Search

The oxygen demand, acidification potential, and waste loads of carbon dioxide, nitrogen, and phosphorus from feed were determined for production of channel catfish Ictalurus punctatus, tilapia Oreochromis spp., Atlantic salmon Salmo salar, rainbow trout Oncorhynchus mykiss, and whiteleg shrimp Litopenaeus vannamei. Loads of these variables in culture systems (system loads) at typical FCRs ranged from 1090 to 1500 kg t− 1 for feed oxygen demand, 270–440 kg t− 1 for acidification potential, 1186–1885 kg t− 1 for carbon dioxide, 35.9–63.5 kg t− 1 for nitrogen, and 6.1–15.9 kg t− 1 for phosphorus. Using these estimates as representative of feed-based aquaculture and literature data on the proportions of system waste loads typically discharged to the environment (environmental loads), the approximate amounts of waste generated globally by feed-based aquaculture were estimated to be small in comparison to estimates of global anthropogenic waste. Nevertheless, aquaculture should lessen its environmental waste load, and the benefit of improving FCR in reducing waste load was illustrated. Statement of relevance This research will be important in efforts to assess the pollution potential of aquaculture facilities. This will be especially important for aquaculture certification efforts.

Bivalve aquaculture currently utilizes two main farming practices: intertidal (beach) and deep-water (suspended) culture. Although suspended culture offers a number of advantages during both nursery and grow-out phases, two commonly encountered issues – shell deformities and biofouling – lead to reduced seed and final product quality in some species and preclude other species from being cultured in suspension. None of the existing strategies for controlling these issues is efficient and fully reliable. In this study we tested the efficiency of two new methods for controlling biofouling and shell deformities in suspended culture of bivalves using basket cockle Clinocardium nuttallii as a model species. The first method involved a short-term increase in bivalve stocking density during peak plankton concentrations and biofouling settlement periods. The second method comprised adding artificial growth medium (expanded clay aggregate) to culture enclosures. Both high-density and growth medium treatments significantly reduced the incidence of C. nuttallii shell deformities compared to the control treatment (by 86 and 72%, respectively). This finding suggests that clam shell deformities in suspended culture primarily develop due to the lack of structural support normally offered by the substratum. Both treatments also significantly reduced barnacle fouling rate (by 67 and 83%, respectively). Additionally, growth medium treatment led to a significant reduction in tube worm fouling, as well as combined fouling rate and intensity, but it was less effective in controlling sponge fouling. Overall, both high-density and growth medium treatments showed promise in reducing the incidence of shell deformities and the amount of biofouling on C. nuttallii in suspended culture. These treatments are inexpensive, environmentally-friendly, readily available to shellfish growers, and may be further refined and adapted for a variety of cultured bivalve species. They have the potential to improve the efficiency of suspended grow-out systems and extend the option of suspended culture to bivalve species currently grown on the beach only.

Biofiltration allows for environmentally sustainable mariculture. An intensive, biofiltered recirculating integrated system producing fish and seaweed on a semi-commercial scale was evaluated with respect to production and to nutrient and heat budgets. The system consisted of abalone (Haliotis discus hannai) and sea urchin (Paracentrotus lividus) tanks, an intensive fishpond (Sparus aurata), and a three-stage Ulva lactuca biofilter, which cleaned and recirculated 50% of the effluent back to the fishpond. To preserve water heat, the shellfish and fishpond units were both covered with greenhouses; the biofilter unit was covered with a greenhouse only during winter. Seaweed yield was variable and averaged 94 and 117 g m−2 day−1 (fresh weight) in periods with and without greenhouse cover, respectively. Protein content of U. lactuca averaged above 34% of dry weight. The biofiltration of only 50% of the water through the seaweed biofilter reduced the export of dissolved nutrients to the environment by nearly 30%. Peak ammonia excretion by the morning-fed fish coincided with maximum seaweed light-dependent ammonia uptake and concentrations of ammonia in the fishpond remained within nontoxic limits. Also, daytime photosynthesis of U. lactuca (uptake of CO2) met fish respiration (production of CO2), thus balancing fishpond pH levels within safe limits regarding ammonia toxicity. Daytime oxygen demand by the fish was partially met by the photosynthetically generated oxygen. Before covering the biofilter with a greenhouse, it lost much heat, reducing the temperature in the fishpond. Following the greenhouse covering of the biofilter, heat loss ceased and consequently the fishpond temperature was raised. Recirculation through the biofilter improved system sustainability; it reduced water use, lowered negative environmental impact, and maintained stable and safe water quality conditions in the fishpond.

This note summarizes a review by Hindar et al. (1991) outlining the genetic consequences of aquaculture on natural fish populations. Publication of the full paper (Hindar et al., 1991) has preceded that of the present volume; this note is included to permitt a more complete presentation of the papers read at the Loen symposium on interactions between cultured and wild Atlantic salmon ( Salmo salar ).

The efficacy of a silicone coating (Veridian 2000) to reduce fouling on salmon-cage netting was examined at a salmon farm in Tasmania, Australia. Significantly less fouling occurred on the white silicone-coated netting (1.9 kg/m 2 ) compared to uncoated white (7.8 kg/m 2 ) and black (8.5 kg/m 2 ) netting after 163 days immersion. On silicone-coated netting the green alga Ulva rigida dominated the fouling mass, with smaller amounts of solitary ascidians. In contrast, solitary ascidians dominated the uncoated black and white netting and accounted for more than 75% of the fouling mass. Netting colour significantly affected the growth and composition of algal fouling, but had no effect on invertebrate fouling. Cleaning experiments demonstrated that fouling organisms were poorly adhered to the silicone coating and that relatively little effort was required for their removal. Silicone coatings may provide an effective non-toxic solution to reduce fouling on sea-cages and to increase the ease of fouling removal.

The water-quality characteristics of a new system for the integrated culture of fish ( Sparus aurata L.) and seaweed ( Ulva lactuca L.) were examined. Seawater was recirculated between intensive fishponds and seaweed ponds. The seaweed removed most of the ammonia excreted by the fish and oxygenated the water. A model consisting of several tanks and a pilot consisting of two 100-m 3 , 100-m 2 ponds were studied. In both, the metabolically dependent water-quality parameters (dissolved oxygen, NH 4 + -N, oxidized-N, pH and phosphate) remained stable and within safe limits for the fish during over 2 years of operation. The design allowed significant increases in overall water residence time (4.9 days), compared with conventional intensive ponds, and produced a high yield of seaweed in addition to the fish. The design provides a practical solution to major management and environmental problems of land-based mariculture.

The fate of orally administered oxytetracycline in a fresh-water hatchery was investigated using high-performance liquid chromatography. A filter of nominal porosity 50 μm in the farm effluent was capable of at least a 500–650-fold concentration of the oxytetracycline into the filter retentate flow. No oxytetracycline was detected in the filtered farm effluent (limit of detection 0.02 μg·ml−1). Analysis of hourly samples of the retentate taken over a 24-hour period allowed an estimate of the daily amount of oxytetracycline retained by the filter. This estimate (1250 g) was of the same order as the amount of oxytetracycline used on the farm (904 g on the day of sampling and 1104 g on the preceding day). Thus the quasi-totality of the input oxytetracycline was removed from the farm effluent by the filter. A sedimentation trap on the filter retentate flow removed oxytetracycline from this flow at a variable and lower (12–92%) efficiency. It is argued that correct design of effluent treatment systems could significantly reduce the environmental impact of land-based fish farms.

Experiments were conducted to determine the efficacy of coffee pulp as a constituent of a feed used in the culture of common carp ( Cyprinus carpio L.) and catfish ( Clarias mossambicus Peters). The carp were fed two commercially prepared pelleted feeds, one with 30% coffee pulp, in an earthen pond. Daily growth increments were reduced from 1.65 g to 0.34 g when fed with coffee pulp. Catfish were tested in an earthen pond, in a floating cage and in concrete tanks under variable densities. In all cases, daily growth increments were reduced by 45% or more.

