Mariculture has its problems

Mariculture is becoming very popular, with four mariculture zones having been established in Eastern Visayas alone. The main proponent — Bureau of Fisheries and Aquatic Resources-Fisheries Management Project (BFAR-FRMP) — plans to establish two more before the year ends.

"A mariculture zone is an area of about 100 to 400 hectares encompassing several barangays. It is expected to produce different target finfishes for sea cage culture such as bangus, siganids (danggit), grouper (lapu-lapu), red snapper (maya-maya). Other mariculture producers can engage in seaweed farming, aquasilviculture, mussel culture, pearl oyster culture, and searanching of lobsters and seahorses in the coral reef and sea grass areas," said Gil A. Adora, BFAR-FRMP Reg. 8 director.

"Our mariculture zone project envisions the socioeconomic transformation of marginal fisherfolk and fishing communities into empowered and productive organizations through a thriving mariculture industry and the ancillary industries that accompany it. It is also a boost to efforts to ensure our food security, and can develop the skills of our fisherfolk in supporting mariculture," added Adora.

Some scientists and technical specialists, however, have warned against some adverse effects of mariculture noted in various areas of the world. For one, the carrying capacity of the host marine ecological system has to be carefully considered. Sedimentation from the natural wastes of organisms in the mariculture areas contributes to nutrient flow that disrupts the normal marine ecology. This nutrient flow can later create adverse effects such as red tide and fish kills as had been witnessed in Lingayen Gulf and other areas where mariculture is prevalent.

Maintenance of culture structures sometimes include the use of chemicals, drugs and other noxious substances found detrimental to corals and other marine habitats, water quality, sea floor and other components of the ecosystem. Mariculturists can also inadvertently release into the wild some of their broodstock and seed supply that can threaten endemic and existing marine species, and genetic diversity in general. Organisms in the mariculture zones can also transfer their diseases to natural populations in the wild, borne by water currents.

As the secretariat of the convention on biological diversity had warned, "mariculture can modify, degrade, or destroy habitat, disrupt trophic systems, deplete natural seedstock, transmit diseases, and reduce genetic variability." It would also inadvertently give rise to perverse practices such as converting coastal mangroves into shrimp ponds.

Aware of this, Adora said "operators in mariculture zones shall guard against pollution and protect the marine ecosystem from the harmful effects of mariculture. This shall be done by preventing the release of pollutants to waters in the mariculture zone, setting up a process for settling of compensatory claims as a result of pollution incidents such as oil spills and the release of other contaminants. Aquatic food products shall be monitored to protect the public from the consumption of contaminated foods and culture species."

As proposed by BFAR-FRMP Reg. 8, all mariculture development proposals shall be subjected to an Environmental Impact Assessment (EIA), and the United Nations-Food and Agriculture Organization-sponsored Code of Conduct for Sustainable Aquaculture shall be implemented, adopted and enforced.

"Locators in the mariculture zones shall be encouraged to invest not only in fish cages, but in other mariculture ventures such as culture of natural biofilters such as oysters and scallops. The scallops can be put under the fish cages to feed on the excess feeds that drop on the bottom. Reg. 8 is noted for the production of oysters, and we are encouraging locators to engage in the culture of pearl oysters such as Pinctada martensii and Pinctada maxima, which are prolific and grow fast," said Orbita.

Orbita also noted that in waters like Carigara Bay, where water currents are fast and the waters circulate very well, there would be less problem with pollution due to mariculture.

Polyculture in fish cage production is also encouraged, not only to increase income yield, but also to minimize pollution. For instance, milkfish can be grown side by side with siganids (danggit) in a caged net. The siganids can gobble up excess feeds intended for the bangus.

For all its critical stance, the Secretariat for the Convention on Biological Diversity looked at the other side of fence, and stated: "Mariculture also provides local biodiversity enhancement under certain circumstances. Birds could be attracted to mariculture sites, and artificial reefs acting as species aggregating devices may result in enhanced biodiversity. In situ coral replanting have also proved to have a positive effect on reef biodiversity."

With guarded optimism, BFAR-FRMP Reg. VIII gears up to promote its vision to invite investors, specially the small fisherfolk, into the rich waters of Eastern Visayas.