Este proyecto se refiere a dos grupos de peces incluidos en la Norma Oficial Mexicana-059-SEMARNAT-2001 (NOM-059). El primero es un grupo taxonómico, la familia Cichlidae (mojarras de agua dulce), del cual aparecen en la NOM-059 ocho especies, seis de ellas carentes todavía de la ficha correspondiente; todas se asignaron en la NOM erróneamente al género Cichlasoma, a pesar de que desde hace más de 20 años quedó demostrado que ese taxon no existe en México (Kullander, 1983). De las seis especies sin ficha, en el sur de México están C. grammodes (excluida de la presente propuesta por estar ya incluida en otra), C. (= Vieja) hartwegi, C. intermedium (= V. intermedia), C. (= Thorichthys) socolofi y, en el norte, C. (= Herichthys) steindachneri y C. (= Herichthys) minckleyi, esta última con un interesante polimorfismo trófico. El segundo grupo abordado en esta propuesta se refiere a los peces de la frontera sur (entendida aquí como toda la península de Yucatán y el estado de Chiapas) enlistados en la NOM-059. Además de los cíclidos mencionados, este segundo grupo consiste en once especies: Astyanax armandoi, los Cyprinodon endémicos de la laguna de Chichancanab, Quintana Roo (C. beltrani, C. labiosus, C. maya, C. simus y C. verecundus – la NOM no toma en cuenta todavía al sexto, C. esconditus Strecker 2002, ni al séptimo, C. suavium Strecker 2005), Poecilia velifera, Profundulus hildebrandi, Potamarius nelsoni, Ogilbia (=Typhliasina) pearsei y Ophisternon infernale; la NOM contempla además a Rhamdia guatemalensis, que ya cuenta con una ficha, a pesar de que su validez taxonómica ha sido cuestionada (Silfvergrip 1996), y a pesar de su amplísima distribución y abundancia. El objetivo central de la contribución fue elaborar las fichas correspondientes y obtener el valor que asigna a cada una de estas 16 especies el Método de Evaluación del Riesgo de Extinción de las especies silvestres en México (MER), para recomendar su reclasificación o su exclusión de la lista, si fuera necesario. La información necesaria se ha tomado de la literatura, tanto publicada como “gris”, ésta última integrada fundamentalmente por datos inéditos de los investigadores participantes, sus estudiantes y otros colegas. Como resultado de lo anterior, se anexan tres propuestas formales de cambio de categoría de riesgo: C. beltrani (de [P] a [A]), Th. socolofi (de [Pr] a [A]) y V. hartwegi (de [Pr] a [A]). En el caso de A. armandoi, la ficha incluye y fundamenta una observación sobre el carácter dudoso de su identidad taxonómica, aunque, por principio precautorio, no se propone (todavía) excluirla de la NOM. Las demás especies estudiadas permanecen sin cambios en su categoría de riesgo. Además, siempre con base en la aplicación del MER, se recomienda la inclusión de otras siete especies de la frontera sur hasta ahora ignoradas por la NOM-059: Astyanax altior, Cyprinodon esconditus, C. suavium, Fundulus grandissimus, F. persimilis, Lacantunia enigmatica y Menidia colei. Finalmente, se recomienda formalmente la exclusión de Rhamdia guatemalensis de la NOM-059.

A grant has been awarded to Dr. Richard L. Mayden at Saint Louis University to conduct field and laboratory research in collaboration with other USA scientists and several scientists from Mexico on the environmental status, distribution, conservation and genetics of native trout populations of Mexico. While biologists have been aware of the existence of native trout in Mexico for over a century, they have received little study. Beginning in the mid-1990's a group of ichthyologists and conservation biologists from both Mexico and USA jointly formed an international alliance, Truchas Mexicanas, to better understand the native trout of the Sierra Madre Occidental. Through these efforts, scientists have discovered previously unknown trout species restricted to Mexico and introduced (non-native) populations of rainbow trout. The existence of these non-native rainbow trout originating from streams in the US and Canada in the ranges of the unique Mexican trout species is a significant threat to the future existence of native species. Rainbow trout are known to displace native trout species through competition or genetically "swamp out" their gene pools through aggressive hybridization. Other native populations of trout are also predicted to occur in the upper Rio Conchos; these populations are predicted to also be in danger from habitat destruction and introductions of rainbow trout. In this study we will inventory many river systems of the sierras for native and introduced trout species, including the upper Conchos River system. Genetic samples will be examined from all of these populations to evaluate genetic variability of native species and determine if any native populations are compromised genetically through hybridization with introduced rainbow trout. This research supports the development of an international alliance investigating native trout populations of Mexico and southwestern United States. Trout species are important game and forage species for human populations, constituting a major element of diets in some regions. Trout fisheries are also very important economic elements to some regions as trout are highly prized sport fish species. Understanding native trout species diversity in Mexico and its conservation and maintenance in these streams has a major impact on both fisheries and economic areas. Mexican trout species are the southern-most trout and are adapted to theses unique ecosystems. Introductions of non-native rainbow trouts will seriously jeopardize these adapted populations and lead to their extirpation from the region. This will have serious sociological and economic impacts for the native people of the region.