A combined tertiary sewage treatment—marine aquaculture system has been developed, tested and evaluated using several different experimental sizes and configurations located both at Woods Hole, Mass. and Fort Pierce, Fla. Domestic wastewater effluent from secondary sewage treatment, mixed with sea water, is used as a source of nutrients for growing unicellular marine algae and the algae, in turn, are fed to oysters, clams, and other bivalve molluscs. Solid wastes from the shellfish are fed upon by polychaete worms, amphipods, and other small invertebrates that serve as food for flounder, lobsters, and other commercially valuable secondary crops. Dissolved wastes excreted by the shellfish and other animals and any nutrients not initially removed by the univellular algae are removed by various species of commercial red seaweeds (Chondrus, Gracilaria, Agardhiella, Hypnea) as a final ‘polishing’ step. The final effluent from the system is virtually free of inorganic nitrogen and is incapable of supporting further growth of marine life or of contributing to eutrophication of the receiving waters. A description of experiments with the above food chains and preliminary results with some alternative approaches are discussed, including a detailed account of the nitrogen mass balance through all of the components of one of the experimental systems.

Chemical and biochemical oxygen demands were measured in the feeds used and in the inlet-outlet water at some freshwater trout farms. The oxygen consuming potential of 1 kg feed corresponded to 5–10 population equivalents. The biochemical oxidation rate during 10 days of the “net loading” (BOD outlet-BOD inlet) was equal to that of sewage. Characterizing the organic loadings from fish farms in terms of population equivalants therefore seems proper. The regression of COD on BOD 7 was also calculated.

The literature on late-stage larval and puerulus settlement of tropical spiny lobsters suggests that a broad range of visually-assessed variables may play a role in the selection of settlement substrates. These variables include light level, luminosity, degree of exposure, and the availability of edges, crevices and clefts. A fishery has developed in Indonesia, that captures pueruli for grow-out purposes, along the entire southern coastline from Java to Sumbawa. The present study builds on knowledge gained on the behaviour and substrate preferences of settling pueruli by examining aspects of collector design and substrate surface characteristics in regard to catch rates. A series of tank-based experiments were used to examine preferences for various attributes of collector materials, and preferred material characteristics were then tested in a field experiment to verify the laboratory results. In the tank experiment the most preferred substrate was cement bag paper, followed by insect mesh, weed netting, PVC rubber and cement bag plastic. Crevice angles of 10° and 20° were significantly preferred over 30°. The substrate level and other substrates had less influence on settlement. However, both the lunar phase and type of materials tested in the field had a significant effect on settlement. Significantly greater numbers of pueruli were caught at the time of the new moon than at other moon phases. Cement bag paper was the most preferred material in the field, followed by cement bag plastic, insect mesh, weed fabric, and PVC rubber.

International audience; The Thau lagoon, located at the South of France, provides 10% of the French pacific oyster Crassostrea gigas production. Despite this intensive shellfish production, the larval recruitment of this species within the Thau lagoon is still misunderstood and spat collection remains highly variable; as a consequence, shellfish farmers rely mostly on hatchery”s spat. The present study aimed to describe reproduction features of C. gigas within the Mediterranean, as well as to explore spawning triggers of this species. To achieve this goal, the reproduction cycle from gametogenesis to spawning was followed during two years in several locations within the Mediterranean Thau lagoon. The spawning behavior of C. gigas within the Thau lagoon appeared to be slightly different from the one of the Atlantic Coast, showing several spawning events from June to October. The minimal temperature for massive spawning was 23 °C, which is much higher than temperatures mentioned in the literature for this species. A strong relationship was found between phytoplankton communities and gametogenesis, the latter being improved by a higher diatom/dinoflagellate ratio. Temperature was insufficient alone to explain spawning, highlighting other potential triggers such as the moon or lightning strikes. We made the hypothesis of a hierarchy of events triggering spawning, encompassing locking, synchrony and intensifying triggers. Statement of relevance This paper is filling in a gap in the literature regarding to reproduction of C. gigas in the Thau lagoon, which is always associated to temperature. However, temperature may not be the only factor involved in oyster reproduction, that is what we tried to show in this paper.

This paper provides the first continuous assessment of behavioural quiescence in Eastern oysters (Crassostrea virginica) overwintered at their northernmost (48°N) distribution range. The paper also describes how quiescent oysters respond to sediment burial, which may occur inadvertently when cultured stocks are lowered onto soft-sediment seabeds. Long term monitoring of valve opening indicated that quiescence persisted for 164.9 ± 1.8 days (mean ± SE, n = 14 oysters) in 2014–2015. Quiescence was initiated in mid-November 2014 when the water temperature fell to 2.7 ± 0.2 °C and ended in early May 2015 when the water temperature rose to 4.4 ± 0.4 °C. The low mortality rate (3.4 ± 1.9%) of the control groups indicated that this species is well-adapted to such overwintering conditions. When buried in late October, oysters initially exhibited low-amplitude and sporadic shell movements, possibly in an attempt to clear the sediment covering their valve margins. Following a period of quiescence, behavioural morbidity ensued, with lethargic opening of valves beginning 153.3 ± 9.9 days after burial (n = 16 oysters). Death occurred 186.5 ± 3.6 days following burial (n = 16 oysters). Removing buried quiescent oysters from the sediment in late winter accelerated the depletion of energy reserves, particularly lipids and proteins, thereby advancing death. In conclusion, detrimental health effects associated with the burial of oysters in autumn cannot be mitigated through winter or spring desiltation. Thus, reducing the risk of burial by avoiding soft estuarine sediment whenever possible remains the best husbandry practice.

Rainbow trout is one of the promising cultivable fish species in coldwater and has enormous scope for its expansion in the Himalayan region. Being a low volume high value commodity, the trout has good potential for domestic consumptions as well as foreign export. In spite of having excellent positive traits and prosperity, the development and expansion of trout farming in Himalayas has yet to be intensified for large-scale productions. There are enormous aquatic resources in the form of river, reservoirs and lakes in the Himalayan region yet agricultural production of trout is very limited. This paper presents the available trout production system, available infrastructure and production trend highlighting the need of improved feed, infrastructure, improved strain, application of triploid trout production for stocking in cages and pens and also the possibilities of organic trout farming so as to clinch the production intensification, environmental management and trout promotion objectives. Based on 15 years experience of trout culture in India, potential success in trout production could be acquired through technological modernization, better governance and significant improvement in the management practices. The knowledge needed to form a comprehensive trout-farming ecosystem beyond farm activities has been suggested in this paper which will be useful not only to the country but also to the transboundary Himalayan region where trout farming is still rudimentary.

The Nan'ao Golden Scallop discussed in this paper is a new breed of noble scallop, Chlamys nobilis, produced by four generations of genetic breeding selections and two generations of culture demonstrations. Performed for the first time at Shantou University, the genetic breeding program was motivated by the need to reduce vulnerability and improve the adaptive capacity of noble scallops to the dynamic environment. This paper reviews the scientific evidences on aquaculture advantages of Nan'ao Golden Scallop, and identifies gaps in knowledge that require further research. From the analysis of published data, it is obvious that Nan'ao Golden Scallop is more nutritious and less susceptible to stress than common brown scallops. The high TCC of Nan'ao Golden Scallop up-regulate the expression of various immune related genes under stressful conditions. Since molluscs do not possess specific immunity, the information in this paper is very useful for improving the aquaculture performance of molluscs by selective breeding techniques.

