Life histories of 24 species of sturgeons are briefly summarized and threats to their existence are reviewed. The most important of these are fishing and physical disturbance of rivers (barriers; fluctuating water levels; gravel extraction). Conservation measures to limit and compensate for these impacts are reviewed. In Europe the common sturgeon, Acipenser srurio, is an endangered species; it has been the object of a conservation programme in France since 1982.

Rougier, T., Lambert, P., Drouineau, H., Girardin, M., Castelnaud, G., Carry, L., Aprahamian, M., Rivot, E., and Rochard, E. 2012. Collapse of allis shad, Alosa alosa, in the Gironde system (southwest France): environmental change, fishing mortality, or Allee effect? – ICES Journal of Marine Science, 69: 1802–1811. At the end of the 20th century the allis shad population in the Gironde was the largest in Europe. During the first decade of the 21st century, catches declined dramatically by two orders of magnitude, and a fishery moratorium was implemented in 2008. This deterioration in the status of the stock was confirmed by three independent assessments (abundance of juveniles and of potential and effective spawners). Three hypotheses on the cause of the collapse were examined: (i) an environmental change in freshwater and/or in the estuary; (ii) an increase in marine and/or estuarine mortality; and (iii) the presence of an Allee effect. Changes in flow, temperature, and water quality over the period were inconclusive, but remain a possible causative factor. The instantaneous rate of marine (mean: 0.7 year−1, s.e. 0.1 year−1) and estuarine (mean: 2.6 year−1, s.e. 0.1 year−1) mortalities showed no trend between 1991 and 2003. Nevertheless, the past high estuarine (fishing) mortalities combined with a demographic Allee effect in the reproduction dynamics could explain the population collapse and hamper the stock recovery under the moratorium. This conclusion is, however, tentative as it was not possible to prove the presence of the density-dependent mechanism associated with the demographic Allee effect.

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Traditional estimation of migration speed is based on telemetry or marking of individual fish. Only a few numbers of fishes (or batches) are followed, often over short periods of time. We propose a method based on capture data from the professional fishery. It is applied to glass eel (Anguilla anguilla) in the Gironde basin (France).Migration speed is estimated using 2 methods: a rough method based on the analysis of seasonal abundance peaks for two métiers and a more precise method of cross-correlation, which compares speeds between several fishing areas. The methods are coherent and lead to mean migration speed ranging from 3 to 4 km/day.We define an index of efficiency of migration using selective tidal stream transport (STST efficiency index) as the ratio of the observed migration speed to the potential speed (flood tide current speed and swimming speed). For the glass eel in the Gironde basin this index ranges between 0.15 and 0.19. The glass eel behavior, which can explain this low value, is reviewed.Our STST efficiency index can be successfully applied for many fish or crustaceans using selective tidal stream transport. It can also be used for one species to compare results obtained on different basins. Key-words:Migration speed, sequential fishery, cross-correlation, selective tidal stream transport, glass eels, Anguilla anguilla, STST efficiency index. EFFICACITÉ DE LA MIGRATION DES CIVELLES ENTRANT DANS LE BASSIN DE LA GIRONDE EN UTILISANT UN TRANSPORT SÉLECTIF TIDAL RÉSUMÉLes méthodes traditionnelles d'estimation de la vitesse de migration reposent sur la télémétrie ou les techniques de marquage. Seulement un nombre restreint de poissons (ou lots de poissons) sont ainsi suivis, souvent sur un temps court. Nous proposons une méthode basée sur les données de capture de la pêcherie professionnelle. Elle est appliquée au cas de la migration de la civelle (Anguilla anguilla) dans le bassin de la Gironde (France).

-The meagre Argyrosomus regius is a large Sciaenid fish known to reproduce in the eastern Atlantic and Mediterranean Sea in just five distinct and restricted geographic areas: along the Mauritanian coast and at estuary openings (Gironde, Tagus, Guadalquivir and Nile). The biological traits of A. regius (high dispersal capabilities, high fecundity, long larval phase, overlapping generations, reproduction until 40 years of age) are, in principle, favourable to high gene flow, which should lead to genetic homogeneity over large geographic scales. Nevertheless, the high geographic distances between the few reproductive areas leads one ask whether there is genetic differentiation in this species. In the present study, the genetic differentiation of the wild A. regius was investigated across most of its natural range from the Atlantic Ocean (France, Portugal, Spain, Mauritania) to the Mediterranean Sea (Egypt, Turkey), using 11 microsatellite markers previously identified in another Sciaenid, the red drum Sciaenops ocellatus. At least two very distinct groups could be identified, separated by the Gibraltar Strait. Genetic divergences (F ST values) were intermediate between the Atlantic samples (0.012-0.041), high between Egypt and the Atlantic (0.06-0.107) or Aegean Sea (0.081) and extremely high between the Aegean Sea and the Atlantic (0.098-0.168). A. regius exhibited a very high level of genetic differentiation rarely reported in marine fishes. These results also demonstrate the existence of a sixth independent spawning area in the Menderes delta (Turkey). Factors potentially involved in this very high genetic fragmentation are discussed, including physical barriers, glaciation pulses and biological traits.

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dans les cours d'eau affluant à la mer et sur certaines zones côtières adjacentes. Cette activité a commencé à s'intensifier à la fin des années 60 avec l'apparition de la technique du drossage et l'augmentation du nombre de pratiquants, professionnels et non-professionnels, liée à l'augmentation des prix d'achat de la civelle par les Espagnols. Les enregistrements statistiques de capture et d'effort de pêche des administrations sont souvent fragmentaires et peu fiables. Ce travail a donc consisté à réaliser, à partir des données officielles disponibles et des résultats des enquêtes et systèmes de suivi des pêcheries de civelles développés par NFREMER et le CEMAGREF depuis la fin des années 70, un bilan de l'exploitation pour l'année de référence 1989 et un diagnostic sur les tendances de l'abondance des civelles. 4360 pêcheurs dont 1160 pêcheurs professionnels (27 %) et 3200 nonprofessionnels (73 %) ont débarqué 520 tonnes de civelles en 1989, réalisant un chiffre d'affaires de plus de 200 millions de francs. La part des non-professionnels était de 33 % soit 170 tonnes et 68 millions de francs. L'analyse des séries chronologiques d'indicateurs halieutiques obtenues sur les bassins de la Vilaine, de la Loire et de la Gironde, autorise à penser qu'on a assisté au début des années 80, à une chute de l'abondance des flux de civelles, qui ne s'est pas démentie depuis. La pertinence et les limites des résultats sont discutées et un certain nombre de mesures concernant la ressource et l'activité de pêche sont proposées.