recent developments and prospects

Transcription

1 Larvi09 Gent-Belgium Cobia (R. canadum) aquaculture in Vietnam: recent developments and prospects Van Can Nhu a,b, Quang Huy Nguyen a,c, Thanh Luu Le a, Mai Thien Tran a, Patrick Sorgeloos b, Kristof Dierckens b, Helge Reinertsen c, Elin Kjørsvik c and Niels Svennevig d (a) Research Institute for Aquaculture No1, Vietnam (b) Laboratory of Aquaculture & Artemia Reference Center, Belgium (c) Norwegian University of Science and Technology, Norway (d) Tropical Center, SINTEF Fisheries and Aquaculture, Norway Laboratory of Aquaculture & Artemia Reference Center Faculty of Bioscience Engineering Ghent University, Belgium

2 Introduction and background duction Value of aquacu ulture pro (US S$/kg) years: 3000 fold Prod uction (m t) Time (years) Cultured (mt) Captured (mt) Value of aquaculture production (US$/kg) Global l production and value of cobia (FAO, 2009) slide 2 of 24

3 23 countries and territories involved in cobia aquaculture Asia-pacific (11) PR China (25,855 mt) * Taiwan (3,998 mt) * Vietnam (1,500 mt) ** Singapore Indonesia Malaysia India Thailand Philippines Australia Japan Americas and others (12) United States Mexico Brazil France Panama Belize Guatemala Cuba Reunion/Mayotte (6 mt) * Oman Abu Dhabi Iran (*) FAO, 2007; (*) Estimated by the authors, year 2008 slide 3 of 24

4 History of cobia aquaculture in Vietnam 1998: research on reproduction commenced 1999: first success with production of 12,000 fingerlings 2002: Commercial production of 20,000 fingerlings 1999: Tested the HDPE circular floating cages for grow-out slide 4 of 24

5 Broodstock management and conditioning Cultured and conditioned in sea cages Diet based on trash fish supplemented with squid liver oil and vitamins Spawning in tanks (50-70 cubic) slide 5 of 24

6 Effects of broodstock diets on egg quality FA composition of the eggs reflected the dietary n-3 HUFA levels in the diets % Total FA Nguyen et al. accepted No significant effects of D1 dietary (0.94%) n-3 HUFA (0.94- D2 (1.31%) 1.72%) Eggs on spawning quality D3 (1.72%) D4 (RF) (1.86%) 10 % Total FA Diets D 1 D 2 D 3 D : 0 1 6:0 1 6 : 1 n :0 1 8 : 1 n :2n : 3 n : 4 n : 5 n : 6 n - 3 m o noe n e s s a tu ra t e s n-3 H U F A n -6 P U F A slide 6 of 24

7 Comparison of breeding induction methods Natural induction: recognized by big belly and chasing behavior Hormonal linduction: injection of flh-rh t20 a at μg kg -1, h Natural induction Hormonal induction Hatching rate Fertilization rate Fecundity (eggs x 1,000,000/kg) Successful spawning rate ,2 04 0,4 06 0,6 08 0, ,2 14 1,4 slide 7 of 24

8 Larviculture of cobia Intensive technology Live food production Using RAS High density (30-50 larvae/l) Semi-intensive technology Natural zooplankton 500 m 2 outdoor ponds Low density (2 larvae/l) slide 8 of 24

9 Intensive larviculture technology SL, cm) Cobia size ( Formulated diets (Proton, NRD, Bio-optima ) Enriched EG Artemia nauplii AF En. rotifers Microalgae (N. oculata) Cobia age (days) and their feeding regimes Feeding regime and growth pattern of cobia larvae and juveniles slide 9 of 24

10 Semi-intensive larviculture technology Supplementation of: - natural zooplankton - Artemia nauplii Pre-nursing in cement tanks (1-7 dph) Weaning and nursing in cement tanks (3-12 cm) Larvae obtained from broodstock in sea cages Rearing in out- door ponds (8-20 dph) Nursing in tanks or hapas in sea cages (12-20 cm) Grow-out in sea cages Diagram of cobia larviculture in semi-intensiveintensive system slide 10 of 24

11 Comparison of intensive and semi-intensive productions Finger rlings pr roductio on Semiintensive production Intensive production Years slide 11 of 24