The aim of the present study was to investigate retention of pigments and composition of fatty acids (FA) in farmed organic- and conventional Atlantic salmon fed commercial feed adapted to organic and conventional salmon farming, respectively. Moreover, stability of pigments, FAs and color was investigated throughout the fillet shelf life. No significant differences were observed in fish weight between organic- and conventional salmon (5.44 and 5.40 kg, respectively). However, the average condition factor (Cf) was significantly lower in organic (1.00) as compared to conventional salmon (1.15). The fillet characteristics of the organic salmon investigated were; similar total content of muscle carotenoids, lower content of astaxanthin, more diverse composition of muscle carotenoids, higher contents of SFAs and PUFAs, lower contents of MUFAs and significantly darker appearance as compared to a conventional salmon. Only small differences were however found regarding stability of carotenoids, Vitamin E, FAs and color during 22 day ice storage. Hence, the pigment stability for both groups was regarded as good. Statement of relevance: • The paper compare today's production of organic- versus conventional farmed Atlantic salmon. • The paper investigates the retention and stability of carotenoids from the pigment source Panaferd-AX in Atlantic salmon and in salmon flesh during ice storage. • The paper investigates the effects of different carotenoid compositions and fatty acid profiles on the flesh color throughout the fillet shelf life. This is a submitted manuscript of an article published by Elsevier Ltd in Aquaculture, 12 September 2015.

The environmental effects of fish culture operations are important issues in Michigan as well as many other parts of the world. The State of Michigan Department of Natural Resources operates the Platte River State Fish Hatchery (PRSFH) located near Honor, Michigan (USA). This facility has a restrictive discharge permit that limits the input of phosphorus into the Platte River that subsequently drains into a downstream oligotrophic lake (Platte Lake). The permit has been violated on occasion in recent years. Hatchery managers and operators need to understand the cause of these violations and prevent them in the future; and at the same time meet production goals to satisfy fishery management objectives. This paper describes the development and application of models designed to quantitatively analyze these issues. First, a bioenergetic growth and consumption model is developed for juvenile coho ( Oncorhynchus kisutch ) and Chinook ( Oncorhynchus tshawytscha ) salmon to quantify the relationship between fish production and by-product phosphorus loads. Next, phosphorus mass balance equations are used to calculate the phosphorus discharge from the facility as a function of the by-product phosphorus load and the efficiency of various phosphorus removal equipment and processes. The accuracy and consistency of the energy and mass balance equations are verified using extensive measurements. The ability of the model to successfully match various aspects of system performance supports the contention that the bioenergetic modeling approach developed here can provide reliable estimates of salmonid growth and feed requirements for a variety of food compositions, rations, and temperatures. This capability, along with knowledge of the effectiveness of phosphorus removal equipment, forms the basis of a practical operational and management tool. An example of model utility is presented that analyzes the PRSFH phosphorus discharge and provides insights into why permit violations occurred in 2009 but not in 2010. The model demonstrates how to avoid food waste caused by over feeding, lower the food conversion ratio, and evaluate the effectiveness of phosphorus removal treatment processes. A steady-state version of the model can be used by managers to establish production goals that avoid future violations of the phosphorus discharge limits. Statement of relevance The environmental effects of fish culture operations are important issues in many parts of the world. This paper describes the development and application of models designed to quantitatively analyze the relationships among fish production, by-product phosphorus loads, and the phosphorus concentration of the discharge following treatment. The ability of the model to successfully match various aspects of system performance supports the contention that the bioenergetic modeling approach developed here can provide reliable estimates of salmonid growth and feed requirements for a variety of food compositions, rations, and temperatures. This capability, along with knowledge of the effectiveness of phosphorus removal equipment, forms the basis of a practical operational and management tool. The model demonstrates how to avoid food waste caused by over feeding, lower the food conversion ratio, and evaluate the effectiveness of phosphorus removal treatment processes. A steady-state version of the model can be used by managers to establish production goals that avoid future violations of the phosphorus discharge limits.

This paper reports on successful hatchery production of the winged pearl oyster, Pteria penguin, without the use of live micro-algae. Larval nutrition was provided by commercially available micro-algae concentrates, Instant Algae® (“Isochrysis 1800®” and “Pavlova 1800®”, Reed Mariculture Inc., San Jose, CA, USA). Larvae were first transferred to settlement tanks on day 17 when their mean antero-posterior measurement (APM) was 240.2 ± 8.6 μm. Approximately 6.4% of larvae survived to day 17 and more than 700,000 eyed pediveligers were transferred to settlement tanks between day 17 and day 25. Approximately 33,000 spat were harvested from spat collectors on day 105, representing a survival rate of 4.7% from the eyed pediveliger stage. Growth and development of larvae in this study were superior to those reported in a prior study that used a ternary live micro-algae diet to feed P. penguin larvae. Our results indicate that the products used in this study proved nutritious for P. penguin larvae and supported normal growth and development through settlement. The use of commercially available micro-algae concentrates as a replacement for live micro-algae in pearl oyster hatcheries supports development of simplified larval rearing protocols, without live micro-algae culture, that are more appropriate to Pacific island nations. Statement of relevance This paper reports for the first time on successful hatchery production of pearl oysters without the use of live micro-algae. Successful replacement of live micro-algae with commercially available micro-algae concentrates as a larval food source supports development of simpler, cheaper hatchery facilities, and larval rearing protocols that are more appropriate to Pacific island nations.

Spiny lobster farming is a feasible strategy to address increasing export demand currently not met by the capture fishery. However, farming currently relies on natural lobster seed availability, which in turn is limited by the fishers' lack of skill in catching and handling pueruli as well as applying suitable grow-out practises. In Indonesia, particularly on Lombok, a viable puerulus fishery has been established supporting a local grow-out industry. Anecdotal evidence suggests water depth may be an important factor for the effectiveness of collecting equipment. This paper reports on an experiment that examined the effect of depth and trap type on the effectiveness of puerulus collectors at the end of the wet season, when pueruli abundance is greatest. Four trap types were deployed at 5 depths: i) 1 m below surface; ii) 2 m below surface; iii) middle of the water column; iv) 1 m above the sea floor; and v) touching the sea floor, with 6 replicates of each. The data were analysed to identify the effect of depth and trap type using a two-way ANOVA. Significant differences for depth and trap type were found for the primary species caught, Panulirus homarus and Panulirus ornatus . The greatest catch of P. homarus was on the sea floor using a cement paper trap. For P. ornatus catch rate was less strongly correlated with a specific depth or trap type, although catch was highest at or near the sea floor in cement paper traps.

Mulloway is an Indo‐West Pacific sciaenid fish with a short history of commercial culture in Australia. In January 2005, a harvest sample of these fish cultured off South Australia was observed macroscopically with large numbers of a blood‐feeding polyopisthocotylean. Epizootics of this parasite may pose a threat to the economics of farming this species, since it appears to be associated with anemia, as indicated by pale gills. Based on morphological characters, we identify the monogenean as Sciaenacotyle sciaenicola [Murray, F.V., 1932. Correction: note on a microcotylid from Sciaena antarctica. Parasitology 24, 448.] Mamaev [Mamaev, Yu.L., 1989. On species composition and morphological features of theMicrocotyle genus (Microcotylidae,Monogenoidea). In: Lebedev, B.I. (Ed.), Investigations in Parasitology. Collection of Papers. DBNTs AN SSSR: Vladivostok, pp. 32–38 [In Russian].]. Maximum likelihood analysis of ITS2 rDNA confirms that the genus Sciaenacotyle is not closely related to two other microcotylid genera also known from sciaenid fishes: Diplostamenides (represented by D. sciaenae (Goto, 1894) Mamaev [Mamaev, Yu.L., 1989. On species composition and morphological features of the Microcotyle genus (Microcotylidae, Monogenoidea). In: Lebedev, B.I. (Ed.), Investigations in Parasitology. Collection of Papers. DBNTs AN SSSR: Vladivostok, pp. 32–38 [In Russian].] from white croaker, Pennahia argentata, in Japan) and Anchoromicrocotyle (represented by A. guaymensis [Bravo‐Hollis, M., 1981. Helminths of fish of the Mexican Pacific. XXXVI. A new genus and subfamily of the familyMicrocotylidae Taschenberg, 1879 emended. An. Inst. Cienc. Mar Limnol. Univ. Nac. Auton. Mex. 8, 305–313.] from white seabass, Atractoscion nobilis, in California). In more intensive sampling of gills, we detected two other species of metazoan parasites, the monopisthocotylean Calceostoma glandulosum Johnston et Tiegs, 1922; and a copepod we identify as Caligus cf. elongatus, a sea louse very similar to C. elongatus Nordmann (1832), which affects farmed salmonids in the North Atlantic. Praziquantel bath treatment at an initial concentration that removed S. sciaenicola from mulloway gills did not remove C. glandulosum.

