Aquaculture of cobia

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A female broodstock cobia weighing about 8 kilograms prior to transport to broodstock holding tanks Rachycentron canadum.jpg
A female broodstock cobia weighing about 8 kilograms prior to transport to broodstock holding tanks

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

Cobia species of fish

The cobia is a species of perciform marine fish, the only representative of the genus Rachycentron and the family Rachycentridae. Other common names include black kingfish, black salmon, ling, lemonfish, crabeater, prodigal son and black bonito.

Offshore aquaculture

Offshore aquaculture, also known as open ocean aquaculture, is an emerging approach to mariculture or marine farming where fish farms are moved some distance offshore. The farms are positioned in deeper and less sheltered waters, where ocean currents are stronger than they are inshore. Existing ‘offshore’ developments fall mainly into the category of exposed areas rather than fully offshore. As maritime classification society, DNV GL, has stated, development and knowledge-building are needed in several fields for the available deeper water opportunities to be realized.

Contents

Their rapid growth rate in aquaculture, as well as the high quality of their flesh, makes cobia potentially one of the more important potential marine fish for aquaculture production. [3] Currently, cobia are cultured 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 is the third largest producer of farmed cobia in the world where production was estimated at 1500 tonnes in 2008. [2] The possibility is also being examined of growing hatchery reared cobia in offshore cages around Puerto Rico and the Bahamas. [5]

Hatchery facility for incubating and hatching animals

A hatchery is a facility where eggs are hatched under artificial conditions, especially those of fish or poultry. It may be used for ex-situ conservation purposes, i.e. to breed rare or endangered species under controlled conditions; alternatively, it may be for economic reasons.

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 during transport from nursery tanks or inshore cages out to grow-out cages. Also, diseases in the nursery stage and the grow-out culture can result in low survival rates and a poor harvest. [2]

Mortality rate measure of the number of deaths in a population

Mortality rate, or death rate, is a measure of the number of deaths in a particular population, scaled to the size of that population, per unit of time. Mortality rate is typically expressed in units of deaths per 1,000 individuals per year; thus, a mortality rate of 9.5 in a population of 1,000 would mean 9.5 deaths per year in that entire population, or 0.95% out of the total. It is distinct from "morbidity", which is either the prevalence or incidence of a disease, and also from the incidence rate.

Production

Cobia fingerlings in aquaculture Cobia fingerlings.jpg
Cobia fingerlings in aquaculture

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, or broodfish, are a group of mature individuals used in aquaculture for breeding purposes. Broodstock can be a population of animals maintained in captivity as a source of replacement for, or enhancement of, seed and fry numbers. These are generally kept in ponds or tanks in which environmental conditions such as photoperiod, temperature and pH are controlled. Such populations often undergo conditioning to ensure maximum fry output. Broodstock can also be sourced from wild populations where they are harvested and held in maturation tanks before their seed is collected for grow-out to market size or the juveniles returned to the sea to supplement natural populations. This method, however, is subject to environmental conditions and can be unreliable seasonally, or annually. Broodstock management can improve seed quality and number through enhanced gonadal development and fecundity.

Oil of clove oil of cloves

Oil of clove, also known as clove oil, is an essential oil extracted from the clove plant, Syzygium aromaticum. It has the CAS number 8000-34-8.

Gill respiratory organ

A gill is a respiratory organ found in many aquatic organisms that extracts dissolved oxygen from water and excretes carbon dioxide. The gills of some species, such as hermit crabs, have adapted to allow respiration on land provided they are kept moist. The microscopic structure of a gill presents a large surface area to the external environment. Branchia is the zoologists' name for gills.

Broodstock are reared in controlled ponds or tanks. These tanks are often stocked with 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]

Cleaner fish tribe of fishes

Cleaner fish are fish that provide a service to other species by removing dead skin and ectoparasites. Although the animal being cleaned typically is another fish, it can also involve aquatic reptiles, mammals or octopuses. The cleaning symbiosis is an example of mutualism, an ecological interaction that benefits both parties involved. However, the cleaner fish may sometimes cheat and consume mucus or tissue, thus creating a form of parasitism. A wide variety of fish including wrasse, cichlids, catfish, pipefish, lumpsuckers and gobies display cleaning behaviors. Similar behavior is found in other groups of animals, such as cleaner shrimps.

