pacific threadfin. commonly known as pacific threadfin or six finger threadfin also known by the...

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.

1.3-1.5 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’aAncient 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

ReproductionProtandrous 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 Aquaculture6-8 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

RequirmentsLarvae 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

ProblemsPower outages cause population crashes in hatcheries and

nurseriesBack up generators required, especially during peak spawning

season

High losses due to cannibalism immediately after metamorphosisKeeping nursery tanks shallow and a circular current moving

prevents food stratification, which eliminates the size differential that prompts the cannibalism