|
|
|
| Registros recuperados: 23 | |
|
| |
|
| |
|
| |
|
|
| Petit, Didier; Gerlotto, François; Petitgas, Pierre. |
| Biomass evaluation by means of echo-integration, needs to be applied with strictness. The better the dominant factors acting on the area are targeted and analyzed, the better will be the accuracy of estimation. A phase of descriptive observation is necessary, taking into account abiotic and biotic factors, as well as the one on species behaviour, as it can appear throughout the acoustics tool. This descriptive stage will comfort the elaboration of a stratification which will serve as a model to calculate the abundance level and its accuracy. During acoustic cruises performed from 1992 to 1994 in the Java Sea open waters, various parameters were measured. Regional differences can be observed, and they allow a three-area stratification to be elaborated.... |
| Tipo: Text |
Palavras-chave: RESSOURCES HALIEUTIQUES; POISSON MARIN; ESPECE PELAGIQUE; DENSITE DE POPULATION; ACQUISITION DE DONNEES; ECHOINTEGRATION; REPARTITION GEOGRAPHIQUE; VARIATION SPATIALE; STRATIFICATION. |
| Ano: 1997 |
URL: http://www.documentation.ird.fr/hor/fdi:010017251 |
| |
|
|
| Petit, Didier; Cotel, Pascal; Nugroho, D.. |
| The coastal borders of northern Java and eastern Sumatra have been prospected during the acoustic surveys, in the depth of about 115 to 50 m, in wet season. The measures of relative density per nautical mile, the vertical distribution of the abundance and shoals have been analyzed. The general characteristics can be drawn-up : they are the extension of an abundant semipelagic fauna occupying the bathymetric strata from 25 to 45 m, and the existence of a dominant pelagic fauna are more coastal. Shoals, low reverberating, are present in all areas but are dominant in the coastal border ; the more reverberating aggregations are more off shore. From the East to the West, their bathymetric localization increases in the sectors near oceanic influences, they are... |
| Tipo: Text |
Palavras-chave: RESSOURCES HALIEUTIQUES; ZONE COTIERE; POISSON MARIN; ESPECE PELAGIQUE; DENSITE DE POPULATION; REPARTITION VERTICALE; ETHOLOGIE; RYTHME NYCTHEMERAL; VARIATION SAISONNIERE; SAISON HUMIDE; ZONATION ECOLOGIQUE. |
| Ano: 1997 |
URL: http://www.documentation.ird.fr/hor/fdi:010017252 |
| |
|
| |
|
|
| Potier, Michel; Petit, Didier. |
| Fishing strategies and tactics are related to the knowledge fishermen have about environment, to the behavior of the fish and to the socio-economical factors which affect the fishery. The fishermen knowledge is applied to the strategy (time scale from the trips - less than one month up to one year), and to the tactics which is the way fish are caught (time scale, fishing operations). The strategy of the Javanese fishermen is highly correlated with the monsoons regime. The alternation of these seasons induces changes in the abundance of fish in the Java Sea. Fishermen choose their fishing areas according to the fluctuation of the abundance. Before 1992, the trip strategy was to choose one fishing ground and to spend all the fishing days in this zone. Since... |
| Tipo: Text |
Palavras-chave: PECHE MARITIME; TECHNIQUE DE PECHE; SENNE; ZONE DE PECHE. |
| Ano: 1995 |
URL: http://www.documentation.ird.fr/hor/fdi:42772 |
| |
|
|
| Gerlotto, François; Petit, Didier; Fréon, Pierre. |
| Des mesures d'écho-intégration et de TS #in situ$ effectuées de nuit à l'aide d'un sondeur à faisceaux concentriques ont permis de vérifier l'effet d'éclairement d'un navire de prospection sur les distributions bathymétriques des poissons. Deux résultats principaux ont été obtenus : les poissons des couches supérieures, contrairement à ce qu'avaient montré d'autres expériences dans la même zone, n'ont pas plongé lors des périodes éclairées, mais ont en partie évité latéralement le bateau, l'importance de cet évitement étant apparemment à relier à la taille et/ou à l'espèce des poissons; si l'on ne tient pas compte de la disparition des cibles les plus importantes, les niveaux de réflectivité moyens n'ont pas varié entre périodes obscures et éclairées, ce... |
