Through a review of the scientific literature and a more in-depth qualitative meta-analysis of 16 case studies distributed worldwide, this article aims to study impacts of MPAs on marine living resources, ecosystems and related fisheries and to highlight their criteria of efficiency as management tools for a sustainable exploitation. MPAs are efficient for conservation purposes and resource restoration, especially inside their borders. MPAs can also be part of fisheries management systems, but there is a lack of knowledge about their wider scale impacts on fish stocks, ecosystem and fisheries. Adjacent fisheries can increase their catches near closed areas, but such effects are delayed until after MPA establishment and are often limited over distance. Even though local specificities in ecosystems and fishing resources lead to high variability in MPA effects, four major criteria modulate the efficiency of MPAs for fisheries management: (1) the size of the closed area; (2) the level of protection of essential habitats for exploited resources; (3) MPA integration as part of wider integrated fisheries management plans; and (4) efficient monitoring and regulation systems, including participative decision making, to ensure that restrictive measures are respected.

To understand the mechanisms that influence recruitment of the commercially important chokka squid Loligo vulgaris reynaudii, knowledge of its early life history is required. This paper evaluates the influence of food supply on yolk utilization, metabolism and growth of paralarvae. Eggs collected on the spawning grounds were incubated and the paralarvae reared in the laboratory under “fed” and “starved” conditions for 22 d at 16 ± 1 °C. Some paralarvae lasted 42 d in the laboratory. Mantle length (ML), wet and dry weights (WW and DW) and yolk weight (YW) were measured daily from samples of ~30 (10−51) paralarvae from each group. Yolk weight was estimated using image analysis to determined yolk volume. Three methods (growth model, O2 consumption rates and yolk utilization rates) were used to estimate metabolic rates. Input parameters included daily mean wet weight of paralarvae and temperature. Mean ML, WW, DW and YW at hatching were found to be 2.3 mm, 1.86 mg, 0.45 mg and 0.21 mg, respectively. The experiment revealed that daily yolk utilization rates were 86 and 95% d−1 for fed and starved paralarvae respectively, and that the yolk reserve was almost exhausted 3−4 d after hatching. Starved paralarvae survived for 6 days (with 80% mortality), while fed paralarvae attained a growth rate of 7.8% body WW d−1 over the first 22 days after hatching. Results illustrate that temperatures on the chokka squid spawning grounds allow paralarvae to grow at the fastest rates possible without being subjected to a growth “slow down” caused by a high temperature dependent imbalance between sustaining high metabolic and commitment high feeding rates.

This article describes tracking experiments conducted on eleven yellowfin tuna using ultrasonic transmitters in French Polynesia between 1985 and 1997. Nine fish were caught near Fish Aggregating Devices (FADs) while the other two were tracked in coastal areas without FADs. The fish showed different patterns of horizontal movements: tight associations with FADs lasting several days, foraging movements confirmed by simultaneous acoustic observations of prey-sized fauna, movements parallel to the shore, and traveling between FADs. This intra- and inter-individual variety of behaviour might depend on the local environment (prey), and on individual biological differences. The influence of FADs, coastlines, and prey on tuna movements is discussed. The lack of information about the surrounding environment, the internal state of the fish and the recent history of the fish usually prevent scientists from adequately interpreting the observed movements. Ideas for future research to studying tuna behaviour near FADs are discussed.

Triploid hybrids between female rainbow trout (Oncorhynchus mykiss) and male arctic char (Salvelinus alpinus), together with triploid and diploid rainbow trout controls from the same dams, were tested in freshwater farming from fry stage up to the age of 3 years. When farming was operated in cold water, the survival rate of the hybrids was as good as those of the diploid and triploid rainbow trout. Hybrid growth was noticeably hindered relative to that of diploid controls at the beginning of the juvenile period, but this was partly tempered later on by the effect of diploid sexual maturation; at 3 years of age, the hybrid weighed 20% less than the diploid rainbow trout and did not differentiate significantly from the triploid rainbow trout. The impairment of sexual maturation was very much the same in the hybrid as in the triploid rainbow trout, and dressing traits were therefore quite similar, despite a slight difference in perivisceral fat losses of immature individuals, to the advantage of the hybrid. These results allow one to consider the suitability of this hybrid for large-sized fish production in cold water farming.

