Les variations mensuelles des captures de crevettes Penaeus notialis (Perez Farfante, 1967) entre 1962 et 1984 et les variations annuelles entre 1965 et 1984, dans l'estuaire de la Casamance, ont été étudiées. Les salinités extrêmes de 0,8 et 69 ‰ ont été enregistrées durant cette période. Les crevettes sont pêchées pendant leur migration de retour vers la mer, à l'aide de filets à maille de 12–14 mm de côté, fixés de part et d'autre de pirogues ancrées. Les données de salinité étant rares, une corrélation a été recherchée entre la salinité et la pluviométrie de manière à pouvoir utiliser les données de pluviométrie, disponibles pour chaque année. Il y a deux maxima de captures durant l'année. Lorsquela pluviométrie est importante (1,25–1,50m) ils sont observés en milieu d'année, quand la salinité est la plus élevée. Au contraire, lorsqu'elle est faible (0,75 à 1 m) les maxima se situent plutôt vers le début et la fin de l'année. Quand la pluviométrie est moyenne (1 à 1,25 m) le premier maximum survient en mai et le second en septembre-octobre. Les captures annuelles sont bien corrélées, négativement, avec l'indice pluviométrique qui détermine la salinité au premier semestre (pluviométriemoyenne des deux années précédentes). Cependant, en 1984, alors que la valeur de l'indice était très faible (0,795 m), les captures se sont effondrées. Aussi est-il supposé qu'il existe une relation parabolique entre les captures et la pluviométrie. Les captures maximales sont obtenues alors que l'estuaire est sursalé toute l'année par rapport à la mer. Les variations des captures pondérales traduisent celles des captures numériques et, dans une large mesure, celles du poids individuel des crevettes pêchées.

Virtual population analysis requires information on the fishing mortality rate (orabundance) for one age group from each cohort. In many cases available data areinsufficient to estimate these rates for every age group and structural assumptions mustbe imposed to reduce the number of effective parameters. Past assessments of westernAtlantic bluefin tuna (Thunnus thynnus) have reduced the number ofparameters by assuming pre-specified values for the ratios of the fishing mortality rateson adjacent age groups. More recent bluefin tuna assessments have estimated terminalfishing mortality rates (F) on each age with a constraint that restrictschange from one year to the next. We explore the implications of these methods ofestimating terminal-year F through retrospective analyses of the 2006bluefin tuna assessment and through stochastic simulations. The use of pre-specifiedratios for F created strong retrospective biases and may have led tooverly optimistic projections. Constraining annual changes in the terminal-yearF appeared to mute retrospective patterns and resulted in abundanceprojections less prone to spurious initial leaps. Simulation results indicate that theconstraint improves estimation, particularly with moderate to low interannual changes inselectivity.

The effect of fish farming on dissolved amino acid concentrations, bacterioplankton abundance and exoproteolytic activity was assessed in 3 experimental marine ponds. Different standing stocks of fish were introduced (semi-intensive pond: 250 g.m−2, semi-extensive pond: 50 g.m−2, control pond: 0). Sea bass farming increased dissolved combined amino acid (DCAA) concentrations only in the semi-intensive pond. Bacterial standing stock was unaffected by fish food supply. However, bacterial exoproteolytic activity was strongly stimulated by aquaculture intensification; the average maximal rate of dissolved protein hydrolysis (Vm) increased with intensity (control pond: 1 500 nM.h-1; semi-extensive pond: 2 600 nM.h−1; semi-intensive pond: 5 100 nM.h−1). DCAA fluxes through bacterial exoproteolytic activity ranged between 16 (semi-extensive) and 11% (semi-intensive) of the daily nitrogen input by fish food. Bacterial exoproteolytic activity allowed a substantial part of the increased supply of dissolved amino nitrogen to be incorporated into bacterial biomass, then available for transfer to higher trophic levels within the ponds. It also significantly decreased dissolved organic nitrogen export from the ponds to the surrounding environment.

Fisheries can be characterized as a network of interactions between natural and social systems, and thus should be viewed as complex, dynamic systems. Due to the multiplicity of components and processes, the involvement of various disciplines is required to understand the inter-relationships within and between the systems, and more so to adequately address management issues that typically affect several elements in the systems. To be successful, multidisciplinary approaches require mutual understanding of the perspectives, concepts, vocabulary and methods held by various disciplines, and agreement on the objects to be studied in common. In that spirit, at framework is suggested whereby fisheries systems are decomposed into related sub-systems that can be recognized by both Social and Life Sciences. Some key concepts attached to cach module and to its interactions with the others are identified, and may be starting points for dialogue and common undertakings by various disciplines, with a view to improving our understanding of the dynamics of the whole system.

