Commercial rearing of the sea cucumber <Emphasis Type="Italic">Apostichopus japonicus</Emphasis> in Peter the great bay: Methodical peculiarities and results of the work of a mariculture farm in Sukhodol Bight

Methodical approaches to commercial rearing of sea cucumber at mariculture farms in Peter the Great Bay in the Sea of Japan are discussed. This includes two basic phases, viz., intermediate rearing of underyearlings in cages and sea ranching. The survival rate of juvenile sea cucumbers during intermediate rearing in cages in Sukhodol Bight (Ussuri Bay) was shown to depend on the body size and rearing density of the juveniles and its value varied from 35 to 82%. The survival rate of two-year-old juveniles on artificial reefs reached 85%. Monitoring studies of the bottom sites showed that for the entire period of functioning of the farm, 8 years, a sea cucumber colony with the average distribution density of 1.5 inds/m² was formed on an area of about 30 ha. The harvest of the commercial production of sea cucumbers purchased at hatcheries can be calculated taking the survival rates of juveniles during the first years of their life into account. The calculation of the production of juvenile sea cucumbers picked by collectors was based on an appraisal of the current state of their aggregation (abundance, biomass, and size structure) with use of conservation protection measures (the allowable harvest rate of 6.4%).     

Satellite data identify decadal trends in the quality of Pygoscelis penguin chick‐rearing habitat

Pygoscelis penguins are experiencing general population declines in their northernmost range whereas there are reported increases in their southernmost range. These changes are coincident with decadal‐scale trends in remote sensed observations of sea ice concentrations (SIC) and sea surface temperatures (SST) during the chick‐rearing season (austral summer). Using SIC, SST, and bathymetry, we identified separate chick‐rearing niche spaces for the three Pygoscelis penguin species and used a maximum entropy approach (MaxEnt) to spatially and temporally model suitable chick‐rearing habitats in the Southern Ocean. For all Pygoscelis penguin species, the MaxEnt models predict significant changes in the locations of suitable chick‐rearing habitats over the period of 1982–2010. In general, chick‐rearing habitat suitability at specific colony locations agreed with the corresponding increases or decreases in documented population trends over the same time period. These changes were the most pronounced along the West Antarctic Peninsula where there has been a rapid warming event during at least the last 50 years.     

Saline preferendum for the European sea bass, Dicentrarchus labrax, larvae and juveniles: effect of salinity on early development and sex determination

The sea bass, Dicentrarchus labrax, is an eurhyaline marine fish. Juveniles of this species are known to frequent estuaries and lagoons where salinity is lower than in the open sea. Sex determination occurs during this phase of fish life and has been shown labile and sensitive to environmental factors. In this work, the effect of rearing salinity on sex determination and early development of the sea bass was investigated. An excess of males (87%) was found in all groups and the salinity level [(natural sea water salinity, mean: 37‰) vs. (15‰)], when maintained constant, had no effect on the sex-ratio. The transfer from low to high salinity at 93 days post-fertilization (p.f.) increased the percentage of males (93%) suggesting that sexual differentiation in this species may be influenced by such an osmotic stress. Growth was improved by a 15‰ salinity at the beginning of larval rearing (14 days p.f.) and at the end of pre-growing (234-458 days p.f.), periods during which low temperatures were applied. Survival during larval rearing and nursery were also improved in the groups reared at low salinity and so was swimbladder inflation. These results show that sea bass juveniles have a low saline preferendum, a finding that corresponds to the conditions they actually encounter in the wild during their juvenile ecophase; sex determination is not directly modulated by the salinity level but seems to be subjected to complex environmental regulations.     

Foraging strategy of the little auk Alle alle throughout breeding season – switch from unimodal to bimodal pattern

