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Debido a sus características ecológicas, su alta biodiversidad y la gran cantidad de endemismos presentes, la Reserva de la Biosfera del Alto Golfo de California y Delta del Río Colorado es considerada a nivel global como una zona única e irremplazable. Forman parte de la Reserva zonas terrestres y marinas que son hábitat de anidación, alimentación, maduración, reproducción o crianza de distintas especies de aves, mamíferos, reptiles y peces, algunas de ellas con estatus en riesgo, entre las que destacan la totoaba, la vaquita y las tortugas marinas.

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Scorecard

Score Legend Trend Legend
Superior
Rapidly Improving
Good
Improving
Fair
Stable
Poor
Diminishing
Critical
Rapidly Diminishing
Undetermined
Undetermined

Water

  • Stressors

    Question

    To what extents are specific or multiple stressors, including changing watershed, oceanographic, and atmospheric conditions, affecting water quality, quantity, distribution and timing and how are the stressors changing?

    Why This Score?

    Selected conditions may preclude full development of living resource assemblages and habitats, but are not likely to cause substantial or persistent declines.

    Basis of Judgement

    The reduction in the freshwater flows of the Colorado River has drastically altered the Delta ecosystem. Only 10% of the approximately 800,000 hectares of previously existing wetlands still exists today. In the 1920s and 1930s the Delta was an extensive forest in the middle of the Sonora Desert, and it was inhabited by pumas, jaguars and wildcats that moved freely between wetlands and mesquite forests. Currently, there are new pressures on water quality: the growing population centers in the Gulf of Santa Clara, Puerto Peñasco and San Felipe and the growth of areas dedicated to aquaculture and agricultural activities have increased the demand for water, thereby limiting its access and increasing discharges of agricultural wastes and sewage. The beginning of operations at the Yuma desalinization plant will signify a considerable reduction in water for the Santa Clara marsh.
  • Nutrient Health

    Question

    To what extents are altered nutrient loads affecting ecosystem health and how are they changing?

    Why This Score?

    Selected conditions may inhibit the development of assemblages, and may cause measurable but not severe declines in living resources and habitats.

    Basis of Judgement

    With the exception of the drastic reduction in water and nutrients from the Colorado River—and these changes were not monitored throughout the 20th century—there is no other evidence suggesting alterations in marine ecosystems as a result of the negative effects from nutrient dynamics. Local contributions have remained constant and have not generated serious problems. Harmful algae blooms have not been recorded in the Reserve. Nutrient dynamics in the area are dominated by long-term oceanographic phenomena. Natural wealth is associated with cyclical upwellings. In May 2007 nutrients were measured south of El Tapón, and phosphates averaged at 112 ppb. The level recommended in standards is below 100 ppb. There is concern, however, that in the future human settlements in the area may increase nutrient levels in the marine environment.
  • Human Health

    Question

    To what extent do water conditions pose risks to human health and how are they changing?

    Why This Score?

    Selected conditions that have the potential to affect human health may exist but human impacts have not been reported

    Basis of Judgement

    According to results from the Comprehensive Clean Beaches Program (Programa Integral de Playas Limpias), it was reported for San Luis Río Colorado, Sonora, that during the 2006–2007 period the limit of 500 NMP of enterococcus/100 ml of water was not exceeded at any time. This amount is the limit considered to be below the health risk for human health. Nevertheless, a sample scheme that is more representative in space and time is required in order to determine the quality of water in the major public beaches. The wastes from agricultural inputs are under control. A clean countryside program is being carried out to control the disposal of used agro-chemical packaging, and to prevent exposure and contact with air, soil and water. The detected levels of organic material in discharges from livestock operations are low. The coliform levels are low, and there is no evidence of risk for human health. The region’s development planning points to a stable tendency. It will be necessary to focus attention on transporting wastes to a centralized area due to effects from large amplitude tides. Explosive growth in tourism is generating irregular human settlements. Those who find jobs in hotels, restaurants and other tourist activities live in such settlements, where adequate sanitary infrastructure is lacking. This situation may present problems in the future.
  • Human Activities

    Question

    To what extent do human activities influence water quality and inputs and how are they changing?

