Assessing the effects on stocks of selectivity changes in a fishery

Kvamme, Cecilie; Frøysa, Kristin Guldbrandsen

doi:10.1016/j.fishres.2004.02.010

Cited by 19 publications

(16 citation statements)

References 14 publications

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“…The analysis of our data, supported by the results of Kvamme and Isaksen (2004), indicate that in this respect there is no signi cant di erence between grids and traditional diamond mesh codends. Moreover, modelling of the stock e ects of changes in eet selectivity has shown changes in SR to have smaller impact on long-term yield than a change in L 50 (Kvamme and Frøysa, 2004). Another management objective could be to minimise yield variability froma given stock (MacLennan, 1995).…”

Section: Discussionmentioning

confidence: 99%

Size selection of cod by rigid grids—Is anything gained compared to diamond mesh codends only?

et al. 2006

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Size selective grids were introduced into the Barents Sea demersal trawl shery in 1997. It was believed at the time that in comparison to standard diamond mesh codends, grids had better selective properties, i.e. narrower selection range. Few studies have directly compared the selective properties of the combined grid and codend with that of the codend only. In this study we describe two experiments carried out in 2002 and 2003, where we directly compared the properties of codend selectivity for cod (Gadus morhua ) with the combined selectivity of a Sort-V grid and a codend. In 2002 we used small-meshed covers, whereas the twin trawl method was used in 2003. In both experiments we compared the selectivity of a 135 mm codend only with that of a trawl tted with a 135 mm codend and a 55 mm grid, which is the mandatory con guration. In 2003 we also estimated the selectivity of a 155 mm diamond mesh codend, having an L 50 similar to that of the grid and 135 mm codend combination. The results presented no evidence that the grid and mesh combination had sharper size selection than codend meshes. The introduction of the mandatory use of grid in the shery in 1997 therefore only increased L 50 , and corresponded to a mesh size increase of around 20 mm. Mean selection length of the grid was inversely related to catch rates in the 2002 experiment when large catches were taken. Grid selection appeared less a ected by seasonal variations in degree of stomach fullness or condition than mesh selectivity. Other situations where grid selection might perform better than mesh selection are discussed.

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Section: Discussionmentioning

confidence: 99%

Size selection of cod by rigid grids—Is anything gained compared to diamond mesh codends only?

et al. 2006

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“…The most widely acknowledged ones rely on the biological impact of selectivity measures. Selectivity has positive consequences on non-commercial species and on the biomass and age-structure of commercial stocks (Beverton and holt 1957;Kvamme and Fröysa 2004;Maclennan 1995;Salini et al 2000;Stergiou et al 1997;Suuronen and Sardà 2007;VanMarlen 2000;Ward 1994) 1 . Another important social benefit is due to the fact that rights-based systems of fisheries management are easier to implement when fishing is selective; i.e., when unsought joint productions are minimized.…”

Section: Introductionmentioning

confidence: 99%

“…Apart from the possible higher price of selective gears, a major source of costs arises from the use of more selective gears, which often reduce catches of marketable fish per unit of effort (Fonseca et al 2005;Kvamme and Fröysa 2004;Madsen et al 1999;Tschernij, Suuronen, and Jounela 2004;VanMarlen 2000). This feature suggests that net benefits provided by selectivity depend on the level of fishing effort.…”

Section: Introductionmentioning

confidence: 99%

Optimal Selectivity and Effort Cost A Simple Bioeconomic Model with an Application to the Bay of Biscay Nephrops Fishery

Macher

Boncœur²

2010

Marine Resource Economics

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“…Otra táctica está relacionada con una modificación de la ojiva de selectividad del arte de pesca tendiente a generar selección de pesca en referencia al tamaño y/o edad de los ejemplares capturados. Kvamme & Frøysa (2004) evaluaron los efectos de estos cambios en la pesquería del bacalao del Atlántico (Gadus morhua), encontrando una importante ganancia en el tamaño del stock y rendimiento en las capturas al generar escape a la fracciones etarias más juveniles. Vasilakopoulos et al (2011), mediante un meta-análisis con 38 especies en la costa Atlántica noreste, encontraron que la explotación sobre fracciones inmaduras de los stocks, exhibe un efecto negativo sobre la condición actual de los mismos, considerando métricas vinculadas a la explotación y selectividad.…”