Studies on the nutritional requirements of fingerlings and juvenile fish (a few grams to 50 g of body weight) were initiated in the 1960s. The main nutritional requirements of certain freshwater fish were clarified during the first half of the 1980s. Since the early 1990s, the focus has been on marine fish larvae. It has been thought that the definite nutritional requirements of the young and adult stages of fish could be directly applied to the larvae. Many differences, however, have been observed in the nutritional requirements of larval marine finfish (less than 1 g) using live foods. In this paper, the characteristics of nutritional requirements during the early life stage of marine finfish are presented together with the development of live food in Japan. The following aspects are covered in this paper: 1. Taurine requirements of juvenile Japanese flounder, Paralichthys olivaceus; 2. Negative effects of vitamins A and D and their related compounds on larval Japanese flounder, P. olivaceus; 3. Nutritional effects of docosahexaenoic and eicosapentaenoic acids on behavior of larval yellowtail, Seriola quinqueradiata; 4. Enrichment material developed for certain live foods; 5. New types of a microparticle diet developed for larval red sea bream, Pagrus major.

Four-month-old juvenile Tridacna gigas were placed in plastic bags and exposed to pure oxygen in combination with four treatments: seawater, seawater+antibiotic, wet paper toweling (below clams), wet paper toweling (above and below clams). The only treatment which had high survival (98.5%) after 30 h application was seawater+antibiotic (streptomycin sulphate, 25 ppm). Desiccation as a cause of death was apparent, especially in smaller size classes in other treatments. A shipment of 5000 5.5-month T. gigas juveniles was sent to Fiji Fisheries. Despite a 40-h period from packing to reimmersing clams, survival was 64% after 4 days of reimmersion in the quarantine system in Fiji.

Fishery and aquaculture sectors use blockchains to enhance traceability and transparency in value chains and to fight illegal, unreported, and unregulated fishing. The aim of this paper is to provide the current status and future prospects of blockchain application in worldwide fisheries and aquaculture. A literature review was conducted using blockchain and global value chain frameworks. Results indicate that generally, the use of blockchain is vertically driven by the requirements of markets and business competitiveness. The majority of the blockchain use cases are for traceability and storytelling, and to a lesser extent for payments or incentives. Moreover, there has been limited use cases of blockchain at horizontal level, such as decentralized finance (de-fi), enabling fishers to gain capital access and entering global markets. Overall, enhancing the adoption of blockchain should address suitability, incentives, and trust factors in using blockchain. As future prospects, projects in fishery and aquaculture could better utilize the full potential of blockchains by (1) incorporating financing, capital, and insurance through de-fi solutions, (2) providing tangible incentives, and (3) using automation such as Internet-of-Things (IoT) in data collection to improve quality and trust in data.

A marine parasite on an anadromous host has a unique transmission challenge. It must infect a subsequent generation (or an alternate host species) prior to its current host's entry into freshwater, where the parasite (and often its host) will die. The salmon louse, a salmonidspecific parasite, faces just such a problem, and we would expect this species to have evolved a strategy to maximize transmission during the limited window of opportunity when incoming adults and outmigrating juveniles (or alternate hosts) are present in an area simultaneously. In their 2007paper “A proposed life historystrategy for the salmon louse, Lepeophtheirus salmonis in the subarctic Pacific”, Beamish et al. (hereafter BEA) hypothesize a strategy enabling sea lice to solve this problem. The data in this paper are interesting in showing that adult Pacific salmon carry salmon lice into the coastal environment during their migration and overlap with juveniles in the late summer (August). Although these data confirm anecdotal evidence of the presence of sea lice on adult salmon in the marine coastal environment, something known to all fishermen, we argue that BEA's hypothesis is fundamentally flawed and their paper invites misleading citation. BEA use incorrect terminology and vague definitions, and omit important literature while arriving at highly speculative and, in our opinion, inappropriate conclusions.

Several papers have reported on the development of antibiotic resistance and implications for human medicine but fewer deal with environmental impacts of antibiotic use. Marine sea cage aquaculture ...

The supply chain for salmon is, in many respects, the world's most efficient seafood supply chain. Adopting new technologies and expanding the scale of production have improved competitiveness leading to increased production and industry growth. The transfer of knowledge and processes from other food producing industries has facilitated growth in salmon aquaculture in particular, and in aquaculture in general. As such, the maturity of the salmon industry relative to other food producing industries can provide indications of further growth potential. We argue that the salmon industry still has much to learn from similar processes in other food-growing industries. Notably, the production and processing of poultry has experienced significant increases since the 1940s, becoming the fastest growing and most rapidly changing highly-intensive livestock farming segment, with often fully-automated processing environments. Although farmed salmon has a production history closely following that of poultry, it remains semi-automated with less control over production processes and a more limited product specter than poultry. While this gives important avenues of growth for salmon, it holds even more potential for other aquaculture species with even less control over the production processes and supply chain. Statement of relevance Innovations leading to productivity growth and improved competitiveness throughout the supply chain have been key to the development of successful aquaculture industries. To a large extent, innovations have built on knowledge from the agrosciences. In this paper we compare the development of salmon aquaculture, one of the most sophisticated aquaculture industries with chicken, one of the most sophisticated terrestrial animal production industries. This sheds new light on the development of salmon aquaculture and it show that there is s large knowledge potential still to be tapped form chicken production, giving substantial promise of further development.

This paper reports a case of natural co-infection of Tilapia Lake Virus (TiLV) and Aeromonas veronii in a Malaysian red hybrid tilapia (Oreochromis niloticus × O. mossambicus) farm. In May 2017, a tilapia farm operator reported a mass mortality among cultured red hybrid tilapia juveniles, approximately 45 days after introduction into earthen ponds. Affected fish showed lethargy, loss of appetite, swim near the pond edge, pale and isolated from schooling group. There were skin redness and haemorrhages, particularly at the operculum area and at the base of dorsal, caudal and anal fins. Histopathological examinations revealed swollen hepatocytes, haemorrhagic spleens and perivascular cuffing consisted of mononuclear cells in the brains. PCR and sequence analyses confirmed the presence of TiLV and A. veronii in the diseased fish. Phylogenetic tree revealed that Malaysian's TiLV strain was more closely related with the virus isolated in Israel than in Egypt or Thailand, while Malaysian's A. veronii strain 5L was closely related with strains from China. TiLV infection is a significant threat to global tilapia industry. However, synergistic co-infection of TiLV and other bacterial might aggravate the problem.

