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Journal ArticleDOI

Estado de explotación del recurso besugo (Epigonus crassicaudus) en Chile

01 May 2005-Investigaciones Marinas (Pontificia Universidad Católica de Valparaíso)-Vol. 33, Iss: 1, pp 57-67

AbstractThe exploitation status of cardinalfish (Epigonus crassicaudus) yielded in Chile between 33° to 41°S was analyzed. An indirect assessment was performed between 1997 and 2003 through size-structured model with a transition matrix defining the changes among sizes. The model was calibrated using size structures, official landings, catch-per-unit of effort (CPUE) taken from commercial fishing logbooks and standardized by generalized linear models (GLM). After 7 years of an intense fishery activity, we concluded that the cardinalfish resource in Chile is on the recruitment overfishing limit. On 2003, the spawning biomass with respect to the virginal spawning biomass is close to 40%. The biological references points (BRP) based on spawning per recruit biomass (SPR) support this assesment because the fishing mortality level on 2003 (F act ) was very close to fishing mortality level of 40% of SRP at virginal value (F 40% ).

Topics: Overfishing (52%)

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Journal ArticleDOI
TL;DR: A non-linear regression model in which the error distribution allows for heteroskedasticity and belongs to the skew-normal (SMSN) distributions family of scale mixtures, thus eliminating the need to transform the dependent variable using techniques such as the Box–Cox transformation.
Abstract: Our article presents a robust and flexible statistical model of the age–length relationship of cardinalfish ( Epigonus crassicaudus ) Specifically, we consider a non-linear regression model in which the error distribution allows for heteroskedasticity and belongs to the skew-normal (SMSN) distributions family of scale mixtures, thus eliminating the need to transform the dependent variable using techniques such as the Box–Cox transformation The SMSN is a tractable and flexible class of asymmetric, heavy-tailed distributions that is useful for robust inference when the normality assumption for the error distribution is questionable Two well-known important members of this class are the proper skew-normal and skew- t distributions In this work, the skew- t model is emphasised However, the proposed methodology can be adapted for each of the SMSN models with some basic changes The present work is motivated by a previous analysis of cardinalfish where the oldest specimen was 15 years of age In this study, we use the proposed methodology on a data set based on an otolith sample where the determined longevity is higher than 54 years

30 citations


Journal ArticleDOI
Abstract: We analyzed the allocation of effective fishing effort and the standardization of cardinalfish (Epigonus crassicaudus) catch rates in the multispecies demersal trawl fishery off central Chile. The period analyzed covered from 1997 to 2004 and included detailed information about fishing hauls. Each haul that contained cardinalfish was assigned into a particular fishing tactic (cluster) by using multivariate analysis of their catch composition. The catch rate standardization was carried out by generalized linear models (GLM). Three fishing tactics were discovered: the first directed effort at cardinalfish, the second at common hake (Merluccius gayi gayi), and the third at Patagonian grenadier (Macruronus magellanicus). Fishing tactic was used as an explanatory variable in the proposed GLM. The fishing tactic effect was one of the most important factors in explaining the variance in the GLM. These results are discussed in the context of how the assignation of a fishing tactic allows unbiased abundance indices to be obtained in this kind of multispecies demersal fishery Se analizo la separacion del esfuerzo de pesca efectivo y la estandarizacion de las tasas de captura de besugo (Epigonus crassicaudus) en la pesqueria multiespecifica de arrastre en Chile central. El periodo analizado correspondio de 1997 a 2004 y comprendio informacion detallada acerca del lance de pesca. Cada lance que contenia besugo en sus registros fue asignado a una tactica de pesca (agrupacion) particular mediante analisis multivariado de la composicion de la captura. La estandarizacion de las tasas de captura se realizo usando modelos lineales generalizados (MLG). Se descubrieron tres tacticas de pesca: una cuyo esfuerzo es dirigido sobre el besugo, otra sobre la merluza comun (Merluccius gayi gayi) y una tercera sobre la merluza de cola (Macruronus magellanicus). La tactica de pesca fue usada como variable explicatoria en el MLG propuesto. La tactica de pesca es uno de los factores que en mayor medida explican la varianza del MLG. Por ultimo, estos resultados son discutidos en el contexto de como la asignacion de una tactica de pesca permitiria obtener indices de abundancia sin sesgos en este tipo de pesquerias demersales multiespecificas.

14 citations


Cites background from "Estado de explotación del recurso b..."

  • ...En Chile, E. crassicaudus es una especie que habita la plataforma continental, formando densas agregaciones (Wiff et al. 2005)....

