Statistiques de pêche des sardiniers ivoiriens - année 1983

The sardinella fleet landed the same quantity of sardines in 1983 (11200 tons) as in 1982. Sardinella aurita catches would be more important if the "Syndicat des Armateurs" did not impose quotas - in July 300 boxes and in August 100 boxes by fleet by trip. The extension of the effort to herring stock increased the catches of this species and an over estimation of 44% of the effort have been observed in 1983.

Analyses physico-chimiques des eaux de la Lagune Ebrié effectuées de 1979 à 1981 au cours des programmes "Variabilité interannuelle" et "Baie de Biétri"

Physico-chemical data collections aimed to assess the interannual variability of the lagoon hydroclimate and the impact of an airport dam on the water quality of the Ebrié lagoon.

Statistiques de peche des chalutiers ivoiriens - annee 1981

This publication gives fishery statistics relating to the landings of the Ivorian trawlers in Abidjan in 1981. The data used are the inquiries made by the C.R.O. on the boats and the auction sheets of the fishing harbour. The data processing was executed on the C.R.O. computer.

Campagnes Nizery: Togo 1 (26 et 27/01/83) et Togo 2 (07 au 10/06/83). Resultats des chalutages

This publication gives the results of the bottom trawlings made during the cruises Togo 1 and Togo 2 by the oceanographic research vessel "Andre Nizery" on the continental shelf of Togo during the estimation program of halieutic resources. The report includes: 1 - The report of the cruises Togo 1 and Togo 2; 2 - Some information on the presentation of the results; 3 - The trawl recording cards for the 2 cruises; 4 - The length frequency distributions of the measured samples.

Transformation empirique des tables numeriques de Galton en tables des probits

Comparison between Galton equation and preston normal logarithms models allowed an empirical reconstitution of probits tables.

Statistiques de peche des chalutiers ivoiriens - annee 1983

This publication gives fishery statistics relating to the landings of the Ivorian trawlers in Abidjan in 1983. The data used are the inquiries made by the C.R.O. on the boats and the auction sheets of the fishing harbour. The data processing was executed on the C.R.O. computer.

Campagnes Nizery: Togo 5 (01 to 03/03/84) and Togo 6 (26 to 28/03/84). Resultats des chalutages

This publication gives the results of the bottom trawlings made during the cruises Togo 5 and Togo 6 by the oceanographic research vessel "Andre Nizery" on the continental shelf of Togo during the estimation program of halieutic resources. The report includes: 1 - the report of the cruises Togo 5 and Togo 6; 2 - Some information on the presentation of the results; 3 - the trawl recording maps for the 2 cruises; 4 - The length frequency distributions of the measured samples.

Die Entwicklung des Aufwandes in der deutschen Garnelenfischerei und der Versuch einer Standardisierung der jährlichen Einheitsanlandungen (LPUE) zwischen 1976 und 2010

Brown shrimp is a fastgrowing, shortlived species, and all attempts to use stock assessment methodologies typically applied to other fisheries are usually unsuccessful. Here landings per unit effort data (LPUE) for the German fleet based on a number of effort metrics are used as indices of stock size. Their utility in relation to describing stock development and fisheries management is discussed. LPUE estimates indicate that stock sizes between 1976 and 1989 were relatively stable. In 1990, the lowest reported landings of brown shrimps in Germany coincided with severe economic problems for the shrimp fisheries. From 1990 to 2010 standardised annual indices show that both landings and LPUE estimates have increased at variable rates suggesting large stocks of brown shrimps in recent years. This is discussed in relation to the positive effects of reduced predator abundance and favourable climatic factors.

Synthèse des travaux effectués au CRO sur les végétations envahissantes flottantes (1985-1990). Propositions et recommandations

The present document represents a synthesis of the scientific knowledge gathered by the CRO in the years 1985-1990, and related to the proliferation of aquatic macrophytes, commonly called floating aquatic weeds, in the Ebrié lagoon.