This research investigates a status assessment approach for remnant lake salmonin populations, using the lake charr (Salvelinus namaycush Walbaum) of Crean Lake (105 km2) as an example. A mark-recapture program was implemented employing small-mesh gill nets to ensnare charr by the teeth at spawning. Prior to sampling, potential spawning sites were designated primary or secondary based on habitat. Most charr were caught on three primary reefs, with some spawners moving between reefs. The spawning period peaked at day 2, enhancing spawning synchrony, and lasted up to 10 days. Results produced very low sampling mortality (5.7%), consistent estimates of the number of spawning charr ( $\sim $ 60 y−1) and a very low (<2000) estimate of the total number of mature charr in Crean Lake. The approach offers an effective means of assessing remnant salmonins with minimal impact on their populations.

A holistic perspective of the last 150 years of studies in ocean biology reveals two distinct scientific activities. The first involved scientists in many expeditions from the "Challenger" in the 1870s to the Indian Ocean Expedition in the 1960s. These studies ended with what Ray (1970) has called the "Marine Revolution". This was caused by the need for marine biologists to pay much more attention to practical problems of fisheries, pollution, undersea mining and in particular the biology of the 200-mile economic zone which was established by many maritime nations in the 1970s. The new biological science of the oceans moved from largely descriptive ecology into the field of dynamic processes, holistic models, ocean monitoring and networking of different national and international organizations. Further progress in the biological sciences is needed in these areas, particularly in determining the canying capacity of the seas and oceans and the ecological consequences of removing manne species of fish from the oceans as part of the annual industrial harvest. These problems are only likely to be solved by a consideration of the properties of entire ecosystems, which are often different, to that expected, from the sum of the determinate parts.

A method of geometric morphometrics was used to characterize body shape variation inmeiotic gynogenetic and triploid sea bass in comparison with diploid controls. A total of13 coordinate landmark data were recorded on the profile of 34-month-old control(n = 81), gynogenetic (n = 117) and triploid(n = 131) siblings generated from two females (A and B). Three mainaxes of morphometric variation were consistent, and these accounted for 60.8 and 57.6% ofthe total variability in females A and B, respectively. There were significant shapedeviations of triploid and gynogenetic fish relative to the controls, and differences wereparticularly evident in the progeny of one female. Overall, triploids displayed a moreslender shape than diploids, whereas gynogenetic fish were deeper bodied and had flexedcaudal peduncles and cranial features. The results are discussed especially in relation tothe characterization of triploid fish for commercial purposes.

Diel, nocturnal and lunar input patterns of pre-settlement coral reef fish were described in Wallis, a typical high-island in the south-central Pacific, with a mid-size lagoon and a 2-m spring tidal range. Crest nets were set on the barrier reef to collect incoming pre-settlement fish. A diel input pattern was observed, with 82 to 99% of the larvae arriving at night. Nocturnal input of pre-settlement fish occurred throughout the night, at different times depending on the lunar phases. In contrast to studies done in other locations, the input was not higher during the first part of the night. The input level was related to moonlight and water level, but independent of tide direction. High input levels were recorded during all lunar phases, except the full moon. This lunar pattern differed from maximum settlement observed during the new moon in other locations. Consequently, a sampling strategy for studying temporal patterns of coral reef fish settlement in typical west Pacific high-islands should include new and quarter of the moon phases and should be extended to the entire night.

To better understand the molecular mechanisms involved in the biodegradation of hydrocarbon compounds from the “Erika” oil-spill, we have studied the ability of Marinobacter hydrocarbonoclasticus strain sp 17 to cope with hexadecane as sole carbon and energy source. Growth kinetics of cultures shifted from acetate to hexadecane revealed the presence of a 20 hours adaptation phase. Changes in global protein expression in response to hexadecane was analyzed by two-dimensional gel electrophoresis. Of the 370 proteins detected 42 had their expression level altered in presence of hexadecane indicating that alkane adaptation may involve many cellular functions.