The total water use (TWU) and consumptive water use index (CWUI) in carp polyculture under varying intensity levels [T 1 : 6000 fingerlings ha − 1 , T 2 : 8000 fingerlings ha − 1 , T 3 : 10,000 fingerlings ha − 1 ] were quantified. Treatment-wise estimated TWU was 3.71 × 10 4 , 3.92 × 10 4 and 4.34 × 10 4 m 3 ha − 1 180 d − 1 while, the CWUI was 6.38, 5.61 and 5.89 m 3 kg − 1 fish production in T 1 , T 2 and T 3 , respectively. The estimated evaporation and seepage loss ranged between 2.1–3.1 and 1.9–2.8 m 3 water kg − 1 fish production respectively and contributed significantly to consumptive water use (CWU). Treatment-wise sediment load ranged between 57.1 and 61.1 m 3 t − 1 fish biomass. Faster growth rate and biomass contribution (%) to yield was maximum by C. catla followed by C. mrigala and L. rohita in all the treatments. In this study, under best management practice (T 2 ), 1 m 3 of water produced 178 g of carp biomass and its economic value per unit of water used (USD m − 3 ) greatly exceeds that of T 1 and T 3 . Among the treatments, minimization of total water use (3.92 × 10 4 m 3 ), CWU (2.03 × 10 4 m 3 ) and water exchange (0.20 × 10 4 m 3 ) at stocking density of 8000 fingerlings ha − 1 (T 2 ), resulted in higher ( P − 1 180 d − 1 ), output value - cost of cultivation ratio (1.88), net consumptive water productivity (USD 0.15 m − 3 ) and lower AFCR (1.74). Further, farming systems with low water exchange, serves to keep the water quality suitable for the fish growth, improves water use efficiency and helps in minimizing the quantity of pollutant outputs. Statement of relevance This paper presents findings and analysis, from a methodologically rigorous investigation and provides insight regarding density-dependent optimum water use, its effect on pond water quality, sedimentation rate, growth performance and water productivity. The knowledge derived from this study may be a basis to optimize pond rearing efforts in carp polyculture and the water management strategies can be tailored to prevent wasteful use of water and enhance water use efficiency and water productivity.

The integrated multi-trophic aquaculture (i.e., IMTA) is a practice combining organisms with different trophic levels with the final purpose of transforming the continuous waste of food by targeting species into nutrient input for other non-target species. This practice very often involves filter feeders, such as bivalves, by the use of which bioenergetics budgets are strongly influenced by the quality and quantity of different foods. However, to date, scant information is available, to really understand the rebounds of food availability on the growth performances of these harvested biomasses in the natural environment. By choosing the mussel Mytilus galloprovincialis as a model, this study aims to (1) characterize the functional response of the species to define all parameters related to food intake strategies and (2) to investigate how responses change as a function of varying food sources. Laboratory procedures have been designed to evaluate the clearance rates (CR) and assimilation efficiencies (AE) of M. galloprovincialis with varying food concentrations, while different diets (i.e., seagrass, phytoplankton, and pellets) have been provided to investigate how differently they reach saturation. Results show that in the presence of phytoplankton and seagrass as food sources, the feeding strategies of M. galloprovincialis follow a II-type Holling's curve, while it shows a I-type Holling's curve when pellet food is provided. Investigating the behavioural components of functional responses may improve our ability to predict where to place shellfish cultures, as it may be useful in the context of IMTA management and in addressing siting studies. Statement of relevance Our paper focuses on a question central to understanding and predicting the likely impacts of one among the most important human economic activity like the aquaculture in coastal habitats. The main question deals with the possibility to combine experimental procedures with the new mechanistic functional trait based bioenergetic models in order to effectively predict life history traits of cultivated species.

Tilapia production in most Southern African countries has remained low despite the high potential that exists. This sector is particularly important for inland countries. Government and donor driven programmes have largely failed to boost tilapia production in the last four decades in most Southern African countries. However, Zambia has experienced significant growth in tilapia production in recent years. In other Southern African countries namely, South Africa, Namibia, Botswana, Mozambique, Malawi, and Eswatini tilapia production has remained low. In this paper the physical, biological, and socio-economic factors that have affected tilapia production in the region are identified. Intervention measures are suggested. Economic factors, the choice of the tilapia species and the production system to be used were identified as the key factors affecting tilapia production in the region. The overriding factor affecting tilapia aquaculture production in Southern Africa is the lack of profitability. Tilapia culture is not profitable because of the cheaper wild caught tilapia and the Chinese imported tilapia. A paradigm shift in the way aquaculture is viewed is necessary. Instead of looking at aquaculture as a poverty alleviation tool it must be viewed as a business. A new approach in the training of fish farmers at a regional level is also suggested.

Farmed fish escaping into the wild and other environmental concerns have curbed the expansion of the Norwegian aquaculture industry. Detailed knowledge of both direct and underlying causes of previous escape episodes is crucial to ensure successful development of new technology and targeted safety-measures at fish farms. This paper provides detailed descriptions of both technological, human and organisational factors relevant to escape of fish from Norwegian fish farms during 2010–2018. Fish farmers in Norway are obliged by law to report escape incidents to the Norwegian Directorate of Fisheries. A total of 305 reported escape incidents with Atlantic salmon (Salmo salar) or rainbow trout (Oncorhynchus mykiss) were confirmed from 2010 to 2018, involving in total 1.960.000 registered escapees. Analysis of 298 of these incidents shows that most registered escapees came from sea-based fish farms (92%), while 7% were from land-based facilities and 1% from transportation between sites. Most escape incidents were directly caused by technological factors, with holes in the net as the most common cause of escape. Bad weather or handling of weights and net prior to delousing have been associated with increased probability of escape incidents. In addition to direct and contributing causes, mostly technological, escape incidents may also have underlying causes related to human and organisational factors. These causes may have triggered the incidents or prevented barriers from being effective, with technical damage and escape of fish as result. Relevant human and organisational causes were explored through interviews with employees that have experienced escape incidents.

The characteristic that enables mussels to settle on filamentous type substrates is exploited to supply seeds for mussel farming via spatfall on ropes. This produces a strong socio-economic impact, as it allows independent and micro-producers to participate directly in an activity that produces > 3 million tonnes annually worldwide. Despite the importance of this ecosystem service, there is no record of an association between the dynamics of natural beds and spatfall on ropes in literature published to date. This paper presents the case of Mytilus chilensis a species that dominates the inter-tidal and shallow sub-tidal communities in estuaries on the Chilean coast and part of the Argentine coast. Cultivation of this species in Chile produces about 240,000 tonnes annually. Our aim is to study the dynamics of natural M . chilensis beds in Reloncavi fjord, one of the most important areas for mussel spatfalls in Chile, and investigate their relationship with spatfall on collectors (ropes) installed by local producers. Veliger competent larvae were present in relative abundance during most of the breeding season, which was reflected in a high spatfall on ropes. However, this larval abundance resulted in low recruitment into the natural beds, suggesting a mismatch between larval supply and recruitment. Oversupply of artificial substrate can promote recruitment failures in natural beds, which can be a threat to the mussel farming industry. There is a risk that the search for a possible alternative to natural seed supply (e.g. seed production in the laboratory) to satisfy mussel farming requirements, may come into conflict with the principles of the Ecosystem Approach to Aquaculture; thus, management measures should be implemented, in order to ensure the long-term sustainability of this activity.

Since a couple of decades, coral aquaculture has been developed in many countries to face an increasing live coral market and to support conservation of endangered natural coral reefs. To evaluate the potentiality of community-based coral aquaculture in Madagascar, we experienced suitable farming techniques using the species Acropora nasuta and Seriatopora caliendrum . Survival and growth rate of the nubbins were monitored during wet, warm and dry, cold seasons. To determine economical feasibility, the coral market was investigated and the yields were also calculated using the technical, biological and social parameters of the production. Coral nubbins were reared in situ at appropriate conditions. Coral nubbins reared during the wet, warm season showed a final survival rate of 67 ± 6% and 57 ± 4% respectively for A. nasuta and S. caliendrum , while in the dry, cold season, the survival rates were of 85 ± 7% and 69 ± 1% respectively. A. nasuta had a significantly higher survival rate than S. caliendrum during both seasons. During the wet, warm season, growth rates were 0.46 ± 0.16% d − 1 and 0.54 ± 0.16% d − 1 respectively for A. nasuta and S. caliendrum . In the dry, cold season, A. nasuta had 0.63 ± 0.18% d − 1 of growth rate, while S. caliendrum grew 0.65 ± 0.15% d − 1 . Significant difference was observed between both species during the wet, warm season, but not during the dry, cold season. Furthermore, both species grew faster during the dry, cold season. These results are in the range of reference values for corals. The activity can be profitable from 25 coral nubbins sold per month. Profit can already be perceived from the second year and a total of more than EUR 27,000 earned after 5 years of developing project, for an initial investment of EUR 1978. Marine animals wholesale companies and biodiversity conservation NGOs seem to be the appropriate clients for this form of aquaculture on Madagascar. Statement of relevance This paper provides new form of coral aquaculture: the community-based coral aquaculture. The socially and environmentally responsible production of coral is among the benefits of this new economically viable form of aquaculture.