    Why This Score?

    Some potentially harmful activities exist, but they do not appear to have had a negative effect on water quality and quantity

    Basis of Judgement

    Agricultural activity is intensive in the region, on both Mexican and US sides of the border. The greatest impact from agriculture is a result of the channeling and disposal of sewer water that enters through various points on the north side, particularly into the Santa Clara marsh, the El Indio lagoon, and the main Colorado River channel. Nevertheless, results indicate that the levels of pollutants from the Mexicali and San Luis Rio Colorado valleys in Mexico and the Yuma valley in the United States are not alarming, even though they represent potential danger that should be taken into consideration. Even though the population density in the Reserve is not significant, annual growth rates of the population centers within the Reserve and the surrounding area are high, due to the intensive tourist activity that is beginning to take hold in the region. This is producing an increase in the number of human settlements, particularly from Golfo de Santa Clara in San Luis Río Colorado, to the Choya Bay in Port Peñasco and to the north, to San Felipe in the Mexicali municipality. This situation must be considered in the planning and control of impacts from contamination. Existing pressures indicate that the demand for water will increase, and so will the generation of wastes and wastewater. The tendency will be toward less water and less water quality. Existing pressures indicate a declining tendency.

Habitat

  • Extent and Distribution

    Question

    To what extent does habitat alteration, including the extent and distribution of major habitat types, affect ecosystem health, and how is it changing?

    Why This Score?

    Selected habitat loss or alteration has taken place, precluding full development of living resources assemblages, but it is unlikely to cause substantial or persistent degradation in living resources or water quality.

    Basis of Judgement

    The retention of Colorado River waters, through the existing system of dams all along the watershed on the US side of the border, caused a drastic decrease in water in the Colorado River Delta wetlands area in Mexico. The original conditions of the wetlands changed as a result, and the same happened to other environments with a high diversity of flora and fauna in the region. Nevertheless, the ecosystem appears to have stabilized, intermittently receiving water—unlike the historic seasonal system, and with a minimal volume of freshwater. This was a change that was not expected in the medium-term. These impacts modified the landscape and the habitats of migratory birds. Some endemic bird species were lost. In the wetlands that still remain, such as the Santa Clara marsh and the riparian corridor, there is still significant activity from migratory aquatic birds that use the area for rest and reproduction. In the marine habitat, major fishing activity has characterized the Upper Gulf region. The most significant has been shrimp fishing with trawl nets and gill nets. The trawling system used for decades by the largest shrimp fleet has significantly altered biotic conditions at the sea bottom. There is empirical evidence of changes in the composition of the benthonic ichthyofauna. There is also evidence of the importance of freshwater in the Colorado River estuary, which when combined with Upper Gulf tides, has a positive effect on fishing, especially shrimp fishing. Although major Upper Gulf productivity has remained stable due to upwellings, salinity has been modified, and this affects eurihaline species, particularly the shrimp’s reproductive cycle. Also, sediments accumulate due to the effect from the tides. Fishermen are convinced that every time the Colorado River rises and reaches the sea, there is a considerable effect on the reproduction and breeding of commercial species. This is congruent with data obtained from shrimp fishing, with repercussions for the entire food chain.
  • Contaminants

    Question

    To what extent do contaminants in habitats affect living resources or water quality, and how are they changing?

    Why This Score?

    Selected contaminants may preclude full development of living resource assemblages, but are not likely to cause substantial or persistent degradation.

    Basis of Judgement

    The waters that feed into the Santa Clara marsh are waters with a high level of pollutants since they were previously used in US agriculture. It does not appear there are significant discharges of water contaminated with agrochemicals or from other sources into the marine environment. Nevertheless, evidence is very limited. There are open-air trash-dumps, and a great deal of trash is washed up on the beaches. There are programs addressing this issue. For example, a group of women in the Gulf of Santa Clara have organized to collect PET containers, store them and recycle them. If controls are applied, the condition will remain stable.
  • Human Activities

    Question

    To what extent do human activities influence habitat extent and quality, and how are they changing?

