The Effect of Hydrological Connectivity on Fish Assemblages in a Floodplain System From the South-East Gulf of California, Mexico

The effect of hydrological connectivity of the fish assemblages was assessed on a floodplain in the SE Gulf of California, Mexico using a before–after control-impact (BACI) design. Community structure attributes of species abundance, biomass, richness, diversity, and differences in the structure of fish assemblages were compared between two periods (January to June in 2011 and 2015) and two flood plains, one designated as the control zone which was divided by a road, and another one designated as the treatment zone which from January to June 2011 was divided by a road, and then sampled from January to June 2015, as the site was rehabilitated by removing the road in the year 2012. Fish were sampled at monthly intervals using a seine net at different stations in both floodplains. A total of 7024 organisms, comprising of 14 species belonging to 11 families, were analyzed. In the control zone during both periods and in the treatment zone before removal of the road Poecilia butleri was the most abundant species and two exotic species (Tilapia) accounted for more than 95% of the total biomass. After the removal of the road in the treatment zone Poeciliopsis latidens was the most abundant species and the relative biomass of both species of tilapia decreased to 85%, but was still the most important in terms of biomass. However, richness and diversity were higher and the structure of the fish assemblages was different in the treatment zone after the road was removed, due to the presence of species with estuarine and marine affinity in this zone and period. Our results indicate that hydrological connectivity proved to be a key factor influencing the fish composition and abundance in the floodplain system in the region. Hence, a better hydrological connectivity implied higher abundance and diversity, likely related to an increase in the habitat complexity. The priority in the management of the ecological functioning of the floodplain system should be set on minimizing the modifications of the natural flow and thus avoiding the changes on the fish biota

A new record of Huttonella bicolor (Hutton, 1834) (Mollusca, Gastropoda, Streptaxidae) in Mexico

A specimen of Huttonella bicolor = Gulella bicolor (Hutton, 1834) was collected from clayey-sandy soil in Tabasco, Mexico, which constitutes its second record in the state and the third in Mexico. This small gastropod is a predator that has mainly spread through tropical and island regions as an exotic species. Its introduction to Asian and Caribbean Islands is noteworthy. Its pupiform shell and the lamella or tooth complex were compared against previous descriptions. In Mexico, this species has been found in northern Veracruz and Tabasco, which confirms that it is spreading along the Gulf of Mexico from the United States towards Brazil. The features of this streptaxid as a potential hazard through its preferred prey are discussed.Un ejemplar de Huttonella bicolor = Gulella bicolor (Hutton, 1834) fue capturado en suelo limo-arenoso en Tabasco, México; el cual constituye el segundo registro para el estado y el tercero para México. Este pequeño gasterópodo es un depredador que se ha extendido como especie exótica en regiones preferentemente tropicales e insulares; destaca su introducción en islas de Asia y del Caribe. La concha tiene forma de pupa con lamelas o dientes en la abertura. Se comparó con la descripción de la especie. La distribución de la especie en México se extiende a los estados de Veracruz y en Tabasco, lo cual confirma el avance en su distribución a lo largo de la costa del Golfo de México de los Estados Unidos hasta Brasil. Las características de este estreptaxcido en cuanto al riesgo a través del tipo de presa preferida son discutidas

Modelo de fiscalización electrónica

  Objetivo: proponer y validar un modelo teórico de fiscalización electrónica para ser integrado al proceso de fiscalización de la Administración General de Auditoría Fiscal Federal del Servicio de Administración Tributaria en México, a fin de predecir, prevenir, detectar, corregir y comprobar el incumplimiento de obligaciones fiscales de los contribuyentes, usando herramientas y técnicas forenses de auditoría. El modelo propuesto (creación de los autores, quienes lo nombraron KAF) se compone de cuatro elementos: instrumentos, fases, enfoques y efectos; su interacción y funcionalidad se explica a través de criterios; las fases propuestas se alinean a las del proceso de auditoría y los instrumentos especializados pueden aplicarse sin mediar un delito fiscal o llegar a tribunales. Métodos: investigación de enfoque cuantitativo y alcance descriptivo con diseño no experimental. Se emplearon encuestas para la recopilación de datos, la validación del modelo fue con criterio de expertos y haciendo uso del coeficiente de concordancia. Resultados: se obtuvo el coeficiente de concordancia entre jueces ,96 (sig < 0,05), lo que indica el grado en que los elementos del cuestionario se relacionan con la coherencia en las respuestas otorgadas por los expertos al analizar la información obtenida. Conclusiones: La principal aportación del presente estudio fue proponer un modelo de fiscalización electrónica con cuatro elementos: instrumentos, fases, enfoques y efectos para integrarse en el proceso de fiscalización de la Administración General de Auditoría Fiscal Federal aplicado en las administraciones desconcentradas de auditoría fiscal; mismo que fue validado por criterios de expertos. El modelo KAF de fiscalización electrónica puede ser utilizado tanto en el sector público como en el privado y propicia el incremento de la percepción del riesgo en los contribuyentes por incumplimiento en las obligaciones fiscales