A broad-scale survey of potential trout habitats in upper tributaries of the Río Conchos of Chihuahua, México resulted in the re-discovery in 2005 of a long-lost native, endemic, and now endangered, undescribed trout species that we call the "Conchos Trout." We are currently in the process of scientifically describing this rare trout, the only native Mexican trout known from an Atlantic drainage. Our extensive field efforts to date clearly indicate that this species was formerly much more widely distributed historically. Though surveys should continue, our extensive field surveys found only one small isolated and extremely vulnerable population, leaving us less than optimistic that many other, if any, additional populations will be found. Persistence of this new critically endangered endemic Conchos Trout clearly requires rapid conservation action. Our consensus expert opinion is that we cannot over-emphasize the urgency of protection for this critically endangered population of this unique trout, and so we have produced this "white paper" in hopes that it might encourage others to join us in initiating appropriate conservation programs. The potentially viable population is restricted to a short reach of a very small stream where it and another newly discovered, undescribed fish species, a sucker (and likely another unique taxon), could be relatively easily protected, studied and managed. Additionally, adjoining arroyos where the species recently occurred offer the possibility of restoring native fish populations to them following appropriate protection and habitat restoration efforts. All members of our highly qualified and diversely specialized, binational "Truchas Mexicanas" team stand prepared to join collaborators and invest personal resources in hands-on actions to help this new species persist. We recommend immediate establishment of a small reserve centered around currently occupied habitat and adjacent streams having suitable habitat, combined with education and compensation of local residents for their cooperation with reserve management. We recognize that we are largely ignorant of the local political and cultural systems via which conservation actions will have to proceed and are limited with regard to our ability to raise funds. We thus hope that readers of this white paper will add their financial and in-kind support and additional expertise to help us conserve the Conchos Trout!

The gut contents of Herichthys minckleyi were examined to determine if variation in jaw morphology in this trophically polymorphic cichlid fish is associated with feeding specialization. First, individual H. minckleyi were categorized as having molariform, papilliform, or undetermined pharyngeal morphology. Molariforms possess large molar-like teeth and robust crushing musculature, papilliforms exhibit only small pointed papilliform teeth on their more gracile jaws, and undetermined individuals (\textless 50 mm standard length) were not clearly assignable to one of the other two morphotypes. Undetermined individuals did not consume as great a percentage of plant material as papilliforms and never crushed snails. Aquatic arthropods comprised a small proportion of prey material recovered from the three pharyngeal morphotypes. Papilliforms, once size was accounted for as a covariate, consumed substantially more plant detritus than molariforms, while molariforms consumed snails more frequently than papilliforms. Even when only comparing molariforms and papilliforms that did consume snails, molariforms consistently crushed a greater number of the robust and extremely abundant snails Mexipyrgus churinceanus, Mexithauma quadripaludium, and Nymphopilus minckleyi. Contrary to expectation, there was no relationship between molariform standard length and the number of snails crushed. However, greater molariform tooth number, adjusted for standard length, was correlated with the inclusion of snails in molariform gut contents. The diet differences recovered between molariform and papilliform H. minckleyi suggest current ecological differentiation plays a role in maintaining this trophic polymorphism.

Stromatolites, the dominant Precambrian life form, declined in the Phanerozoic to occur today in only a few sites. This decline has been attributed to evolution of metazoan grazers, but stromatolites in our study site, Cuatro Cie'negas, Coahuila, Me'xico, harbor diverse macroinvertebrates. Drawing on food chain theory, we hypothesized that fish predation on invertebrates controls invertebrate populations, allowing stromatolites to flourish in Cuatro Cie'negas. Our experiment used small mesh (1 mm) cages to exclude all but larval fishes, and larger (6.5 mm) cages to exclude all larger fishes (including the molluscivorous and omnivorous endemic polymorphic cichlid, Herichthys minckleyi), but allow access to all sizes of the abundant endemic pupfish, Cyprinodon bifasciatus. No effects of treatments on invertebrate densities were noted at 6 week, but significant effects were observed on specific taxonomic groups after 3 month. In absence of fishes, hydrobiidae snails and ceratopogonids increased 3- and 5-fold, respectively, and invertebrate assemblage composition varied among treatments. Algal biomass was not affected by treatments, but algal species composition appeared to change. Overall results suggest that fish assemblages structure invertebrate assemblages, and that fishes may also be factors in determining algal communities.