Subterranean Fishes of the World

5092

2020

IUCN and ABQ BioPark.

Cambridge, UK and Albuquerque, New Mexico, USA

The inland waters of Mexico support a highly diverse group of freshwater fishes with high levels of endemism that occur across a broad range of aquatic habitat types. These aquatic ecosystems provide many direct (e.g., fisheries) and indirect (e.g., agricultural irrigation) benefits to people, and support local livelihoods and economies across Mexico. Freshwater ecosystems are undervalued and receive insufficient funding, political attention and protection. Developing interests and funding for freshwater species conservation is crucial for “bending the curve” to reduce and ultimately reverse freshwater biodiversity declines. Historical disregard for the health and sustainable use of freshwater ecosystems has resulted in alarming rates of loss in the quality and availability of aquatic habitat. This report presents the most recent information on the conservation status and distribution of freshwater fishes in Mexico, and examines the stressors that are driving their declining conservation status. Important conservation actions and considerations are also presented. Five hundred and thirty-six species of freshwater fishes were assessed against the IUCN Red List Categories and Criteria, representing the most comprehensive assessment of freshwater biodiversity in Mexico to date. This assessment seeks to address the insufficient information available on freshwater fish conservation status, which has resulted in their inadequate representation in environmental planning and management. The full data set, including all species distribution maps, is freely available through the IUCN Red List website (www.iucnredlist.org). Forty percent of all extant species assessed are threatened with extinction, assuming all Data Deficient species are threatened in the same proportion as those for which enough information was available. The most pervasive threats are related to habitat loss and degradation, which is driven primarily by unsustainable water use and widespread agricultural activity. Excessive extraction of groundwater and diversion of surface water for human consumption, industrial processes, and plantation agriculture has led to widespread flow reductions, reduced water tables, and subsequent drying of aquatic habitat, which is especially prevalent in the arid, endorheic spring systems of northern and central Mexico. Mexico’s vast hydroelectric infrastructure has altered the historical flow regime of many major rivers, blocking natural migration routes and fragmenting subpopulations of native fishes. Agricultural runoff, inadequate wastewater treatment, and industrial discharges have also resulted in increased levels of pollution. A number of non-native fish species have been introduced both intentionally and unintentionally throughout many of Mexico’s natural and artificial surface waters, with profound impacts on native species distribution and abundance. Given the high connectivity of riverine surface waters and underlying aquifers, the impacts of these threats spread rapidly throughout freshwater ecosystems. Future conservation efforts must place greater emphasis on upstream, downstream, and lateral connectivity within water catchments. Systematic conservation planning approaches should be implemented to develop an integrated conservation action plan for freshwater fishes in Mexico, including broad stakeholder participation, environmental monitoring schemes, and the development of protected areas designed to maintain high levels of aquatic connectivity. Another priority is to direct additional research effort towards the high proportion of species assessed as Data Deficient due to insufficient information on their conservation status and distributions. This lack of information presents a significant bottleneck to the effective management and conservation of Mexico’s freshwater habitats and ichthyofauna. From a policy perspective, the information presented in this report will help support the implementation of multilateral environmental agreements in Mexico, guide conservation planning and priority setting at the national and international level, and provide a baseline of conservation success in subsequent assessments of extinction risk. In addition, this new information will help efforts to achieve the targets of the UN Sustainable Development Goals (SDGs), such as: Target 6.6 for protecting and restoring water-related ecosystems; Target 6.5 on implementing integrated water resources management at all levels; Target 15.1 for conservation, restoration and sustainable use of terrestrial and inland freshwater ecosystems and their services; and Target 15.5 focused on urgent and significant action to reduce the degradation of natural habitats, halt the loss of biodiversity and, protect and prevent the extinction of threatened species. The IUCN Red List is one of the most authoritative global standards supporting policy and action to conserve biodiversity. The analysis presented in this report, based on an assessment of species Red List status, will provide new information to help guide conservation actions and development planning to safeguard the diversity of freshwater ichthyofauna in Mexico. Periodic update of IUCN Red List species assessments will enable calculation of a Red List Index of change in freshwater species extinction risk over time, which will inform managers on the conservation effectiveness of any management interventions.

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