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  • ...De acuerdo con Wiff et al. (2005), uno de los factores claves en la evaluación del stock de besugo en Chile central es el manejar un índice de abundancia construido sobre una pesquería altamente multiespecífica, donde la intensión de captura no es fácil de determinar a partir de una inspección…...

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  • ...According to Wiff et al. (2005), one of the key issues involved in assessing the cardinalfish population off central Chile is dealing with an abundance index constructed upon a highly multispecies fishery, where catch intention in each haul is not easy to determine from a rapid examination of the…...

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  • ...crassicaudus inhabits the slope of the continental shelf, forming dense aggregations (Wiff et al. 2005)....

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  • ...In Chile, E. crassicaudus inhabits the slope of the continental shelf, forming dense aggregations (Wiff et al. 2005)....

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Journal ArticleDOI
01 Jan 2009-Gayana
Abstract: Se estudio la distribucion batimetrica y latitudinal de besugo (Epigonus crassicaudus) en la costa de Chile analizando los registros de la pesqueria y a traves de informacion complementaria recopilada desde los lances de pesca realizados en la evaluacion directa de merluza comun. Adicionalmente, se reportan antecedentes sobre los habitos alimenticios de besugo a traves de analisis del contenido estomacal de ejemplares recolectados en la zona central de Chile. Segun la informacion de la actividad comercial, el recurso concentraria su distribucion entre Valparaiso (33°04'S) y Puerto Montt (41 °46'S). Sin embargo, el crucero de evaluacion, registra capturas positivas de besugo desde su limite norte de operacion (29°00'S). En relacion a la batimetria, tanto la frecuencia de lances positivos como la captura, mostraron un patron coincidente en ambas fuentes de informacion, evidenciando una concentracion del recurso en el rango de profundidad de 300 a 400 m. Respecto de la alimentacion, las presas mas consumidas por E. crassicaudus fueron organismos planctonicos representados por eufausidos y estomatopodos. Apareciendo ocasionalmente algunos componentes del bentos en su dieta. Los resultados del presente estudio sugieren que E. crassicaudus presentaria habitos migratorios desde el pelagos al bentos, determinado por la oferta ambiental de alimento, concentrando su distribucion sobre la plataforma y talud continental. Ademas se confirmo una distribucion latitudinal mas amplia del recurso de la reconocida a traves de informacion exclusiva de la pesqueria.

8 citations


Journal ArticleDOI
Abstract: a b s t r a c t The use of different trawl nets is a factor to be considered when analysing historical swept-area research surveys aimed to characterize temporal variations in the relative abundance of demersal resources. If factors that may affect the performance of the bottom trawls were considered, more reliable temporal trends could be established. Due to the high species diversity that characterizes tropical areas, this kind of analysis is often carried out at the multispecies level. Therefore, the objective of this study was to establish the effect of two technical factors, mesh size and towing speed on the multispecies catch rates obtained in different demersal surveys carried out in the Colombian Caribbean Sea between 1988 and 2001, using two generalized linear models: one covering the entire study area and another restricted to one eco-region. For the global model, the effect of the mesh size on the multispecies catch rates was marginally significant (p 0.10). In contrast, for the eco- region model, the effect of mesh size was not significant (p > 0.10), while towing speed had a significant effect (p < 0.05). Size structure analysis showed escapement mainly through the codend meshes for the larger mesh size evaluated (50.8 mm), confirming the appropriateness of considering mesh size when analyzing historical data of swept area surveys. The effect of the towing speed, beyond the clear incidence on the area actually swept, point to the complexity of the relationship between speed and catch rates. In brief, the results showed that, when assessing historical databases, indices of relative abundance of tropical demersal resources can be improved by including mesh size and towing speed factors.

4 citations


Cites background from "Estado de explotación del recurso b..."

  • ...…variances f 13.1 and 52.4% in GLMs fitted to CPUE for Norway lobster Nephros norvegicus) and red shrimp (Aristeus antennatus), respecively, while Wiff et al. (2005) found a explained variance of 37% n a study by using GLMs to standardize catch rates of cardinal fish Epigonus crassicaudus) in…...

