Browsing by Subject "Sinaloa"
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Item Biodviersityof Mexican Trout (Teleostei: Salmonidae: Oncorhynchus): Recent findings, conservation concerns, and management recommendations(Universidad Autónoma de Nuevo León, Facultad de Ciencias Biológicas, Monterrey, Nuevo León, México, 2004-09) Mayden, Richard L.Until very recently the diversity of trout in Mexican rivers of the Sierra Madre Occidental has been very poorly understood and only the Rainbow Trout, Oncorhynchus mykiss, and the Mexican Golden Trout, 0. chrysogaster, have been recognized. Recent efforts in the last decade by a binational organization of scientists and laypersons interested in the diversity and conservation of Mexican trout, Truchas Mexicanus, have revea led considerable diversity within the river systems of the Pacific Slope south to the Rio Acaponeta . These trout forms are highly differentiated and distinctive, and are considered native to these high-elevation river systems in pine-dominated forests. The increased occurrence of trout growout facilities and hatcheries within the range of these native Oncorhynchus and the escapes from these facilities threaten the native trout diversity through both introgressive hybridization and through resource competition, end products already known to occur in other trout populations in the other areas of North America exposed to exotic hatchery trout. Other threats to the native and previously unknown trout biodiversity in Mexico include timber harvesting, some pollutions associated with these activities, and siltation of critical habitats. Recommendations are provided to aid in the safe management and protection of this diversity which center around the future use of sterile trout in growout facilities and the use of undisturbed buffer zones along streams. The divergence observed in forms of Mexican trout is equivalent to the levels of divergence found between currently recognized subspecies of trout in the Rainbow and Cutthroat trout groups. Upon review of the diversity and divergence known to exist in these groups and our current understanding of conceptualizations of species, it is argued that the recognition of subspecies within these highly diverse trout lineages is inconsistent with the natural evolutionary history of these groups. The long-term use of the Biological Species Concept for these species is argued as not only inappropriate but an inadequate and illogical characterization of diversity. The logical consequences of hanging on to this concept as the operational and theoretical framework of trout diversity would necessitate the synonymization of all Rainbow and Cutthroat trout taxa as subspecies because of the known propensity of these groups to demonstrate introgressive hybridzation in some areas. These subspecies are considered va lid evolutionary lineages that are demonstrate divergence at morphological, genetic, and ecological characters that are well known to many trout taxonomists and biologists. All of these therefore qualify as Evolutionary Species that are easily diagnosable under the Phylogenetic Species Concept and should be recognized as valid species.Item Fishes of the Río Fuerte, Sonora, Sinaloa and Chihuahua, México(Universidad Autónoma de Nuevo León, Facultad de Ciencias Biológicas, Monterrey, Nuevo León, México, 2002-11-10) Hendrickson, Dean A.; Varela Romero, AlejandroThe Rio Fuerte drains 33,835 km2.of the Sierra Madre Occidental of the Mexican states of Chihuahua, Sinaloa, Durango, and Sonora. Its tributaries pass through Barranca del Cobre (Copper Canyon) as they drop from headwaters as high as 2,808 m above sea level to the Mar de Cortes (Gulf of California). Its headwaters interdigitate closely with east-flowing tributaries of the Rio Conchos, an important tributary of the Rio Bravo (Grande), and interior drainages of Chihuahua and Durango, such as the Rio Nazas. The Fuerte shares its fish fauna with these neighboring drainages, and has no endemics. Northernmost tributaries are relatively arid, but southern tributaries drain sub-tropical areas with much higher rainfall. Dams and diversions now block movements of many marine fish species that used to move far upstream, and more are in construction or planned. Large river fish habitats at lower elevations have been converted almost entirely into canals and the natural mainstream channel now carries only minimal or highly modified discharges, often contaminated by agricultural runoff. At higher elevations, fish habitats have been severely impacted by