Selective characteristics of a shark-excluding grid device in a Mediterranean trawl

Brčić, Jure; Herrmann, Bent; Carlo, Francesco De; Sala, Antonello

doi:10.1016/j.fishres.2015.07.035

Cited by 42 publications

(31 citation statements)

References 36 publications

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“…(EC) n. 1967/2006 imposed an increased mesh size (square, 40 or 50 mm diamond) in the cod-ends, almost all the shark specimens continue to be retained by the cod-end (in Ref. [24]). Regarding the GFCM geographical Sub-Area no 16, named South of Sicily, a standardized scientific data base was obtained after the implementation of MEDITS international program, launched in 1994, and based on a high vertical opening (ca 2-3 m) trawl net.…”

Section: Introductionmentioning

confidence: 99%

A Tale on the Demersal and Bottom Dwelling Chondrichthyes in the South of Sicily through 20 Years of Scientific Survey

Geraci¹,

Ragonese²,

Norrito³

et al. 2017

Chondrichthyes - Multidisciplinary Approach

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In the present work, an overview of the demersal (sharks-chimaera) and bottom dwelling . Results suggest that most of the Chondrichthyes in South of Sicily are in a steady state, although in the last few years, they seemed to recover. The spatial distribution of sharks-chimaera in the geographical sub-area (GSA) 16 is mainly concentrated in the southern and north-western zones. Nevertheless, possible management actions to promote the recovering of these very important ecological and threatened species are discussed.

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Section: Introductionmentioning

confidence: 99%

A Tale on the Demersal and Bottom Dwelling Chondrichthyes in the South of Sicily through 20 Years of Scientific Survey

Geraci¹,

Ragonese²,

Norrito³

et al. 2017

Chondrichthyes - Multidisciplinary Approach

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“…This is what Millar et al (2004) named a fishery selectivity curve. The approach of estimating a fishery selectivity curve based on a group of hauls has been applied in several recent trawl selectivity studies (Brčić et al 2015, Özbilgin et al 2015, Lövgren et al 2016). However, all these studies were based on covered or paired data collection, and the bootstrapping method applied to account for the uncertainty in the results is different from the one described in this study.…”

Section: Discussionmentioning

confidence: 99%

Estimating the selectivity of unpaired trawl data: a case study with a pelagic gear

et al. 2016

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Summary:Most selectivity experiments employ either the covered codend or paired gear methods. It is not always possible, however, to use these methods. Owing to operational, biological and/or environmental considerations, there may be no obvious way or it may be inappropriate to pair the test and control data. Hence, it will not be possible to estimate the selectivity of the gear and its uncertainty using standard statistical methods. This study presents a methodology for analysing the selectivity of fishing gears from unpaired test and control data. The uncertainty in the control and test population structures is accounted for by using a double bootstrapping procedure that takes into account both between-haul and within-haul variation. This bootstrapping approach is used to assess the selectivity of two different devices, a 139.5 mm T90 codend and a 135.9 mm codend with 140.9 mm lateral exit windows, in the Barents Sea pelagic cod trawl fishery. The purpose of the experiment was to test and compare the performance of the two devices in pelagic trawl fisheries, where high densities of fish can be encountered. Significant differences were detected between the T90 codend and the codend with the exit windows but only for sizes of cod between 55 and 76 cm.Keywords: trawl selectivity; pelagic fisheries; unpaired data; cod.Estimando la selectividad en redes de arrastre con lances no pareados: un caso de estudio con una red pelágica Resumen: La mayoría de los experimentos de selectividad emplean el método de copo cubierto o el de lances pareados. Sin embargo, la utilización de estos métodos no es siempre posible. En ocasiones, no se puede encontrar una manera lógica de emparejar los datos provenientes de lances de prueba y lances control, o esta puede ser inapropiada debido a consideraciones de tipo operacional, biológico o medioambientales. Por lo tanto, no sería posible estimar la selectividad de la red y la incertidumbre de los resultados obtenidos utilizando métodos estadísticos estandarizados. Este estudio presenta una metodología que facilita el análisis de la selectividad en artes de pesca en los que los datos provienen de lances no pareados. La incertidumbre en las estructuras poblacionales capturadas en los lances prueba y control se tiene en cuenta utilizando un método de doble "bootstrapping" que considera la variabilidad en cada lance y entre lances. Utilizamos este método de "bootstrapping" para estimar la selectividad de dos dispositivos diferentes en la pesca pelágica de bacalao del mar de Barents: un copo T90 con mallas de 139,5 mm y un copo con mallas romboidales de 135,9 mm con ventanas laterales de 140,9 mm. El propósito del experimento fue comparar el comportamiento de ambos dispositivos en la pesca de arrastre pelágico de bacalao, donde se pueden encontrar altas densidades de pescado. Se detectaron diferencias significativas entre el copo T90 y el copo con las ventanas pero solo para tallas de bacalao comprendidas entre 55 y 76 cm.

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“…Trawl is considered the most detrimental fishing gear for numerous elasmobranches and chimaeras [60]. Several trawl fisheries exist depending on gear-species interactions and fishing area.…”

Section: Trawlmentioning

confidence: 99%

“…Pelagic trawling usually target small pelagic fish (anchovies and sardine), while bottom trawling mainly catch groundfish, shellfish and shrimps. A number of factors, such as duration of the trawl, the size of the catch and sorting time can influence post-capture survival of vulnerable species like chondrichthyes [60]. Of particular note, in a contest of multi-species trawl fishery (e.g.…”

Section: Trawlmentioning

confidence: 99%

“…coastal trawl fisheries in the Mediterranean), bottom trawling can cause a substantial impact by changing demersal fish assemblages, thus reducing chondrichthyes abundance and diversity [61]. Several non-target elasmobranches and chimaeras are often discarded after being caught by bottom trawl fisheries in many areas [60]. The North West Pacific, North East Atlantic and Mediterranean Sea have historically been the most exploited areas by trawl fisheries with a consequent high rate of chondrichthyes bycatch [11,13,62].…”

Section: Trawlmentioning

confidence: 99%

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Fisheries Bycatch of Chondrichthyes

Bonanomi¹,

Brčić²,

Colombelli³

et al. 2017

Chondrichthyes - Multidisciplinary Approach

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This chapter reviews the current state of knowledge about global chondrichthyes bycatch, including how the combination of biological characteristics of these species and the impact of different fishing methods reflect their vulnerability to bycatch. Specifically, it summarizes the present status of elasmobranchs and chimaeras bycatch worldwide.Following this, it illustrates the main ecological consequences behind such incidental captures. Hence, it provides a description of how chondrichthyes bycatch occurs across broad fishing gear categories. Moreover, it outlines potential mitigation options available to reduce bycatch. As such, the main technical measures tested and applied in different fishing practices are listed. In addition, an overview about which are the current management measures implemented at international level to ensure long-term conservation of cartilaginous fish is reported. Then, two case studies summarize how chondrichthyes bycatch occurred in some of the most exploited fishing areas. Finally, the chapter ends with relevant considerations about potential for new research needed to monitor and reduce chondrichthyes bycatch.

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Selective characteristics of a shark-excluding grid device in a Mediterranean trawl

Cited by 42 publications

References 36 publications

A Tale on the Demersal and Bottom Dwelling Chondrichthyes in the South of Sicily through 20 Years of Scientific Survey

A Tale on the Demersal and Bottom Dwelling Chondrichthyes in the South of Sicily through 20 Years of Scientific Survey

Estimating the selectivity of unpaired trawl data: a case study with a pelagic gear

Fisheries Bycatch of Chondrichthyes

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