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Journal ArticleDOI
Abstract: El besugo, Epigonus crassicaudus, es una especie de importancia economica para la actividad pesquera que opera en el centro-sur de Chile. A pesar de ello, poco es lo que se conoce respecto a su biologia. En este sentido, este trabajo estudio los habitos alimentarios combinando analisis estomacales y de estabilidad isotopica. Los resultados del analisis dan cuenta de la importancia de los peces mesopelagicos (Myctophidae, Stomiidae) en la dieta con un aporte del 80%, seguido por crustaceos ( Sergestes arcticus ) alcanzando un 10%. No se detectaron diferencias en la dieta en peces con distinto grado de madurez sexual. En tanto, los valores de los isotopos de nitrogeno y carbono mostraron valores de promedio de 17,12 ± 1,1 δ 15N y de -17,51 ± 0,7 δ 13C, respectivamente. La constitucion de valores de δ 13C fue proporcional al tamano corporal de los besugos: individuos de mayor tamano habitan en ambientes mas demersales que ejemplares de menor tamano. De acuerdo a estos resultados, el besugo se situa como consumidor secundario.

3 citations


Cites background from "Estado de explotación del recurso b..."

  • ...Esta especie es capturada de forma habitual como fauna acompañante en la pesquería de camarón nailon (Heterocarpus reedi) y merluza común (Merluccius gayi) (Wiff et al. 2005, 2008)....

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  • ...En Chile y sobre la base de los registros pesqueros, su distribución va desde los 29° y 41°S, ocupando un rango de profundidad entre los 100 y 500 m en agrupaciones asociadas a la pendiente del talud y montes submarinos (Wiff et al. 2005, Leal et al. 2009)....

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References
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Book
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TL;DR: The results show clear trends in population growth, Mortality, and the Fishing Process, and age Structured Models: Renewal Theory and Assessment Methods show clear patterns in growth, mortality, and migration.
Abstract: 1. Population Growth, Mortality, and the Fishing Process 2. Stock Productivity and Surplus Production 3. Stock and Recruitment 4. Growth and Fecundity 5. Delay-Difference Models 6. Age-Structured Models: Per Recruit and Year-class Models 7. Age Structured Models: Renewal Theory 8. Catch-Age and Age-Structured Assessment Models 9. Size Structured Models and Assessment Methods 10. Migration and Movement 11. Optimal Harvesting

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"Estado de explotación del recurso b..." refers background in this paper

  • ...Se utilizó una versión discreta de los modelos genéricos de rendimiento por recluta (Quinn & Deriso, 1999)....

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  • ...Se estandariza la CPUE de besugo empleando un Modelo Lineal General (MLG), debido a que este tipo de modelos permite incorporar tanto variables continuas como categóricas asociadas con la evolución de la flota y que pueden resultar en cambios de la capturabilidad (Quinn & Deriso, 1999)....

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Abstract: This volume contains 31 papers presented in three theme sessions by fisheries scientists from around the world at a Department of Fisheries and Oceans' workshop in 1991 Papers presented address the use, strengths and weaknesses of commonly-used biological reference points; methods for identifying and quantifying uncertainties associated with using various reference points; and alternative management strategies or suggested strategies for dealing with novel situations Answers to specific questions relating to fisheries management, compiled by four working groups at the workshop, are included, as well as a list of participants

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Abstract: Risk analysis can enhance the value of scientific advice to fishery managers by expressing the uncertainty inherent in stock assessments in terms of biological risk. I present a case study involvin...

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Abstract: The methods used to develop catch rate based indices of relative abundance for the school shark Galeorhinus galeus resource off southern Australia are outlined. These methods are based on fitting generalized linear models to catch and effort data for several regions in this fishery. This is to take account of the multi-gear nature of the fishery and the spatial structure of the trends in catch rate. The data on whether or not the catch rate is zero and the catch rate given that it is non-zero are analysed separately and then combined to provide indices of abundance. The former analysis is based on assuming the data are Bernoulli random variables. Given the uncertainty about the appropriate error-model to assume when fitting generalized linear models to catch and effort data, four alternative error-models — log-normal, log-gamma, Poisson, and negative binomial — were explored when modelling the non-zero catch rates.

166 citations


"Estado de explotación del recurso b..." refers background in this paper

  • ...Además, los MLG son flexibles a diferentes formas de analizar la información, en especial en la exploración de diferentes alternativas para la distribución del error (Punt et al., 2000)....

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Journal ArticleDOI
TL;DR: A length-structured population model, which incorporates von Bertalanffy growth, is used to describe changes in population abundance over time and the parameter estimates of Pacific cod obtained from this algorithm were comparable with the values that were originally used to simulate the data.
Abstract: A length-structured population model, which incorporates von Bertalanffy growth, is used to describe changes in population abundance over time. The model is incorporated into a catch-at-length algo...

96 citations