Suivi cartographique de l'expansion des macrophytes envahissant le système lagunaire Ebrié (Côte d'Ivoire)

Remote mapping were realised from December 1986 to September 1989 to describe the seasonal evolution of macrophytes colonizing the surface waters of the eastern sector of the Ebrié lagoon. The vegetal cover of this sector and associated lagoons is essentially composed of Eichhornia crassipes (water hyacinth). Its expansion is favored by the decrease in the salinity of the lagoon waters which is due to rain falls. Its migration through the lagoon environment is ensured by the overflow of the Comoé river. The opening of the Bassam inlet induced its temporary disappearence from the newly created estuarian zone.

Contribution à l'étude des modifications hydro-sédimentaires consécutives à la réouverture artificielle de l'embouchure du Comoé à Grand-Bassam

The Bassam artificial inlet was opened (in September 22, 1987) in order to revacuate offshore invasive aquatic plants. This has considerably modified the hydro-sedimentary environment of the lagoonal domain at Grand-Bassam. Tidal currents effect has confered the lagoonal waters an estuarine feature, the saline intrusion (25-35%o) increased beyond the Moossou bridges up to the confluence of the Comoe river. This has led to a cleaning of the river lower course and above all to the bottoms of the lagoon, which were previously confined. The remobilization of mud (from lagoonal bottoms around Bouet Island) evacuated offshore, has exposed lagoonal and oceanic sandy features. This new system remains fragile, with the seasonal (low river-flow) clogging.

Incidences de la modification de la circulation des eaux sur l'hydrochimie et le degré de contamination bacterienne d'un estuaire eutrophe tropical

In order to control the proliferation of floating aquatic vegetation in Côte d'Ivoire, a coastal inlet, allowing a direct communication between the Comoe river and the ocean, was created in September 1987. The impact of this operation on the hydrochemistry (salinity, nutrients, algal biomass) and the bacterial contamination level was studied in the area close to the Vridi canal.

Analyse des effets de l'ouverture du chenal de Grand Bassam (estuaire du fleuve Comoé, Lagune Ebrié) sur la macrofaune benthique lagunaire

This paper presents the results of a comparative study of three series of samples collected in the area near the Bassam channel before, six and twenty months after its opening in September 1987. Observed effects are the decrease in the abundance and the modification of the benthic macrofauna composition. These effects appeared to be definitive, without recovery of the most abundant species Corbula trigona. Most differences noted in the population structure are due to the increase of the salinity and at a least degree to the modification of the nature of the sediment.

Doses efficaces en glyphosate et en 2,4-D pour le contrôle chimique des laitue d'eau (Pistia stratiotes, Linn.) et toxicité du glyphosate vis-à-vis des tilapias (Sarotherodon melanotheron)

The toxic effects of two herbicides Round up (gliphosate) and 2,4-D (herbazol) were tested on Pistia stratiotes (Linn. Araceae) samples cultivated in glass aquariums. The gliphosate appears to be more toxic on Pistia Stratiotes than 2,4-D. It was then tested on tilapia Sarotherodon melanotheron juveniles. The lethal dose for tilapia (CL50 = 13.25 mg.l -1) is about 18, 37 and 74 times higher than the glyphosate toxic dose for plants at 1, 2 and 4 meters water depth respectively.

Catalogue des ennemis naturels des macrophytes flottants Pistia stratiotes, Salvinia molesta et Eichhornia crassipes

We identified from bibliographical review and field observations fourty two species composed essentially of molluscs and insects. These animals attack floating plants such as E. crassipes, P. stratiotes and S. molesta. They indifferently consume or destroy the aquatic plants except N. bruchi, N. eichhorniae and S. albiguttalis which specifically attack E. crassipes. N. putchellus, L. guinaicus and P. africana graze preferably P. stratiotes; C. salviniae, C. singularis and P. acuminata consume only Salvinia molesta.