Development & Aid, Environment, Tierramerica

Exotic Fish Has Bad Reputation but High Yields

HAVANA, May 18 2009 (IPS) - A foreign catfish in Cuba is a symbol of all the challenges posed by exotic species, which once introduced in a habitat become invasive.

Known for eating everything in its path, and even for “biting” people, the African catfish (Clarias gariepinus) is feeding debates in Cuba while at the same time, once turned into a filet, is filling the family dinner plates.

The species was introduced in Cuba in 1999 with the aim of raising the fish in freshwater tanks. But the torrential rains of 2001 and 2002 from hurricanes Michelle, Isidoro and Lili, spread the fish throughout the country. Since then, a thousand tales only add to their negative image.

They are seen as “very ugly” and as disgusting because “they eat anything”, and as frightening because they can move on land, making use of their rigid fins. The worst charge against them is that they are killing off other species, endangering the ecological balance.

That is what may have happened at a lake on El Retiro estate in Cárdenas, some 150 kilometers from Havana, where no other fish species are found since the arrival of the catfish, not even ducks or geese. Workers there blame the invasive species for having eaten the birds’ offspring.

“But the filet of those fish is good, and we should think about how to raise them in the farm’s ponds. That we will be contributing to greater availability of food,” said Raimundo García, director of the Christian Center for Reflection and Dialogue, head of the project at El Retiro.

The introduction of exotic species is among the main causes of loss of biological diversity in Cuba, as is “the weak integration of strategies for conservation and sustainable use of biodiversity and economic development.”

For the ecologists, the problem is not so much that the African catfish is “exotic”, but rather that the mechanisms for regulation and control are not infallible, and natural disaster is very difficult to reverse.

The United Nations has dedicated this May 22, International Biodiversity Day, to the question of exotic invasive species, a great threat to biodiversity and the “ecological and economic well being of society and of the planet.” Since the 17th century, exotic species – animals, plants, viruses, bacteria and other organisms – have contributed to nearly 40 percent of animal extinctions of known cause, according to the Convention on Biological Diversity.

In Cuba, the official strategy to protect biodiversity includes conservation, rehabilitation and restoration of ecosystems and degraded habitat, assessment of environmental impacts, management plans and control of exotic plant and animal species.

In defense of the catfish, technicians from the fishing industry say that any species, faced with a prolonged lack of food, can surprise us by eating organisms that are not part of their habitual diet.

“The catfish is resistant, it survives in adverse conditions,” ministry adviser Julio Baisre told this reporter.

“Studies of the stomach contents of this species, the characteristics and position of its mouth, its limited teeth and the fact that uses only its senses of touch and smell to locate its prey, indicate that it usually feeds on organisms found on lake bottoms,” he said.

Baisre believes the negative opinions about the catfish are “exaggerated and second hand,” because there is no “scientifically based evidence” that any freshwater Cuban species have become extinct as a result of the presence of an exotic species.

He added, “there are probably other environmental impacts, related to the use and management of water and the destruction of habitat,” which have had a greater impact than the presence of the catfish or of tilapia, another foreign fish.

But more rigorous study is needed of the environmental impacts of many exotic species, admitted Baisre. “When they ask me about the catfish, I respond with another question: Do you know of any species that serves as human food and that has turned into a plague?”

Other defenders of the introduction of catfish in aquiculture argue that more than 65 percent of the freshwater species farmed in the Americas are not from this hemisphere, as was the case centuries ago with the introduction of sugarcane and coffee.

“The introduction of fish species are based on comparative advantages with autochthonous species, like greater growth, efficient production technology, high value in the foreign market or nutritional properties,” said Orestes Gonzáles, assistant director of the magazine “Mar y Pesca”.

The catfish is known and accepted on the Cuban dinner table and is frequently among the offerings of the commercial network of aquiculture products in national currency. Cuba is trying to develop aquiculture intensively.

Dionis Cruz, a vender at a Havana fish market, where one kilo of catfish filets costs the equivalent of 1.5 dollars, says it is a fish in high demand. “It sells quickly. I receive 200 kilos to sell, and they are gone in two days,” he said.

Experts agree that freshwater fish farming is a “global necessity,” because ocean fishing has reached its limit. Raising catfish is not a Cuban “discovery” – more than 30 countries are farming these fish.

In 2008, Cuban aquiculture produced more than 30,000 tons of fish, including the ‘tenca’, tilapia, catfish and other species, many of them grown in ponds and where fish feed on natural plankton.

In recent years, intensive farming of tilapia in floating cages has been promoted, as well as the catfish in earthen or cement tanks. According to Baisre, this is sustainable and forms part of the national strategy for food security.

The intensive approach allows control of the number of fish that can be maintained in a specific site.

Thanks to a project financed by the United Nations Development Program (UNDP) and the UN Food and Agriculture Organization (FAO), Cuban aquiculture has homegrown feed for the fish.

The feed is based on the very byproducts of the catfish, to which soy, wheat and bran flour are added.

“The idea is to substitute imports of fishmeal,” said Mirtha Vinjoy, assistant director of the aquiculture training center that produces the feed.