Résumé des connaissances actuelles sur la biologie et la pêche des thons tropicaux en Atlantique

This work summarizes the present knowledge on biology and fisheries of Atlantic tuna such as yellowfin (Thunnus albacares), skipjack (Katsuwonus pelamis) and to a lesser extent, bigeye (Thunnus obesus) and albacore (Thunnus alalunga). Current appraisal of these stocks

Peuplements zooplanctoniques dans les régions de remontées d'eau du littoral atlantique africain

The introduction is followed by a resume of the biogeographic factors and the principal work. The characteristics of zooplankton in different regions are presented based on regular research in Santa Helena Bay and Walvis Bay and the research carried out by William Scoresby. Certain factors of the digestive system of South African plankton are discussed. The next section concerns research in intertropical and equatorial regions in the Gulf of Guinea. It considers the littoral region of Angola, the Pointe Noire region and discusses the density and complexity of stocks. The last section concerns the zooplankton of Nigeria, Ghana and the Ivory Coast and discusses the grouping of species and compares the results.

Croissance du patudo (Thunnus obesus) de l'Océan Atlantique intertropical oriental

The growth of big eye tuna (Thunnus obesus) in the Eastern Tropical Atlantic Ocean was studied using Petersen's method, by the analysis of the length frequency data of the F.I.S. (French-Ivorian-Senegalese) surface tuna fleet from 1969 to 1977. The results are in agreement with a previous study by Champagnat and Pianet (1973) and with observations made in the Pacific Ocean.

Excrétion organique du phytoplancton et activité bacterienne hétérotrophe dans le Dôme de Guinée (Océan Atlantique Tropical Est)

Primary production rates in the Gulf the Guinea (east tropical Atlantic) were measured with in situ incubations. The extracellular organic carbon passed through 0.8 u pore size membrane filters averaged 29.5% of the carbon fixed by photosynthesis. These is a good linear correlation (r=0.86) between assimilation and organic excretion. The significance and limits of the method for the measurements of low rates of photosynthesis is discussed. The influence of ecological factors (nutrients, light and stability) cannot be demonstrated. The importance of bacterial regeneration processes by reutilization of algal extracellular products is assessed.

Récolte et traitement des données statistiques de la pêche des palangriers asiatiques dans l'Atlantique

The authors report on the computer programmes developed in the Oceanographic Research Centre of Abidjan for the collection and treatment of statistical data on the fisheries of the asiatic trawlers in the Atlantic. They provide yield by boat, by fishing sector (5 degrees x 5 degrees) and by 15 days fishing in the Atlantic.

Circulation dans la partie orientale de l'Atlantique sud

The authors studied the circulation in the South Tropical Atlantic from hydrology and current measurements made during a cruise of the N.O. Capricorne in Nov 1971. Direct current measurements confirm the existence of the eastwards South Equatorial Counter-Current. The authors discuss the counter-current as confirmed by current measurements and high salinity core.

Recherches des larves de thonides dans l'Atlantique tropical-oriental: campagnes effectuées en 1976-1977 par le N/O Capricorne

This study gives the results of oblique plankton hauls (from the sea-surface to the top of the thermocline), made during the dry season (January to March) by oceanographic vessel R.V. Capricorne during three cruises, of tuna larvae research in 1976 and 1977, between the African Coast and the Equator, from 17 degrees W to 9 degrees E.

Distribution et abondance des larves de thonidés dans l'Atlantique tropico-oriental. Étude des données de 1963 à 1974

From several sources of data, the authors study seasonal variations of larval abundance for five species of tuna in Eastern Tropical Atlantic and its relation to the hydrological conditions. Distributional maps and TS graphs are given.

Biomasses du phytoplancton et du zooplancton dans l'Atlantique tropical le long du méridien 1O' W (Résultats de la campagne Capricorne 7314)

The standing stock of chlorophyll, the quantities of copepods collected with a 30 liter Niskin bottle and the standing stock of zooplankton collected with a 'Bongo' net were measured from 0 to 200 m depth during a cruise along 10' W from 1' N to 12' S. These parameters are correlated to hydrological conditions measured simultaneously. 6 zonal areas have been delimited and described; the north equatorial convergence, the northern flow of the south equatorial counter-current, the trade winds drift, the south equatorial counter-current and the Benguela's drift.