    Why This Score?

    Selected activities have resulted in measurable habitat impacts, but evidence suggests effects are localized, not widespread.

    Basis of Judgement

    The dominant activity in the marine environment has been fishing, and it has been characterized by overfishing and by the use of fishing systems that are damaging to the environment. The totoaba was taken to the brink of its commercial extinction. And as a result of the incidental bycatch of the vaquita in gill nets, it is considered to be in critical danger of extinction. Shark populations have been reduced significantly, and the structure and composition of the benthonic ichthyofauna were altered drastically as a result of the use of trawl nets. Fishing activity must be restructured with the goal of recuperating productivity levels in the majority of the most important fishing sectors. Recently, the fishing effort corresponding to the shrimp fleet has been reduced, from nearly 400 fishing vessels a couple of years ago, to only 115 vessels today, and exclusively during the three-month fishing season. There are also programs operating with the aim of reducing the river fishing effort, while opening up other economic activities in the tourist and commercial sectors. This will contribute toward recovering fish and crustacean populations subject to excessive fishing pressure. There is also an opportunity to consolidate a level of fishing that is stable and even further reduced, making it possible to develop an adaptive management plan in accordance with the principles in the new General Act on Sustainable Aquaculture and Fisheries (Ley General de Pesca y Acuacultura Sustentables—LGPAS). There are efforts to make fishing and environment policies compatible, in order to both improve the natural conditions in ecosystems and improve the social conditions for local inhabitants. Only an in-depth organization of the fishing sector will make it possible to reduce the fishing effort, establish the conditions for recovering fish species with commercial importance (such as shark, shrimp, bigeye croaker, etc.), eliminate gill nets that unintentionally catch vaquita, and modify trawling systems to make them more environment friendly. Only in this way will it be possible to modify the tendencies currently observed, and to lay the groundwork for recovering dominant fish and crustacean populations, and increasing the vaquita population. Continuity in the policies implemented is necessary in order to achieve sustainable development in the region.

Living Resources

  • Biodiversity

    Question

    What is the status of biodiversity and how is it changing?

    Why This Score?

    Selected biodiversity change has taken place, precluding full community development and function, but it is unlikely to cause substantial or persistent degradation of ecosystem integrity.

    Basis of Judgement

    The reduction in freshwater discharges into the Colorado River Delta represented the total loss of some mollusks. The lack of freshwater has been a limiting factor for healthy shrimp development. Overfishing took the totoaba to the edge of its survival and trawling systems altered the ichthyofauna at the sea bottom. The vaquita is in critical danger of extinction. The overall state of biodiversity appears to be remaining at a stable level. It will be necessary to implement programs for recovering species, as well as fishing management plans. These actions will make it possible to re-establish marine biodiversity to then change the current tendency. The reduction in trawling fleets and the modification of trawling systems with technological innovations that reduce effects on the sea bottom will facilitate the recovery of the communities at the sea bottom.
  • Extracted Species

    Question

    What is the status of extracted species and how is it changing?

    Why This Score?

    Key extracted species have declined, but there is no evidence of effects on community development and function.