| Tipo: Text |
Palavras-chave: PROSPECTION ACOUSTIQUE; POISSON MARIN; ETHOLOGIE; ECLAIREMENT; DISTRIBUTION SPATIALE. |
| Ano: 1990 |
URL: http://www.documentation.ird.fr/hor/fdi:31196 |
| |
|
| |
|
|
| Petit, Didier; Nugroho, D.; Potier, Michel. |
| An acoustic survey, from Semarang towards the South China Sea, allows the haline situation and the distribution of abundance in pelagic fishes at the end of the wet season to be described. At that moment, the fleet of Javanese seiners operates in the south-west of the Natuna Islands, in depths of 50 meters. The analysis of haline vertical profiles shows the presence of three zones : the Java Sea with vertical gradients due to the coastal desalinization, the Karimata Strait with isohaline water at 33.5% and the South China Sea with deep waters at 34%. The last sector where the fleet was operating, was three times richer than the Javanese waters at that time. Without direct correlation with that, the zonation of the abundance (scattered or aggregated fishes)... |
| Tipo: Text |
Palavras-chave: RESSOURCES HALIEUTIQUES; POISSON MARIN; ESPECE PELAGIQUE; SALINITE; DENSITE DE POPULATION; VARIATION SPATIALE; REPARTITION VERTICALE; RYTHME NYCTHEMERAL; PROSPECTION ACOUSTIQUE; ABONDANCE; BANC. |
| Ano: 1997 |
URL: http://www.documentation.ird.fr/hor/fdi:010017255 |
| |
|
| |
|
|
| Levenez, Jean-Jacques; Gerlotto, François; Petit, Didier. |
| Des études sur le comportement du poisson en milieu tropical et ses conséquences sur les estimations de biomasse par echo-intégration ont été menées de chaque côté de l'Atlantique, au Sénégal et au Vénézuela. Trois séries d'observations réalisées de nuit à des profondeurs comprises entre 15 et 30 mètres ont montré que lorsque les lumières de pont sont allumées sur les bateaux de recherches, les poissons plongent et/ou s'écartent, mais que les conséquences, en ce qui concerne les évaluations de biomasse, dépendent des espèces, de l'orientation de l'éclairage du bateau et de la vitesse de ce dernier. Quand les lampes éclairent latéralement (Sénégal) les évaluations de biomasse peuvent être grandement sous-estimées, tandis que si les lumières sont focalisées... |
| Tipo: Text |
Palavras-chave: POISSON MARIN; ESPECE PELAGIQUE; ECHOINTEGRATION; ECLAIREMENT; BIOMASSE; -. |
| Ano: 1990 |
URL: http://www.documentation.ird.fr/hor/fdi:31195 |
| |
|
|
| Conand, François; Boëly, Thierry; Petit, Didier. |
| Two acoustic surveys have been done in the lagoon all around New Caledonia, with a digital integrator. The cruises lasting two weeks were done at six month interval. Much information has been obtained on stock biomass and spatial distribution of fish and schools. Fish are dispersed at night and stay near the surface. During the day they form schools, usually of very small size. Some species are found mostly along the coasts, on the reef flats and far inside in the bays. Some others stay in the middle of the bays or in the central part of the lagoon and occur usually in deeper water at some distance of the bottom. Aerial and diving observations have shown that the fish of coastal schools were feeding on the reef. Species schooling during the day in the... |
| Tipo: Text |
Palavras-chave: LAGON; RECIF CORALLIEN; POISSON; ESPECE PELAGIQUE; DYNAMIQUE DE POPULATION; DISTRIBUTION SPATIALE; BIOMASSE; STOCK. |
| Ano: 1988 |
URL: http://www.documentation.ird.fr/hor/fdi:42377 |
| |
|
|
| Cotel, Pascal; Petit, Didier. |
