Caribbean Fish on the Decline

Several saltwater fish species are growing scarce in Cuban waters, where in the past it was not unusual to snag a porgy or a mero weighing as much as 15 kilos.

HAVANA - Over-fishing, climatic factors and unregulated tourism are taking their toll on some of the most prized fish of the Caribbean, biologist Rodolfo Claro Madruga, of the oceanography institute at Cuba's Ministry of Science, Technology and Environment, says in a dialogue with Tierramérica.

Claro Madruga has directed a group of experts from the institute for more than 20 years in studying the Cuban sea's environmental conditions and their potential for fishing.

The greatest concern is about the situation of the Sabana-Camagüey archipelago, where important species are on the decline, says the biologist.


--What are the causes behind the decline in the Caribbean's fish resources?
-- There are a series of things. In Cuba there is over-exploitation, although regulations do exist to prevent unlimited fishing. I won't say that the measures are optimal. There is truly a "war" between the fishing community and the scientists, but the situations is better here than in other Caribbean countries, where there are no limits on fishing.

-- There are sectors of the Sabana-Camagüey archipelago, a 465-km stretch along north-central Cuba, that have suffered major environmental changes, due to natural causes and to human activities. What was the impact on marine species?
-- In 1988 and 1989 we conducted a study of the reefs, mangroves and lagoons in that area, and we repeated it in 2000 to compare data. We began the investigation when construction started on the stone causeways (roads to link the islets to the mainland). We found that the average density of fish (per 100 square meters) fell from 3.4 to 1.9 kg. Meanwhile, the biomass (total mass of an ecosystem's biological components) fell from 17 kg per 100 square meters to nine kg.

-- Which species suffered most?
-- The jurel, macarel, mero and porgy -- all very important to the commercial fishing industry. In the case of the pargos (porgy), the most important to Cuban fishing, the decline in density was from 10 kg on average to 2.9 kg per 100 square meters. Biomass fell from 10.35 to 0.85 kg.

-- How is that decline explained?
-- In part, it is due to over-fishing, but also we found that in the exterior reefs, along the archipelago, there was a sharp reduction in coral surface and a proliferation of algae that covered 70 to 80 percent of the sea bottom. By covering the coral, the algae prevent the coral from fixing and growing, reducing the number of refuges for the invertebrates that the fish consume, and for the fish themselves. All of this causes the biomass to decline.

-- What led to the destruction of the coral?
-- The coral died following three ENSO (El Nino-Southern Oscillation) marine current events, in 1995, 1997 and 1998. The warming of the water produced a reduction in the coral mass, an increase in algae in the reefs, a decline in invertebrates that fish eat and, as a result, the nearly two-thirds decline in the biomass and fish densities in the ecosystem.

-- Are the stone causeways or viaducts uniting the islets with the mainland contributing to changes in the ecosystem?
-- The causeways prevent circulation and the water stagnates. The flow of freshwater from the mainland is blocked, evaporation occurs, so salinity increases, reducing the possibility of maintaining marine life. There are three causeways in the area, but two, the Cayo Coco and Jiguey, have caused the most damage. As a result of our investigations, decisions were taken to increase the flow of freshwater to the bay, which helped bring down the salinity level, more bridges were built and water accesses were expanded.

* Patricia Grogg is an IPS correspondent.