logging and grazing. Logging development continues, recently expanding from traditional conifers to lower-elevation oaks. Exotic fishes have had, or surely will have, broad impacts on the native fauna through predation, competition and hybridization. Tilapias from Africa are widely established now, as are several centrarchids that will undoubtedly impact on the native cichlid (Cichlasoma beani), cyprinids, catostomids, poeciliids, and others. While not well studied taxonomically, the basin's native catfish, closely related to Ictalurus pricei, is now broadly hybridizing with introduced channel catfish (I. punctatus). At higher elevations, the beautiful native Mexican golden trout is very likely to hybridize with rainbow trout being widely introduced for fish culture. El Rio Fuerte drena 33,835 km2 de la Sierra Madre Occidental en los estados de Chihuahua, Sinaloa, Durango y Sonora. Sus tributarios fluyen a traves de la Barranca de! Cobre (Copper Canyon) y caen desde las cabeceras de 2,808 m sobre el nivel del mar hacia el Mar de Cortes (Gulf of California). Sus cabeceras interdigitan cercanamente con los tributarios de flujo este del Rio Conchos, un importante tributario del Rio Bravo (Grande) y drenajes interiores de Chihuahua y Durango como el Rio Nazas. El Fuerte comparte su fauna de peces con estos drenajes vecinos y no presenta endemicos. Los tributarios norteños son relativamente aridos, pero los tributarios sureños drenan areas subtropicales con mayor regimen de lluvias. Las presas y canales, que bloquean ahora el movimiento de muchas especies de peces marinos que lo usaban para remontar el rio, siguen en construcción y planeación. Los habitats de peces de rios grandes en bajas elevaciones han sido convertidos en canales y el canal principal natural ahora mantiene descargas minimas o altamente modificadas, frecuentemente contaminadas por desechos de la agricultura. A grandes elevaciones, los habitat de los peces han sido impactados severamente por la tala y el pastoreo. Los desarrollo madereros continuan y recientemente se han expandido de las tradicionales coniferas a los encinos de mas baja elevaci6n. Los peces exóticos tienen o seguramente tendran grandes impactos sobre los peces nativos a traves de la depredación, competencia e hibridación. Las tilapias de Africa estan ahora ampliamente establecidas al igual que varios centrarquidos, que indudablemente impactan sobre el ciclido nativo (Cich/asona beani), ciprinidos, catost6midos, pecilidos y otros. Aunque no esta bien estudiado taxonomicamente, el bagre nativo de la cuenca, cercanamente relacionado a Ictalurus pricei, esta ahora hibridizandose ampliamente con el bagre de canal introducido. A grandes elevaciones, la hermosa trucha dorada Mexicana nativa, es muy posible que hibridice con la trucha arcoiris, que ha sido ampliamente introducida como pez de cultivo.Item Geographic variation in morphology of Agosia chrysogaster, a Sonoran desert cyprinid fish(Arizona State Univeristy, Tempe, AZ, 1987-05) Hendrickson, Dean A.Morphometric analyses of Agosia chrysogaster (Girard) indicated a northern morph native to Bill Williams, Gila, Sonoyta and de la Concepcion basins of Arizona, New Mexico and Sonora, and a southern form from Willcox Playa of Arizona and Rios Sonora, Yaqui, Mayo, Fuerte and Sinaloa of Sonora and Sinaloa, Mexico. The latter is smaller, and less sexually dimorphic, but has longer pre- and postdorsal body lengths. Populations in the geographically intermediate Rios Sonoyta and Sonora are morphologically intermediate. Males differ more between morphs than do females. Meristic characters show considerable overlap between morphs, but the northern form has higher mean lateral line scale counts. Highly tuberculate nuptial males, characteristic of the northern morph, were not found in the south, nor were "spawning" pits characteristic of breeding activities of the former. Morphs differ on a multivariate axis on which temporal variation at single localities is also reflected. Distances among some intra-locality samples on this axis were greater than least inter-morph morphological distances. Measures of morphological dissimilarity were weakly correlated with inter-sample differences in elevation, latitude, and longitude, but more highly correlated with an index of hydrologic isolation among localities. Differentiation among basins thus appears to reflect hydrographic isolation, rather than ecological conditions. Electrophoretic data on A. chrysogaster produced relationships patterns largely incongruent with results of the