Feeding Habits and Trophic Level of the Panama Grunt Pomadasys panamensis

The Panama grunt is an abundant and commercially important species in the southeastern Gulf of California, but the research undertaken on this species is scarce despite its ecological and economic importance. We studied the feeding habits of Panama grunt through stomach content analyses as a first step towards understanding the biology of this species in the study area. Our results indicate that the Panama grunt is a benthic predator throughout its life cycle and feeds mainly on infaunal crustaceans. Diet differences among grunt were not found according to size, diet, or season. Shannon diversity index results indicate that Panama grunt has a limited trophic niche breadth with a diet dominated by a limited number of taxa as crustaceans. The estimated trophic level of this species is 3.59. Overall, the Panama grunt is a carnivorous fish occupying the intermediate levels of the trophic pyramid

Age and growth of the scalloped hammerhead shark, Sphyrna lewini (Griffith & Smith, 1834) from the Southern coast of Sinaloa, México

Age and growth for the scalloped hammerhead shark (Sphyrna lewini) were determined from opaque bands (OBs) on postcephalic vertebrae from 109 organisms (44 females, 52 cm to 276 cm total length (TL) and 65 males, 47 cm to 245 cm TL) obtained bimonthly from commercial fisheries off the southern coast of Sinaloa state (23º45´25´´N and 106º05´15´´W to 21º52´N and 105º54´W) from January 2003 to February 2005. The Bowker test of symmetry and the Index of Average Percent Error, suggest that this ageing method represents an unbiased and precise age assessment. Results show that immediately after birth (in summer), the first OB was formed and in the next winter showed the second OB. Later it was observed that two OBs were formed each year, one during summer and the other during winter, influenced by the sea surface temperature (SST). Based on the comparison of five back-calculation methods, the best methods were FraserLee. The parameters of the von Bertalanffy growth function were, for females: L? = 376 cm, K = 0.1 year-1, t0 = -1.16 years, b = 3 and W? = 222 kg; for males: L? = 364 cm, K = 0.123 year-1, t0 = 1.18 years, b = 3 and W? = 193 kg. The standard index growth (?´) was 4.2 (s = 0.1). According to these results the largest sharks observed, a female of 280 cm TL would be 12.5 years old and a male of 281cm TL would be 11 years old

AFS Position Paper and Policy on Mining and Fossil Fuel Extraction

Following a four-year period of writing, member comment, and multiple revisions, the AFS Position Paper and Policy on Mining and Fossil Fuel Extraction was approved unanimously by the membership at the Society's annual business meeting August 19, 2015, in Portland, Oregon. The entire document can be read at fisheries.org/policy_statements; a brief summary follows

Hábitos alimenticios del lenguado panámico Cyclopsetta panamensis (Paralichthyidae) en el Sureste del Golfo de California

The feeding habits of the Panamic flounder Cyclopsetta panamensis caught in the SE Gulf of California were studied. The specimens were collected by demersal fish surveys during the years 2004-2008. The panamic flounder is a predator focusing mainly on crustaceans inhabiting the bottom belonging to Squillidae and Penaeidae. The diet of the Panamic flounder did not vary significantly according to depth or sex, and not size related variations in the diet composition were observed. Based on the TROPH value, the Panamic flounder can be considered as a top carnivore from the demersal community in the Gulf of California