Silliman University and international scientists, who set out to track the dispersal of fish larvae among marine protected areas (MPAs) along the southern coast of Negros Island, found that larvae travelled from their natal reefs to adjacent MPAs and nearby fishing grounds, providing potential replenishment of fish stocks.
The study area covered 23 marine protected areas and 26 reefs across 7 municipalities and a city, from Amlan to Siaton, including the famous Apo Island Protected Landscape and Seascape in Dauin.
Carried by ocean currents and seasonal winds (habagat and amihan), the fish juveniles were inferred to settle on neighboring reefs until they grow into adult fish, thereby enhancing fish populations and fisheries.
This was reported by Dr. Rene A. Abesamis of the SU Angelo King Center for Research and Environmental Management and James Cook University, Australia, principal author of the article that was published in the international journal Coral Reefs on March 2017.
The article suggested establishing networks of marine protected areas (MPAs), also called no-take marine reserves (NTMRs), clustered within a few tens of kilometers of each other, to ensure a sustainable supply of fish in the networks and adjacent fishing grounds.
The concept of MPAs was introduced and sustained since the 1970s by National Scientist Angel C. Alcala, founding director of the former SU Marine Laboratory (now Institute of Environmental and Marine Science) and now Director of the SU Angelo King Center for Research and Environmental Management. MPAs are said to be the most feasible option for reversing declining fisheries and biodiversity of coral reefs in developing countries like the Philippines.
MPA “protects 20% of a marine environment from human and extractive exploitation, especially fishing,” but opens 80% of the area to non-destructive fishing, wrote Alcala. Protection is managed by the local community in collaboration with local government and scientific and technical advisers.
The famous Apo Island MPA showcases the success of the Silliman MPA experiment in the country.
Abesamis et al. wrote that individual MPAs that form a network through connectivity via larval dispersal are needed for effective marine conservation; and since networks extend across jurisdictions, local governments should work together for their mutual benefit.
Using genetic parentage analysis, the study obtained DNA from thousands of samples of Chaetodon vagabundus (butterflyfish) and found 37 juveniles that could be matched genetically to at least one of their parents. This technique made possible the tracking of larval dispersal.
“Connectivity among NTMRs and fishing grounds can promote synergistic population recovery and enhance fisheries by boosting recruitment to both protected and fished populations within a network,” Abesamis et al. reported.
“Most larvae could settle within several tens of km from their parents, which indicates that any of the 23 NTMRs has a reasonable chance of supplying recruits to a good number of NTMRs and fishing grounds within the study area.”
Half of the larvae originating from a population would attempt to settle within 33 km, and 95% within 83 km, they wrote.
The Sillimanian co-authors are Dr. Angel C. Alcala and Claro Renato L. Jadloc, among six others including Dr. Garry Russ of James Cook University and collaborating scientists from the University of the Philippines, King Abdullah University of Science and Technology (Saudi Arabia), Universidad de Austral (Chile), University of Melbourne (Australia), Tokyo Institute of Technology (Japan) – Celia E. Acedo, SU Research and Environmental News Service
Featured image from EcoTipping Points