English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Muchos planes de manejo de pesquerias tienen aproximaciones deterministicas, sin considerar la incertidumbre en los modelos utilizados. El efecto del esfuerzo pesquero en la estructura de edad tampoco ha sido considerado en muchos modelos. Para considerar tanto la incertidumbre como la estructura de edad, se empleo un modelo matricial densodependiente basado en la forma discreta de la ecuacion logistica utilizando la matriz de Leslie, con simulaciones Monte Carlo. Se estructuraron 66 diferentes escenarios de explotacion para el atun aleta amarilla (Thunnus albacares) en el Pacifico oriental. El diseno experimental consistio en 400 iteraciones de diez anos cada una para cada uno de los 66 escenarios de explotacion, considerando las clases de edad. La incertidumbre en el modelo se considero para la mortalidad natural, la capacidad de carga del sistema, la cantidad total de lances, la captura por lance de cada tipo (sobre delfines, brisas y palos), y el reclutamiento. La estructura de edad presento la mayor importancia relativa en el modelo, de acuerdo con el analisis de sensibilidad. Una de las maneras de controlar la estructura de edad es dirigiendo el esfuerzo pesquero hacia los tres tipos de lances pesqueros. Las estrategias de pesca que presentaron las mayores probabilidades de exito (porcentaje de iteraciones arriba de un nivel arbitrario) fueron aquellas con dominancia de lances sobre delfines, una pequena cantidad de lances sobre brisas y una cantidad minima o nula de lances sobre palos. Las mejores estrategias de pesca obtienen altas probabilidades de exito para las clases de edad especialmente susceptibles y para la biomasa total. Dichas estrategias de pesca aseguran altas capturas totales, minimos descartes de atunes juveniles y bajos niveles de captura incidental. El modelo predice una diferencia del 32% en las capturas entre escenarios dominados por lances sobre delfines y los dominados por lances no asociados con delfines.    Many fishery management plans have deterministic approaches, without considering uncertainty in the models used. The effect of the fishing effort on the age structure has not been considered in many models. To consider both uncertainty and age structure, a density-dependent matrix model based on a discrete time-form of the logistic equation using the Leslie matrix was employed, with Monte Carlo simulations. A total of 66 different fishing scenarios were structured for the yellowfin tuna (Thunnus albacares) in the eastern Pacific. The experimental design consisted of 400 ten-year runs for each of the 66 fishing scenarios, considering each age-class. The uncertainty was considered for natural mortality, environmental carrying capacity, total number of sets, catch per set of each type (on dolphins, schools and logs), and recruitment. The age structure had the greatest relative importance in the model, according to sensitivity analysis. One way of controlling the age structure is directing the fishing effort towards the three types of fishing sets. The fishing strategies that presented the highest success probability values (percentage of iterations above arbitrary levels) were those with dominance of dolphin-sets, a small amount of school-sets and almost no log-sets. The best fishing strategies obtain high success probabilities for the especially susceptible age-classes and total biomass. These fishing strategies assure higher total catches, minimum juvenile tuna discards and lower incidental catches. The model predicts a 32% difference in the catches between non-dolphin-sets and dolphin-sets.

ciencias marinas

Analysis of the fishing strategies of the yellowfin tuna (Thunnus Albacares) Eastern Pacific Fishery Based on Monte Carlo simulations of a density-dependent matrix model