Pour décrire la cinétique de l'ovogenèse et la stratégie de ponte chez la limande, Limanda limanda (L., 1758) les ovaires de 74 femelles capturées en baie de Douarnenez et en baie de Seine en 1990 et 1991 ont fait l'objet de prélèvements. Une échelle de développement ovocytaire en six stades a été utilisée pour classer les ovocytes. L'apparition d'alvéoles corticaux à la périphérie du cytoplasme est le premier signe de la vitellogenèse. Ils sont visibles dans les ovocytes dont le diamètre est de 120 μm, taille limite à utiliser lors d'études de la fécondité. Chez les femelles à ponte précoce un hiatus existe avant les pontes entre les ovocytes prévitellogéniques et vitellogéniques. Ceci permet de classer la limande parmi les espèces à fécondité déterminée. Chez ces femelles l'intensité de l'atrésie est faible et leur fécondité annuelle est proche de la fécondité potentielle. Par contre chez les femelles à ponte tardive tous les ovocytes vitellogéniques ne parviendront pas à maturité et ceux non encore émis à la fin du printemps dégénèreront.

Un système expert simple, reposant exclusivement sur des statistiques de pêche, a été élaboré afin d'estimer des migrations de poissons entre zones. Les flux de migration par trimestre sont calculés à partir de la comparaison de deux estimations distinctes des effectifs par zone et par âge, la première tenant compte du phénomène des migrations, la seconde non. La première estimation est obtenue en répartissant par zone les effectifs par âge issus d'une analyse des cohortes, la seconde est calculée période par période, à partir des effectifs présents dans chaque zone à l'âge précédent. Le modèle est appliqué au listao de l'Atlantique tropical Est. Les flux de migration estimés sont alors analysés, par groupe d'âge puis pour l'ensemble de la population. Bien qu'un certain nombre de limitations inhérentes au modèle existent, les résultats obtenus apparaissent valides par rapport aux schémas connus des migrations du listao.

This paper examines the Canadian experience with quota managed fisheries, reviewing institutional structures and approaches. It begins with a review of management objectives following the extension of jurisdiction and traces the nature and rationale of changes. The specific measures used to achieve objectives are examined from a theoretical and practical perspective. The measures fall into two broad categories: conventional input controls: vessel and gear restrictions; and, output controls: tradable and non-tradable enterprise/individual quotas.

The experience indicates that input controls are largely ineffective in constraining effort. These measures fail to address the common property characteristics of the resource and consequently failed to blunt the incentives for share maximization and increased capitalization. These in turn lead to overfishing and misreporting, thereby undermining management objectives. Output controls in the form of individual tradable quotas fare better in constraining effort. They lead to fleet rationalization and improved quality and flow of raw material to processing facilities. But they may also lead to highgrading and discarding, as quantity incentives give way to unit-value incentives under the rights-based regime.

Some of the carly failures and more recent successes of policy are outlined, lessons are drawn and suggestions made about future directions.

Production of channel catfish (Icta1urus punctatus), the most widely cultured foodfish in the United States, is confined for the most part to the southern states. The states of Alabama, Arkansas, Louisiana, and Mississippi account for more than 95% of total commercial production and processing. Mississippi accounts for more production and processing than the rest of the United States combined. Channel catfish are native to the United States. However, the farm-raised catfish, processed into many different consumer products, is considered to be a newly developed fish for marketing purposes.Production methods include intensive tank culture, raceway culture, and open pond systems. The open pond method accounts for almost all of the commercial production because it is more profitable. The other methods usually represent special situations as opposed to general cost effective systems. The culture of catfish in North America attained industry status in 1974 as production methods were adopted to provide fish for processing throughout the year. This development enhanced market development and tremendously contributed to the growth of the industry over the past 20 years. The industry is still in its infancy and shows much potential for continued growth in the United States. This potential is based upon the following: products from farm-raised catfish are widely accepted by consumers; the resources required are available for expansion on an economically efficient basis; and institutional support in terms of research, education, and market development is available to the industry.

To reveal the kinematical aspects of schooling development in the Pacific bluefin tuna Thunnus orientalis, changes in its schooling behaviour traits, local behaviour transmission among school members and morphological traits were investigated as fish developed from the larval to the juvenile stage. Schooling was first observed at around 24 days post-hatching (27 mm body length) in T. orientalis. Behaviour transmission among individuals took much longer among 24 d post-hatching individuals than among older fish. The compactness and polarity of the school progressively improved as the time required for behaviour transmission decreased. One cause of the reduction in the time required for behaviour transmission was the development of manoeuvrability, which resulted from further morphological development of the caudal fin and other organs related to swimming.