Cobia: Difference between revisions
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Cobia are sold commercially, and command a high price for their firm texture and excellent flavor. However, there is no directed fishery owing to their solitary nature. They have been farmed in [[aquaculture]] for this reason. The meat is usually sold fresh. They are typically served in the form of grilled or poached fillets. Chefs [[Jamie Oliver]] and [[Mario Batali]] each cooked several dishes made with cobia in the "Battle Cobia" episode of the [[Food Network]] program ''[[Iron Chef America]]'', which first aired in January 2008. [[Thomas Keller]]'s [[French Laundry]] offers Cobia on its tasting menu.<ref>[http://www.tkrg.org/upload/fl_menu.pdf French Laundry menu, September 2011]</ref> |
Cobia are sold commercially, and command a high price for their firm texture and excellent flavor. However, there is no directed fishery owing to their solitary nature. They have been farmed in [[aquaculture]] for this reason. The meat is usually sold fresh. They are typically served in the form of grilled or poached fillets. Chefs [[Jamie Oliver]] and [[Mario Batali]] each cooked several dishes made with cobia in the "Battle Cobia" episode of the [[Food Network]] program ''[[Iron Chef America]]'', which first aired in January 2008. [[Thomas Keller]]'s [[French Laundry]] offers Cobia on its tasting menu.<ref>[http://www.tkrg.org/upload/fl_menu.pdf French Laundry menu, September 2011]</ref> |
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==Aquaculture |
==Aquaculture== |
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{{main|Aquaculture of cobia}} |
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Cobia, ''Rachycentron canadum'', is considered one of the most suitable candidates for warm, open-water marine fish [[aquaculture]] in the world. <ref>Kaiser, J.B. & Holt, G.J. 2004. Cobia: a new species for aquaculture in the US. ''World Aquaculture'', 35:12-14</ref> <ref name="Liao" /> Their rapid growth rate in aquaculture, as well as the high quality of the flesh makes cobia potentially one of the most important marine fish for future aquaculture production.<ref>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. ''Aquaculture'' 315:20-25</ref> |
Cobia, ''Rachycentron canadum'', is considered one of the most suitable candidates for warm, open-water marine fish [[aquaculture]] in the world. <ref>Kaiser, J.B. & Holt, G.J. 2004. Cobia: a new species for aquaculture in the US. ''World Aquaculture'', 35:12-14</ref> <ref name="Liao" /> Their rapid growth rate in aquaculture, as well as the high quality of the flesh makes cobia potentially one of the most important marine fish for future aquaculture production.<ref>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. ''Aquaculture'' 315:20-25</ref> |
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Greater depths, stronger currents and distance from shore all act to reduce 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. <ref>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</ref> However, some problems still exist in cobia culture that needs to be addressed and solved for increasing production. These include high [[mortality]] due to stress during transport from nursery tanks or inshore cages out to grow-out cages. Also diseases during nursery and growout culture can result in low survival, and consequently poor harvest. <ref name="Liao" /> |
Greater depths, stronger currents and distance from shore all act to reduce 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. <ref>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</ref> However, some problems still exist in cobia culture that needs to be addressed and solved for increasing production. These include high [[mortality]] due to stress during transport from nursery tanks or inshore cages out to grow-out cages. Also diseases during nursery and growout culture can result in low survival, and consequently poor harvest. <ref name="Liao" /> |
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===Production=== |
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Wild [[broodstock]] of cobia are captured with the help of professional fishermen. Captured fish are transferred into onboard-tanks on a transport vessel to be transported to hatchery facilities. Fish are [[anesthetized]] with clove oil if required to reduce stress during transportation. Broodstock fish are treated to remove any [[ectoparasites]] from their gills and skin that could later inhibit or later proliferate after transfer to maturation tanks. <ref name="Benetti2007">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. ''RSMAS'', p. 1-21</ref> <ref name="Benetti2008">Benetti, D. D., Orhun, M. R., Sardenberg, B., O’Hanlon, B., Welch, A., Hoenig, R. Zink, I., Rivera, J. A., Denlinger, B., Bacoat, D., Palmer, K. & Cavalin, F. 2008. Advances in hatchery and grow-out technology of cobia ''Rachycentron canadum'' (Linnaeus). ''Aquaculture Research'' 39:701-711</ref> |
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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. Diet consists of formulated feeds as well as squid and sardines. Vitamin and mineral supplements are added to the broodstock diet. Spawning is controlled by manipulating water temperature. <ref name="Benetti2007"/> <ref name="Benetti2008"/> |