    Basis of Judgement

    Fish species that are particularly important for commercial fishing are over-exploited. Shark populations are becoming scarce, the larger fish are gone, and shrimp are also over-exploited. Fish spawning aggregations are nearly non-existent in the case of some groupers and snappers that use this reproductive strategy, since their populations have diminished significantly. The minimum size for fish caught, in the case of fish important in commercial fishing, has been reduced significantly over the last 50 years. Current fishing systems such as those using trawl nets do not favor the recovery of threatened species. This is the case for the totoaba, which despite an ongoing prohibition banning the fishing of this species, juveniles are caught in shrimp nets, and this clearly limits its recovery. The only recovered species recently incorporated into Upper Gulf fishing has been the gulf corvina. Fishing for this species surged in 1995–1996, and it came under intense fishing pressure. Currently, fishing for this species is being controlled in order to prevent its over-exploitation. It is necessary to control the fishing effort and fishing levels in order to reverse the current deteriorating tendencies. Fishing management plans are indispensable for achieving this. A reduction in both the larger and smaller fleets operating in the area, the incorporation of innovations in fishing arts and methods—discontinuing the use of gill nets and modifying trawl nets to reduce impacts on the sea bottom—as well as the consolidation of alternative economic activities will make it possible to recover the most important fish and crustacean species and lay the groundwork for recovering the vaquita.
  • Alien Species

    Question

    What is the status of alien species and how is it changing?

    Why This Score?

    Alien species exist that may preclude full community development and function, but they are unlikely to cause substantial or persistent degradation

    Basis of Judgement

    In the Delta region, the salt cedar (Tamarix spp.) has invaded a significant portion of the habitat. These trees/bushes demand a great deal of water, and have become one of the dominant species in the southern part of the Valley of Mexicali. Even in these conditions, they offer an important habitat to certain birds, particularly because they are found near water bodies. In early 2009 the zebra mussel (Dreissena polymorpha), which comes from the United States, was reported in the Colorado River Delta for the first time. This freshwater mussel has the potential to invade other freshwater habitats in Mexico if its expansion is not prevented immediately through the implementation of intensive control programs. There are approximately 13 alien fish species and a number of species of invertebrate that could be competing for food and habitat with native populations. It is important that their impact be assessed. These species have had the greatest impact in the wetlands area. For example, tilapia and poeciliidae species have caused a decline in desert pupfish populations. There are no reports of alien marine species.
  • Keystone & Indicator Species

    Question

    What is the status and condition of keystone and indicator species and how is it changing?

    Why This Score?

    Keystone and/or indicator species approach natural, pristine levels and conditions

    Basis of Judgement

    Tule, found in the Delta’s riverine environments and freshwater lagoons, is the habitat’s most fundamental element, and it is an indicator species. Its conservation status is satisfactory, and it constitutes an important component of the different sites making up one of the most important stops on the Pacific migratory route for both aquatic birds and neotropical migratory birds. The region’s marine mammals, with the exception of the vaquita, have adequate population status at this time, although they can come into contact with fishing activities. The common bottlenose dolphin does not suffer significant negative impacts from fishing activities. The main threat for the vaquita, which has been identified as a species in critical danger of extinction, is incidental bycatch in scalefish, shark and shrimp fishing using gill nets. The Mexican government has implemented an emergency program for eliminating the incidental bycatch of the vaquita, and enabling its recovery in the medium and long term. The program includes technological reconversion activities (use of fishing arts that do not harm the vaquita) and productive reconversion that offers sustainable productive alternatives, other than fishing, for local inhabitants.
  • Focal Species

    Question

    What is the status and condition of focal species and how is it changing?

    Why This Score?

    Selected focal species have declined substantially, but populations do not appear to be at risk; recovery appears possible.

    Basis of Judgement

    The dolphin and seal populations in the Gulf of California do not appear to show signs of negative impact. In the case of the totoaba and gulf corvina, tendencies could point to their recovery, although studies are still needed. After more than 30 years of prohibitions on totoaba fishing, the illegal fishing of adult specimens has diminished considerably. And while smaller totoaba (sub-adults and juveniles) continue to get caught in shrimp trawl nets, the population is stable and recovering. The Autonomous University of Baja California (Universidad Autónoma de Baja California—UABC) has made efforts to release young totoaba (machorros) produced in laboratories to contribute to the recovery of this species. Sea turtle populations have diminished considerably, according to reports from local residents. The future of the vaquita is uncertain, as it is in a critical state. Nevertheless, significant, coordinated efforts aimed at its recovery continue. There is confidence that once its incidental bycatch is eliminated, conditions for its recovery could be generated for the medium term.
  • Species of Common Concern

    Question

    What is the status and condition of species of common conservation concern?

