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Pangasius hypophthalmus, a Potential Aquaculture Species for Tropical Regions of the Americas PDF  | Print |  E-mail
Michael V. McGee, Ph.D.
Caribe Fisheries Inc.


 Catfish of the genus Pangasius have been cultured as food in Southeast Asia for many years. One species in particular, Pangasius hypophthalmus, now commonly known as Pangasius or basa catfish, has proven particularly adaptable for intensive production. This catfish is native to the Mekong River of Vietnam and has been introduced throughout the region as an aquaculture species. In the past, production was limited because techniques to reproduce the fish in captivity had not been refined or widely applied. Fingerlings were collected from the wild and transferred to ponds or cages for grow out. Since 1997 the production of Pangasius in Vietnam has increased greatly due to the application of hormone spawning techniques for controlled reproduction and the development of international markets for the product.

The aquaculture potential of this species in tropical regions of the world outside of SE Asia would appear to be excellent. Until now there have been no efforts to produce Pangasius as food in the Western Hemisphere. Production of the fish as an ornamental species for the aquarium trade does occur in Florida and Puerto Rico where it is sold at a small size and marketed as the iridescent or mystic shark. While grow out potential in Florida is limited by low temperature in winter, in Puerto Rico conditions are favorable for year round production. This has led to a growing interest in establishing aquaculture of Pangasius on the island. Caribe Fisheries Inc. a tropical aquaculture farm located in western Puerto Rico produces Pangasius and is leading the effort to evaluate production yields and economics.

BIOLOGY AND CULTURE

 Pangasius hypophthalmus is a member of the Pangasiidae family of the order Siluriformes which includes all catfish. It is a tropical species native to Vietnam where it occurs in large rivers. Pangasius reach sexual maturity at 2-3years of age and can grow to 10 – 15 pounds. Females are larger than males. In nature the fish are seasonal spawners during the warmer months. In Puerto Rico the fish may be spawned from June through September when water temperatures are above 27C. Individuals may be induced to spawn more than once during this time. Females can produce as much as 60,000 ova / kg. At the time of ovulation the eggs are around 1 mm in diameter. Release of eggs and sperm can be induced by injection of hormones to ripe fish. Eggs are dry stripped from females and mixed with milt from males. Water is added to induce fertilization. The eggs are dispersed over spawning mats in hatching tanks and are highly adhesive. Hatching occurs in 22 to 24 h at 26 – 30 C. Hatching percentages are variable and may range from 20 to 80%.depending on egg quality and fertilization rate.  Larvae are free-swimming and begin feeding on artemia or similar live food 24 hours post-hatch. Cannibalism can be significant if adequate food is not provided. Fry grow rapidly and can be weaned to powdered feed beginning after around 10 days. Production of fingerlings may be accomplished by stocking in nursery ponds with established zooplankton populations. Grading of the juveniles is recommended to remove larger individuals. Fingerlings can reach 4-6 cm in 40 days post-hatch.

In Vietnam basa catfish are cultured in large floating cages in rivers or stocked into earthen ponds. . Fish are fed a prepared diet and can reach harvest size of around 1.5 kg in 8 months. Fingerlings weighing from 50-100 g are stocked into cages at a density of 5-10 kg per cubic meter. Yields from cages average 81.2 kg per cubic meter per year but up to 170 kg per cubic meter has been reported. In ponds, fingerlings are stocked at around 3000kg per hectare with yields ranging from 200 to 300 mt per hectare per year. In Puerto Rico initial production trials in ponds have resulted in excellent growth and food conversion and suggest that with additional experience and refinements yields similar to that reported from Vietnam can be achieved.

ISSUES

The impact of the increased production and exportation of the basa catfish from Vietnam is an interesting example of how global economics can affect regional production of similar products. After the United States signed a free trade agreement with Vietnam, seafood buyers began bringing quantities of Vietnamese catfish filets to the U.S. market. Because of its lower cost and similarity to domestic catfish products imports increased rapidly and by 2002 reached 18.3 million kg, or by other estimates nearly twenty percent of the US domestic market for frozen catfish filets. Since catfish farming is an important and successful aquaculture business in many southern states U.S. catfish farmers became concerned about this trend and the concomitant drop in prices paid for their domestically produced fish. As a result of intense lobbying and political pressure by catfish producer organizations Congress passed a resolution dictating that the only seafood products which could be labeled as catfish and sold in the U.S. had to be of the native species, belonging to the family Ictaluridae. Beyond this the catfish farmers filed an antidumping suit against Vietnam with the U.S. International Trade Commission (ITC) in 2002 resulting in a ruling by the Department of Commerce (DOC) adding tariffs from 32-64 percent to the imported catfish. While many in both the U.S. and Vietnam felt these actions were unfair and a violation of the free trade agreement the actions taken by the U.S. government and the catfish farmers to protect domestic producers continue to be enforced. Ironically, despite higher prices and continued efforts to disparage the Vietnamese product the publicity generated by the controversy and continued consumer demand has assisted importers of Pangasius to maintain sales. In Vietnam, catfish processors, in an attempt to accommodate production which reached over 1,000,000 mt in 2007, have developed over 65 value added products made from basa catfish and boosted domestic consumption while expanding their export market to over 60 countries throughout the world.

Pangasius from Vietnam is an aquaculture success story which has grown quickly from being a regional product to impacting markets on international scale. The extent to which aquaculture of Pangasius will be developed in tropical regions of the Western hemisphere remains to been seen however its potential appear to be excellent.  





   
 
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