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Eggs are collected using a surface skimmer and mesh screen bags. Eggs are transferred to incubation tanks where they are treated with 100ppm formalin for an hour to disinfect them. This provides a good indication of potential egg quality and viability. <ref name="Benetti2007"/> |
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[[Phytoplankton]] concentrations are maintained as well as enriched ''Artemia'' nauplii and rotifers are fed to the cobia larvae 3-7 days after they hatch from the eggs. The larvae require rotifers for a minimum of 4 days from hatch. <ref>Faulk, C.K. & Holt, G.J. 2003. Lipid nutrition and feeding of cobia ''Rachycentron canadum'' larvae. ''Journal of the World Aquaculture Society'', 34:368-378</ref> Presence of enriched live prey in conjunction with live algae in rearing tanks has been shown to improve the growth and survival of larvae in recirculating systems. <ref>Faulk, C.K. & Holt, G.J. 2005. Advances in rearing cobia ''Rachycentron canadum'' larvae in recirculating aquaculture systems: live prey enrichment and greenwater culture. ''Aquaculture'', 249: 231-243</ref> |
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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. <ref>Hitzfelder, G.M., Holt, G.J., Fox, J.M. & McKee, D.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'', 37:204-209</ref> In addition, juveniles exposed to varying salinities exhibited sustained growth and improved health at higher salinities, 15 and 30 ppt. <ref>Denson, M.R., Stuart, K.R., Smith, T.I.J., Weirich, C.R. & 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</ref> |
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Cobia larvae [[metamorphose]] to gill respiration 11-15 days post hatching. At 15-25 days post hatching, cobia are weaned onto commercially available formulated feeds. Rearing cobia larvae at salinities as low as 15ppt is possible. <ref>Faulk, C.K. & Holt, G.J. 2006. Responses of cobia ''Rachycentron canadum'' larvae to abrupt or gradual changes in salinity. ''Aquaculture'', 254:275-283</ref> Fully weaned fingerlings weighing up to 1g are transferred to juvenile culture tanks. <ref name="Benetti2007"/> <ref name="Benetti2008"/> Later cobia juveniles can be raised in ponds or shallow, near-shore submerged cages. |
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Juveniles can thrive on a wide range of protein and lipid but will benefit from optimal dietary protein and lipid levels. After an 8-week growth trial, juvenile cobia displayed a peak in their weight gain with a dietary protein concentration of 44.5%. <ref name="Chou2001">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</ref> Weight gain is also likely to increase with increased lipid content in diet, however, levels exceeding 15-18% produces little practical benefit because of higher fat accretion in cobia. <ref name="Chou2001"/> <ref>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''). ''Aquaculture'', 249:439-447</ref> In addition, up to 40% of [[fish meal]] protein can be replaced by [[soybean meal]] protein without causing reduction in growth and protein utilization. <ref>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''. ''Aquaculture'', 229:325-333</ref> <ref>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. ''Aquaculture'', 261:384-39</ref> Cobia also currently has low feed conversion rates, yielding 1kg of fish biomass for 1.8 kg of pellets containing 50% fish meal. <ref name="Benetti2010">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. ''Aquaculture'' 302:195-201</ref> |
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They are then transferred to open ocean cages for final growout reaching 6-10kgs. <ref name="Benetti2007"/> <ref name="Benetti2008"/> Growth and survival rates of cobia during growout stages in open water cages have varied considerably from as low as 10% to as high as 90% throughout the Americas and Caribbean. <ref name="Benetti2010" /> Low survival rates are primarily due to disease outbreaks, but also due to shark attacks which can tear holes in the nets of cages in Bahamas and Puerto Rico allowing caged cobia to escape. However, better growth rates were experienced in offshore cage farms in Taiwan. <ref name="Liao" /> In addition, cobia are considered to be [[gonochoristic]], exhibiting differential growth rates between sexes where females grow faster and have been shown to be significantly longer and heavier within year classes. <ref>Franks, J.S., Warren, J.R. & Buchanan, M.V. 1999. Age and growth of cobia, ''Rachycentron canadum'', from the northeastern Gulf of Mexico. ''Fishery Bulletin'' 97:459-471</ref> <ref name="Benetti2007"/> <ref name="Benetti2008"/> |
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===Diseases=== |
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* [[Nephrocalcinosis]] (kidney stones) are considered a major cause of mortality during both the hatchery and growout stages. These stones vary in size from 2- 6mm in diameter in the kidney or block the urethra. This condition is not fully understood, but is thought to a symptom of prolonged exposure to free carbon dioxide greater than 10-20mg/L. Another cause could be an imbalance in the calcium to magnesium ratio of the diet. <ref name="Benetti2010"/> |