The distribution and population structure of the red shrimp, Aristeus antennatus, were investigated for an unexploited fishing ground in the Greek Ionian Sea (middle-eastern Mediterranean). A total of 8618 specimens, 7273 females and 1345 males was caught during a 12-month survey, from January to December 1997, at depths ranging from 400 to 800 m. Monthly size frequency distributions were analysed using different techniques, resulting in estimates of growth and mortality. Carapace lengths (cephalothoracic lengths, CL) ranged between 12 and 62 mm for females and 9 and 45 mm for males. The mean size of specimens exhibited statistically significant differences in relation to sex and months. Recruitment of both sexes occurred in mid-winter (January). Only the mean size of females seemed to increase with depth. Estimation of the von Bertalanffy growth parameters revealed high k values and a life expectancy of 4 and 5 years for males and females, respectively. A high percentage of specimens bore spermatophores during May and August, indicating that these months were peak breeding periods. Natural mortality rates ranged from 0.55 to 0.70 for females and from 0.62 to 0.79 for males, depending on the method used. Based on its biology and population dynamics, it appears that the red shrimp population in the study area has the potential to support a viable fishery.

A fyke net survey of the juvenile and small fish assemblage of the Gambia estuary was conducted on three sampling occasions during the maximum recruitment season, from May to November 2002. This is the first detailed description of that particular component of the fish community in the Gambia estuary. The overall fyke net fish assemblage comprised 51 species, with a majority of young individuals of large and medium size species and the adults of small species. This assemblage is defined as the “small fish component of the mangrove channels”. The assemblage is dominated by true estuarine and certain marine species, all able to complete their life cycle within the estuary. The sea spawning species whose juveniles use the estuary mainly as a nursery ground, are not very diverse or abundant during the recruitment season. They are limited to the lowest part of the estuary due to the low salinity prevailing in the middle and upper reaches during the rainy season. This suggests that extreme seasonal variability (river flooding) in certain West African tropical estuaries at the time of maximum recruitment by certain marine species may reduce the nursery ground value for these taxa.

Age and growth of the brown meagre Sciaena umbra (Sciaenidae) collected (n = 532) in the north-western Adriatic Sea was studied by means of transverse otolith sections. The maximum age estimated was 19 and 16 years for males and females, respectively. The length at age estimated for each sex indicated that females attain a larger size and grow slightly faster than males. Both marginal increment analysis and edge analysis confirmed that annuli are formed once a year, with opaque zones laid down in summer (June-July). Age readings were very precise, with a percentage agreement of 98% between readers and low values of the index of average percent error (0.9%) and coefficient of variation (1.3%). Von Bertalanffy growth function was fitted to age-length data, and growth parameters were estimated for males (L ∞ = 44.9 cm; k = 0.27,t 0 = −2.17 years) and females (L ∞ = 47.2 cm; k = 0.28, t 0 = -1.82 years). In both sexes of brown meagre, growth rate was high until they attain 2–3 years of age, i.e. at sexual maturity. Most of catches were obtained in late summer-early autumn. On the basis of present data, the sampled population of brown meagre mostly consisted of small fish younger than three years of age (about 90%). In addition, landings of this species in recent years largely decreased. As reported elsewhere in north-western Mediterranean, brown meagre stock in the Adriatic Sea showed clear signs of depletion, thus specific management measures for this species are urgently required.

The Chilean jack mackerel (Trachurus murphyi) is one of the mostimportant exploited fish populations in the world. Its area of distribution covers thesub-tropical waters of the South Pacific Ocean, from South America up to New Zealand andeven Australia. It is subject to high variations in biomass, with annual world catchesvarying from less than 0.5 to almost 5 million tonnes. Management of this species and itsfishery requires a correct understanding of the population structure. Although severalhypotheses have been proposed, suggesting that there are up to four independentpopulations, genetic analysis indicates only a single population in the South PacificOcean. We consider the two most probable structures for this population: a “patchypopulation”, where all the fish belong to a single population that expands and contractsdepending on the biomass; and a metapopulation, where a source population creates severalsubpopulations that can remain independent during prolonged periods, depending on theenvironmental conditions. We studied the conditions for these hypotheses to representreality, especially the demographic structure and existence of different spawning areas.Using knowledge obtained from fisheries and acoustic surveys, we show that if we applytheir definitions strictly, neither of the two hypotheses can be fully rejected.Nevertheless, some particular spatial characteristics observed recently between thePeruvian and Centre-South Chilean parts of the distribution lead us to conclude that themetapopulation definition is likely to better describe the stock. The consequences of eachpopulation structure for fisheries management are listed, showing that the metapopulationhypothesis represents a safer definition for stock assessment. We conclude that T.murphyi can be described as a metapopulation, but also that the definitionsproposed in the literature on metapopulations are not fully adapted to pelagic fishpopulations with a basin-scale distribution range, and suggests specific research thatcould be done in this field.

