Seed production of common snook (Centropomus undecimalis) in Cuba

Seed production of common snook (Centropomus undecimalis) in Cuba

Masatoshi Futagawa

December 3, 2013

Since 2008 JICA-CIP project is running, development of seed production technique about mutton snapper (Lutjanus analis) and common snook (Centropomus undecimalis), at Santa Cruz del Sur in Cuba. The project produced some snapper and snook juveniles in 2013 with semi intensive seed production method with copepods (SISPC). It is the first history of successful marine seed production about both species in Cuba, and second of the world about common snook especially.

Common snook has high demand in the market and sports fishing in Central America. However, seed production of the species is very difficult due to its small mouth which unable to intake rotifer at larva stage. The project introduced maturation inducement by HCG (Human chorionic gonadotropin) for broodstock and SISPC, rearing large pond and fed wild copepoda nauplius, for larva culture. The project collected around one million eggs and produced 3 thousand juveniles (TL 6 cm, BW 2 g) at 71 dph (days post hatch-out). The fish are reared intensively and have showed high growth. The project preparing semi intensive culture at vacant shrimp pond for reduce production cost and easy culture.

Maturation inducement and spawning

According to Carlos Yanes Roca and Kevan L. Main, rising of water temperature triggered to spawning of common snook from May to September, June and July especially, and the fish spawn within 3 days after new or full moon in Florida. Our wild captured broodstock (2 years rearing, 7 females and 20 males, ABW 2.5 Kg) showed well appetite which related to water temperature increasing, from July 2013. The project added fish oil, supplement for human, and shrimp to moist pellet for increase egg quality.

On August 5 (new moon), 5 females showed over 400 µm egg diameters and 7 males had sperm according to cannulation even sperm and eggs were not observed to pressed abdomen. We injected HCG (500IU/Kg) at dorsal part of all fishes (male and female). Spawning (977 thousand eggs) occurred on following day and a little more egg on 8^th and 9^th. The eggs showed a diameter of 665±14μm with 1 to 3 oil droplet, well floating egg rate (91.8 %) and hatch-out rate (78.3 %) and survival rate until 2 dph was over 80 %.

Seed production under SISPC

Semi intensive seed production method with copepods (SISPC) is producing seeds at large tank or pond and feed propagation wild copepods under low density culture. The advantages are: do not require cultured rotifer which needs several equipment and intensive management, and easy to produce seeds. Disadvantages are low survival (1 -5 %) and difficult to estimate survival.

The project stocked larvae (300 thousand, 2 dph, SL 2 mm) at reservoir (1600 ton) on August 9. We gave aeration with 3 air stones from 5 dph, applied ammonia sulfate (1 ppm) and super phosphate (2.2 ppm) on 16 dph, and supplied water (800 ton whole culture period) when low water level. From 15 dph, several larvae were observed at surface and feeding started. During culture period, we fed rotifer (106 million, unenriched), Artemia nauplii (64 million), fish eggs (11 million), ground fish meat (5.3 Kg), moist pellet (3.0 Kg) and dry crumble (8.7 Kg). Also, coconuts leaves were installed for shelter and confirmed that fries lived on 37 dph. Wild small crabs were observed inside stomach on 53 dph and dry pellet was taken 4 % (dry weight) of body weight based on stomach contents on 68 dph.

Based on observation and sampling, fries were shown at surface from 16 dph, body shows transparent, orange mark at opercle by blood, and air bladder appear clearly. On 19 dph, lower jaw extended as sign of carnivorous, TL reached 10 mm. Black spot appeared at tip of 1^st dorsal fin on 23 dph that remained until juvenile stage. On 27 dph TL reached 12 mm, the head grows big due to development of jaws. Fry grew TL 17 mm and BW 0.04 g and black spot occupied half of the fin. On 46 dph, grew TL 26 mm and BW 0.2 g, spine of anal fin extended to improve exercise capacity to capture other fish possibly. Fry grew to TL 42 mm and BW 0.8 g on 55 dph, show high growth (refer growth curve at figure below), and anal fin spine extend longer. On 66 dph, fry grew TL 53 mm and BW 1.6 g and body color turn to silver due to development of scales, and the black spot shrunk. On October 17, juvenile (3017 fishes, 71 dph, TL 59 mm, SL 47 mm, BW 2.1 g) were collected (SR 1.0 %) by purse-net and stocked two 10 ton tanks according to size.

It is proved that SISPC produce common snook seed that fed ground fish meat and supply some water without sophisticate rotifer culture and intensive care. Especially common snook seed production is very difficult with intensive seed production fed with rotifer due to its small mouth during larva stage. Even so, SISPC has task about improvement of survival (reduce cannibalism) that occurred 40 to 60 dph. For the next trial, we are planning to install more shelters, early harvest or partial harvest to improve survival. Also, culture with small tank (40 to 90 ton) and select size by net and harvest easily.

In addition to that, the juveniles showed well appetite of moist pellet and fast growth, large group (719 n) reached 15 g and small group (2019 n) grew 4 g on 91 dph with FCR 1.5. We are planning to rear experiment at vacant shrimp pond that reduces production cost and culture easily.