Energy and time allocation differs between incubation and chick‐rearing periods, which may lead to an adjustment in the foraging behaviour of parent birds. Here, we investigated the foraging behaviour of a small alcid, the little auk Alle alle during incubation and compared it with the chick‐rearing period in West Spitsbergen, using the miniature GPS (in Hornsund) and temperature loggers (in Magdalenefjorden). GPS‐tracking of 11 individuals revealed that during incubation little auks foraged 8–55 (median 46) km from the colony covering 19–239 (median 120) km during one foraging trip. Distance from the colony to foraging areas was similar during incubation and chick‐rearing period. During incubation 89% of foraging positions were located in the zone over shallower parts of the shelf (isobaths up to 200–300 m) with sea surface temperature below 2.5°C. Those environmental conditions are preferred by Arctic zooplankton community. Thus, little auks in the Hornsund area restrict their foraging (both during the incubation and chick‐rearing period) to the area under influence of cold, Arctic‐origin water masses where its most preferred prey, copepod Calanus glacialis is most abundant. The temperature logger data (from 4 individuals) indicate that in contrast to the chick‐rearing period, when parent birds alternated short and long trips, during the incubation they performed only long trips. Adopting such a flexible foraging strategy allows little auks to alter their foraging strategy to meet different energy and time demands during the two main stages of the breeding.     

A Glimpse into the Microbiota of Marketed Ready-to-Eat Crickets ( Acheta domesticus )

The present study was aimed to get an insight into the bacterial biota of ready-to-eat small crickets (Acheta domesticus) already marketed in the European Union. 16S rRNA gene of the DNAs extracted from thirty-two samples of ready-to-eat crickets commercialized by 4 European Union producers located in Austria, Belgium, France and the Netherlands (2 batches per producer) was analyzed by Polymerase Chain Reaction–Denaturing Gradient Gel Electrophoresis (PCR–DGGE). The species belonging to the genera Hespellia, Ruminococcus and Clostridium were detected in samples from Austria, while those from genera Lysobacter, Staphylococcus and Clostridium were detected in samples from Belgium. Moreover, samples from France were characterized by Staphylococcus, Pseudomonas, and Hydrogenophilus genera. Finally, the genera Staphylococcus, Hydrogenophilus, Clostridium and Ruminococcus were identified in the samples produced in the Netherlands. When insects are intended for commercialization, rearing, processing and handling could affect the presence of the occurring microbial species. Hence, to assure a safe product, the need for a full standardization of production technologies, including feed supply as well as rearing and processing practices, is recommended.     

Genetic and environmental influences on shape variation in the European sea bass (Dicentrarchus labrax)

This paper demonstrates the contribution of both genetic and environmental effects on cultured European sea bass shape. We used the progeny of five populations of sea bass, in a partly diallel design, to investigate the genetics of shape (estimated with geometric morphometrics) in European sea bass. This was done using a common garden experiment with microsatellite markers assignment to parents and populations to avoid confusion between genetic and environmental effects. Additionally, one of the populations was studied over four different aquaculture facilities to investigate the effects of environment on shape. For the first time in this species, shape‐related traits were linked with genetic variation. The first relative warp analysis axis clearly differentiated rearing sites, demonstrating that the main shape/weight effects are related to culturing conditions, thereby accounting for ecomorphologically related differences. The second axis strongly differentiated groups by parental origins; there was a good correlation between shape differences and geographic distances between broodstock sampling locations. High heritabilities of axes scores (0.40–0.55) showed high genetic variation for shape within populations. This study shows that variation in shape has a high genetic component in sea bass, both at the population level and within populations. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 101 , 427–436.     

Lamprey (Entosphenus sp. and Lampetra sp.) estuarine occupancy is regionally variable and constrained by temperature

Temperature and sea level are predicted to rise with climate change, bringing an urgency to evaluating future viability of native fish. Lamprey are confronted with widespread habitat degradation, migratory barriers, and episodes of environmental change projected to be commonplace in the future. In California, range contraction likely shifted lamprey rearing downstream, but the extent and physiological constraints that restrict estuarine rearing are unclear. We used a single-season occupancy model to describe juvenile lamprey estuarine distribution and found occupancy was regionally variable and constrained by temperature. Habitat and hydrology providing thermal refugia may be critical for future persistence.     

Optimization of Weaning Elvers in a Closed Cycle System: Preliminary-Results

Replicated tests to study the best combination of environmental conditions were carried out with a total of about 200 kg of glass eels of the Thyrrenian sea. Conditions tested were; stocking density, feed formulation, form of feed, grading frequency, cage and tank dimensions and protection of rearing units. Production and survival rates are reported, as well the size — class distribution at the beginning and at the end of the rearing period and the component chart of percentages of different size classes.     