Fisheries management now extends from the stock to the ecosystem. The foundation for fisheries management on an ecosystem basis must lie in appropriate modelling of the ecosystems. A prerequisite for such models requires data on the two interactive components of the ecosystem: the biotope (physical environment), and the community of living species. In this context, acoustics become essential, as this tool can provide qualitative and quantitative data on various communities of species, and furthermore allows the seldom-attainable study of their interactions. In fact, acoustics allow the monitoring of entire communities, from plankton to large predators, as well as certain aspects of the physical environment, such as substratum characteristics. Acoustics have been used during the last two decades mainly to provide fishery-independent estimates of stocks. The intention of this paper is to promote the use of acoustics for studying marine ecosystems and to encourage the emergence of new generations of ecosystem models. As an example of integrative research based on acoustic data, we will present the approach and the results of a scientific programme (ECOTAP) carried out to study the tuna pelagic ecosystem in French Polynesia. We then discuss the use of acoustics as a tool for ecosystem-based studies and management.

Carob seed germ meal (CSGM), and soybean meal (SBM), were tested as ingredients of diets for rainbow trout (Oncorhynchus mykiss) fingerlings at three levels of inclusion, contributing 20 to 50% of the total protein of the diet. Fish growth decreased as the level of the plant by-product in the diet increased. Diets containing CSGM resulted in lower growth than comparable SBM diets, especially at inclusion levels contributing 37 and 53% of the total protein. High dietary CSGM levels decreased body protein and increased liver protein indicating possible amino acid deficiencies and/or imbalances at high inclusion levels. Mortality was also high at the high dietary CSGM level. The results are discussed with référence to the antinutritional factors contained in the raw materials tested and their possible effects on protein availability.

Results are presented from laboratory-based experiments in which we investigated short-term responses of Mytilus edulis L. to experimental changes in the amount and composition of suspended seston. Working with large quantities of cultured algae, we have studied feeding behaviour over ranges of food availability and quality that extend well beyond earlier limits. Findings confirm the ability of mussels to selectively reject inorganic particles as pseudofaeces prior to ingestion, thereby enriching the organic content of ingested matter by 30% more than the organic content of natural filtered seston. Our findings also establish acclimation both of selective and absorptive processes, indicating that the extent to which growth of M. edulis can be stimulated in the short-term will depend upon prior nutritional history. Present maximal growth of 14.8% dry soft tissue d−1 in a standard M. edulis of 1 g dry soft tissue was much higher than has previously been documented for any adult mussel. Maximal growth was achieved when natural seston that had been enriched to more than about 60% organic content with a mixture of algal monocultures was available at concentrations above about 11.5 mg total particulates 1−1. Neither ingestion rate nor net energy balance were improved with further increases in food availability, associated with regulatory reductions in the rate of water filtration (clearance rate) that maintained organic ingestion rate independent of increases in both the amount and organic content of available seston. These findings suggest that digestive processes had become saturated when organic ingestion reached about 6.5 mg organics g−1 dry soft tissue h−1 in a standard M. edulis of 1 g dry soft tissue, representing as much as 20.6% of all soft tissue organic mass mussel−1 d−1. Such saturation of organic ingestion is consistent with previous conclusions based on comparative allometries showing that limitations to growth in M. edulis and other bivalves are associated with the rate of food processing.

We have analyzed a series of 22 groundfish surveys conducted between 1989 and 1999 on the Portuguese shelf and upper slope (97 sampling station grid, 36−710 m) in the summer, autumn, and winter, to address the hypotheses of latitudinal and depth trends in species richness (number of species) and whether these patterns changed over time and among seasons. Richness was modelled by means of a Generalized Additive Model (GAM) with significant covariates being latitude and longitude, in a joint-spatial smooth, and depth, chronological time, and season. A decrease in richness was detected along the continental margin, when moving higher in latitude, with lowest richness being found in the shallow northern area. Thus, although our study spanned only about 5 degrees in latitude, we found no exception to the equator-pole latitudinal decrease in richness commonly acknowledged by ecologists. There is no common agreement on the way marine fish species richness varies with depth, yet our findings were consistent for the entire eleven-year period: richness decreases slightly with depth, from the coastline to the shelf break (200−300 m), steadily increasing afterwards down the slope. The patterns of change in latitude and depth persisted in time and among seasons but their magnitude changed. Richness was higher in the winter compared to the other seasons.

