Many attempts by so many people have been made to conserve or preserve biodiversity. But none of these have been fully successful in reaching the goal of species conservation, which is preventing species from becoming rare or extinct. Examples of these are limiting exploitation pressures on a resource and periodic closures of fishing grounds. Fisheries managers have traditionally used these modes of management but have failed to prevent the global downward trend in fish catches.
I think the main reason is because these management tools open the windows of opportunity for people to violate the rules so that exploitation goes on without abatement. What is needed is the implementation of absolute management rules permitting or not permitting exploitation at specified sites of a habitat or ecosystem. Management under such a regime may be reduced mainly to strict implementation of the rules, such as those needed to maintain no-take and take zones of MPAs and terrestrial protected areas.
This column today continues to discuss the need for strict protection of habitats of species (discussed in last week’s column) as the most effective means of ensuring the survival of Philippine biodiversity. Here I provide further evidence of the superiority of no-take marine reserves to other conservation and management tools insofar as marine biodiversity is concerned.
I would like to use the example of a no-take m protected marine area, the Jojo de la Victoria Demonstration Marine Reserve (JVDMR) on the island of Bantayan Island, off northern Cebu fronting the property of my friend, Atty. Tony Oposa. This sea area of ca 14 hectares has a bottom substratum consisting of a mixture of sand, coral rubble with algal growth, and coral reef patches. In 2007, three years after its establishment in 2004, its fish component consisted of about 40 species with a density of more than 200 (primarily) reef fish individuals per 500 square meters of sea bottom and ca 12 tons of fish per square kilometer.
A rapid survey using snorkels and a rapid photographic method by Abner Bucol and Jasper Maypa of SUAKCREM, Silliman University in March 2011, three years after the second survey in 2007, showed that the fish species increased in number from 40 to 68 species, a density of a little less than 200 individuals per 500 square meters and a biomass (reef fish only) estimated at 11.6 tons per square kilometer, which is about the same as that in the first survey in 2007. The most dramatic change during the preceding three years of protection was the finding of several thousands of a pelagic species, the scad Selaroides leptolepis, which colonized the reserve between 2007 and early 2011.More species will colonize the reserve in the future. Full protection of the JVDMR no-take reserve was the factor responsible for the increase in the number of species and the entry of a pelagic species in the Marine Reserve. No other human input can explain this increase.
The lack of observable increase in the biomass follows the pattern for the Visayan Sea, which is a shallow area, a factor that apparently limits fish growth. The causes of this slow growth, which is true of Sagay Marine Reserve, could be due to oceanographic factors and the shallow seas of the Visayan Sea area. But the mechanisms that lead to the findings need to be studied.
To summarize, there may be environmental constraints to the productivity in the Visayas area. Despite this, productivity of coastal areas can still be increased if habitats and ecosystems are fully protected. In the case of marine resources, the establishment of no-take marine reserves stands as the single most important strategy to follow if we are to fully benefit from our marine resources.
