Pacific Threadfin

Commonly known as Pacific Threadfin or Six Finger Threadfin Also known by the common name moi, or the “fish of kings” Fingerlings from aquaculture have been used to replenish depleted fisheries, now over 70% of all specimens caught were raised in aquaculture facilities Modern aquaculture pioneered by Oceanic Institute in Waimanolo, HI Polydactylus sexfilis

$4-$7/lbs FCR $2.50-$4.25 production cost/lbs. Still exclusively grown in Hawaii, but shipped to markets on the mainland, Asia, and Europe Highly popular fish due to its taste and ability to be prepared essentially any way Marketplace

Loko i’a Ancient form of aquaculture used in Hawaii Walled ponds built along the coast to trap and raise fish At low tide nutrient-rich water drained from the pond and attracted additional fish to be trapped So efficient that one pond could feed an entire community Still utilized today by placing stock inside PVC cages within the original loko i’a

Reproduction Protandrous hermaphrodites Spawn for 3-6 nights 8-10 days after the full moon, year round in optimal conditions, with highest egg viability in the summer months By dawn viable eggs reach the embryo stage Known as prolarva until D3 when feeding begins, then postlarva until metamorphosis to juvenile form at D21-D25

Current Aquaculture 6-8 month grow-out period, >90% survival rate Eggs are hatched and raised in recirculating aquaculture systems for the first 25 days Moved to nursery tanks with a strong circular current and continuous feeding to prevent cannibalism until moving to grow-out at D60 Grow-out techniques include: loko i’a, intensive round tank (RAS), off-shore cages, and raceways

Requirments Larvae eat algae paste, rotifers, and Artemia sp. napulii before weaning to a dry diet Dry diet needs 50% protein and 12% lipid content Broodstock are fed a diet of frozen squid, smelt, and shrimp DO: >5ppm Salinity: >20ppt, preferable 33-36ppt Temperature: 24-30°C

Problems Power outages cause population crashes in hatcheries and nurseries Back up generators required, especially during peak spawning season High losses due to cannibalism immediately after metamorphosis Keeping nursery tanks shallow and a circular current moving prevents food stratification, which eliminates the size differential that prompts the cannibalism