During the past weeks, the production of diwal was so noticeable, particularly in the towns of Valladolid and Pulupandan in the southern part of Negros Occidental. This development is quite interesting, as this marine species, known in English as angel wing, was getting rare in previous years.
Diwal is one of the pricey marine resources amounting to more than P1.000 per kilo in some instances, but recently it only cost from P200 to P300 per kilo from the source. I can no longer remember when was the last time I tasted diwal and so I bought some when I passed by in a boulevard in Valladolid while on my way from Bacolod to Kabankalan last week.
I realized that the declaration of the Negros Occidental Coastal Wetlands Conservation Area as the country’s 7th Wetlands of International Importance under the Ramsar Convention of the United Nations was, indeed, crucial for the sustainable production of numerous marine resources found in the site.
This Ramsar Site of the province spans from Bago City down to the municipality of Ilog, which includes Pulupandan and Valadolid where diwal and other commercially viable marine species are thriving. The purpose of Ramsar Convention is to ensure the protection of wetlands not only for ecological purposes but also to maintain and sustain their importance when it comes to food security and sustainable income of communities.
Among the ecological units found in the NOCWCA are mudflats, which are essentially the production areas of diwal and other mollusks. These are usually the gleaning areas where coastal communities gather shells, crustaceans, and other marine resources. Gleaning sites are characterized with sandy-muddy features, the reason why they are generally called mudflats but certain parts are covered with mangrove swamps.
The continuing production of valuable marine resources in mudflats, like diwal, requires, therefore, the protection of these areas from conversion into other purposes and pollution. Marine organisms, including numerous varieties of sea shells are sensitive to pollution, while mudflats are vulnerable to washouts from soil erosion and other land-based pollutants that find their ways to coastal and marine ecosystems.
With the huge market demand of diwal, it is inevitable that it is subject to over harvesting and exploitation, too. Aside from protection of diwal’s habitats, there is a need to regulate the harvesting of this species to ensure that it will thrive for a lifetime for the generations to come to enjoy this expensive marine resource. I don’t know if Valladolid and Pulupandan have already issued ordinances regulating the collection of diwal, but I learned from one seller that they are only allowed to harvest it in March.
Bago City had issued an ordinance declaring Diwal Fishery Reserve covering about 31 hectares within the coastal areas in Barangays Calumangan and Sampinit. Such declaration was made in 2006 based on the recommendation from the research team of the University of the Philippines-Visayas and Provincial Agriculture Office of Negros Occidental. The research finding showed that the declared reserve in Bago City is potential breeding ground of diwal.
On the other hand, the Department of Agriculture had issued Fishery Administrative Order 208 in 2001 that declared certain fishery species as threatened and endangered. It listed diwal or angel wing as part of threatened species.
This FAO, however, is problematic since it labeled the scientific name of diwal as Barneamanilensis, which according to Carlo Custodio, former Regional Technical Director of the Department of Environment and Natural Resources Region VI, is incorrect.
Custodio, also a longtime senior staff of the Biodiversity Management Bureau, said the scientific name of diwal is Pholasorientalis, the same scientific name used in the ordinance of Bago City. He further claimed that scientific names prevail in a policy concerning species because the local name varies in some locations, and, therefore the FAO of the DA does not apply for diwal or angel wing. That is an important consideration because threatened species are usually prohibited from harvesting or collecting.
While there is only a limited study on the ecology of diwal, particularly its natural production, it is necessary that clear regulations are made.
With the observation that diwal production and harvesting dwindled in the past years, there is a possibility that this species may be may face extinction in the wild. Local knowledge, especially from the seasoned diwal’s collectors, could serve as good inputs in the drafting of a policy for the species in addition to scientific knowledge of experts.*