Distribución y abundancia de la ictiofauna del lago de La Alberca, Villamar, Michoacán

" Main objective of this study was to analyze the icthyofauna structure of the Lake “La Alberca”, Villamar, Michoacán aiming to recommend sustainable management and conservation of native icthyofauna resources. In order to achieve this objective, samples were taken from three different sites during two sampling programs: a mainly diurnal monthly sampling from November 2001 to October 2002; and a diurnal-nocturnal seasonal sampling from autumn 2007 to summer 2008. First sampling was done to assess monthly variation in the distribution and abundance of fish species, and the second sampling was done to analyze fish behavior during their circadian cycle. Fish sample collection methods included two fishing gears: a purse seine in the Northern and Southern sites, and a fishing trawl was used in center of the lake which is the deepest zone. Weight-length relationships were estimated to assess fish growth. The importance index value (IVI) was assessed to quantify the importance of fish species and to determine which fish species are the dominant ones in this lake. In order to analyze biological and environmental variables a cluster index was calculated using the mean grouping through the Bray-Curtis dissimilarity measure to determine spatio-temporal affinities among sampling sites. An ordering analysis was done through NMS Sorensen multidimensional scaling. Fish composition in this lake included 11 native and 2 introduced species. In considering fish relative abundance, cluster representation and grouping analyses, this lake is divided into two major areas: the Northern and Southern stations, and the center station, which is ratified by the ordering analysis as well. Poeciliopsis infans is the dominant fish species in the Northern and Southern sampling stations whilst Chirostoma consocium is the dominant fish species the center station along with Chirostoma lucius at night time. All goodeid fish species, P. infans and C. consocium exhibited an isometric growth which indicates good habitat conditions. Atherinopsids, C. chapalae and C. jordani, exhibited positive allometric growth, and in contrast C. contrerasi and C. lucius growth was negative allometric. Lake fishery is considered to be in a relatively healthy state as long as introduced fish species are controlled and native species are favored through time. Water quality indicates that this lake is a polymictic without signs of stratification. Temporally environmental variables follow well defined seasonal patterns "