Land based aquaculture has the potential to mitigate future shortfalls of food fish supply in Solomon Islands. However, aquaculture is relatively new in the Pacific and such potential is hampered by a lack of aquaculture knowledge and practice within local cultures. A participatory action research approach was used to conduct on-farm trials with farmers in Solomon Islands to develop relevant and improved ways of farming and maximising productivity of the resident exotic tilapia Oreochromis mossambicus. During the 34 month period when the research was undertaken improvements were evident, through increased farmer participation and improved knowledge of farmers on pond design and fish husbandry techniques. One of the contributing factors to improved farmer understanding was the production of knowledge products which were co-developed with and based on the farmers' local context. Productivity of a typical 20–38 m2 pond ranged from 726 to 1819 kg ha− 1 year− 1. Because 80% of this production was consumed by households, such ponds, producing easily harvestable small tilapia, have a role in supplementing household diets and contributing to improved nutrition at the subsistence level. While pond system productivity reached levels equivalent to low input tilapia ponds in other regions, the resident tilapia in Solomon Islands has limited opportunity for more than low level commercial enterprises. Established ponds are included in the daily livelihood tasks of both men and women and explicitly gender equitable approaches to partnerships with pond farmers provide opportunities to further increase benefits to households. A participatory action research approach, and the principles embodied therein, is recommended for further development of household aquaculture enterprises, regardless of species, in Solomon Islands. Statement of relevance We feel that our paper makes significant and novel advance to the field of aquaculture by: (1) Presenting results of a research that shows the importance and potential role of aquaculture in mitigating food and nutrition security in locations where it is increasingly difficult to access fish based protein sources, even in a South Pacific location perceived to contain an abundance of fish. (2) Participatory Action Research (PAR) has been employed in agriculture and aquaculture in Asia and Africa in the last 20 years. We report in here the use of the PAR method within the Pacific Islands context in conducting research and developing aquaculture in a location where there is very little history of aquaculture within the local culture.

Production of the mola carplet (Amblypharyngodon mola), a small vitamin A rich fish, has the potential to reduce human malnutrition in Bangladesh. However, although efforts have been made to promote mola culture, the factors affecting its production are poorly understood. Therefore, this study was undertaken to identify factors contributing to mola productivity in polyculture systems. A total 177 farms in three sub-districts of Barisal district, Bangladesh, were surveyed. Production of carp was higher (P Statement of relevance This paper assesses the productivity of vitamin A rich mola carplet, farmed in polyculture with carp in Bangladesh, and identifies factors contributing to mola carplet productivity to support the design of attempts to promote mola culture in future.

In a field study, five different stocking densities ( i . e . 0, 30, 60, 90, 120 ind. net − 1 or 0, 2.46, 4.91, 7.37, 9.82 ind. m − 2 ) of adult green sea urchins ( Strongylocentrotus droebachiensis ) were randomly assigned to 30 predator-exclusion nets ( i . e . n = 6) around cultured mussels ( Mytilus spp.) to test the effect of urchin density on biofouling intensity (percent net occlusion) and urchin/mussel growth. After 174 days of culture, nets in all treatments containing sea urchins were significantly less fouled than those in the control treatment without urchins. Fouling intensities on nets with the two highest stocking densities of urchins (90 and 120 ind. net − 1 ) were approximately 40% less than that on nets with urchins held at the lowest stocking density (30 ind. net − 1 ) and 45% less than that on nets without urchins. The differences in fouling intensity among nets with 60, 90, and 120 ind. net − 1 were not statistically significant. While fouling was significantly reduced in the presence of urchins compared to the control treatment with no urchins, it was not completely eliminated since they were only able to access the inside surface of the nets. Sea urchin somatic and gonad growth declined with increasing stocking density, but there was no significant difference in mussel growth at the different urchin stocking densities. Mussels and sea urchins can be successfully co-cultured with no food input, but there may be a trade-off between the effectiveness of biofouling control and sea urchin growth. Statement of relevance This paper examined the use of sea urchins ( Strongylocentrotus droebachiensis ) to mitigate biofouling in mussel ( Mytilus spp.) aquaculture and the effect of sea urchin density on biofouling coverage and mussel growth. Treatments containing sea urchins showed significantly less fouling than a control treatment without urchins. Urchin density had no significant effect on mussel growth.

The use of triploid fish can potentially reduce two of the major obstacles in Atlantic cod aquaculture; early sexual maturation that causes reduced profitability, and avoiding introgression between farmed cod and native populations, by preventing spawning in the netpens or that escapees reproduce. Cod eggs were pressure treated to produce triploid fish. However, we observed that the pressure treatment produced a mixture of triploid and diploid individuals. The diploid and triploid fish were reared together; in a seawater pond during their larval and juvenile period, and in a commercial cod farm from juveniles to slaughter. Two experiments were performed on two separate year-classes of cod: in the first experiment, fish were reared under artificial continuous light, while in the second experiment the fish were reared under ambient light conditions. Triploid cod had lower gonadosomatic index at all measurements compared to the diploids. However, from a production point of view, triploidisation alone only slightly reduced the gonadosomatic index and had to be combined with traditionally employed artificial light in order to be effective. Triploid fish were generally lighter than the diploids, but this difference disappeared towards time-of-harvest in the year-class without artificial light, possibly because of the lower maturation rate among the triploids. The triploid fish had a higher incidence of skeletal deformities compared to the diploids. Statement of Relevance The use of sterile fish by means of triploidisation is a promising method to reduce sexual maturation and the same time eliminate potential interbreeding of escaped cod with wild cod. In this paper we compare growth, maturation and deformities between triploid and diploid cod reared in common garden under commercial condition.

New research is currently underway to explore the potential of macroalgae for the production of biofuels. Marine biofuels in general and macroalgae in particular, offer a number of advantages over terrestrial biofuels including reduced competition for freshwater resources and for land use. Sugars can be extracted from macroalgae and processed into biofuels by anaerobic digestion and fermentation. This process generates significant waste biomass, which, if used, could improve the economic sustainability of the biorefinery sector. Bivalves' aquaculture relies heavily on the production of unicellular algae to feed juvenile individuals and this can represent a bottleneck for the bivalve industry especially in locations where sunlight is limited. Previous research explored the use of macroalgae derived digestate as alternative or integrative feed for juvenile bivalves, exploiting the notion that organic particulate matter (detritus) is an integral part of this animal class natural diet. The prospect of using waste products from the emerging biorefinery industry to solve a bottleneck for aquaculture businesses and, by so doing, improving profitability of both, is an exciting one. In this paper we describe the main nutritional profiles (Protein, Lipid, Carbohydrates and Fatty acids) of the tested diets and investigate the potential for the use of a biorefinery a by-product as replacement option for bivalves' production, by benchmarking it against aquaculture industry standards (live microalgae and commercially available algae paste) and natural detritus constituted by farmed sea urchin digesta. Both the digestate and the natural detritus supported the survival and growth of bivalve spat, especially when used at 50% inclusion rate, over the course of 4-week preliminary trials. Data suggest that a synergistic effect of the nutritional profiles of the diets employed may underpin the observed results. Statement of relevance With this study we compare the biochemical composition and suitability as oyster feed of the Single Cell Detritus produced by S. latissima enzymatic saccharification and natural detritus produced by sea urchin digestive action, with live microalgae as well as commercial algae paste. A comparison between biochemical composition and suitability as aquaculture feed between biorefinery by-products and natural detritus was, to our knowledge, lacking. Results indicate that both the digestate and the natural detritus supported the survival and growth of oyster spat, especially when used at 50% inclusion rate, over the course of 4-weeks trial.