The eggs are collected with a surface skimmer 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 conjunction with live algae in rearing tanks has been shown to improve the way larvae grow and survive in recirculating systems [9]

Optimal rearing densities are required when rearing larvae. Even though water quality and food can be controlled, it has been shown that high rearing densities may still affect growth and survival of the larvae through responses related 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 metamorphose to gill respiration 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 ponds or shallow, near-shore submerged cages.

Juveniles thrive on a wide range of protein and lipid, 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 as 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 a reduction occurs in growth rates 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 transferred to open ocean cages for final the grow-out when they reach 6–10 kilograms. [5] [7] The growth rate and survival rate of cobia during grow-out stages in open water cages throughout the Caribbean and Americas vary from as little as 10% up to 90%. [17] Low survival rates are mainly due to disease, but also to shark attacks which tear holes in the nets of cages 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 occurring between sexes. Females grow faster and have been shown to be significantly longer and heavier within year classes. [18] [5] [7]

Diseases

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 less polluted open water environments can produce better products, and the high flushing rates experienced in the open ocean reduces the effect of effluents on benthic communities.

However, such operations require more developed infrastructure than near-shore aquaculture systems, which makes them expensive. Offshore sites have access difficulties and much higher labour costs.

See also

Related Research Articles

Mariculture economic sector

Mariculture is a specialized branch of aquaculture involving the cultivation of marine organisms for food and other products in the open ocean, an enclosed section of the ocean, or in tanks, ponds or raceways which are filled with seawater. An example of the latter is the farming of marine fish, including finfish and shellfish like prawns, or oysters and seaweed in saltwater ponds. Non-food products produced by mariculture include: fish meal, nutrient agar, jewellery, and cosmetics.

Fish farming Raising fish commercially in enclosures

Fish farming or pisciculture involves raising fish commercially in tanks or enclosures such as fish ponds, usually for food. It is the principal form of aquaculture, while other methods may fall under mariculture. A facility that releases juvenile fish into the wild for recreational fishing or to supplement a species' natural numbers is generally referred to as a fish hatchery. Worldwide, the most important fish species produced in fish farming are carp, tilapia, salmon, and catfish.

Milkfish species of fish

The milkfish is the sole living species in the family Chanidae. However, there are at least five extinct genera from the Cretaceous.

Indian prawn species of crustacean

The Indian prawn, is one of the major commercial prawn species of the world. It is found in the Indo-West Pacific from eastern and south-eastern Africa, through India, Malaysia and Indonesia to southern China and northern Australia. Adult shrimp grow to a length of about 22 cm (9 in) and live on the seabed to depths of about 90 m (300 ft). The early developmental stages take place in the sea before the larvae move into estuaries. They return to the sea as sub-adults.

Fish hatchery place for artificial breeding, hatching and rearing through the early life stages of fish

A fish hatchery is a place for artificial breeding, hatching, and rearing through the early life stages of animals—finfish and shellfish in particular. Hatcheries produce larval and juvenile fish, shellfish, and crustaceans, primarily to support the aquaculture industry where they are transferred to on-growing systems, such as fish farms, to reach harvest size. Some species that are commonly raised in hatcheries include Pacific oysters, shrimp, Indian prawns, salmon, tilapia and scallops. The value of global aquaculture production is estimated to be US$98.4 billion in 2008 with China significantly dominating the market; however, the value of aquaculture hatchery and nursery production has yet to be estimated. Additional hatchery production for small-scale domestic uses, which is particularly prevalent in South-East Asia or for conservation programmes, has also yet to be quantified.

Pacific oyster species of mollusc

The Pacific oyster, Japanese oyster, or Miyagi oyster, previously and currently also known as Crassostrea gigas, considered by part of the scientific community to be the proper denomination as an accepted alternative in WoRMS, is an oyster native to the Pacific coast of Asia. It has become an introduced species in North America, Australia, Europe, and New Zealand.

Oyster farming commercial growing of oysters

Oyster farming is an aquaculture practice in which oysters are bred and raised mainly for their pearls, shells and inner organ tissue, which is eaten. Oyster farming was practiced by the ancient Romans as early as the 1st century BC on the Italian peninsula and later in Britain for export to Rome. The French oyster industry has relied on aquacultured oysters since the late 18th century.

Aquaculture of tilapia

Tilapia has become the third most important fish in aquaculture after carp and salmon; worldwide production exceeded 1.5 million metric tons in 2002 and increases annually. Because of their high protein content, large size, rapid growth, and palatability, a number of coptodonine and oreochromine cichlids—specifically, various species of Coptodon, Oreochromis, and Sarotherodon—are the focus of major aquaculture efforts.

