October 1, 2008
High Economic Value for Threatened Mexican Mangroves
The ecological value of coastal mangrove forests in Mexico has been apparent to marine scientists for years, but for the first time, researchers have used a wide-ranging compilation of fisheries landings-the official record of fish catches-to place an economic price tag on that value. Scientists at Scripps Institution of Oceanography at the University of California, San Diego, showed that Mexican mangroves, trees that form forest ecosystems at the land- sea interface, demonstrably boost fishery yields in the Gulf of California. The more mangroves, the more landings, the study showed.
The researchers found that 13 fishing regions in the Gulf of California produced an average of 11,500 tons of mangrove-derived fish and blue crab per year between 2001 and 2005, generating nearly $19 million for local fishermen.
The researchers worked with landing records provided by Mexico's National Fisheries and Aquaculture Commission, and the geographic information was derived from several sources, including satellite images and trips to the field.
Mangroves in the Gulf of California serve as homes to a variety of fish and crab species and host nursery habitats for commercially valuable fishes such as snappers, snooks and mullets. The trees also protect the coastline from erosion and filter water between the continent and ocean. They provide a resource to generate money for local economies, and more than 30 percent of the annual small-scale fishery landings in the Gulf of California come from a mangrove source, according to the study.
The annual worth of mangrove ecosystem services worldwide has been estimated at more than $1.6 billion. Such services benefit human populations through climate regulation, water supply availability, erosion control, waste treatment, food production and recreation.
Despite their value, the number of mangrove forests is dwindling at a regional rate of two percent per year in Mexico.
A report published in 1984 indicated that 23 percent of the mangrove forests near La Raz were eliminated between 1973 and 1981.
The researchers weighed economic, geographic and ecological factors and determined that a hectare, or 10,000 square meters, of mangrove fringethe edge of mangrove forest in contact with the sea- in the Gulf of California is valued on average at about $37,500 per year.
Octavio Aburto-Oropeza of the Scripps Center for Marine Biodiversity and Conservation, lead author of the study, said that the study's end valuation is a low estimate, as the researchers only included fishery value, rather than any potential recreational or ecotourism earnings.
"Because property rights are poorly defined for critical environmental inputs such as mangroves, it is necessary to measure and highlight the real monetary benefits they provide," said coauthor ]ason Murray, a professor at the University of South Carolina.
Copyright Compass Publications, Inc. Sep 2008
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