Pacific Central-American Coastal large marine ecosystem
The Pacific Central-American Large Marine Ecosystem (LME) is characterized by its tropical climate and upwelling system. It extends along the Pacific Coast of Central America, from Cabo Corrientes in Mexico to the vicinity of the Equator. The continental shelf is narrow and steep, and extreme ocean depths are reached very near the coast. The LME is enriched by a high level of nutrients. The LME borders the Middle America Trench, located about 100 kilometers (km) offshore. Much of the LME lies within the sweep of the Intertropical Convergence Zone (ITCZ). It is situated between the California and the Humboldt Currents and differs from those two LMEs in terms of temperature: the upper ocean layers are much warmer, with large-scale monthly mean ocean temperatures remaining above 26 degrees Celsius throughout the year. LME book chapters and articles pertaining to this LME include Bakun et al, 1999.
A subduction zone, located immediately offshore and stretching along the coastline, results in frequent earthquakes. Major topographical features include the East Pacific Rise, the Guatemala Basin, the Panama Basin, and the Peru-Chile Trench. An upwelling regime drives this LME. For information on the physical setting, seasonal ocean current patterns, upwelling and the oxygen minimum layer, see Bakun et al, 1999.
For maps showing the 9 countries and the major geographical features, see Bakun et al, 1999, p. 269 and p. 175. For a map of seasonal ocean surface circulation patterns, see Bakun et al, 1999, p. 272. The Pacific Central-American Coastal LME is considered a Class II, moderately high (150-300 gC/m2-yr) productivity ecosystem based on SeaWiFS global primary production estimates. For more information on nutrient enrichment, upwelling, and the strong tropical thermocline off of Costa Rica, see Wyrtki, 1964. An episodic upwelling is caused by winds blowing across the Panama Isthmus from the Caribbean side. Coastal upwelling plumes extend offshore from 3 locations corresponding to major gaps in the mountainous topography of the region (see Bakun et. al., 1999). A SeaWiFS image provided below by NASA depicts plankton blooms off the coast for May 2004.
Fish and Fisheries
The Food and Agriculture Organization (FAO) 10-year trend shows a decrease in the catch from over 200,000 tons in 1990 to 190,000 tons in 1999 (see FAO, 2003), with a peak of 300,000 tons in 1998. The most important species group in terms of shelf catches are clupeoids (herrings, sardines and anchovies), representing more than ½ of the total catch.
For more information on fisheries, see Bakun et al, 1999. Offshore tunas (yellowfin, skipjack, and bigeye) are caught mainly by long-distance fleets from Korea, Japan, USA, and Venezuela. The species most important to the coastal communities is the Penaeid shrimp, exported at high price to the USA. It represents a significant source of foreign exchange for all the coastal communities in the area. Most shrimp stocks are considered to be overexploited, and several hundred species of demersal fish are commonly taken as bycatch. Small coastal pelagic fisheries such as the Central Pacific anchovetta and the Pacific thread herring have existed in the Gulf of Panama since the 1950s. Currently most of the production is used for fishmeal and oil. There are artisanal shark fisheries operating in El Salvador and Guatemala, but there is a lack of statistics concerning those fisheries. Shrimp aquaculture projects occupy an extensive area. 23,000 tons of shrimp were produced in 1994 (see PRADEPESCA, 1995). At least 90% of the shrimp farms have been constructed on former mangrove or salt pond areas. The University of British Columbia Fisheries Center has detailed fish catch statistics for this LME.
Pollution and Ecosystem Health
The LME is enriched by a high level of nutrients. Increased population pressures on the Pacific coast have led to the pollution of rivers, streams, lakes and coastal waters. This has resulted in losses of plant and animal species. For threatened species and habitats issues, see Bakun et al, 1999. The lack of facilities for proper solid waste disposal, the lack of basic infrastructure and problems relating to mining create a variety of pollution situations. One issue is the rapid destruction of mangroves, vital nurseries for fish. Estuaries are increasingly subject to pollution. Pollution from land is potentially more damaging in the coastal waters of the Northeast Pacific because of the numerous sheltered bays and gulfs (Gulf of Fonseca, Gulf of San Miguel, Bay of Panama), where chemicals cannot easily be dispersed. The small Gulf of Fonseca, an important shrimp nursery, is polluted from the effects of extensive banana plantations. There is pulp waste from coffee processing in Guatemala. Sewage and other pollutants are being discharged from cities into the Pacific Ocean. The runoff of fertilizers from agricultural land is adding to the risk of algal blooms in the region's coastal waters. Such blooms can produce toxins that kill fish. These discharges are compromising the harvesting of shellfish, as well as endangering the health of bathers using the Pacific waters. They can lead to outbreaks of water-borne diseases such as cholera. The Pacific entrance into the Panama Canal lies within this LME. There is heavy traffic on the shipping lanes, and maritime routes follow the entire length of the coastline. This heavy use increases the dangers of marine debris and oil spills.
