Aquaculture of cobia

Cobia , a warm water fish, is one of the most suitable candidates for offshore aquaculture . [1] [2] Cobia are large pelagic fish, up to 2 meters (78 inches) long and 68 kilograms (150 pounds) in weight. They are solitary fish except when spawning , found in warm-temperate to tropical waters.

Their rapid growth rate in aquaculture, and their high quality of their flesh, makes them one of the most important potential marine fish for aquaculture production. [3] Currently, cobia are grown in nurseries and grow-out offshore cages in many parts of Asia and off the coast of the United States, Mexico and Panama. In Taiwan cobia weighing 100-600 grams are cultured for 1-1.5 years to reach the 6-8 kilograms needed for export to Japan. Currently, around 80% of marine cages in Taiwan are devoted to cobia culture. [2] In 2004, the FAO reported that 80.6% of the world’s cobia production was by China and Taiwan. [4]After China and Taiwan, Vietnam was the third largest producer of cobalt in the world where production was estimated at 1500 tons in 2008. [2] The possibility is also being examined of growing markets in Puerto Rico and the Bahamas . [5]

Greater depths, stronger currents, and distance from shore all act to reduce the environmental impacts often associated with fin fish aquaculture. Offshore cage systems could become some of the most environmentally sustainable methods for commercial marine fish aquaculture. [6] However, some problems still exist in cobia culture that needs to be addressed and solved for increasing production. These include high mortality rates due to stress from transportation During inshore nursery tanks or cages out to grow-out cages. Also, diseases in the growing nursery and growing-out can result in low survival rates and a poor harvest. [2]

Production

Wild cobia broodstock are captured by professional fishermen. The fish are transferred into onboard-tanks on a transport vessel for transport to hatchery facilities. They are anesthetized with clove oil if Necessary to Reduce Stress During transportation. They are also treated for ectoparasites on their gills and skin that could proliferate later after transfer to maturation tanks. [5] [7]

Broodstock are reared in controlled ponds or tanks. These tanks are often stocked with a cleaner fish , Gobiosoma oceanops , as a biological control for any remaining ectoparasites. The broodstock diet includes sardines, squid and formulated feeds, as well as vitamin and mineral supplements. The water temperature is used to control spawning. [5] [7]

The eggs are collected with a surface using mesh screen bags. The eggs are transferred to incubation tanks where they are disinfected for an hour with 100 ppm formalin . [5]

Phytoplankton concentrations are maintained, and enriched Artemia nauplii and rotifers are fed to the cobia larvae for 3-7 days after They hatch. The larvae require rotifers for at least four days after hatching. [8] The presence of enriched live prey in a live and portable environment has been shown to improve the growth and survival of recirculating systems [9]

Optimal rearing densities are required when rearing larvae. Even though water can be controlled, it has been shown that high rearing densities may still affect growth and survival of the larvae through responses to crowding. [10] In addition, juveniles exposed to varying salinities exhibited sustained growth and improved health at higher salinities, 15 and 30 ppt. [11]

Cobia larvae metamorphosis to gill breathing 11-15 days post hatching. At 15-25 days post hatching, cobia are weaned onto commercial formulated feeds. Rearing cobia larvae at salinities as low as 15 ppt is possible. [12] Fully weaned fingerlings weighing up to one gram are transferred to juvenile culture tanks. [5] [7] Later cobia juveniles can be raised in shallow gold ponds, near-shore submerged cages.

Juveniles thrive on a wide range of lipid and protein, but there are optimal levels where they get the most benefit. After an 8-week growth trial, juvenile cobia displayed a peak in their weight gain with a dietary protein concentration of 44.5%. [13] Weight gain is also likely to increase the lipid content in the diet increases. However, levels exceeding 15-18% produces little practical benefit because of higher fat accretion in the cobia. [13] [14] In addition, up to 40% of fish meal protein can be substituted with soybean meal protein before reduction in growth rate and protein utilization. [15] [16]Cobia has low feed conversion rates, yielding 1 kilogram of fish biomass for 1.8 kilograms of pellets which contain 50% fishmeal . [17]

The cobia are then released to open ocean cages for grow-out when they reach 6-10 kilograms. [5] [7] The growth rate and survival rate of cobia during grow-out courses in open water cages throughout the Caribbean and the Americas as low as 10% up to 90%. [17] Low survival rates are mainly related to disease, but also to shark attacks in the Bahamas and Puerto Rico and allow caged cobia to escape. However, better growth rates were experienced in offshore cage farms in Taiwan. [2] In addition, cobia are considered to be gonochoristic, with differential growth rates between sexes. Females grow faster and heavier within a year. [18] [5] [7]

Diseases

  • Nephrocalcinosis (kidney stones) causes significant mortality during both the hatchery and grow-out stages. These stones vary in diameter from 2-6 mm in the kidney and can block the urethra. This condition is not fully understood, but is thought to be a symptom of prolonged exposure to free carbon dioxide in excess of 10 mg / L. The ratio of calcium to magnesium in the diet could also be out of balance. [17]
  • Sphaerospora -like myxosporean infection caused 90% mortality during one month in a marine cultured cage in Taiwan. [19]

Benefits and constraints

Offshore aquaculture , regardless of the species, is beneficial because it can avoid conflict with recreational activities and local fisherman, as well as potentially improving the coastal aesthetics. [20] Further, repositioning aquaculture facilities in the open water environment can produce better products, and the effect of effluents on benthic communities.