The population abundance estimates used in stock assessments or required to establish management measures, depend on the sampling of the entire demographic spectrum of a population resident in a given area. However, for sea turtles, most population estimates are based mainly on nesting beach survey data and only consider a fraction of the population. The Southwest Atlantic Ocean (SWA) is an important foraging and development area for juveniles of the loggerhead sea turtle Caretta caretta where reproductive stocks from various nesting beaches mix. Declines in C. caretta populations have been observed in many parts of the world and bycatch rates of this species in the SWA are among the highest worldwide. This study standardizes the catch rates of loggerheads caught by pelagic longline fisheries in the region, using data collected by observer programs from Brazil and Uruguay. Generalized linear models (GLM) with a delta lognormal approximation were used. The variables used in the model take into account spatial and temporal variations as well as the characteristics of the fleet. In total, 6 272 344 hooks were observed between 1998 and 2007, with minimum effort registered in 2000 (12 010 hooks) and maximum effort in 2005 (1 989 431 hooks). During this period 3778 loggerheads were incidentally captured. The catch rates of loggerheads by the Uruguayan and Brazilian pelagic longline fisheries show oscillations through the years without a clear tendency; however, a low negative trend was observed from 1998 to 2005 with an increase in the last two years (2006 and 2007). The capture per unit of effort (CPUE) values varied between 0.38 to 1.78 ind/1000 hooks in 2005 and 2007, respectively. Distinct zones with differential catch rates were identified, with the higher CPUE values over the continental slope of Uruguay and adjacent waters. The incidental catch rates of this species are influenced, not only by fishing area, but also by year, season, sea surface temperature and gear type. In consequence, these variables and other potential ones should be considered in bycatch estimates by different fisheries because the loggerhead sea turtles are not uniformly distributed. This study intends to contribute not only to the general knowledge of loggerhead sea turtles in the SWA but to a future assessment of their populations at a global scale.

Deux études préliminaires ont été conduites en vue de déterminer dans quelles proportions l'aliment distribué et la productivité naturelle des marais atlantiques interviennent dans la ration alimentaire de Penueus japonicus en élevage semi-intensif (île de Noirmoutier). Deux méthodes ont été utiliséessimultanément : le marquage par les isotopes stables du carbone sur les tissus des crevettes et sur certains composants de la productivité, ainsi que la récupération de fécès marqués à l'oxyde de chrome. Il est apparu que l'aliment composé joue un rôle minime en début d'élevage; sa participation à la ration alimentaire augmente par la suite jusqu'à devenir essentielle en fin d'élevage. Par contre, il joue un rôle fertilisant primordial pour la conservation et la longévité de la richesse naturelle du bassin, saparticipation globale à la productivité pouvant atteindre 30 % de la biomasse totale.

Initiatives for the sustainable development of aquaculture have so far focused on theproduction of codes of conduct, of best management practices, of standards etc., most ofwhich have been developed by international organisations, the industrial sector and nongovernmental organisations. They were, to a large extent, produced using a “topdown” process and inspired by models from intensive industrial shrimp and sea fish farming(mainly salmon). However, most of global aquaculture production comes from small- andmedium-sized farms, essentially in Asia which contributes 92% of the total worldaquaculture production volume. The objective of this article is to define the contours ofsystemic typologies that are able to express the sustainability conditions of aquaculturesystems. The proposed approach builds on surveys of aquaculture systems which differ interms of their biogeographical nature (temperate/tropical and north/south countries) ortheir farming techniques and their governance systems. This work is a prerequisite to anyattempt at an individualised and comparative evaluation of specific aquaculture systemsfrom either global or territorial viewpoints. In order to go beyond the cleavage of atypology based on the differentiation between developed and developing countries, threetypologies were produced. These typologies allow for discriminatory variables to beidentified such as for example the marketing methods or the pace of innovation: astructural typology, a functional typology and a systemic typology. Finally, therepresentations of aquaculture activity and of its sustainability that producers have ofthe 4 different types that emerge from the systemic typology were recorded andanalyzed.