Aquaculture in Australia

Aquaculture in Australia is the country's fastest growing primary industry, accounting for 34% of the total gross value of production of seafood. 10 species of fish are farmed in Australia, and production is dominated by southern bluefin tuna, Atlantic salmon and barramundi. Mud crabs have also been cultivated in Australia for many years, sometimes leading to over-exploitation. Traditionally, this aquaculture was limited to pearls, but since the early 1970s, there has been significant research and commercial development of other forms of aquaculture, including finfish, crustaceans, and molluscs.

<i>Tectus niloticus</i> species of mollusc

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Scallop aquaculture

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<i>Holothuria scabra</i> species of echinoderm

Holothuria scabra, or the sandfish, is a species of sea cucumber in the family Holothuriidae. It was placed in the subgenus Metriatyla by Rowe in 1969 and is the type species of the subgenus. Sandfish are harvested and processed into "beche-de-mer" and eaten in China and other Pacific coastal communities.

Octopus aquaculture

The development of octopus aquaculture, the farming of octopus, is being driven by strong market demands in the Mediterranean and in South American and Asian countries. Octopus live short lives, growing rapidly and maturing early. They typically reach two or three kilograms. There is little overlap between successive generations.

Aquaculture of sea cucumbers

Sea cucumber stocks have been overexploited in the wild, resulting in incentives to grow them by aquaculture. Aquaculture means the sea cucumbers are farmed in contained areas where they can be cultured in a controlled manner. In China, sea cucumbers are cultured, along with prawns and some fish species, in integrated multi-trophic systems. In these systems, the sea cucumbers feed on the waste and feces from the other species. In this manner, what would otherwise be polluting byproducts from the culture of the other species become a valuable resource that is turned into a marketable product.

Holothuria spinifera, the brown sandfish, is a species of sea cucumber in the family Holothuriidae. It is placed in the subgenus Theelothuria, making its full name Holothuria (Theelothuria) spinifera. In India it is known as "cheena attai" or "raja attai". It lives in tropical regions of the west Indo-Pacific Ocean at depths ranging from 32 to 60 metres. It is fished commercially to produce "beche-de-mer".

<i>Centropomus parallelus</i> species of fish

Centropomus parallelus is a species of fish in the family Centropomidae, the snooks and robalos. It is known by several common names, including fat snook, smallscale fat snook, little snook, and chucumite. It is native to the western Atlantic Ocean and Gulf of Mexico, its distribution extending from southern Florida in the United States to southern Brazil near Florianópolis.

ICAR - Central Institute of Fisheries Education, Rohtak also called as ICAR-CIFE Rohtak is one of the regional research and education campus of the Central Institute of Fisheries Education (CIFE), which is a Deemed to be University and institution of higher learning for fisheries science.