Foraging behaviour of Magellanic Penguins during the early chick‐rearing period at Isla de los Estados,Argentina

Studies of the at‐sea distribution and trophic ecology of penguins are essential to understand their role in the broader marine food web. Magellanic Penguins Spheniscus magellanicus have a wide distribution and their foraging behaviour varies across breeding sites and between sexes, among others. In this study, we characterized the at‐sea areas, the diving strategies and the relative trophic level of Magellanic Penguins breeding at Isla de los Estados, Argentina, during the early chick‐rearing period. In addition, we quantified the interannual, sexual and individual variability in those parameters during three breeding seasons (2011–2013) using devices recording position and dive depth, and obtained blood samples for stable isotope analysis. During the early chick‐rearing period, Magellanic Penguins showed small differences between the sexes in their foraging behaviour and large overlap in the at‐sea areas used, suggesting no intraspecific variation between sexes. Although there was interannual variability in the foraging behaviour and the trophic level of the penguins, most of the studied nests managed successfully to raise both chicks during the first stage of the breeding cycle (guard stage). The foraging ecology of Magellanic Penguins from this colony was comparable with results of past studies at other breeding colonies. This study contributes to the identification of important at‐sea areas for Magellanic Penguins at the southern edge of their distribution and also to the identification of possible threats in the study area such as interaction with fisheries.     

Success of a low‐sloping rack for improving downstream passage of silver eels at a hydroelectric plant

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Antarctic krill breeding facilities at port of nagoya public aquarium

Antarctic fishes and invertebrates, including Antarctic krill, are generally stenothermal, and it is necessary to maintain water temperature about 0°C to keep them in good condition. Because the effects of nitrifying bacteria are limited by the extremely low temperature of about 0°C, biological filtration does not keep up with the deterioration of water quality resulting from the excrement of animals and un-eaten food. It is therefore necessary to exchange seawater frequently in our present cold-water aquarium.

We developed a new system at Port of Nagoya Public Aquarium (PNPA) that keeps Antarctic marine animals in good condition. The improved system increases the temperature of sea water to 10°C prior to biological filtration and thereby increases the effectiveness of the biological filter. The krill-rearing container was constructed inside the main tank so that the water flow inside the rearing container could be stopped. This avoids a rapid reduction of phytoplankton feed due to turnover of the seawater in the system while krill were fed. As a result of these improvements, long-term rearing, mass culture and reproduction of Antarctic krill are possible. We have exhibited Antarctic marine animals since the opening of PNPA in 1992, and we have exhibited Antarctic krill continuously since 1997. In this article, we detail the Antarctic krill breeding facilities at PNPA.     

Visualizing mineralization in deformed opercular bones of larval gilthead sea bream (Sparus aurata)

During the rearing process of gilthead sea bream (Sparus aurata), abnormal development of the opercular bone is particularly common (Aquaculture 156, 1997, 165). In order to alleviate its occurrence in rearing facilities, it’s crucial to identify the very first physical signs of deviation in normal skeletal development. Nano‐CT‐scanning was tested for its applicability to quantify deviations in bone mineralization levels. Seven opercles were dissected from larvi of 65 days post hatching, randomly sampled at the commercial sea bream hatchery Maricoltura di Rosignano Solvay (Livorno, Italy). The samples were nano‐CT‐scanned and computationally reconstructed. Mineralization intensity was colorcoded using Amira software, resulting in a detailed visualization of opercular morphology and mineralization patterns. In conclusion, nano‐CT‐scanning promises to be a good tool to both describe morphology and detect mineralization levels in the early onset of deformities.     

Comparison of growth and RNA: DNA ratios in three populations of juvenile turbot reared at two salinities

Salinity significantly influenced growth and RNA: DNA ratios in three populations (Iceland. Norway and France) of juvenile turbot Scophthalmus maximus as these variables were higher at 15 than at 33.5‰ salinity. Furthermore, growth and RNA: DNA ratios of the two high latitude populations (Iceland and Norway) were higher than those of the low latitude population (France): the Norwegian and the Icelandic populations had RNA: DNA ratios of 6.028 and 5.91, respectively, whereas the ratio of the French population was 5.01. It is concluded that in the upper temperature range for turbot, growth can be improved by rearing at intermediate salinities at least during the first year.     

