by Jason Murray, Department of Economics, University of California and Octavio Aburto, Center for Marine Biodiversity and Conservation, Scripps Institution of Oceanography
This project was to determine the economic importance of mangrove forests in Baja California based on their contribution to the fisheries and their susceptibility to human-induced degradation.
The authors examined 13 regions of Baja California and the Gulf of California and compiled 54,679 records, including monthly crustacean and fish landings reported. They extracted records from: the 25 fisheries offices that have mangrove ecosystems within a 50 km range and biological groups related to mangroves in any part of their life cycle, such as blue crab, grunts, snappers, snooks, mojarra, mullets, and marine catfishes. Additionally, they mapped mangrove distribution and extent including coverage data estimated from Landsat Thematic Mapper (TM) satellite images.
1) Fisheries landings increased positively with total mangrove area in all years analyzed and fisheries landings were not significantly correlated to any other environmental variables.
2) The yearly landings for fish and blue crab in the Gulf of California between 2001 and 2005 averaged 11,600 tons, generating an average annual income of US$ 19 million for fishermen and their communities in the 13 fishing regions.
3) Mangroves in the Gulf of California are producing an important amount of food each year. For fish alone, 31.74% of the small-scale fishery landings from 2001 to 2005 comprised species related to mangrove forests.
4) The annual productivity of fringe mangrove alone is approximately US$ 25,000 to US$ 50,000, with a median value of US$ 37,500, on a per hectare basis.
5) Over 30 years, the transformation of one hectare of mangrove fringe would cost local economies around US$ 605,290.
6) These estimates represent only a lower bound because we considered only the local benefits generated by fish and blue crab fishing activities, without taking into consideration indirect and existence values.
7) In the Mexican government administration time frame (6 years), the fisheries-based long-term value of one hectare of fringe mangrove is an astonishing 200 times higher than the standard value established by the Mexican National Forest Commission (CONAFOR; US$ 1,020 ha).
A scientific article with this information was submitted to the journal Proceedings of the National Academy of Sciences.
Funding provided by PADI Foundation & the US National Science Foundation