Section: Discussionunclassified

Bases conceptuales para la aplicacion de una evaluacion de estrategias de manejo (EEM) en sardina comun (Strangomera bentincki) y anchoveta (Engraulis ringens) en la zona centro sur de Chile

Arteaga

Ernst²,

Vásquez³

et al. 2014

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Bases conceptuales para la aplicación de una evaluación de estrategias de manejo (EEM) en sardina común (Strangomera bentincki) y anchoveta (Engraulis ringens)en la zona centro-sur de Chile RESUMEN. Se identifican los factores claves a considerar en el desarrollo de una evaluación de estrategias de manejo (EEM) para los recursos pequeños pelágicos en la zona de centro-sur de Chile, sardina común (Strangomera bentincki) y anchoveta (Engraulis ringens). En Chile, la EEM no ha sido aplicada al manejo de estas pesquerías y la asesoría científica se ha desarrollado sobre la evaluación de estrategias de explotación utilizando modelos de evaluación mono-específicos. Para ambas especies se analizan los siguientes tópicos: i) alternancia en la abundancia poblacional asociada a los pulsos de reclutamientos y capturas, ii) variabilidad temporal en la fuerza del reclutamiento, iii) estacionalidad del crecimiento cohorte y especie-específico, y iv) relación ambiente-recurso. Los resultados evidencian que los tópicos analizados debieran ser considerados en la construcción de un modelo operativo y/o en la regla de cosecha, dado el carácter mixto de ambas pesquerías, su marcada alternancia y la influencia de las condiciones ambientales. Por lo tanto, se propone que el diseño e implementación de una EEM para sardina común y anchoveta, incluya los elementos señalados en un marco de evaluación multi-especifico y de manejo de carácter mixto. Palabras clave: anchoveta; sardina común, modelo operativo, estrategias de manejo, ambiente-recurso, Pacífico suroriental. Conceptual bases for implementing a management strategy evaluation (MSE) for common sardine (Strangomera bentincki) and anchovy (Engraulis ringens) in south-central zone of ChileABSTRACT. Key factors to consider in the development of a management strategy evaluation (MSE) for small pelagic fish resources of south-central Chile, common sardine (Strangomera bentincki) and anchovy (Engraulis ringens) were identified. In Chile, MSE has not been applied to manage these fisheries and scientific advice has been developed on the evaluation of harvest strategies using single species stock assessment models. For both resources the following topics were analyzed: i) alternation of population abundance pulses associated with recruitment and catches, ii) temporal variability in recruitment strength, iii) seasonality of cohort and speciesspecific growth, and iv) relationship resource-environment. Results show that the topics analyzed in this work should be considered in the development of an operating model and/or harvest control rules, given the mixed nature of both fisheries, the marked alternation and the influence of environmental conditions. Therefore, it is proposed that the design and implementation of a MSE for sardine and anchovy complex, considers the elements outlined in this study and within the framework of multi-specific assessment and mixed fishery management.

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Assessing the effects on stocks of selectivity changes in a fishery

Cited by 19 publications

References 14 publications

Size selection of cod by rigid grids—Is anything gained compared to diamond mesh codends only?

Size selection of cod by rigid grids—Is anything gained compared to diamond mesh codends only?

Optimal Selectivity and Effort Cost A Simple Bioeconomic Model with an Application to the Bay of Biscay Nephrops Fishery

Bases conceptuales para la aplicacion de una evaluacion de estrategias de manejo (EEM) en sardina comun (Strangomera bentincki) y anchoveta (Engraulis ringens) en la zona centro sur de Chile

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