A comparative analysis of legislated and modified Baltic Sea trawl codends for simultaneously improving the size selection of cod (Gadus morhua) and plaice (Pleuronectes platessa)

Wienbeck, Harald; Herrmann, Bent; Feekings, Jordan P.; Stepputtis, Daniel; Moderhak, Waldemar

doi:10.1016/j.fishres.2013.10.007

Cited by 54 publications

(34 citation statements)

References 19 publications

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“…For complete model details, see Wileman et al (1996), Wienbeck et al (2014), and Herrmann et al (2016). To determine which model best described the data, we evaluated fit statistics for each model.…”

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Improving Catch Utilization in the U.S. West Coast Groundfish Bottom Trawl Fishery: an Evaluation of T90‐Mesh and Diamond‐Mesh Cod Ends

et al. 2017

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The limited-entry bottom trawl fishery for groundfish along the U.S. West Coast operates under a catch share program, which is implemented with the intention of improving the economic efficiency of the fishery, maximizing fishing opportunities, and minimizing bycatch. However, stocks with low harvest guidelines have limited the ability of fishermen to maximize their catch of more abundant stocks. Size-selection characteristics of 114-mm and 140-mm T90-mesh cod ends and the traditional 114-mm diamond-mesh cod end were examined by using the covered cod end method. Selection curves and mean L 50 values (length at which fish had a 50% probability of being retained) were estimated for two flatfish species (Rex Sole Glyptocephalus zachirus and Dover Sole Microstomus pacificus) and two roundfish species (Shortspine Thornyhead Sebastolobus alascanus and Sablefish Anoplopoma fimbria). Mean L 50 values were smaller for flatfishes but larger for roundfishes in the 114-mm T90 cod end compared to the diamond-mesh cod end. For Rex Sole, Dover Sole, and Shortspine Thornyheads, selectivities of the 140-mm T90 cod end were significantly different from those of the other cod ends; the 140-mm T90 cod end was most effective at reducing the catch of smaller-sized fishes but with a considerable loss of larger-sized marketable fishes. Findings suggest that T90 cod ends have potential to improve catch utilization in this multispecies fishery.

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Improving Catch Utilization in the U.S. West Coast Groundfish Bottom Trawl Fishery: an Evaluation of T90‐Mesh and Diamond‐Mesh Cod Ends

et al. 2017

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“…The simulations predicted flatfish catch-reduction rates similar to those estimated in the experimental fishery, demonstrating at the same time that FRESWIND can reduce undersized cod catches in the fishery, but with an estimated loss in marketable cod at ∼9%. Wienbeck et al (2014) addressed the problem of flatfish bycatch in the Baltic cod fishery by proposing and testing three different modifications of the mandatory BACOMA codend. However, none of the new codends was found to improve the selectivity for plaice below MLS, compared with the mandatory T90 codend.…”

Section: Discussionmentioning

confidence: 99%

“…This is often the result of a mismatch between the selectivity properties of the gear and the specific characteristics of flatfish morphology. For example, flatfish bycatch often occurs in fisheries targeting roundfish species (Wienbeck et al, 2014;Milliken and DeAlteris, 2004). Attempts to improve the selectivity in these fisheries often involve codend modifications in order to improve the size selectivity of the target species.…”

Section: Introductionmentioning

confidence: 99%

“…As a result, two codselective codends are mandatory in the area (T90 and BACOMA; EU 686/2010). Although these codends present good size-selective properties for cod, flatfish selectivity is an increasing concern in the fishery, because species with limited quotas, such as plaice (Pleuronectes platessa), can disrupt normal fishing strategies due to the landing obligation rules stated in the new European policy (STECF, 2014;Wienbeck et al, 2014).…”

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confidence: 99%

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Reducing flatfish bycatch in roundfish fisheries

et al. 2016

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“…Therefore, as long as these confidence bands are considered when making conclusions, the limited number of hauls in the study should not be a major concern. Herrmann et al (2013b) tested the performance of a 124.4 mm mesh size T90 codend built with 8-mm PE twine in the Baltic and obtained a mean L50 value of 38.90 cm, while Wienbeck et al (2013) found that a 126-mm T90 codend had a mean L50 of 43.4 cm. These sets of results give a selection factor of 0.31 and 0.34 respectively, which again correspond well with the 0.37 of the trials reported here.…”

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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A comparative analysis of legislated and modified Baltic Sea trawl codends for simultaneously improving the size selection of cod (Gadus morhua) and plaice (Pleuronectes platessa)

Cited by 54 publications

References 19 publications

Improving Catch Utilization in the U.S. West Coast Groundfish Bottom Trawl Fishery: an Evaluation of T90‐Mesh and Diamond‐Mesh Cod Ends

Improving Catch Utilization in the U.S. West Coast Groundfish Bottom Trawl Fishery: an Evaluation of T90‐Mesh and Diamond‐Mesh Cod Ends

Reducing flatfish bycatch in roundfish fisheries

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

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