Monitoring the abundance of green turtles (Chelonia mydas) is necessary to assess population trends and risks of collapse. This note presents a study aimed at comparing three techniques for the direct estimation of green turtle numbers in their foraging habitats (seagrass beds and reef flats). The experiment was carried out at Mayotte Island, Western Indian Ocean. The techniques involved were surveys by snorkel, and aerial surveys using a microlight aircraft and a paramotor. Each technique had shortcomings and advantages. While each technique provided estimations of turtle numbers only surveys by snorkel permitted identification of species and sex, whenever visibility and turtle behaviour permitted. Along the shorelines, and over foraging areas, the paramotor was found to be most suitable for direct estimations of turtle numbers. The major advantage of this technique lied in its capability to obtain a synoptic snapshot of turtle distribution over foraging areas. Linear surveys from a microlight aircraft are better suited to monitor foraging areas located further away from the shore.

Information on the distribution of the benthopelagic fauna of the southern Aegean sea was collected through two bottom-trawl surveys carried out at fixed sampling stations in the summers of 1996 and 1997. Discriminant analysis identified that the most important species in discriminating among station-groups in terms of numbers were: Pagellus erythrinus, Mullus barbatus, Mullus surmuletus, Diplodus annularis, Spicara flexuosa, Sardina pilchardus and Parapenaeus longirostris. In terms of weight, the most important discriminating species were: Mullus barbatus, Pagellus erythrinus, Spicara maena, Scyliorhinus canicula, Loligo vulgaris and Parapenaeus longirostris. Supervised machine learning approaches and, in particular, the decision tree construction method were utilized in order to induce rules which determine the station-grouping. Several species, notably, Argentina sphyraena, Aristaeomorpha foliacea, Lepidorhombus bosci, Lepidotrigla cavillone, Mullus barbatus, Serranus cabrilla and Sepia officinalis appeared in most of the rules.

Larvae of the African River Prawn Macrobrachium vollenhovenii, indigenous to West Africa, were reared at various salinities (0-32‰). A salinity range of 16-24‰ was found most suitable with highest survival and growth, and lowest number and duration of instars. Freshwater was lethal already to zoea I - larvae. A mass culture experiment demonstrated the aquaculture potential of this Macrobrachium species. Larval rearing to postlarvae was possible applying the same methods as for M. rosenbergii. Detailed descriptions of rearing techniques are provided.

We studied the reproductive biology of the lesser sandeel, Ammodytes marinus, on the fishing grounds of the east central North Sea and on an unfished ground off the coast of southwest Norway. As in other parts of the North Sea, gonad growth appeared to start in September and spawning occurred in December-January. Based on data from the spawning period, maturity ogives by length and age were derived. The length and age at 50 % maturity was 14 cm and 3.2 years respectively in both study areas. The age estimate is 1 year higher than that found previously in the southern North Sea and adopted for the ICES-assessments of the North Sea spawning stock. Estimates of fecundity appeared higher in the North Sea than in coastal waters, at least for large fish. The coastal water estimates also seemed low compared with fecundity at length relationships previously published from Shetland, Fair Isle, and Dogger bank. The sex ratio seldom deviated substantially from the 1:1 ratio, but in summer there appeared to be a surplus of females. Due to spatial differences in age-structure, the proportion of adults was generally much lower on the fishing grounds of the North Sea proper than on the unfished coastal ground. In the middle of the spawning period, however, aggregations of adults occurred on the North Sea grounds.

A series of physical characterization methods (UV fluorescence microscopy, X-raymicrodiffraction, backscattered electron imaging and X-ray absorption spectroscopy) wereapplied to Polynesian pearls collected after different cultivation periods, varying fromthree weeks to eighteen months. Through this rigorous time-based sampling, 120 pearlsproduced by 20 different donor oysters were compared. Results show that the structure ofthe pearl layer can be understood as a sequence of distinct secretion processes whoseprogressive occurrence through time may lead to variously arranged and sometimes aberrantmineralized structures. By making comparisons with the structure and growth mode of thePinctada margaritifera shell, this study shows that the currentlyaccepted theory that views the pearl-bed as a “reversed shell” cannot account for thediversity of the microstructural patterns and mineralogical properties observed in thepearl layers. From a practical and economic view point, it appears that development ofthese pre-nacreous materials superposed onto a perfectly round-shaped nucleus is the maincause of shape irregularities in pearls and the consequent decrease in their value.