The aim of this study was to test the efficacy of a new marine P ingredient from the bone fraction of herring by-products by evaluating the dietary impacts on growth, mineralization and skeletal development in Atlantic salmon fry. Five experimental diets were produced from a fish meal based diet, only differing in the dietary P source and level; low P control (5.5 g/kg soluble P), intermediate P (6.5 g/kg soluble P) and high P (8.0 g/kg soluble P) from either fish bone hydrolysate (FBH1, FBH2) or from NaH 2 PO 4 (NaP1, NaP2). The diets were given for 168 days from start of feeding (0.17 g fish) until 24 weeks of feeding (33 g). Weight and specific growth rate did not reveal diet dependent differences except in the initial 10 week feeding period where fish fed FBH1 showed lower growth as compared to fish fed the Na–P diets. Mineralization of fish evaluated by whole body and bone ash and mineral contents showed diet dependent differences that were related to dietary P level, but not to P source. Fish fed the low P diet showed clear P deficiency signs with significantly reduced tissue ash and mineral content, reduced whole body Ca:P ratio and morphological deviation from the normal. Histological evaluation of the vertebrae after 19 weeks of feeding (15 g) revealed stagnation in cartilage development, with accumulation of mature chondrocytes in fish fed low P control and FBH1 diet. FTIR showed that fish fed FBH1 had lower mineralization and increased cross binding in the vertebral end plates. Fish fed FBH2 resembled the positive NaP1 control. Real time qPCR analyses confirmed the histological results, by showing up-regulating of col10a1 (a marker for mature cartilage) in fish fed low P diet and FBH1. Osteocalcin (a marker for mineralization) was also activated in fish fed the low P diet and FBH1, possibly indicating a compensatory regulation in response to inadequate P. The dietary impacts on histology, FTIR and qPCR analyses in the FBH1 fed fish disappeared at 24 weeks of feeding (33 g). In conclusion, the results showed that P solubilized from bone fraction of herring can be efficiently utilized for growth, mineralization and bone development in Atlantic salmon fry. However, in the initial weeks of feeding, the FBH was a less efficient P source compared to NaP. Overall, the data suggest that P from fish bone hydrolysate is more suited for fish of minimum 15 g size. Statement of relevance The phosphate (P) rock reserve is a limited resource worldwide. Increased efficiency in the utilization of P and improved recycling of P from waste and manures are examples that could reduce the industry's vulnerability to the limited P supply while also reducing the negative environmental impacts. Recycling of P from fishery offal and development of new available P ingredients to farmed fish will significantly improve the sustainability of the aquaculture industry and reduce the environmental loss. In this paper we show that P hydrolysed from herring bone by-product is as efficient and good for salmon fry as commercially available NaP-salts.

Calanoid copepods from the genus Acartia are well studied because they are promising live feeds in marine larviculture. Several Acartia spp. are adapted to the occurrence of sudden unfavorable environmental conditions and can arrest their embryogenesis by entering quiescence. This trait can be used practically for establishing an egg bank, where embryos can be kept alive and hatched at a later time. The stored embryos can be shipped to end-users and the hatched nauplii used directly as live feed as well as they can be used to establish new copepod cultures. Acartia tonsa (Dana) is a cosmopolite and therefore an obvious candidate for being mass produced centrally at specific offsite installations, transferred and used worldwide. Moreover embryos from other species from this genus are shown in the present paper to have similar capacities in terms of survival in cold storage. To avoid the transfer of exogenous species in new environments, it is recommended to cultivate regional or even local species of copepods. In the present contribution we compare the cold storage capacity of embryos produced by seven strains of Acartia spp. isolated from different zoogeographical regions ranging from Northern Europe to the subtropical USA and tropical Asia. Our results showed that cold storage capacity of embryos is very dependent on egg size. The longest storage capacity, with egg hatching success > 50% is demonstrated for embryos originating from temperate European waters and in particular from Adriatic Mediterranean and Baltic Sea waters (240 and 150 days, respectively) while the shortest storage capacities were found from species from sub-tropical Mexican Gulf, USA (10 days). Higher survival has a tendency to correlate with larger egg biovolume. However, we cannot exclude a possible and unknown unidirectional selection for embryo storage tolerance caused by the management practice in long term continuous cultures. We conclude that the studied embryos from the genus Acartia can all be stored for different time periods and hence are relevant for being used as regional/local egg banks and further studies for developing future live feed items. Statement of relevance We consider calanoid copepod live feed products as a valuable supplement or alternative source for hatcheries. This is due to the fact that by introducing copepod nauplii as first feed items more fish species with small mouth gapes will be cultivated. Copepod organisms cannot be shipped due to the fact that they are fragile organisms. However, their embryos in a cold storage situation enter arrested development that lasts viable for months. We investigate seven strains of Acartia spp. embryos for their capabilities to be cold stored and conclude that all strains have that capability. This is considered promising for future mass production of calanoids for the benefit of the industry.

The aim of this study was to determine biofloc contributions to the antioxidant status and lipid nutrition of broodstock of Litopenaeus stylirostris in relationship with their reproductive performance and the health of larvae produced. Shrimp broodstock reared with BioFloc Technology (BFT) compared to Clear Water (CW) exhibited a higher health status with (i) a better final survival rate during the reproduction period (52.6% in CW against 79.8% in BFT); (ii) higher glutathione level (GSH) and total antioxidant status (TAS); (iii) reduced oxidized/reduced glutathione ratio; and (iv) a higher spawning rate and frequency as well as higher gonado-somatic index and number of spawned eggs. Finally, larvae from broodstock from BFT exhibited higher survival rates at the Zoe 2 (+ 37%) and Post Larvae 1 (+ 51%) stages when compared with those from females from CW treatment. The improved reproductive performance of the broodstock and higher larvae survival rate resulting from BFT treatment may be linked to the dietary supplement obtained by the shrimp from natural productivity during BFT rearing. Indeed, our study confirms that biofloc particulates represent a potential source of dietary glutathione and a significant source of lipids, particularly essential phospholipids and n − 3 highly unsaturated fatty acids (HUFAs) for shrimps. Thus, broodstock from BFT treatment accumulated phospholipids, n − 3 HUFA and arachidonic acid, which are necessary for vitellogenesis, embryogenesis and pre-feeding larval development. The predominant essential fatty acids, arachidonic acid (ARA), eicopentaenoic acid (EPA) and docosahexaenoic acid (DHA), had levels in the eggs that were, respectively, 2.5, 2.8 and 3 fold higher for BFT compared to the CW treatment. Statement of relevance Today, the influence of biofloc technology on shrimp broodstock is not described enough and no information was available on the larvae quality. Moreover, two key pieces of new information emerge from the present study. Firstly, biofloc is a source of further dietary lipids that can act as energetic substrates, but also as a source of phospholipids and essential fatty acids necessary to sustain reproduction, embryonic and larval development. Second, improving the reproduction of the broodstock also leads to an improvement in the quality of the larvae. We think that our research is new and important to increase knowledge on biofloc topic. We believe that the paper will contribute to the development of more efficient and therefore more sustainable systems.