12 Substitution of enriched rotifers by UAF (, 2009) Cobia larvae are able to ingest and digest umbrella Artemia at first feeding Umbrella Artemia only resulted in lower growth and quality by 8 dph, but no significant difference by 18 dph slide 12 of 24

13 Early co-feeding (, 2009) Early co-feeding of Proton as of 8d dph supports growth, but not survival Standard Body weight CV (%) Survivals length (mm) (mg) (%) P1-D8 18.8±2.1 a 62.5±15.5 a 47.25±5.82 b 11.4±3.2 a P2-D ±2.4 b 40.5±17.6 b 56.49±7.23 ab 14.5±2.7 a P3-D ±2.5 b 37.0±16.8 b 65.18±6.05 a 15.7±2.9 a slide 13 of 24

14 Fatty acids of cobia at different development stages (, unpubl.) DHA and other fatty acids as well as total lipids id decrease DHA/EPA ratio increased DHA tends to be preserved rather than other fatty acids. Fatt ty acid con ntent (mg/g DW W) DHA HUFA FAME Ttlli Total lipidsid DHA/EPA ,6 6, , dph 3 dph 12 dph Age of the larvae DH HA/EPA ratio slide 14 of 24

15 Effects of dietary DHA and DHA/EPA ratio (, unpubl.) High dietary DHA level and DHA/EPA ratio resulted in better growth performance (12-30 dph) Dietary DHA contents correlated negatively to cannibalism and positively to survival /day) SGR (% bw/ a a b c Ex1 (3.6) Ex2 (3.8) Ex3 (6.0) Control (3.0) Experimental diet treatments (DHA/EPA) l and cannibalis sm (%) of cobia juveniles Survival y = 0.488x R2 = , P=0.010 Cannibalism Survival DHA content (mg/g gg dw) in the diets y = x R2 = , P=0.026 slide 15 of 24

16 Husbandry factors during weaning (, 2007) Growth and survival affected by the rearing density, but not by the feeding frequency 26 a 25 SGR (% bw/day y) ab b 19 Low density (1 weanling/l) Medium density (2 weanlings/l) High density (4 weanlings/l) Rearing densities slide 16 of 24

17 Cobia farming in Vietnam slide 17 of 24

18 Grow-out pattern of cobia in sea cages (300 cubic) - Trash fish diet - SGR w =0.86% /day ( kg) - No growth when temp < 22 o C - Stop eating bl below 18C o r temperatur re Monthly aver rage sea wate (oc) Water temperature (o C) Weight (g) Cobia weig ght (mean±sd D, g) Time (months) slide 18 of 24

19 Comparison of using extruded feed (EWOS Ltd) and trash fish Advantages of extruded EWOS feed Double final weight Lower FCR Weight (g) Nguyen et al Control group Ewos group Higher biomass gained Lower feed cost (15.8%) /09/04 02/01/05 12/04/05 21/07/05 29/10/05 Culture period Control (TF) group EWOS group Stage (wt) kg kg SGR (% wt/ day) 0.50± ±0.00 FCR (dry basis) 240±0 2.40± ±0 1.80± slide 19 of 24

20 Grow-out productions of cobia in sea cages Production of cobia in Vietnam slide 20 of 24

21 Major challenges: Harsh weather conditions 7-10 storms/ season (disaster in 2005) Monsoon winds during winter Low water temperature re during winter Low growth rate, stop eating and cease growing at 18 o C Mass mortality in 2008: 15 o C for 5 weeks Shortage of locally extruded feed Imported feed for large-scale farms Trash fish for small-scale scale farms slide 21 of 24

22 Major challenges Parasites during hatchery phase: Protozoa infection during larvae & juvenile stages: Benedenia sp, Epistylis sp., Trichodina sp High mortality caused by Amyloodinium ocellatum in gills and skin juveniles Bacteria and virus: Viral Nervous Necrosis (VNN) Bacteria: Vibrio Associated with low water temperature and/or bad weather (starving) slide 22 of 24

23 Future developments Improve quality and quantity of intensive i fingerling production, selective breeding, Development of new cage types (submergible), land-based systems Local production of extruded feed, efficient diet to lower FCR Post-harvest and processing technologies and marketing slide 23 of 24

24 Thank you for your attention! ti slide 24 of 24