    Why This Score?

    The status or condition of selected species has declined substantially from natural historic levels.

    Basis of Judgement

    The vaquita population has been reduced to as little as 5% of its historic numbers, and there is no way to reverse the ongoing tendency unless incidental bycatch in gill nets is eliminated completely. At least 20 consecutive years of conservation strategies will be required to reverse the deterioration process affecting this population, in order for the species to begin to recover and thus avoid its extinction. The Mexican government, through the National Commission of Protected Natural Areas (Comisión Nacional de Áreas Naturales Protegidas—Conanp), has established a special vaquita recovery program called the Action Program for Conservation of the Vaquita (Programa de Acción para la Conservación de la Vaquita—PACE-Vaquita). Coordinated actions are carried out among environmental and fishing authorities, and in addition local authorities have become involved in recovery efforts. Fishing communities and NGOs have established a strategic alliance for guaranteeing sustainable fishing and the vaquita’s recovery, through a coordinating body referred to as the Sustainable High Gulf (Alto Golfo Sustentable—AGS). The Mexican government published the Vaquita Refuge Protection Program (Programa de Protección del Área de Refugio de la Vaquita) in December 2005. In support of that program an Evaluation and Follow-up Entity was established, to function as an advisory body with participation by the federal government, local governments, fishermen and NGOs. The CEC developed a Trilateral Action Program for Vaquita Conservation.
  • Human Activities

    Question

    To what extent do human activities influence living resource quality and how are they changing?

    Why This Score?

    Selected activities have resulted in measurable living resource impacts, but evidence suggests effects are localized, not widespread

    Basis of Judgement

    Currently, fishing activities represent the main threat to the area’s living resources. The current state of the fishing industry can be described as over-exploitation and at the limits of its capacity. Two emblematic species are in danger of extinction, the totoaba and vaquita, and the latter is in critical danger of extinction. Shark and fish populations have been seriously affected; the populations of major predators have diminished; and the sizes of the main carnivores have been reduced by 30%. The current state is one of deterioration. If development patterns are not modified and if order is not brought to fishing and tourist activities, the declining tendency will continue. The potential for change is associated with the vaquita recovery program. Actions to reduce the fishing effort have been carried out, and there is a tendency toward modifying fishing technology to prevent incidental bycatch of non-targeted species. Fishing regulations will tend toward decreasing the fishing effort. The new General Act on Sustainable Aquaculture and Fisheries establishes the development of fishing management plans as an instrument of fishing policy. The enforcement of this law could generate mechanisms aimed at the rational use of fishing resources and the development of responsible fishing in the region. Another significant impact is resulting from tourism development in the coastal area. Alterations in habitats and in the populations of wildlife species have been provoked. Environmental impact assessments are required by the General Act on Ecological Balance and Environmental Protection (Ley General de Equilibrio Ecológico y la Protección al Ambiente—LGEEPA), but it is still necessary to consider and assess accumulative impacts. Priorities include maintaining controls over urban-tourist coastal development and emphasizing the implementation of regulations to assure the compatibility of land uses and to guarantee the protection of critical habitats.

Scorecards 1 to 10 were developed in 2007-2008. Scorecards 11 and 12 were developed in 2010.