The Pacific Central-American coastline is home to a high percentage of Central America’s population and has undergone rapid changes. People migrated to the coast to make a living from subsistence fishing and farming. Offshore tuna (yellowfin, skipjack, and bigeye tuna) are caught mainly by long-distance fleets from Korea, Japan, USA, and Venezuela. The species most important to the local coastal communities is the Penaeid shrimp. This product is exported at high price to the USA, and represents a significant source of foreign exchange for all the coastal communities in the area. For more information on this LME’s socioeconomic background, see Bakun et al, 1999. Tourism represents 20.4% of foreign exchange for the Central America region as a whole (see OMT 1994). Tourism depends on the quality of key coastal habitats like mangrove swamps, coral reefs and beaches. The coastal areas have natural beauty. Coastal development activities center on tourism, mariculture and sport fishing. These activities sometimes compete with the subsistence economy of local populations. There is finfish aquaculture in Costa Rica, El Salvador, Mexico and Colombia. Ecuador raises crustaceans. Seafood exports are quite substantial for Mexico, Nicaragua, Panama, and Ecuador. The region is an important shipping route for vessels sailing from Panama to Alaska. There is a major oil pipeline at Laguna de Chiriqui. Ports of importance include San Carlos, Guaymas, Mazatlan, Manzanillo, Acapulco, and Salina Cruz (Mexico); Champerico and San Jose (Guatemala); San Salvador and Cutuco (Salvador); and Corinto, Puerto Somoza, Puntarenas, Caldera, Puerto Quepos, Golfito and Balboa. The region has been torn by civil wars, but the current situation is much improved and today’s economies are developing.
Nine countries, some among the poorest of the region, share the coastline of the Pacific Central-American LME. These countries are Mexico, Guatemala, Salvador, Honduras, Nicaragua, Costa Rica, Panama, Colombia and Ecuador. Transboundary issues needing to be addressed include fisheries management. Local administrations are poorly equipped to monitor and manage fisheries. There needs to be more awareness among local people and governments of the importance of preserving ecosystem integrity, especially for key coastal habitats like mangrove swamps and coral reefs. Growing numbers of environmental refugees are encroaching on areas in need of protection. The Convention on Cooperation in the Protection and Sustainable Development of the Marine and Coastal Environment of the Northeast Pacific was signed by six of the 9 countries in 2002. The countries were Costa Rica, El Salvador, Guatemala, Honduras, Nicaragua, and Panama. Mexico and Colombia have indicated that they will sign the Convention also. Key parts of this convention address the high levels of sewage and other pollutants being discharged from cities into the Pacific Ocean. Another priority is the assessment of risks from oil pollution and a strategy to deal with such events including an evaluation of the region's access to clean up equipment and personnel. For more information on governance needs in this LME, see Bakun et. al., 1999. A website that may provide additional information on managing sustainable fisheries, socioeconomic issues, and improving environmental conservation measures in the Pacific Central American Region is "Success Stories, Principles, Values and Lessons learned in the Implementation of Sustainability".
Articles and LME Volumes
- Bakun, Andrew; Csirke, Jorge; Lluch-Belda, Daniel; and Rafael Steer-Ruiz. 1999. "The Pacific Central American Coastal LME" In Large Marine Ecosystems of the Pacific Rim. K. Sherman and Q. Tang, editors. Cambridge, MA: Blackwell Science. 268-280.
- FAO, 2003. Trends in oceanic captures and clustering of large marine ecosystems—2 studies based on the FAO capture database. FAO fisheries technical paper 435. 71 pages.
- OMT, 1994. Tendencias del Mercado Turistico: Américas, 1980-1992. Comisión de la Organización Mundial del Turismo para las Américas. Documento preparado para la vigésima sexta reunión. San Salvador, 24 de mayo 1994.
- PRADEPESCA, 1995. Situación Actual y Perspectivas del Cultivo d Camarón en el Istmo Centroamericano. Resumen del III Simposio Centroamericano sobre Camarón Cultivado (ANDAH-FPX), Honduras. PRADEPESCA. Panamá.
- Wyrtki, K. 1964. Upwelling in the Costa Rica Dome. Fish. Bull. US 63:355-372.
- Wyrtki, K. 1965. Summary of the physical oceanography of the Eastern Pacific Ocean. Institute of Marine Resources, University of California, San Diego, Ref. 65-10. 78 pp. ISBN unpublished
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