World Aquaculture December 2019

36 DECEMBER 2019 • WORLD AQUACULTURE • WWW.WA S.ORG temperature and light affect gamete output and egg mass quality (Davis et al. 1984, Shawl and Davis 2004). Except for pH, water quality parameters in this study were within the acceptable range for conch reproduction (Shawl and Davis 2004). The mean pH of 8.0 during the daytime was similar to pH values in natural habitats but low pH values (fluctuated from 7.1–7.7) are low in comparison to pH values of ~8.1 for surface ocean water. This low pHmay be due to the HBOI IMTA system water recirculating through the seaweed culture at night when increased respiration produces carbon dioxide that lowers pH. Ocean acidification studies have shown that low pH has an adverse effect on molluscan development (Ross et al. 2011). In a previous fighting conch breeding study at HBOI, mean pHwas 7.8 in the recirculating system and egg production did not slow down towards the end of the six-week period and veliger development was successful (Gillette 2003). The effect of lower pH and possible other water quality conditions on conch female productivity and egg viability needs to be addressed in future IMTA studies. This study added new knowledge for the aquaculture of the Florida fighting conch such as the establishment of captive breeding program in an IMTA systemwith the use of a sex ratio skewed toward females. An additional benefit of using the IMTA system is the potential savings on feed costs because the conch in this study were observed actively grazing on bioflocs in their tanks that was produced in other components of the IMTA system. This makes the fighting conch an ideal extractive species for the IMTA system. When the findings from this study are combined with results from previous studies, a scenario to produce approximately one million eggs per week (eight egg masses per week) would be possible using a sex ratio of two females (84 females) to one male (42 total). This would be an adequate amount of eggs for an efficient production of the Florida fighting conch in an aquaculture facility that was sized according to product needs. Now that this desirable species can be cultured through all developmental phases in captivity (this study, Gillette 2003, Shawl and Davis 2004, Davis and Shawl 2005, Shawl et al. 2005) potential commercial markets for the seafood and aquarium trade need to be explored. Fighting conch will reach 6 cm shell length in about 8-10 months and could be sold as a seafood product called Ocean Escargot (Fig. 17). It also has potential to help supplement queen conch delicacies such as conch fritters, salad and chowder. In four to five months, conch grow to 3 cm shell length and could be sold as grazers for the aquarium trade, which has been accomplished previously with this species (Shawl and Spring 2003, Davis and Shawl 2005) (Fig. 18). Development of commercial production of Florida fighting conch would provide a new product for the aquaculture industry to grow and sell. TABLE 2. Weekly egg mass production per treatment during the four week study. The egg mass production was standardized as egg masses per female per week per treatment. Results are expressed as mean ± standard deviation (n=number of egg masses). Treatment Week 1 Week 2 Week 3 Week4 (6/21-6/27) (6/28-7/4) (7/5-7/11) (7/12-7/17) 1:5 0.8 ± 0.4 0.2 ± 0.2 0.07 ± 0.10 0.03 ± 0.08 (23) (6) (2) (1) 3:3 1.1 ± 0.5 0.3 ± 0.4 0.08 ± 0.17 0.08 ± 0.17 (13) (4) (1) (1) TABLE 3. Summary of egg mass data from the study. Results are expressed as mean ± standard deviation (n = samples) and ranges. Variable Result s Volume of egg mass (mL) 8.8 ± 3.6 (50) 3 - 19 Number of eggs per mm of egg mass strand 12.0 ± 1.4 (51) 9.6 - 15.0 Length of uncoiled egg strand in an equivalent 1 ml egg mass subsample (mm) 1,144 ± 309 (25) 588 - 1885 Calculated number of eggs per 1 mL egg mass subsample 13,775 Calculated number of eggs per egg mass 120,943 ± 49,727 (50) 41,324 - 261,721