| Using acoustics for biomass evaluation, the back scattering cross section of species has to be determined to convert the data into weighted values. During the cruises of the EU Project "Java Sea Pelagic Fishery", TS measurements on 3 pelagic fishes of economic importance : #Decapterus russelli$, #Selar crumenophthalmus$, and #Rastrelliger kanagurta$ were carried out, using a BioSonics dual beam echo-sounder at a frequency of 120 kHz. The observations on single or multiple targets in a cage, revealed a large dispersion of the responses, even in the same experiment. These results are discussed and compared with Johannesson's (Anonymous, 1984) in the same area. (Résumé d'auteur) |
| Tipo: Text |
Palavras-chave: RESSOURCES HALIEUTIQUES; POISSON MARIN; ESPECE PELAGIQUE; DENSITE DE POPULATION; EVALUATION; SONAR; INDICE DE REFLEXION. |
| Ano: 1997 |
URL: http://www.documentation.ird.fr/hor/fdi:010017253 |
| |
|
| |
|
| |
|
|
| Durand, Jean-René; Petit, Didier. |
| The Java Sea is mainly a continental shelf with an average depht of 40 m and is controlled by the monsoon cycle : eastward current during North-West monsoon, westward current during South-East monsoon. Surface salinity is the best known parameter and its variations allow to describe the global circulation scheme in the Java Sea region. More in depth studies should be conducted to give a more accurate description which would take into account variability according to water depth, regions and years. Despite scarce environmental data, hypothesis on the level of productivity and a more oriental definition of the Java Sea pelagic resources system are given in this article. (Résumé d'auteur) |
| Tipo: Text |
Palavras-chave: MER; CARACTERISTIQUE PHYSIQUE; SALINITE; TEMPERATURE; CLIMATOLOGIE; COURANTOMETRIE; PRODUCTIVITE BIOLOGIQUE. |
| Ano: 1995 |
URL: http://www.documentation.ird.fr/hor/fdi:42768 |
| |
|
|
| Petit, Didier; Cotel, Pascal; Nugroho, D.. |
| From 1991 to 1995, twenty acoustic surveys took place in the Java Sea and the surrounding areas in the frame of the PELFISH Project, sponsored by the European Union, Indonesia and France. Their aim was to study the distribution, abundance and behaviour of the pelagic fauna, especially on the fishing grounds of the seiners. It needed various operations as environmental measurements, echo-integration, TS measurements, school localization, light attraction and trawl samplings. The scientific equipment and its adjustment, as well as the procedures of data acquisition used, are summarized (acoustic and physical measurements, samplings). The spatial, diurnal and bathymetric distribution of the sampling show that the data collection can give accurate information... |
| Tipo: Text |
Palavras-chave: RESSOURCES HALIEUTIQUES; POISSON MARIN; ESPECE PELAGIQUE; ACQUISITION DE DONNEES; ECHOINTEGRATION; TRAITEMENT DE DONNEES; ECHANTILLONNAGE; VARIATION SAISONNIERE; RYTHME NYCTHEMERAL; DISTRIBUTION SPATIALE; BATHYMETRIE. |
| Ano: 1997 |
URL: http://www.documentation.ird.fr/hor/fdi:010017246 |
| |
|
|
| Petit, Didier; Cotel, Pascal; Nugroho, D.. |
| The climate in the Javanese basin is a monsoon regime : dry from June to September and humid from November to March. In regions seasonally subject to substantial precipitation, salinity is one of the more important factors affecting the distribution and abundance of fauna. For this reason, stationary vertical profiles have been performed to measure the variations of salinity. These measurements took place during the acoustic surveys carried out in the Java Sea in the framework of the PELFISH Project. Two surveys covering the central part, the first one in October, the second one in February, supply spatial and bathymetric localization of different water masses. Other transects, from Semarang (Central Java) to the Matasiri Islands, all along the north... |
| Tipo: Text |
Palavras-chave: EAU DE MER; SALINITE; PROFIL VERTICAL; VARIATION SPATIALE; VARIATION SAISONNIERE; CLIMAT; VENT; MOUSSON. |
| Ano: 1997 |
URL: http://www.documentation.ird.fr/hor/fdi:010017247 |
| |
|
| |
| Registros recuperados: 23 | |
|
|
|
