Mangrove                                                            Photo credit: Marco Octavio Aburto  

Economic valuation of mangrove ecosystem services:

the case of the fisheries in the Gulf of California

Marine and coastal ecosystems are invaluable to humans, providing a number of services essential for our survival, including food sources, coastal protection, regulation of climate, and waste absorption. Paradoxically, direct users and policy-makers, who only value the short-term, extractive uses of these ecosystems, have historically undervalued them. However, extractive uses represent only a small proportion of an ecosystem s total value. Non-extractive uses are far more valuable to local communities and benefit a greater portion of the population. We still do not know how much ecosystems are worth from an economic perspective, although we know that they are essential from an ecological perspective. This proposal addresses the ecological and economic valuation of mangroves in Baja California, Mexico, by calculating their contribution to fisheries in the Gulf of California.

Researchers 

Octavio Aburto-Oropeza 1,2,4, Exequiel Ezcurra3, Gustavo Danemann4, Victor Valdez4, Jason Murray5 and Enric Sala1,6   

1 Center for Marine Biodiversity and Conservation, Scripps Institution of Oceanography, 9500 Gilman Drive, La Jolla, CA 92093-0202, USA. Correspondence E-mail: maburto@ucsd.edu 
2 Departamento de Biologia Marina, Universidad Autonoma de Baja California Sur, Carretera al Sur Km 5.5, La Paz, Baja California Sur, CP 23081, Mexico.
3 San Diego Natural History Museum, P.O. Box 121390, San Diego, CA 92112-1390, USA. 
4 Pronatura Noroeste A.C., Calle Decima N 60, Zona Centro, Ensenada, Baja California, CP 22800, Mexico.
5 Department of Economics, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0202, USA. 
6 Centre d Estudis Avancats de Blanes (CSIC), 17300 Blanes, Spain.   

Objective
The goal of 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. This valuation will be presented to local communities as well as state and federal agencies to help develop sound environmental policies.    

Results     
We examined the spatial pattern of fisheries landings in relation to the extent of mangrove forests among 13 regions of Baja California and the Gulf of California. We compile 54,679 records, including monthly crustacean and fish landings reported from 2001 to 2005 in the 41 National Fisheries Commission (CONAPESCA) offices located along the coasts of the five sates surrounding the Gulf of California (Baja California, Baja California Sur, Sonora, Sinaloa and Nayarit). We extracted records from: (a) the 25 fisheries offices that have mangrove ecosystems within a 50 km range (the small-scale fishing pangas, motored fiberglass skiffs equipped mostly with hand lines and gillnets, usually operate within 50 km from their home port), and (b) biological groups related to mangroves in any part of their life cycle, such as blue crab, grunts, snappers, snooks, mojarra, mullets, and marine catfishes. Additionaly, we compile geographic information on mangrove distribution and extent from an extensive inventory of Mexican wetlands, which includes coverage data estimated from Landsat Thematic Mapper (TM) satellite images.

The following conclusions were obtained with this project:
1) Fisheries landings increased positively with total mangrove area. This linear trend was maintained in all years analyzed, both for fish and blue crab. We also found that 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. This production generated 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 to local economies around US$ 605,290.

6) Our 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.    

Work with local communities and decision-makers.

We have presented the valuation of mangrove ecosystem to different decision-makers:

a. On March 2007, the results were presented to the Mexican Secretary of Tourism, Mr. Rodolfo Elizondo, during a meeting on coastal development in the Gulf of California at the San Diego Natural History Museum. 

b. On April 2007, the results were presented to Mexican environmentalists and philanthropists, as well as directors of environmental organizations, at the San Diego Natural History Museum, during a meeting planned by the U.S.   MEXICO International Boundary and Water Commission.

Funding provided by
PADI Foundation