FECUNDITY VACCINE FOR FISHES: AN APPROACH TO IMPROVE REPRODUCTIVE PERFORMANCES UNDER
CAPTIVITYPathogenic Vibrio are a common problem in hatchery and nursery production of Penaeid shrimp. Vibrio species are ubiquitous in the marine environment and the rise in sea temperature due to climate change has resulted in increased incidence of Vibrio globally.
Live and fresh feeds are notorious for being a source of Vibrio contamination. Maturation feeds such as polychaetes and squid, are well known to be source of Vibrio contamination into the hatchery via the broodstock and nauplii. Mass culture of algae in outdoor tanks is also a significant source of contamination.
Artemia cysts have a low bacterial load but the release of nutrients such as glycerol during the hatching process provides an ideal medium for opportunistic bacteria, including V. parahaemolyticus, V. harveyi, V. campbellii, and V. alginolyticus. The newly hatched Artemia are highly susceptible to contamination with these Vibrio and can transmit them to the shrimp. Basic washing and disinfection of the nauplii post-harvest have limited effectiveness as the Vibrio attach to the chitin of the Artemia exoskeleton.
The production of Vibrio-free Artemia requires specific disinfection regimes to eliminate Vibrio and other pathogens during the entire hatching, harvesting and post-harvest process. Use of Vibrio-free Artemia not only reduces the risk of transmission of pathogenic strains but provides additional benefits in terms of larval growth and health.
The application of enriched, Vibrio-free Artemia Instar 2 can also provide significant benefits for PL growth and health, especially during the PL stages. Recent research work shows that feeding enriched, Vibrio-free Instar 2 not only results in improved PL growth and health but also reduces the mortality of PL following a challenge with AHPND. Field trials feeding enriched Artemia for several days during the nursery or post-stocking in farms suggest that the benefits can be maintained right through to harvest.