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* ''Sphaerospora''-like myxosporean infection causing 90% mortality in 1 month in a marine cage cultured in Taiwan. <ref>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'', 24:189-195</ref> |
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===Benefits & Constraints=== |
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[[Offshore aquaculture]] of cobia is beneficial because it can avoid conflict with local fisheries, recreational activities, as well as potentially improving coastal aesthetics. <ref>Naylor, R. & Burke, M. 2005. Aquaculture and ocean resources: raising tigers of the sea. ''Annu. Rev. Environ. Resour.'' 30:185-218</ref> Furthermore, the movement of aquaculture facilities to less polluted open water environments can improve the quality of product. High flushing rates experienced in the open ocean can also reduce the impact of effluents on benthic communities. |
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However, such operations can be expensive and require more developed infrastructure than near-shore aquaculture systems. Offshore sites are also more difficult to access and have phenomenally higher labour costs. Additionally, there is a need for further research prior to initializing such operations with various species. |
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==References== |
==References== |
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Revision as of 09:34, 1 October 2011
| Cobia | |
|---|---|
| |
| Scientific classification | |
| Kingdom: | |
| Phylum: | |
| Class: | |
| Order: | |
| Family: | Rachycentridae
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| Genus: | Rachycentron Kaup, 1826
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| Species: | R. canadum
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| Binomial name | |
| Rachycentron canadum (Linnaeus, 1766)
| |
Cobia (Rachycentron canadum)—also known as black kingfish, black salmon, ling, lemonfish, crabeaters, aruan tasek, etc.—are perciform marine fish, the sole representative of their family, the Rachycentridae.
Description
Attaining a maximum length of 2 metres (78 inches) and maximum weight of 68 kilograms (150 pounds), cobia have elongate fusiform (spindle shaped) bodies and broad, flattened heads. Their eyes are small and their lower jaw projects slightly past the upper jaw. On the jaws, tongue and roof of the mouth are bands of villiform (fibrous) teeth. Their bodies are smooth with small scales, their dark brown coloration grading to white on the belly with two darker brown horizontal bands on the flanks. These may not be prominent except during spawning when cobia lighten in colour and adopt a more prominently striped pattern. The large pectoral fins are normally carried horizontally (rather than vertically as shown for convenience in the illustration), so that, as seen in the water they may be mistaken for a small shark. When boated, the horizontal pectoral fins enable the cobia to remain upright so that their vigorous thrashing can make them a hazard. The first dorsal fin is composed of six to nine independent, short, stout, and sharp spines. The family name Rachycentridae, from the Greek words rhachis meaning "spine" and kentron meaning "sting," is an allusion to these dorsal spines. Mature cobia have forked, slightly lunate tail fins with most fins being a dark brown. They lack air bladders.
Similar species
Cobia somewhat resemble and are most closely related to the Remora of the family Echeneidae. However, they lack the dorsal sucker of the Remora, their body is far stouter and their tail is far more developed, and forked instead of rounded. Juvenile cobia are patterned with conspicuous bands of black and white. Their tails are rounded rather than forked as in the adults.
Distribution and habitat
Cobia are pelagic and are normally solitary except for annual spawning aggregations; however, they will congregate at reefs, wrecks, harbours, buoys and other structural oases. They may also enter estuaries and mangroves in search of prey.
They are found in warm-temperate to tropical waters of the West and East Atlantic, throughout the Caribbean and in the Indo-Pacfic off India, Australia and Japan. [1] The largest taken on rod & reel was taken from Shark Bay, Australia weighing 60 kg (135 lb). They are able to tolerate a wide range of temperatures (eurythermal) and salinity (euryhaline) between 1.6 and 32.2°C and 5-44.5 ppt in the environment.[2]
Feeding habits
Cobia feed primarily on crabs, squid, and other fish. Cobia will follow larger animals such as sharks, turtles and manta rays in hope of scavenging a meal. Cobia are intensely curious fish and show no fear of boats and are known to follow other caught fish up to a boat and linger to see the action. Their predators are not well documented, but the dolphinfish (Coryphaena hippurus) is known to feed on immature cobia. Shortfin mako sharks are known to feed on adult cobia and have been seen by fishermen following cobia during their annual springtime migration in the northern Gulf of Mexico.