However, such operations require more developed infrastructure than nearshore aquaculture systems, which makes them expensive. Offshore sites have access to difficulties and much higher labor costs.

See also

  • List of harvested aquatic animals by weight

References

  1. Jump up^ Kaiser, JB & Holt, GJ 2004. Cobia: a new species for aquaculture in the US. World Aquaculture,35: 12-14
  2. ^ Jump up to:e Liao, IC, Huang, TS, Tsai, WS, Hsueh, CM Chang, SL & Leano, EM (2004) “Cobia Culture in Taiwan: current status and problems” Aquaculture237 : 155-65.
  3. Jump up^ Nhu, VC, Nguyen, HQ, Le, TL, Tran, MT, Sorgeloos, P., Dierckens, K., Reinertsen H., Kjorsvik, E. & Svennevig, N. (2011)Cobia Rachycentron canadum aquaculture in Vietnam: recent developments and prospectsAquaculture 315: 20-25
  4. Jump up^ Rachycentron canadum Cultured Aquatic Species Information, Rome. Updated 23 May 2007.
  5. ^ Jump up to:g Benetti, DD, Orhun, MR, Zink, I., Cavalin, FG, Sardenberg B. Palmer, K., Dnlinger, B., Bacoat, D & O ‘Hanlon, B. (2007) ‘ Aquaculture of cobia ( Rachycentron canadum ) in the Americas and the Caribbean ‘Archived July 26, 2010, at the Wayback Machine . RSMAS , p. 1-21
  6. Jump up^ Benetti, DD, Alarcon, JF, Stevens, OM, O’Hanlon, B., Rivera, JA, Banner-Stevens, G. and Rotman, FJ (2003)Advances in hatchery and growth of marine finfish candidate species for offshore aquaculture in the CaribbeanProceedings of the Gulf and Caribbean Fisheries Institute,54: 475-487
  7. ^ Jump up to:e Benetti, DD, Orhun, MR, Sardenberg, B. O’Hanlon, B. Welch, A. Hoenig, R. Zink, I., Rivera JA, Denlinger, B., Bacoat, D., Palmer, K. & Cavalin, F. (2008) Advances in hatchery and grow-out technology of cobiaRachycentron canadum (Linnaeus) Aquaculture Research, 39 : 701-711
  8. Jump up^ Faulk, CK & Holt, GJ (2003)Lipid nutrition and feeding of cobiaRachycentron canadum larvae Journal of the World Aquaculture Society,34: 368-378
  9. Jump up^ Faulk, CK & Holt, GJ (2005)Advances in rearing cobia Rachycentron canadum larvae in recirculating aquaculture systems: live prey enrichment and greenwater culture Aquaculture,249: 231-243
  10. Jump up^ Hitzfelder, GM, Holt, GJ, Fox, JM & McKee, DA (2006)”The effect of rearing density on growth and survival of cobia, Rachycentron canadum , larvae in a closed recirculating aquaculture system” Journal of the World Aquaculture Society,37: 204-209
  11. Jump up^ Denson, MR, Stuart, KR, Smith, TIJ, Weirich, CR & Segars, A. (2003)”Effects of salinity on growth, survival, and selected hematological parameters of juvenile cobia Rachycentron canadum ” Journal of the World Aquaculture Society,34: 496-504
  12. Jump up^ Faulk, CK & Holt, GJ (2006)”Responses of cobia Rachycentron canadumlarvae to abrupt or gradual changes in salinity” Aquaculture,254: 275-283
  13. ^ Jump up to:b Chou, RL, Su, MS & Chen, HY (2001), “Optimal dietary protein and lipid levels for juvenile cobia ( cobia ). Aquaculture ” 193 : 81-89
  14. Jump up^ Wang, JT, Liu, YJ, Tian, ​​LX, May, KS, Du, ZY, Wang, Y. & Yang, HJ (2005)”Effect of dietary lipid level on growth performance, lipid deposition, hepatic lipogenesis in juvenile cobia ( Rachycentron canadum ) “Aquaculture,249: 439-447
  15. Jump up^ Cabbage, RL, Her, BY, Su, MS, Hwang, G., Wu, YH & Chen, HY (2004)”Aquaculture,229: 325,Substituting fish meal with soybean meals in juvenile cobia Rachycentron canadum ” -333
  16. Jump up^ Craig, SR, Schwarz, MH & McLean, E. (2006)”Juvenile cobia (Rachycentron canadum ) can be used in a wide range of protein and lipid levels without impacts on production characteristics” Aquaculture, 261: 384-39
  17. ^ Jump up to:c Benetti, DD, O’Hanlon, B., Rivera JA, Welch, AW, Maxey, C. & Orhun, MR (2010) “Growth rates of cobia ( cobia ) cultured in open ocean submerged cages in the Caribbean ” permanent dead link ] Aquaculture 302: 195-201
  18. Jump up^ Franks, JS, Warren, JR & Buchanan, MV (1999)”Age and growth of cobia,Rachycentron canadum , from the northeastern Gulf of Mexico”permanent dead link ] Fishery Bulletin 97: 459-471
  19. Jump up^ Chen, SC, Kou, RJ, Wu, CT Wang, PC & Su, FZ (2001)”Mass mortality associated with a Sphaerospora -like myxosporidean infestation in juvenile cobia, cobia (L.) cultured marine cage in Taiwan ” Journal of Fish Diseases,24: 189-195
  20. Jump up^ Naylor, R. & Burke, M. (2005)”Aquaculture and ocean resources: raising tigers of the sea” Annu. Rev. About. Resour. 30: 185-218

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