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| Khaled, Ramez; Priour, Daniel; Billard, Jean-yves. |
| A numerical method for optimization of the cable lengths in trawls with respect to the ratio between the estimated trawl drag and the predicted catch efficiency is developed and applied. The trawl cables of interest are warps, bridles, headline and footrope. The optimization algorithm applies an ordered sequential process changing one cable length at the time. It is assumed in the predictions that the catch efficiency of the trawl is proportional with the trawl mouth area. In a case study optimizing a bottom trawl used on a research vessel by applying the new method it is predicted that it would be possible to reduce the ratio between trawl drag and catch efficiency by up to 46% by optimizing the cable lengths. Thus this would enable a considerable... |
| Tipo: Text |
Palavras-chave: Bottom trawl; Modeling; Optimization; Fuel consumption; Drag; Swept area; Mouth surface; Fish distribution. |
| Ano: 2013 |
URL: http://archimer.ifremer.fr/doc/00130/24106/22857.pdf |
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| Priour, Daniel. |
| Trawls energy efficiency is greatly affected by the drag, as well as by the swept area regarding pelagic trawls and by the swept width for bottom ones. The drag results in an increase of the energy consumption and the sweeping influences the catch. In order to reduce the drag per swept area (or width) a numerical tool dedicated to the automatic optimisation of the trawl design has been developed. Based on a finite element method model for flexible netting structures, the tool modifies step by step a reference design. For each step the best-modified design, in terms of drag per swept area (or width), is kept. Such a methodology was used in two cases: which show a 43% increase in energy efficiency regarding the pelagic trawl case and 27% for the bottom trawl... |
| Tipo: Text |
Palavras-chave: Swept width; Swept area; Drag; Fuel consumption; Optimisation; Modelling; Trawl; Fishing gears. |
| Ano: 2009 |
URL: http://archimer.ifremer.fr/doc/2009/publication-6583.pdf |
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| Pérez, M.; Aubone, A.; Simonazzi, M.A.; Irusta, C.G.. |
| Precision of abundance index estimation Merluccius hubbsi is directly related with the variability that normally occurs during the fishing operation and consequently in the geometry of the net duringeach haul. Some of these factors can be controlled, therefore the standardization of the sampling methodology avoids differences in the behaviour and 'work' of the net minimizing variations in the catchability between hauls. The acoustic equipment (SCANMAR) in there search vessels, allows to monitore the fishing operation during the trawl and to develop strategies in order to reduce the variability and to improve the precision of the estimations. The applicability of the methodology and there for the validity of the estimates indifferent cruises must be studied... |
| Tipo: Journal Contribution |
Palavras-chave: Fishing operations; Abundance; Sampling; Fishery surveys; Eco surveys; Swept area. |
| Ano: 1998 |
URL: http://hdl.handle.net/1834/5786 |
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