This question has often been asked by non-scientists and marine biologists, including those who have no or little experience in establishing fully protected no-take marine reserves.
A related question is: If there is, in fact, export or net spillover to areas surrounding marine reserves, how much is it? Is it worth the effort and money spent in establishing and maintaining marine reserves?
Answers to these questions are necessary if the general belief that no-take marine reserves can become effective tools for marine biodiversity conservation, and fishery management is to influence policy makers and practitioners of marine conservation.
Our research findings on marine reserves at Silliman University since the early 1970s, and continuing up to the present, tell us that there is no doubt that fully protected no-take marine reserves do work, and our answers to the question stated above are a resounding Yes, provided these reserves are fully protected from fishing for decadal time periods.
The answer to how much and what percentage of the total fishery catch is the net spillover depends on certain factors, such as area of the protected system (no-take reserve and adjacent fished area, the fish biomass in the reserves, age of reserves, etc.).
It is now clear that the tentative conclusion we made in our papers published in the 1970s, 1980s and 1990s that the large biomass that was built up in marine reserves for a decade or so of full protection resulted in net spillover from marine reserves to adjacent fished areas with much lower biomass; this net spillover allowed fishers to harvest more fish as evidenced by higher catch per unit effort (cpue) near the reserve boundaries compared to cpue from areas some distance away from the boundary.
From where else can a fished area adjacent to reserve get its steady supply of fish biomass that is continuously reduced by fishing? This supply must come only from the adjacent no-take reserve and not from unprotected fished areas because the fish biomass of the latter is always low.
More empirical evidence was gathered in the later years (1990s-2000s) showed that net spillover occurred and the net movement is from no-take reserves into fished areas.
Therefore, it is concluded that no-take marine reserves generate adult fish biomass.
It is also concluded that based on simulation another spillover (recruitment spillover of fish larvae) probably also occurs from no-take marine reserves to outside areas, that is, from one reserve to other reserves and non-reserves, but more empirical evidence is needed. The search for this evidence is on-going.
One reason why doubt persists on the reality of spillover is that some researchers use inappropriate methods to demonstrate spillover.
For example, some social scientists interview reserve managers, many of whom do not conduct actual fish visual census, to learn whether they have experienced more fish catches. These managers obviously cannot answer the question.
Researchers must use appropriate research methods to demonstrate increased fish catches from data on surveyed no-take marine reserves.
It is a pleasure to acknowledge the contributions and painstaking effort of my research colleagues in Silliman University to provide answers to the frequently asked questions on the important role of marine reserves in enhancing fish catches in areas surrounding no-take areas (thereby contributing to nutrition and increased incomes of small scale fishers) and in maintaining and/or improving the quality of the marine biodiversity.
No less important is the influence of the research contributions of these colleagues on the reputation of academic institutions.
This impact is measured in terms of scholarly outputs, which are in this case nearly 40 peer-reviewed scientific journal publications dealing with marine reserves, of which at least eight are specifically concerned with the documentation of fishery and fish spillover (one paper has just been submitted for publication in a top American scientific journal).
The quality of research publications is considered by scholars as an important indicator of the best universities in a country.
In this connection, the Philippines reportedly lags behind most countries in Southeast Asia.
I wish to take this opportunity to thank A. Maypa, P. Nillos-Kleiven, H. Calumpong, J. Maypa, R. Abesamis, A. Bucol, R. Jadloc, B. Stockwell, G. Russ, and R. Weeks for helping enrich Philippine scientific literature in the field of marine biology through the research program of SUAKCREM.
The reader will note that the names mentioned represent four countries, namely, Australia, United States, United Kingdom, and the Philippines.
The Marine Laboratory and the SUAKCREM at Silliman University provided the venue for this international cooperation in research.
It should also be noted that the research program used two main islands, Sumilon and Apo, as the field laboratory, and we must recognize the generosity of the local governments of the Oslob municipality and the Dauin municipality in allowing the use of these two islands for fieldwork associated with the research on marine reserves.
The marine reserve program of the Silliman University has been supported financially over the years by the Philippine National Research Council, the Great Barrier Reef Marine Park Authority, Asia Foundation, Pew Fellowship in Marine Conservation to G. Russ and A. Alcala, Center of Excellence for Coral Reef Studies at James Cook University, and various small grants to the S.U. Marine Laboratory and SUAKCREM.
The concept of marine reserves as tools for fishery management and biodiversity conservation had its origin in the Central Visayas, Philippines in 1974. There are now more than 1,000 marine reserves in the country, yet, the total area encompassed by these reserves is only about five percent of the total area of coral reefs, which is some 25,000 square kilometers.
If we are aiming to improve fish catches in coastal areas, we should do two things: 1) make existing marine reserves functional by fully protecting them from fishing and from pollution and 2) establish more fully protected marine reserves to increase the percentage to at least 20 percent of the total fishing area. This requires full support on the part of government.
