The Caribbean island of Grenada is rich in fisheries and agricultural history, but also faces challenges to support fish farming. The Grenada government, in partnership with the United Nations, has launched a “Zero-hunger Initiative” and “Climate Smart Agricultural Program” to provide opportunities for sustainable tilapia (Oreochromis mossambicus, O. niloticus, O. aureus) aquaponics. The goal is to improve food security, provide rural employment, and reduce exploitation of natural fisheries. The Aquatic Animal Medicine Research Laboratory at St. George’s University, School of Veterinary Medicine has developed a collaborative program to enhance the productivity and sustainability of aquaculture in Grenada through capacity building and training, disease diagnostics, veterinary support, and applied research.
A key component of this program is to identify infectious diseases of concern that may limit the industry. This study investigated pathogens of feral tilapia from three waterways (n=60 fish per waterway) known to be sources of fish for farmers, and documented diagnostic findings from seven aquaponics farms (n=25). Diagnostic methods used in this study included wet mount microscopy of gill and skin, aerobic bacterial culture of spleen and kidney, virus isolation, and pathogen-specific PCR. Pathogens identified in feral tilapia are similar to those identified in aquaponics systems. Results showed a relatively high incidence of parasites including Ichthyopthirius multifilis, Dactylogyrus spp., motile and sessile peritrichs, and encysted metacercaria. Bacterial pathogens thus far have been opportunistic including Aeromonas spp. and Plesiomonas spp. No viral etiologies have been identified to date. These results indicate that aquaculture in Grenada is largely affected by parasitic and opportunistic bacteria with relatively little impact by primary pathogens.
This emphasizes the importance of appropriate husbandry and biosecurity practices within local farms and international biosecurity for importation of fish and fish products into the country. Results additionally provide a baseline list of endemic pathogens to guide disease outbreak investigations.