Stations cotières et station Vridi: exploitation des données des années 1984 et 1985

Along the Ivorian seaboard we have seven (7) stations where sea water temperature is measured every morning between 7:30 and 8:00. The hydrologic station of Vridi located at point A (5°05N, 4°05W) is generally exploited twice a week. In this report we are going to deal with data collected in 1984 and 1985. The irregularity of the dynamic height at point A enables us to identify water masses that go over the continental plateau.

Simulierte Auswirkungen des mehrjährigen Bewirtschaftungsplans für die Dorschfischerei in der westlichen Ostsee und die Möglichkeit einer technischen Alternative

The cod stock in the Western Baltic Sea is assessed to be overfished regarding the definitions of the UN World Summit on Sustainable Development at Johannesburg in 2002. Thus, the European Fisheries Council enforced a multi-annual management plan in 2007. Our medium term simulations over the future 10 years assume similar stock productivity as compared with the past four decades and indicate that the goals of the management plan can be achieved through TAC and consistent effort regulations. Taking account of the uncertainty in the recruitment patterns, the target average fishing mortality of age groups 3 – 6 years of F = 0.6 per year as defined in the management plan is indicated to exceed sustainable levels consistent with high long term yields and low risk of depletion. The stipulated constraint of the annual TAC variations of ±15% will dominate future fisheries management and implies a high recovery potential of the stock through continued reductions in fishing mortality. The scientific assessment of sustainable levels of exploitation and consideration in the plan is strongly advised, taking account of uncertainties attributed to environmental and biological effects. We recommend our study to be complemented with economic impact assessments including effects on by-catch species, which have been disregarded in this study. It is further demonstrated, that the goals of the management plan can alternatively be achieved by mesh size adaptations. An alternative technical option of mesh size increases to realize the required reductions in fishing mortality provides avoidance of discards of undersized fish after a few years by means of improved selectivity, another important element of the Common Fisheries Policy. However, it is emphasized that technical regulations since 1990 failed to affect the by-catch and discards of juvenile cod. In any way, the meaningful implementation of the multiannual management plan through stringent control and enforcement appears critical.

Begrenzung des Fischereiaufwandes oder Erhöhung der Mindestmaschenöffnung – Ein Vergleich der Alternativen bei der Dorschfischerei in der Ostsee

The basis for a long-term profitable fishery is a precautionary and environment-compatible use of fish stocks. The fishery management presently models the exploitation through the parameters of fishing mortality and the age at first capture. These two parameters are translated into the technical measures of fishing effort and mesh openings and quotas, which are then used in practice for controlling the fishery. Stock protection can be achieved by reducing the fishing effort, by assigning smaller quotas, by reducing the number of days at sea, or by increasing the mesh opening. The respective protection measures have different effects on the development of the stocks but also on the revenue obtained by the fishery. These alternatives have been examined taking as an example the cod stock in the western Baltic. The optimization goal was the maximization of profit observing at the same time the prerequisites for stock protection according to the precaution approach. For these calculations the same models and data have been used as are beeing used in the stock management of the ACFM of ICES. The response of altered technical measures to the recruitment of cod stock was considered, and a proposal to overcome overfishing of cod in the western Baltic Sea was derived.

Zustand und Entwicklung ausgewählter Fischbestände Einschätzung und Empfehlungen des ICES im Jahr 2004

The state of North Atlantic, Baltic Sea and North Sea commercially exploited fish stocks are assessed annually by the International Council for the Exploration of the Sea (ICES). Estimates of the stock size (biomass), recruitment, landings, current exploitation rates and of future harvesting possibilities are provided for those stocks where sufficient information is available to conduct a full analytical assessment. For all other stocks, only landings and stock trends can be given. This paper presents the development of north-east Atlantic fish stocks which are of general or specific interest for the German fishery and fish industry. Generally, it may be concluded that most pelagic fish stocks, such as herring, sprat, mackerel, and blue whiting, are in good condition, while the majority of the demersal stocks, like cod, plaice or whiting are in critical state. There are, however, a number of remarkable exceptions to this pattern.

Die Entwicklung des atlantischen Kabeljaubestandes vor Grönland in der zweiten Hälfte des 20. Jahrhunderts

Based on the results of an analytical assessment, the Atlantic cod stock off Greenland collapsed already in the late 60s and, since then, reached rarely the 10 % level of its size in 1955. Applying the concept of a self-sustaining stock, the drastic harvesting strategy of the past four decades must be considered inadequate. The stock collapse was therefore found consistent with annual exploitation rates being not adjusted to conservative management options and exceeding the productivity of the stock by far. The results of a multiplicative model explained the following recruitment failure based on significant effects of spawning stock size as well as temperature. Certainly, cold periods have negatively affected the recruitment process and consequently contributed to the stock collapse. However, such ecological effects should not be itemized causal but must be taken into account regarding appropriate stock management. Till today, the spawning stock remained severely depleted causing a low probability of a successful recruitment and a substantial stock recovery.

La pêche artisanale en lagune Aby (Côte d'Ivoire): analyse des captures en 1988 et 1989

The exploitation of fish stocks in Aby lagoon was marked by an increase of total fishing effort, yields and therefore by the increase of total production. Fishing effort evolution was due to: the increasing of the number of beach seines which has increased from 26 in 1987 to 32 in 1988, the reappearance of syndicat seines and finally the importance of fishing teams activity.

Statistiques de pêche en Lagune Aby (Côte d'Ivoire): évolution de l'effort et des captures de 1979 à 1990

Two kinds of fishing gears insure the exploitation in Aby lagoon: the individual gears are represented essentially by gill nets and collective gears by seines. The number of gill nets varies between 1500 in 1981 and 5600 in 1986. The beach seines, which number varies between 40 and 60, are regularly used. The purse seines (15-30) have been superseded by "syndicat" seines (15) in 1990.

Résultats du groupe de travail FAO/COPACE sur l'évaluation des stocks démerseaux côtiers du secteur Côte d'Ivoire - Congo

The exploitation rate of demersal stocks in the Côte d'Ivoire-Congo area is in most cases below the level permitting maximum sustainable yield. Any increase in total catch would be achieved through an increase in catch per effort which implies bigger mesh sizes than those in use now (40-45 mm). A first step would be to fix the minimum legal mesh size to 60 mm. New, probably limited resources (crab, squids, benthic sharks) are to be sought along the continental slope.

Contribution à l'étude des Iles Paracels: les phosphates

Authorized by the Government General of Indochina to attend a two weeks cruise on “De Lanessan” towards the Paracel Islands in 1931, the author focused on determining the wealth of phosphatic grounds and collect all relevant documentation regarding a possible exploitation.