Growth and mortality parameters of Orthopristis ruber (Perciformes: Haemulidae) from Los Frailes Archipelago, Venezuela. Orthopristis ruber is a species in high demand in Eastern Venezuela, but production has been decreasing in recent years. For this reason, our objective was to estimate the growth and mortality parameters of this resource. Monthly samples were collected from June 2011 to May 2012, obtaining 2 980 specimens in El Tirano and Puerto Abajo. Data on total length (cm), total weight (g), and sex were recorded for each specimen. No sexual dimorphism was shown with respect to length (t s =1.113, p>0.05), so one length-weight ratio was established for both sexes (Wt=0.0612*Lt 2.54 ); and they both exhibited minor allometric growth. Growth was estimated by analysis of length frequency distributions using FiSAT software. The estimated growth parameters (L ∞ =39.03cm, W ∞ =679.60g, k=0.48/year and t o =-0.32year) showed moderately rapid growth. Length frequency data were adjusted to the von Bertalanffy model, and indicated an exponential tendency of accelerated growth during the first years of life, followed by slow growth until the fish reached its maximum length. The coefficient of variation of the growth index (Ø') demonstrated no differences in growth pattern. The natural mortality rate (M=0.97/year), from fishing (F=1.57/year), and total mortality (Z=2.54/year), were high, as well as the exploitation rate (E=0.62/year). We concluded that O. ruber has been fully exploited by artisanal fishers, and suggest a continuous study on population dynamics, to recommend optimum management techniques for the fishery. Rev. Biol. Trop. 63 (1): 189-198. Epub 2015 March 01.Key words: growth, mortality, population parameters, Orthopristis ruber, Los Frailes Archipelago, Venezuela.Los estudios de crecimiento de peces son esenciales para la mayor parte de los objetivos de la evaluación pesquera, tanto en las regiones tropicales como en las templadas, debido a que el crecimiento individual de los organismos constituye, a través del tiempo, la fuente de suministro de las capturas extraídas por una pesquería (Pauly, 1983). En pesquerías la mortalidad total es interpretada como la disminución en el número de individuos de una cohorte a causa de diversos factores. Los coeficientes de mortalidad que normalmente se usan en el estudio de la dinámica de las poblaciones están relacionados con las dos principales causas de mortalidad a que están expuestos los peces a lo largo de su vida: la mortalidad natural, que depende de las características biológicas de cada stock y de las cohortes que la componen, y la mortalidad por pesca, causada por el hombre, que se utiliza en la administración pesquera (Sparre & Venema, 1997). La mortalidad natural puede considerarse siempre como un factor constante que afecta por igual y en forma permanente a todos los peces, mientras que la mortalidad por pesca no siempre puede ser considerada como una constante, ya que en gran parte está sujeta a los deseos o habilidades del hombre (Csirke, ...

Analysis of energy flows and economic dynamics allows the diversity of variables involved in the agroecosystem production to be observed in the same dimension. In this way, efficiency and performance can be analysed integrally to identify critical points to be improved. The objective of this study was to analyse the energy-economic efficiency within three management strategies (Management I, Management II and Management III) of the maize agroecosystem in the Frailesca region of Chiapas (Mexico). The hypothesis was that systemic typologies, defined by modes of production, can lead to different efficiencies for the system performance. The study was descriptive; case studies were selected as representative based on their technological variants. The efficiency analysis was conducted using a balance of inputs and outputs expressed in energy and economic terms. Management III resulted in better energy use efficiency, with 6.47, while Management I and Management II were more economically feasible, with a benefit/cost ratio of 1.56 pesos.

