Common snook Centropomus unidecimalis is an important commercial and fishery species in Southern Mexico, however the high exploitation rates have resulted in a strong reduction of its abundances. Since, the information about its population structure is scarce, the objective of the present research was to determine and compare the age structure in four important fishery sites. For this, age and growth of common snook were determined from specimens collected monthly, from July 2006 to March 2008, from two coastal (Barra Bosque and Barra San Pedro) and two riverine (San Pedro and Tres Brazos) commercial fishery sites in Tabasco, Mexico. Age was determined using sectioned saggitae otoliths and data analyzed by von Bertalanffy and Levenberg-Marquardt among others. Estimated ages ranged from 2 to 17 years. Monthly patterns of marginal increment formation and the percentage of otoliths with opaque rings on the outer edge demonstrated that a single annulus was formed each year. The von Bertalanffy parameters were calculated for males and females using linear adjustment and the non-linear method of Levenberg-Marquardt. The von Bertalanffy growth equations were FL t =109.21(1-e-0.21(t+0.57)) for Barra Bosque, FL t =94.56(1-e-0.27(t+0.48)) for Barra San Pedro, FL t =97.15(1-e-0.17(t+1.32)) for San Pedro and FL t =83.77(1-e-0.26(t+0.49)) for Tres Brazos. According to (Hotelling's T 2 , p<0.05) test growth was significantly greater for females than for males. Based on the Chen test, von Bertalanffy growth curves were different among the study sites (RSS, p<0.05). Based on the observed differences in growth parameters among sampling sites (coastal and riverine environments) future research need to be conducted on migration and population genetics, in order to delineate the stock structure of this population and support management programs.

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Ions of Sm 3+ , Eu 3+ and Gd 3+ were deposited onto the surface of TiO 2 -P25 using an impregnation method, and the catalysts were calcined to 500°C in order to provide thermal stability to the crystalline phases. A sample of pure P25 was processed under the same synthesis conditions. The materials were characterized by physisorption of N 2 , X-ray diffraction and Scanning Electron Microscope and Spectroscopy UV-Vis with diffuse reflectance. It was observed by SEM that P25 had an amorphous surface forming irregular aggregates and deformations in which the studied lanthanide ions were inserted. Due to heat treatment, the P25 suffered modifications that showed a higher photocatalytic activity in the visible region, by the presence of oxygen vacancies generated by the removal of impurities (C and Cl). XRD analyses determined the distribution and crystal size of the crystalline phases presented in the P25 (anatase and rutile). Lanthanide ions possibly demonstrated an effect of superficial coalescing in the rutile phase of the P25. A completely randomized experimental design was used to determine the catalytic evaluation, and sunlight was statistically shown to be the best condition for the degradation and mineralization of diuron. Comparing treatments indicated a better option: using the catalyst with 0.3 wt% Gd under sunlight.

El robalo blanco (Centropomus undecimalis) es una especie demersal con característica protándrica hermafrodita y hábitos diadrómicos. Se distribuye desde el norte de Florida E.U.A., hasta el sur de Río de Janeiro, Brasil; en el Golfo de México, es abundante en los estados de Tamaulipas, Veracruz y Tabasco. En su área de distribución, el robalo blanco presenta alta importancia comercial y deportiva, esto debido a sus características alimenticias, abundancia, alto valor en el mercado local y regional, así como a la facilidad de obtenerlo por parte de las comunidades pesqueras. En los últimos diez años, el incremento de la demanda en el consumo regional y nacional, así como la modificación de sus hábitats, ha causado que sus niveles de explotación sean altos en el Golfo de México, reduciendo las tallas de captura y la captura por unidad de esfuerzo.

Por su importancia económica y soporte de grandes pesquerías en el Golfo de México, se considera al robalo blanco como uno de los peces más importantes tanto para los pescadores ribereños como para los de aguas marinas, por ello la importancia de generar información para la reproducción de esta especie en condiciones de cautiverio, lo que permitirá no solo la repoblación de cuerpos de agua sino también su producción y engorda involucrando a los pescadores creando conciencia en la necesidad de producir para cosechar.