Research Article
Fabiola Chong Sánche
Abstract
Fighting conch Strombus pugilis is one of six Strombidae species distributed throughout the Caribbean. It is used as food, as an aquarium organism and its shell are popular in jewelry production. Conch aquaculture has been done traditionally by extracting egg masses from wild adults. This is an issue for several conch species protected by CITES. Intensive conch culture requires good growth rates and gonad maturity under laboratory conditions using formulated feed. An evaluation was done of the effect of inclusion of the red algae Halymenia and Spirulina on gonad maturity in S. pugilis using two experimental diets containing low and high concentrations of these algae (2% and 8% of each). Each diet was fed to six groups of conch kept in 20 L aquaria at 27.5°C. They were fed twice daily at 0.1 g feed/conch for 105 days. Gonad development and digestive gland structure were analyzed with histological techniques. Analysis of gonad development and vitellus granule diameter were analyzed for the two treatments and a control (wild conch). Wild conch females exhibited a reproductive cycle with 100% maturity at the beginning of this study, followed immediately by spawning (in two peaks: 50% and 34%) and initiation of a new oogenesis cycle. Females fed the 8% H. floresii and 8% Spirulina diet exhibited two spawning peaks (75% and 100%) spaced a month apart, and larger yolk granules than those in the control and the 2% H. floresii and 2% Spirulina diet. Proteoglycan granule abundance in the digestive cells did not differ between treatments. H. floressi and Spirulina may function as a feeding stimulant, enhancing feed intake and promoting gonadal maturity in S. pugilis broodstock under laboratory conditions.