References

  1. ↑ Kaiser, J.B. & Holt, G.J. 2004. Cobia: a new species for aquaculture in the US. World Aquaculture, 35: 12–14
  2. 1 2 3 4 5 Liao, I.C., Huang, T.S., Tsai, W.S., Hsueh, C.M., Chang, S.L. & Leano, E.M. (2004) "Cobia culture in Taiwan: current status and problems" Aquaculture, 237: 155–65.
  3. ↑ Nhu, V. C., Nguyen, H. Q., Le, T. L., Tran, M. T., Sorgeloos, P., Dierckens, K., Reinertsen H., Kjorsvik, E. & Svennevig, N. (2011) Cobia Rachycentron canadum aquaculture in Vietnam: recent developments and prospects Aquaculture315: 20–25
  4. ↑ Rachycentron canadum FAO Cultured Aquatic Species Information, Rome. Updated 23 May 2007.
  5. 1 2 3 4 5 6 7 Benetti, D. D., Orhun, M. R., Zink, I., Cavalin, F. G., 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. ↑ Benetti, D.D., Alarcon, J.F., Stevens, O.M., O'Hanlon, B., Rivera, J.A., Banner-Stevens, G. and Rotman, F.J. (2003) Advances in hatchery and growout technology of marine finfish candidate species for offshore aquaculture in the Caribbean Proceedings of the Gulf and Caribbean Fisheries Institute, 54: 475–487
  7. 1 2 3 4 5 Benetti, Daniel D.; Orhun, Mehmet R.; Sardenberg, Bruno; O'Hanlon, Brian; Welch, Aaron; Hoenig, Ronald; Zink, Ian; Rivera, José A.; Denlinger, Bristol; Bacoat, Donald; Palmer, Kevin; Cavalin, Fernando (2008). "Advances in hatchery and grow-out technology of cobia Rachycentron canadum (Linnaeus)". Aquaculture Research. 39 (7): 701–711. doi:10.1111/j.1365-2109.2008.01922.x.
  8. ↑ Faulk, Cynthia K.; Holt, G. Joan (2003). "Lipid Nutrition and Feeding of Cobia Rachycentron canadum Larvae". Journal of the World Aquaculture Society. 34 (3): 368–378. doi:10.1111/j.1749-7345.2003.tb00074.x.
  9. ↑ Faulk, C.K. & Holt, G.J. (2005) Advances in rearing cobia Rachycentron canadum larvae in recirculating aquaculture systems: live prey enrichment and greenwater culture Archived 2012-04-25 at the Wayback Machine Aquaculture, 249: 231–243
  10. ↑ Hitzfelder, Glenn M.; Holt, G. Joan; Fox, Joe M.; McKee, David A. (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 (2): 204–209. doi:10.1111/j.1749-7345.2006.00028.x.
  11. ↑ Denson, Michael R.; Stuart, Kevin R.; Smith, Theodore I. J.; Weirlch, Charles R.; Segars, Al (2003). "Effects of Salinity on Growth, Survival, and Selected Hematological Parameters of Juvenile Cobia Rachycentron canadum". Journal of the World Aquaculture Society. 34 (4): 496–504. doi:10.1111/j.1749-7345.2003.tb00088.x.
  12. ↑ Faulk, C.K. & Holt, G.J. (2006) "Responses of cobia Rachycentron canadum larvae to abrupt or gradual changes in salinity" Archived 2012-04-25 at the Wayback Machine Aquaculture, 254: 275–283
  13. 1 2 Chou, R.L., Su, M.S. & Chen, H.Y. (2001) "Optimal dietary protein and lipid levels for juvenile cobia (Rachycentron canadum). Aquaculture" 193: 81–89
  14. ↑ Wang, J.T., Liu, Y.J., Tian, L.X., Mai, K.S., Du, Z.Y., Wang, Y. & Yang, H.J. (2005) "Effect of dietary lipid level on growth performance, lipid deposition, hepatic lipogenesis in juvenile cobia (Rachycentron canadum)" Archived 2012-04-25 at the Wayback Machine Aquaculture, 249: 439–447
  15. ↑ Chou, R.L., Her, B.Y., Su, M.S., Hwang, G., Wu, Y.H. & Chen, H.Y. (2004) "Substituting fish meal with soybean meal in diets of juvenile cobia Rachycentron canadum" Archived 2011-12-15 at the Wayback Machine Aquaculture, 229: 325–333
  16. ↑ Craig, S.R., Schwarz, M.H. & McLean, E. (2006) "Juvenile cobia (Rachycentron canadum) can utilize a wide range of protein and lipid levels without impacts on production characteristics" Archived 2012-04-25 at the Wayback Machine Aquaculture, 261:384–39
  17. 1 2 3 Benetti, D. D., O’Hanlon, B., Rivera, J. A., Welch, A. W., Maxey, C. & Orhun, M. R. (2010) "Growth rates of cobia (Rachycentron canadum) cultured in open ocean submerged cages in the Caribbean" [ permanent dead link ]Aquaculture302: 195–201
  18. ↑ Franks, J.S., Warren, J.R. & Buchanan, M.V. (1999) "Age and growth of cobia, Rachycentron canadum, from the northeastern Gulf of Mexico" Fishery Bulletin97: 459–471
  19. ↑ Chen, S-C; Kou, R-J; Wu, C-T; Wang, P-C; Su, F-Z (2001). "Mass mortality associated with a Sphaerospora-like myxosporidean infestation in juvenile cobia, Rachycentron canadum (L.), marine cage cultured in Taiwan". Journal of Fish Diseases. 24 (4): 189–195. doi:10.1046/j.1365-2761.2001.00287.x.
  20. ↑ Naylor, R. & Burke, M. (2005) "Aquaculture and ocean resources: raising tigers of the sea" Annu. Rev. Environ. Resour.30: 185–218
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