 



Percentage of mating (the number of males and females 

 mating divided by the total number of conch observed 

 during that season) and spawning (the number of females 

 spawning divided by the total number of females observed 

 during that season I in nearshore conch and offshore conch 

 by season I adapted from McCarthy et al.. 2002 ). Numbers 

 in parentheses represent the number of observations; 

 P represents the probabilities from Fisher's exact test 

 of differences in reproductive behavior between resi- 

 dent nearshore and translocated nearshore conch. The 

 asterisk (*) indicates that the test was statistically sig- 

 nificant. N/A indicates that statistical analyses were not 

 conducted because no mating or spawning was observed 

 among either resident nearshore or translocated near- 

 shore animals. 



Offshore 

 conch 



Nearshore conch 



Resident Resident Translocated P 



Mating 

 Spring 

 Summer 

 Fall 



Spawning 

 Spring 

 Summer 

 Fall 



5.3(95) 0.0 1 37 i 



2.4(4671 0.0(1061 



0.9(2321 0.0(20) 



46.2(39) 0.0(6) 



16.8(191) 0.0(34) 



5.2(97) 0.0(9) 



0.0(19) N/A 



0.0(81) N/A 



0.0(51) N/A 



0.0(10) N/A 



12.2(41) 0.041* 



18.5(27) 0.214 



and translocated nearshore conch were not observed 

 mating during any of the field surveys; conversely, resi- 

 dent offshore conch were observed mating throughout the 

 study (Table 3). The mating frequency of resident offshore 

 conch was highest during the spring ( 5.3% ) and decreased 

 during subsequent seasons to 0.9% in the fall (Table 3). 

 All observed mating occurred between resident offshore 

 animals. 



Reproductive behavior: spawning 



Neither resident nearshore females nor translocated near- 

 shore females were observed spawning during the spring 

 (Table 3). However, by summer, translocated nearshore 

 females had attained the capacity to spawn and had a 

 significantly higher spawning frequency than resident 

 nearshore females (12.2% vs. 0.0% , respectively) (Table 3). 

 During the fall, spawning frequency of translocated 

 nearshore females peaked at 18.5%, whereas resident 

 nearshore females had still not exhibited any spawn- 

 ing behavior (Table 3). However, this difference was not 

 statistically significant because of the small number of 

 resident nearshore conch observed (Table 3). Looking at 

 individual performance instead of spawning frequency, 

 seven (or about 14%) of the approximately 50 nearshore 

 females translocated offshore were observed spawning at 

 least once during the study period. 