Rearing performances and environmental assessment of sea cage farming in Tunisia using life cycle assessment (LCA) combined with PCA and HCPC

Purpose

The present study aims to understand the influence of rearing practices and the contributions of production phases of fish farming to their environmental impacts and determine which practices and technical characteristics can best improve the farms’ environmental performance. Another objective is to identify the influence of variability in farming practices on the environmental performances of sea cage aquaculture farms of sea bass and sea bream in Tunisia by using principal component analysis (PCA) and hierarchical clustering on principal components (HCPC) methods and then combining the classification with life cycle assessment (LCA).

Methods

The approach consisted of three major steps: (i) of the 24 aquaculture farms in Tunisia, 18 were selected which follow intensive rearing practices in sea cages of European sea bass (Dicentrarchus labrax) and gilthead sea bream (Sparus aurata) and then a typology was developed to classify the studied farms into rearing practice groups using HCPC; (ii) LCA was performed on each aquaculture farm and (iii) mean impacts and contributions of production phases were calculated for each group of farms. Impact categories included acidification, eutrophication, global warming, land occupation, total cumulative energy demand and net primary production use.

Results and discussion

Results revealed high correlation between rearing practices and impacts. The feed-conversion ratio (FCR), water column depth under the cages and cage size had the greatest influence on impact intensity. Rearing practices and fish feed were the greatest contributors to the impacts studied due to the production of fish meal and oil and the low efficiency of feed use, which generated large amounts of nitrogen and phosphorus emissions. It is necessary to optimise the diet formulation and to follow better feeding strategies to lower the FCR and improve farm performance. Water column depth greatly influenced the farms’ environmental performance due to the increase in waste dispersion at deeper depths, while shallow depths resulted in accumulation of organic matter and degradation of water quality. Cage size influences environmental performances of aquaculture farms. Thus, from an environmental viewpoint, decision makers should grant licences for farms in deeper water with larger cages and encourage them to improve their FCRs.

Conclusions

This study is the first attempt to combine the HCPC method and the LCA framework to study the environmental performance of aquacultural activity. The typology developed captures the variability among farms because it considers several farm characteristics in the classification. The LCA demonstrated that technical parameters in need of improvement are related to the technical expertise of farm managers and workers and to the location of the farm.

     

Do hatchery-reared sea urchins pose a threat to genetic diversity in wild populations?

In salmonids, the release of hatchery-reared fish has been shown to cause irreversible genetic impacts on wild populations. However, although responsible practices for producing and releasing genetically diverse, hatchery-reared juveniles have been published widely, they are rarely implemented. Here, we investigated genetic differences between wild and early-generation hatchery-reared populations of the purple sea urchin Paracentrotus lividus (a commercially important species in Europe) to assess whether hatcheries were able to maintain natural levels of genetic diversity. To test the hypothesis that hatchery rearing would cause bottleneck effects (that is, a substantial reduction in genetic diversity and differentiation from wild populations), we compared the levels and patterns of genetic variation between two hatcheries and four nearby wild populations, using samples from both Spain and Ireland. We found that hatchery-reared populations were less diverse and had diverged significantly from the wild populations, with a very small effective population size and a high degree of relatedness between individuals. These results raise a number of concerns about the genetic impacts of their release into wild populations, particularly when such a degree of differentiation can occur in a single generation of hatchery rearing. Consequently, we suggest that caution should be taken when using hatchery-reared individuals to augment fisheries, even for marine species with high dispersal capacity, and we provide some recommendations to improve hatchery rearing and release practices. Our results further highlight the need to consider the genetic risks of releasing hatchery-reared juveniles into the wild during the establishment of restocking, stock enhancement and sea ranching programs.     

Comparative biology of two rosette crown-feeding flies of the genus Botanophila (Dipt., Anthomyiidae) with potential for biological control of their thistle hosts

The comparative biology of two anthomyiid flies with potential for biological control of their host thistles, Botanophila turcica on Carthamus lanatus and Botanophila spinosa on Onopordum acanthium , was studied using field surveys and collections, and by rearing collected eggs and larvae in the laboratory in southern France. The thistle hosts are significant weeds outside their native range, particularly in Australia. Both flies attack the rosette meristems of their hosts prior to flowering. Larval stages are described together with natural attack rates (21–33% of field plants) and the mortality of field-collected larvae reared in the laboratory. A successful rearing protocol for these flies is also described. The results of preliminary host-specificity tests showed that both species are highly specific, being restricted to their host genus in the tests conducted. Furthermore, Botanophila turcica could not complete development on safflower (a congener of its natural host) under natural conditions. Botanophila turcica had an adult activity period that lasted 6 months from late autumn and laid fewer eggs per host plant than B. spinosa , which was active for 2 to 3 months in spring. Only one parasitoid was observed, an endoparasitic eucoilid, Trybliographa sp., which attacked both fly species, causing 18–23% mortality.     

