[MEXICO CITY] Researchers have shown that the abundance of Mexican mangroves has a direct effect on the health of the fishing industry and the local economy.
The study, published in the Proceedings of the National Academy of Sciences, analysed 13 regions in four states — Baja California Sur, Nayarit, Sinaloa and Sonora — in Mexico's Gulf of California.
Tourist development and shrimp farms have affected the mangrove forests in the region, destroying trees and wetlands to make way for beaches.
Octavio Aburto-Oropeza, a researcher at the Center for Marine Biodiversity and Conservation, at the US-based Scripps Institution of Oceanography, and colleagues analysed over 9,000 fishing landing records between 2001 and 2005 from the Mexican National Fisheries and Aquaculture Commission (CONAPESCA).
Landings averaged 11,600 tonnes, and generated an average annual income of US$19 million for fishermen across the 13 regions.
They found that landings increased with the total area of mangrove fringe, the section of mangrove that is the nursery and feeding ground for a great variety of marine species of economic importance.
"In the Gulf of California, 32 per cent of the varieties of fish and crabs with commercial importance are related to the local abundance of mangrove," Aburto-Oropeza told SciDev.Net.
Aburto-Oropeza and colleagues estimate the value of mangrove ecosystem services to be an average of US$37,500 per hectare per year, far higher than the Mexican government value of around US$1,000.
Mangroves across the regions are disappearing at an annual rate of about two per cent. "The region of La Paz, in the peninsula of Baja California, lost 23 per cent of the mangrove cover in two decades," says Aburto-Oropeza.
"A considerable amount of hectares of mangrove have lost the red mangrove plants that have contact with the sea, which are the main habitat for species of commercial importance," says Aburto-Oropeza.
The researchers want to see mangrove conservation and more efficient and sustainable use of wetlands. "To recover a mangrove ecosystem takes hundreds of years. It is very expensive, but the costs of its loss are several orders of magnitude greater," says Aburto-Oropeza.
PNAS doi 10.1073/pnas.0804601105 (2008)