Life history
Cobia are pelagic spawners; that is, they release many tiny (1.2 mm) buoyant eggs into the water which become part of the plankton. The eggs float freely with the currents until hatching. The larvae are also planktonic, being more or less helpless during their first week until the eyes and mouths develop. Males mature at two years and females at three years. Both sexes lead moderately long lives of 15 years or more. Spawning takes place diurnally from April to September in large offshore congregations where females are capable of spawning up to 30 times during the season. [3] Up to 20 individual spawns may take place in one season, with intervals of about one to two weeks. Cobia are frequently parasitized by nematodes, trematodes, cestodes, copepods and acanthocephalans.
Migration patterns
Cobia make seasonal migrations along the coasts in search of water in their preferred temperature range. Wintering in the Gulf of Mexico, they migrate north as far as Maryland in the Summer, passing East Central Florida in March.
Utilization
Cobia are sold commercially, and command a high price for their firm texture and excellent flavor. However, there is no directed fishery owing to their solitary nature. They have been farmed in aquaculture for this reason. The meat is usually sold fresh. They are typically served in the form of grilled or poached fillets. Chefs Jamie Oliver and Mario Batali each cooked several dishes made with cobia in the "Battle Cobia" episode of the Food Network program Iron Chef America, which first aired in January 2008. Thomas Keller's French Laundry offers Cobia on its tasting menu.[4]
Aquaculture
Cobia, Rachycentron canadum, is considered one of the most suitable candidates for warm, open-water marine fish aquaculture in the world. [5] [6] Their rapid growth rate in aquaculture, as well as the high quality of the flesh makes cobia potentially one of the most important marine fish for future aquaculture production.[7]
Currently, cobia are being cultured in nurseries and grow-out offshore cages many parts of Asia and off the coast of US, Mexico and Panama. In Taiwan 100–600 g cobia are cultured for 1–1.5 years to reach 6–8 kg in size which is suitable for export to Japan. Currently, around 80% of marine cages in Taiwan are devoted to cobia culture. [6] In 2004, FAO reported that 80.6% of the world’s cobia production was by primarily China and Taiwan.[FAO] 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. [6] Following the success of cobia aquaculture in Taiwan, emerging technology is being used to demonstrate the viability of raising hatchery-reared cobia in collaboration with the private sector primarily using SeaStation™ and Aquapod™ submerged cages at exposed offshore sites in Puerto Rico and the Bahamas. [8]
Greater depths, stronger currents and distance from shore all act to reduce 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. [9] However, some problems still exist in cobia culture that needs to be addressed and solved for increasing production. These include high mortality due to stress during transport from nursery tanks or inshore cages out to grow-out cages. Also diseases during nursery and growout culture can result in low survival, and consequently poor harvest. [6]
References
Notations
- "Rachycentron canadum". Integrated Taxonomic Information System. Retrieved 30 January 2006.
- Froese, Rainer; Pauly, Daniel (eds.) (2005). "Rachycentron canadum" in FishBase. 10 2005 version.
- Froese, Rainer, and Daniel Pauly, eds. (2005). "Rachycentridae" in FishBase. May 2005 version.
- Greenberg, Idaz. Guide to Corals & Fishes of Florida, the Bahamas and the Caribbean. Seahawk Press. pp. 2–3. ISBN 0-913008-08-7.
- Applegarth, Allen. Florida Inshore Angler. p. 36.
Footnotes
- ^ Ditty, J. G. & Shaw, R. F. 1992. Larval development, distribution, and ecology of cobia Rachycentron canadum (Family: Rachycentridae) in the northern Gulf of Mexico. Fishery Bulletin, 90:668-677
- ^ Resley, M. J., Webb, K. A. & Holt, G. J. 2006. Growth and survival of juvenile cobia Rachycentron canadum cultured at different salinities in recirculating aquaculture systems. Aquaculture, 253:398-407
- ^ Brown-Peterson, N. J., Overstreet, R. M., Lotz, J. M. 2001. Reproductive biology of cobia, Rachycentron canadum, from coastal waters of the southern United States. Fish. Bull. 99:15-28
- ^ French Laundry menu, September 2011
- ^ Kaiser, J.B. & Holt, G.J. 2004. Cobia: a new species for aquaculture in the US. World Aquaculture, 35:12-14
- ^ a b c d 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, 237:155-165.
- ^ 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. Aquaculture 315:20-25
- ^ Cite error: The named reference
Benetti2007was invoked but never defined (see the help page). - ^ 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