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| Guillard, Jean; Brehmer, Patrice; Colon, Michel; Guennegan, Yvon. |
| Fish schools are aggregative structures encountered in all types of aquatic environments but have as yet been little studied in freshwaters except at small spatial scales. This study represents the three dimensional description of juvenile fish schools (Perca fluviatilis and Rutilus rutilus) in a lake environment using high resolution multibeam sonar system operating at a frequency of 455 kHz, composed of 60 beams of 1.5 degrees allowing a 90 degrees observation plane. The in situ diurnal schooling behaviour of young-of-the-year fish of both species is confirmed. The morphological, energetic and spatial variables of these schools are described and related to one another. The structures described are of the same order of magnitude as those described in the... |
| Tipo: Text |
Palavras-chave: Annecy Lake; Rutilus rutilus; Perca fluviatilis; Sonar; 3 D structure; Shoaling behaviour. |
| Ano: 2006 |
URL: http://archimer.ifremer.fr/doc/2006/publication-1661.pdf |
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| Guennegan, Yvon. |
| INTRODUCTION : « The fishing industry is still flourishing » but in Corsica as elsewhere, it has already been declining; sea floors are getting depleted. Several vessels have laid up. Where are we in 1989? Corsica fishing is strongly seasonal. The bulk of the activity takes place from spring time to early fall and focuses on bottom fish and sea crayfish. Three types of fishing can be identified: - Trawl fishing on the eastern coast plateau, (16 trawlers). - Trammel fishing to catch rock fish and sea crayfish on the western coast of the island (300 low power and tonnage ships, i.e. 50 KW and 4TJB). - Pond fishing (a few small units). Total catching amounts to roughly 1 000 tons. The fishing fleet is very dispersed along 1 080 km of coast and sometimes faces... |
| Tipo: Text |
Palavras-chave: Marketing; Biological study; Fish shrimp; Prospection; Technique; Pandalide plesionika edwards II; Corsica; Artisanal fishings. |
| Ano: 1990 |
URL: https://archimer.ifremer.fr/doc/1990/rapport-1759.pdf |
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| Chardy, Pierre; Guennegan, Yvon; Branellec, Jean. |
| Treatement of faunistical data collected by sub'marine photography is applied on an infralittoral area of "rade de Brest". Automatic cartography of the most important epibenthic species gives, in a first approach, some precisions on spatial pattern of these organisms : size and density of agregats, connecting or excluding relationships, influences of the bottom characteristics. Statistical analysis of individual distribution of each species by both parametric and non parametric tests completes this cartographic examination and point out different levels of heterogencity at different spatial scale. In a third step a synthesis regrouping all the distributions is given by the two first axis of an inertia analysis. This technique may introduce an attempt to... |
| Tipo: Text |
Palavras-chave: Histoire Ifremer. |
| Ano: 1980 |
URL: http://archimer.ifremer.fr/doc/1980/rapport-4788.PDF |
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| Brehmer, Patrice; Vercelli, Catherine; Gerlotto, Francois; Sanguinede, Fabien; Pichot, Yves; Guennegan, Yvon; Buestel, Dominique. |
| The exploitation of offshore mussel farms is becoming important throughout the world, but monitoring this activity remains a difficult task. Here, we propose a specific method for this purpose. A total of 140 long-lines were monitored on a mussel culture ground in the French Mediterranean Sea during four experimental surveys deploying multibeam sonar devices mounted on poles (Reson Seabat 6012, 455 kHz) on small boats. This allowed geo-referenced observations to be made of the submerged mussel long-lines, as well as three-dimensional (3D) drawings of the long-line structures and the sea bed shapes, using long-line longitudinal sonar sampling. Three sonar data-analysis methods were applied: (i) direct two-dimensional (2D) visual interpretation of raw sonar... |
| Tipo: Text |
Palavras-chave: Management; Sonar; Open sea; Long line; Mussel. |
| Ano: 2006 |
URL: http://archimer.ifremer.fr/doc/2006/publication-1672.pdf |
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