Endocrine correlates of parental care in an Antarctic winter breeding seabird, the emperor penguin, Aptenodytes forsteri

Plasma levels of luteinizing hormone (LH) and prolactin associated with parental behavior were measured in the Antarctic winter breeding emperor penguin, Aptenodytes forsteri. Males exclusively incubate the egg while females exclusively brood the nonhomeothermic young; both sexes alternate in rearing the homeothermic young. Birds were sampled on arrival from the sea through egg laying, incubation, and brooding. All parent birds lost their chicks at the end of the brooding period due to harsh weather but sampling continued. In females, LH titers dropped after egg laying but levels were restored when the birds returned from the sea to brood the chicks and were not depressed by high prolactin levels. Plasma prolactin remained low in males captured on arrival and kept until the free-living males finished incubation. In breeders, prolactin secretion increased during the prelaying period when day length decreased. Prolactin levels stayed elevated in males during incubation and in brooding females returning after a 2-month absence at sea. Prolactin values were higher in brooding females than in males ending incubation or returning in late brooding. These levels did not drop after chick loss, and the sexual difference in prolactin values was maintained after breeding failure. In emperor penguins, increased prolactin secretion appears to be triggered around the time of egg laying and continues, driven by an endogenous mechanism, through incubation and brooding until rearing is completed. Prolactin secretion independent of external stimuli may have evolved in pelagic seabirds to maintain parental care despite long absences at sea from the breeding colony.     

The status of marine fish larval-rearing technology in Australia

Over 20 marine fish species have been studied forfarming or stock enhancement in Australia. However,commercial production has been dominated by the cageculture of Salmo salar in Tasmania, Thunnusmaccoyiiin South Australia, and to a lesser extent Latescalcarifer in Queensland. A major impediment to thecommercial production of new species has been thelarge-scale production of juvenile fish. Thedevelopment of marine fish larval rearing technologyin Australia has had four main influences over thelast decade: culture system technology from France,live food culture and nutritional enhancement fromBelgium, artificial diets from Japan and extensivepond culture from the USA. Microalgae and live foodculture is based on traditional aquaculture speciesand methods. Recent Australian research has focusedon induced spawning, the role of stress in inhibitingovulation, factors influencing initial swim bladderinflation in larvae, larval nutrition, extensiveculture and diagnosis of disease. Over the next 5years, Australian aquaculturists should be able toproduce industrial quantities of a range of nativemarine fish, either in intensive fish hatcheries, orin combination with extensive pond culture.     

Rearing temperature enhances hepatic glucokinase but not glucose-6-phosphatase activities in European sea bass (Dicentrarchus labrax) and gilthead sea bream (Sparus aurata) juveniles fed with the same level of glucose

The aim of this work was to elucidate if the previous results observed in hepatic glucokinase (GK) and glucose-6-phosphatase (G6Pase) activities in European sea bass and gilthead sea bream are due to temperature per se or to differences in feed intake at different water temperatures. For that purpose triplicate groups of fish (30 g initial body weight) were kept at 18 degrees C or 25 degrees C during two weeks and fed a fixed daily ration of a glucose-free or 20% glucose diet. At the end of the experimental period, plasma glucose levels in both species were not influenced by water temperature but were higher in fish fed the glucose diet. Higher hepatic GK activity was observed in the two fish species fed the glucose diet than the glucose-free diet. In the glucose fed groups, GK activity was higher at 25 degrees C than at 18 degrees C. Glucose-6-phosphatase activities in both species were not influenced by water temperature. In European sea bass and in contrast to gilthead sea bream it was observed an effect of dietary composition on G6Pase activities with surprising higher activities recorded in fish fed the glucose diet than in fish fed the glucose-free diet. Overall, our data strongly suggest that European sea bass and gilthead sea bream are apparently capable to strongly regulate glucose uptake by the liver but not glucose synthesis, which is even enhanced by dietary glucose in European sea bass. Within limits, increasing water temperature enhances liver GK but not G6Pase activities, suggesting that both species are more able to use dietary carbohydrates at higher rearing temperatures.