morphological analyses, and with unexpected geographic area relationships.Item Species in the spotlight: Treasures of the Sierra Madre – Mexico’s little-known native trout diversity(International Union for the Conservation of Nature, 2020) Hendrickson, Dean A.Few individuals on our planet do not know what trout and salmon are. They are usually recognised as highly palatable, and often colourful species, and most who know them likely visualize cold, beautiful, pristine, free flowing, alpine or forest streams and rivers as their typical habitats. Many will also know of the remarkable migrations taken by some species, moving from their birth locations in rivers to oceans and then returning to their birthplaces to spawn and die. Some may recognise their importance as prized targets of anglers, particularly fly fishers, who spare no expenses to go after these trophies. Many others who might not be so familiar with the characteristics just mentioned may likely recognise species of this family as the tasty, and usually relatively costly fish found frozen or on ice in grocery stores and fish markets, or in cans, or smoked, or served in restaurants. Their flesh, often pink or rosy-coloured, is prized worldwide. There is no doubt that fishes in this family (Salmonidae) are well known in most of the developed and developing countries of the world and that some have become extremely economically and globally important commercial species that support large-scale recreational as well as wild commercial fisheries, and are massively produced by global aquaculture. At the same time many are also imperilled to some degree. Before this project, the Red List database contained 140 species of Salmonids. Here we’ll focus on the genus Oncorhynchus, commonly known as the Pacific salmons and trout, which prior to this project was represented in the Red List by six species. Then, setting aside the many “salmon” of this genus, we’ll focus only on trout, specifically those of a large and diverse lineage, best known for one species, the famous rainbow trout (O. mykiss). Originally known only from California and other Pacific drainages of the U.S., rainbow trout have long been a prized target of anglers, and the species has been bred in captivity for at least 150 years. High demand for it for both sport fisheries, as well as wild and captive protein production, resulted in it now being established on every continent. It has become not only one of the world’s most important recreational fishing species, but also one of the planet’s most widely cultured vertebrates. It is effectively global agriculture’s “fish version” of the chicken, with global aquaculture production of the species in 2014 reaching 812,940 metric tonnes valued at nearly 4 billion US$ (U.N. Food and Agriculture Organization (FAO) n.d.) That rainbow trout of global fishery and aquaculture fame is known to be one of about 10 closely related subspecies of what is called the “coastal rainbow” branch of the evolutionary tree of the genus. Most of those are from California, but two native Mexican taxa have long been recognised as part of this lineage, O. m. nelsoni (Nelson’s trout – recently reviewed by (Ruiz Campos, 2017)) of the northernmost mountains of Baja California, and O. chrysogaster (the Mexican golden trout – recently covered by multiple contributors (Ruiz-Luna & Garcia De León, 2016). Recent genetic studies (AbadíaCardoso et al., 2015) confirm those relationships and reveal, from specimens collected by the bi-national group of researchers known as Truchas Mexicanas (Hendrickson et al., 2003), that Mexico’s share of the diversity in this lineage is much greater. At least 10 more, still undescribed species of native trout reside in remote, rugged and isolated corners of the Sierra Madre Occidental extending as far south as the high mountains between Mazatlán and Ciudad Durango. Truchas Mexicanas’ fieldwork left no doubt that most share a need for conservation actions to help their often small and fragmented populations persist, and some are critically imperilled (Camarena-Rosales et al., 2006; Hendrickson et al., 2007; Hendrickson & Tomelleri 2019). While their formal descriptions have been delayed for various reasons, recent genetic validation of their distinctiveness, and clear need for recognition of the need for conservation actions on their behalf, led those studying them to petition the IUCN to add them to the Red List while their descriptions are being finalized. That petition was accepted and their assessments were completed as part of this project.