Overview

Debido a sus características ecológicas, su alta biodiversidad y la gran cantidad de endemismos presentes, la Reserva de la Biosfera del Alto Golfo de California y Delta del Río Colorado es considerada a nivel global como una zona única e irremplazable. Se le reconoce como una de las zonas de mayor importancia ambiental de la región, no obstante las modificaciones al régimen hidrológico que han transformado las condiciones naturales en el Delta del Río Colorado, ya que las avenidas estacionales de agua provenientes de la Cuenca del Río Colorado hacia el Alto Golfo de California fueron severamente restringidas por la construcción de numerosas presas en el territorio de los Estados Unidos, en particular las presas Hoover (1935) y Glenn Canyon (1962). El paisaje fue alterado de manera radical y los humedales del Delta del Río Colorado fueron impactados drásticamente, desapareciendo el 90% de su superficie. A pesar de todas estas alteraciones, el área marina de la reserva de la biosfera ha mantenido su productividad en virtud de los complejos procesos oceanográficos que sirven de soporte a la reproducción de la vida marina. Los humedales remanentes son la plataforma y espacio de descanso para una gran variedad de aves migratorias (Corredor ripario del Colorado, Río Hardy, el sistema lagunar de bordos y drenes, las ciénagas de Santa Clara y del Doctor); mismos que aún en su mínima extensión, mantienen el corredor de álamos y sauces mas importante del Desierto Sonorense. La extensa zona costera y marina de la Reserva se caracteriza por su riqueza de especies, muchas de ellas endémicas y/o con estatus de riesgo. Forman parte de la Reserva zonas terrestres y marinas que son hábitat de anidación, alimentación, maduración, reproducción o crianza de distintas especies de aves, mamíferos, reptiles y peces, algunas de ellas con estatus en riesgo, entre las que destacan la totoaba, la vaquita y las tortugas marinas. Por otro lado, especies de importancia económica que hacen de la zona una de las más productivas para la actividad pesquera, particularmente el camarón azul, la curvina golfina, el chano, la sierra, los tiburones y las rayas, así como especies de escama, jaiba y almeja, se encuentran cerca de los límites o por encima, de una tasa que permita su aprovechamiento sustentable.

Fact Sheet

State(s) or Province(s): 
Baja California and Sonora
Category: 
Biosphere Reserve
Date Established: 
1993
Area (ha): 
934756
Management Authority: 

CONANP (Comisión Nacional de Áreas Naturales Protegidas)

Human Settlement: 
Yes
Visitors’ facilities: 

Sites for wildlife observation and piers.

Infrastructure: 

Offices, observation sites and docks.

Population: 

There are seven towns within this protected area. These are Golfo de Santa Clara, El Doctor, Mesa Rica and Flor del Desierto, in Sonora; and Salinas de Ometepec, Playa Blanca and Playa Paraíso, in Baja California. Golfo de Santa Clara holds approximately 75% of the population.

Corresponding Marine Ecoregion: 
Gulf of California
Corresponding Priority Conservation Area: 
Alto Golfo de California
Description of the MPA: 

The Upper Gulf of California & Rio Colorado River Delta Reserve is one third terrestrial and two thirds marine. This area is valuable to science, increasingly important for tourism and is an important economic fishery.

Ecosystem diversity: 

18 species of marine mammals, 315 bird species (terrestrial and aquatic), 149 fish species and at least 358 plants species (aquatic and terrestrial) have been reported for this MPA. More than 50 species are considered at risk or are included in national and international conservation lists. These include the totoaba, the vaquita and the Yuma clapper rail, among others. The Santa Clara and El Doctor marshes and the Adair Bay are important resting areas for waterfowl. The variety of intertidal wetlands and sandy and rocky coasts of coquina are important habitats for marine invertebrates and fishes.

Endemisms: 

Totoaba, vaquita, more than 20 endemic fish species, including the desert pupfish and the gulf weakfish.

Focal species: 

Bottlenose dolphin, totoaba, vaquita, fin whale, minke whale, loggerhead turtle, green turtle and whale shark.

Species of Common Conservation Concern: 

Vaquita, loggerhead turtle, green turtle, humpback whale, blue whale, killer whale and grey whale.

Commercial fishing is the main activity within this MPA, and blue shrimp, corvina, northern milkfish, sierra, manta ray, guitarfish, shark, crab and clam are the main targeted species. In the surrounding areas, inhabitants are engaged in agriculture, forestry, mineral extraction, and cattle raising activities. Tourism is also an important activity in this MPA.