Abstract:Octopus vulgaris (Octopoda: Octopodidae) biology and fishery on the shores of Nueva Esparta state, Venezuela. In the State of Nueva Esparta, Venezuela, the fishery of octopus Octopus vulgaris is considered an alternative activity by the artisanal fishers to diversify production and to increase their income. Nevertheless, the inter annual fluctuations that have been witnessed in recent years, suggest that this resource requires an urgent analysis of the species reproduction, growth, mortality and the fishery activity, in order to provide a scientific basis to develop sustainable management strategies. For this, weekly samples were collected during the June-December 2012 El Tirano fishing season. Mantle length (ML), total weight (TW), sex and stage of gonadal development were recorded for 1 268 males (9-25cm ML) and 818 females (9-22cm ML). The monthly sex ratio differed from one, except in June and August, with a high percentage of mature individuals in both sexes. Minimum and average sizes were: 11cm ML (428g) and 16cm ML (1 142g) in sexually mature males, and 12cm ML (476g) and 15.35cm ML (844g) in sexually mature females. The length-weight relationship of males (TW=0.7994*ML 2.62 ) and females (TW=1.4552*ML 2.33 ) showed minor allometric growth. Growth was estimated by analysis of the frequency distribution of lengths, using FiSAT software. Growth parameters, estimated by the von Bertalanffy model, were considered rapid, being L ∞ =26.26cm, W ∞ =3 769g, k=2.3/year, and t o =-0.015/year, in males; and L ∞ =24.28cm, W ∞ =2 287g, k=1.8/year, and t o =-0.09/year, in females. The maximum age in males was A 0.95 =1.3 years and A 0.95 =1.57 years in females. Octopus captures were directly significant with superficial water temperature, but negatively significant with wind velocity and precipitation, which corresponds to a study zone with seasonal hydrologic variability. The actual exploitation rate (E=0.61/ year in males, E=0.60/year in females) was calculated by using the values of total mortality (Z=7.73/year in males, Z=6.63/year in females), for fishing (F=4.7/year in males, F=3.99/year in females), and natural (M=3.03/ year in males, M=2.64/year in females), indicating that the octopus is over-exploited. Consequently, we recommend regulating the fishery by reducing the fishing mortality rate. Rev. Biol. Trop. 63 (2): 427-442. Epub 2015 June 01.

Growth and mortality of the triggerfish Canthidermis sufflamen (Perciformes: Balistidae) from Los Frailes and Los Testigos Archipelagos, Venezuela. Canthidermis sufflamen has become a low cost food resource in high demand in El Tirano fishing community, and captures have been increasing in recent years. Since there is a lack of information on this resource population dynamics in Venezuela, the goal of this research was to provide some biological-fishery parameters, and has as general objective to determine growth and mortality of the triggerfish of Los Frailes and Los Testigos Archipelagos, Federal Territories of Venezuela. For this, a total of 3 595 specimens were collected from El Tirano commercial fishing, every week, from May 2012 to April 2013. We determined total length (cm), total weight (g), and sex for each specimen. No sexual dimorphism was shown with respect to length (t s = -0.96; p > 0.05), so one length-weight ratio was established for both sexes: W = 0.164*L 2.26 ; and they both exhibited minor allometric growth. Growth was estimated by analysis of the frequency distribution of lengths, using FiSAT software. Growth parameters, estimated by the von Bertalanffy model, were considered slow, being L ∞ = 61.69 cm, W ∞ = 1 868.402 g, k = 0.36 / year, and t o = -0.654 years. The maximum age was A 0.95 = 8 years. The growth index (Ø′), showed a value of 3.14. The exploitation rate E = 0.72 / year, using total mortality values Z = 2.67 / year, natural M = 0.73 / year and from fishing F = 1.93 / year, indicates that C. sufflamen is being over-exploited by the artisanal fishers of El Tirano. We recommend following some harvest guidelines that will reduce mortality rate due to fishing. Rev. Biol. Trop. 65 (3): 858-867. Epub 2017 September 01.

El corocoro margariteño Haemulon plumieri es muy abundante en la región nororiental de Venezuela, pero los aspectos biológicos y pesqueros han sido poco estudiados en el país. El objetivo de este estudio fue estimar el crecimiento y la mortalidad de este recurso. Se realizaron muestreos mensuales desde enero a diciembre 2014, obteniéndose 2 967 ejemplares y se registró la longitud total (cm) y peso (g) de cada ejemplar. Se encontró que no existe diferencia entre sexos con respecto a la longitud (ts = 0.093; P > 0.05), por lo que se estimó la relación longitud-peso para ambos sexos: P = 1.4x10-3 * L2.99, mostrando un crecimiento isométrico. Se utilizaron las rutinas del paquete FiSAT para estimar los parámetros del modelo de crecimiento individual de von Bertalanffy: L∞ = 30.95 cm, k = 0.67/año, P∞ = 418.17 g, t0 = -0.24 años. Se calculó una edad máxima de 4 años. El coeficiente de variación del índice de desempeño de crecimiento (Ø′) para el método directo (CV = 5.26 %) mostró una variabilidad en el patrón de crecimiento según la región. La tasa de mortalidad natural (M = 1.36/año) fue alta, posiblemente por causa de depredación y enfermedades, entre otros. Las tasas de mortalidad por pesca (F = 1.95/año) y mortalidad total (Z = 3.31/año) fueron altas. La tasa de explotación (E = 0.59/año) indica que es probable que H. plumieri esté sobreexplotado.