Testing the effectiveness of the marine reserves of Belize
Fish populations around the world are severely threatened from overfishing and inadequate management of fishing fleets. Policies have tried to impose limits on aspects of fishing such as size and quantity of fish caught. However, these policies are regularly set too far beyond scientific recommendations to be effective, or are ignored, as demonstrated by the high levels of illegal and unregulated fishing in the European Union.
The Belizean fisheries on the other side of the Atlantic are no exception. A preferable alternative to these failing techniques to manage fisheries are Marine Protected Areas (MPAs), which are being established worldwide in a variety of forms. One example is the Sapodilla Cayes Marine Reserve (SCMR) where the Earthwatch project Queen Conchs of Belize is based. The project, having looked at the state of the ecosystem before the reserve was implemented, is now going back to the reserve to evaluate how effective the protection of the habitat and introduction of fishery regulations have been, through the study of marine invertebrates such as queen conch (Strombus gigas) and two species of lobster - the spiny lobster (Panulirus argus) and spotted lobster (Panulirus guttatus).
The three species being studied are among the most important for the fisheries industry on the coast of Belize. The queen conch is a large marine gastropod (a group of mollusks commonly known as slugs and snails) which lives throughout the Caribbean and the Gulf of Mexico and is prized for its edible meat and attractive shell. The two lobster species are harvested purely to satisfy demand as food. Traditional regulations for harvesting of queen conch are very strict, imposing minimum weight and length limits; a closed season (1 July - 30 September); and prohibiting use of SCUBA diving for collecting the conch. To regulate, but still enable continuation of fishing for queen conch and other species, a network of 13 MPAs, including the SCMR, have been established along the coast of Belize. At present though, all three focal species are extremely overharvested, even within the MPAs, which is causing populations to decline and increasing concerns about the effectiveness of the MPAs in Belize.
The 15,619 hectare SCMR was established in 1996 at the southern end of the Mesoamerican barrier reef, which runs the entire length of the Belize coast and is the second largest barrier reef system in the world. The reserve consists of various cayes (small sandy islands) and surrounding marine habitats and has been divided into three zones with varying levels of protection - from complete protection where no entry is allowed without a research permit, to general use which allows commercial extraction activities such as fishing, but in a carefully controlled way.
Despite living within an officially designated protected area, however, queen conch and lobster populations in the SCMR are not protected in reality as the laws are not being enforced and unsustainable fishing is ongoing. Before the Earthwatch project began in 2006, no studies had been undertaken to test whether the marine reserve was resulting in any conservation benefits and therefore the shortcomings of the reserve were undocumented.
How can an MPA benefit fisheries and conservation?
MPAs which allow no resource extraction can protect traditional artisanal fishing by local communities, as fish populations are able to recover and reproduce, increasing the biomass and density of the population protected inside the reserve. The population then spills out of the reserve into surrounding unprotected areas and artisanal fishermen working in these areas see their catches improve - a phenomenon known as the overspill effect.
The Earthwatch project is carrying out significant research to test assumptions that are made about the benefits and outcomes of establishing MPAs. While there is wide evidence that reserves help in maintaining diversity of species, and lead to increases in abundance and biomass of protected species, there is less evidence for the overspill effect.
There is, therefore, a need to understand how much a population of a species within a reserve can reproduce to increase its own population size, or whether, for a population to increase, new individuals must come from outside the reserve in a process known as "recruitment," where larvae spawned elsewhere enter and settle in the marine reserve. If recruitment is the only way for a population to grow, then a reserve must either be big enough that multiple populations of one species are encompassed within the boundaries, or a regional network of marine reserves must be set up, between which larvae can successfully migrate. If the Earthwatch project can answer these kinds of questions, then the scientists can deduce whether or not MPAs are a successful tool for conservation, and advise authorities on the best strategies for setting them up.
The project's past and future
From 2006 to 2008, Earthwatch supported the Queen Conchs of Belize project to study the effectiveness of SCMR in protecting and replenishing queen conch populations, and in 2010 work is starting again to follow up on this research. The previous research involved interviewing fishermen and stakeholders about their perception of and level of support for the reserve; conducting underwater population surveys; larvae identification studies; mapping locations of conch aggregations; assessing habitat use; and tagging and recapturing individuals to identify movement patterns. Understanding how populations of a marine species are connected is fundamental to ensuring successful marine reserve design. The project results are therefore directly applicable to the management of queen conch and lobster populations in the SCMR, and other reserves in the Caribbean.
The scientists are not only interested in determining the effectiveness of the reserve from the perspective of the species being protected or the economic gains (i.e. improved artisanal fisheries), but also in sharing the results of the research with local stakeholders and marine area managers to give them the knowledge and expertise to monitor and manage the reserve themselves.
Report by Aina Pascual Cuadras