The aim of this study was to investigate the effect of live transport of rainbow trout and subsequent live storage in an outlet aquarium on water quality, animal welfare and stress. A total of 40 fish were sampled at the following steps in the process: (1) at the raceway before transport, (2) after transport (arrival at fish outlet), (3) 24 h after fish were transferred to outlet aquarium (market), and finally, (4) after 48 h storage in the aquarium. Blood samples were collected from 10 fish at each stage and the levels of plasma cortisol, electrolytes (Na ⁺, K ⁺, Clˉ), and whole blood lactate were assessed. Twitch ability, initial pH, and temperature were assessed in white muscle. Respiration rate and swimming behavior were also assessed while the fish were kept in the outlet. Water quality (temperature, pH, dissolved oxygen, total ammonium nitrogen, total organic carbon, alkalinity and color) were assessed along with all stress measurements. Compared with fish at the farm, live transport, including effects of loading and unloading, represented the main stressor in our study. Heavy oxygen supersaturation, possibly along with elevated levels of carbon dioxide during transport contributed to this result. Despite sub-optimal water quality and excessive respiration rates, the fish in the aquarium seemed to slowly recover after transport. To reduce the effects of stress and improve animal welfare, it is suggested to minimize air exposure time and to avoid exposing the fish to supersaturated and sub-optimal levels of dissolved oxygen. Statement of relevance In a European context, selling live salmonids in the market is unusual. In this way, the highest possible freshness can be assured. However, live transport in closed systems and the live storage in fish outlets can imply risks related to compromised animal welfare and excessive stress as well as possible mortalities. In the present MS we looked into the how present handling routines and water quality affected the fish (behavior, stress and welfare). Possible improvements of present routines are discussed. We are not familiar with other published papers covering such a value chain for salmonids.

Donkey's ear abalone (Haliotis asinina) is a gourmet seafood export of the Philippines but its wild stock is at risk due to high fishing pressure. This paper aims to show evidences that abalone seeds produced in hatcheries can be used to rehabilitate its fisheries in multi-use buffer zones of marine reserves. This study released hatchery-reared abalone juveniles in a community-based resource enhancement site located in multi-use reef surrounding Molocaboc. This island is populated by fisherfolks who participated in protecting the 4000 m2 coralline release site. Molocaboc Reef comprise the buffer zone of Sagay Marine Reserve in Negros Occidental province in central Philippines. Data obtained during monthly monitoring of the release site from 2011 to 2016 showed that hatchery-reared abalone established together with its wild counterparts. Baseline wild abalone catch per unit effort (CPUE = 3 divers 1 h fishing) is 0.005/100 m2 in 2011. Mean monthly CPUE after release increased to 53 hatchery-reared and wild individuals combined. The mean shell length, body weight and body mass index of the hatchery-reared individuals (6.4 cm, 70.9 g, 10.5 g/cm) is not significantly different from those of the recovered wild stocks (6.9 cm, 85.0 g, 12.0 g/cm). The stocks recovered in the midst of undisrupted fishing activities in areas immediately outside and beyond the release site. Thus, mass production of seeds of overfished species is advised to repopulate degraded fisheries, improve catch of fisherfolks living within buffer areas of marine reserves and contribute to production and trade of high-value species.

This paper contains a bibliography of papers published on dietary and nutritional work with shrimps and prawns. In addition, selected papers on related topics, such as the nutrition of other crustacea, the natural food of shrimps and prawns, and physiology, are included. The bibliography is intended to be an aid to existing workers in the field of shrimp and prawn nutrition, to be a launch pad for scientists entering this field for the first time, and to assist those wishing to review specific aspects of this subject.

Phyllosomas of scyllarid lobsters are known to associate with jellyfish in the wild, suggesting that they prey on a wide variety of gelatinous zooplankton species. To investigate the potential of utilizing jellyfish as a diet for Ibacus ciliatus phyllosomas in culture, 22 newly hatched phyllosomas were reared individually and fed with the jellyfish Aurelia aurita and Chrysaora pacifica throughout the rearing period. Of the 18 phyllosomas that survived to stage VII, nine directly metamorphosed into the nisto stage 66.8 days (range: 65–70) after hatching. Among them, five nistos successfully molted into the juvenile stage 85.0 days (range: 83–87) after hatching. On the other hand, eight of the phyllosomas at stage VII molted through an extra instar. Four metamorphosed into the nisto stage 79.3 days (range: 76–82) after hatching; however, these nistos failed to molt into the juvenile stage. Significant differences of the body length between the phyllosomas with and without an extra instar were observed after stage V. The addition of an extra instar in phyllosomas at stage VII may have been caused by the insufficient nutritional conditions during the earlier stages. Complete larval development from hatching to the juvenile stage in I. ciliatus was observed for the first time. Our method of using jellyfish as diet may be useful for improving the aquaculture techniques of I. ciliatus , and other species. Statement of relevance Phyllosoma has been known as a gelatinous zooplankton feeder in the wild. The most important finding in the present paper is that phyllosomas of the scyllarid lobster I. ciliatus can grow into the juvenile stage with feeding on jellyfish. The previous studies have tried to rear I. ciliatus phyllosomas with feeding clams or mussels, and observed that phyllosomas successfully metamorphosed into the nisto stage. However, no one has achieved to obtain the juveniles in culture. We utilized jellyfish as diet for phyllosomas. Consequently, the complete larval development from the newly hatched phyllosoma to the juvenile stages was observed for the first time. Jellyfish has been successfully applied as diet for phyllosoma only in the scyllarid lobster Ibacus novemdentatus until today, so that the present experiment is the second successful achievement. This result suggests that growth and survival rates of scyllarid lobster phyllosoma may be improved by use of jellyfish as diet for phyllosoma in their hatchery. Although the nutrition level of the gelatinous zooplankton has been known to be low, survival and growth rates of phyllosoma which fed on gelatinous zooplankton have been higher than those of phyllosoma which fed on other diet containing much nutrition. Similar results have been obtained in several species of fish. Therefore, we emphasize in this manuscript that the utilization of jellyfish as a nutritional resource for the fish and crustacean aquaculture should be further studied. It is considered that the extra molting may be added under conditions where larvae are unable to obtain sufficient energy reserves for growth and metamorphosis. Such conditions are mainly caused by inadequate nutritional quality; however, there is limited information of the critical timing at which the addition of the extra molting is determined. In our experiments, significant differences of body length between the phyllosomas having an extra molting and the phyllosomas without extra molting were started to be observed during the early stage of phyllosomas. Our results suggest that, in decapod crustaceans, the mortality of decapodid and juvenile stages may be affected by insufficient energy reserves during the early larval stages.

A range of culture units and husbandry methods may be used for pearl oysters and the two most commonly used for Pinctada margaritifera are panel nets and chaplets. In this study, six hundred P. margaritifera were grafted for the first time and cultured using panel nets or chaplets at three commercial farm sites to determine if these different culture methods influences resulting pearl quality. The pearls produced were compared in terms of size, shape, lustre, colour, surface perfection and overall quality. The highest proportion of pearls produced in all treatments was in the 10–11 mm size category (37–54%) but culture method did not significantly (p = 0.211) influence the size of pearls produced. Oysters held on chaplets produced more pearls with concentric surface grooves or ‘circles’ (47–60%) compared to oysters in held panel nets (43–45%) at all three culture sites. Oysters held in panel nets produced higher proportions of pearls in the more desirable ‘round’ and ‘semi-round’ shape categories (6% and 25%, respectively) than oysters held on chaplets (5% and 15%, respectively) at all three culture sites, and culture method had a significant impact (p = 0.031) on pearl shape overall. Higher proportions of pearls in the ‘very high’ and ‘high’ lustre categories (8% and 40%, respectively) were produced by oysters held in panel nets compared to those on chaplets (3% and 16%, respectively) at each of the three culture sites. However, the overall impact of culture methods on pearl lustre was not significant (p = 0.100). At all three culture sites, higher proportions of pearls assigned to grades ‘A’ (6%) and ‘B’ (46%) were produced by oysters in panel nets compared to those held on chaplets where 3% and 29% of pearls were assigned to grade ‘A’ and grade ‘B’, respectively. Oysters held on chaplets produced higher proportions of grade ‘C’ (49%) and grade ‘D’ (19%) pearls than those in panel nets (39% and 9%, respectively) at all three culture sites. The grades of pearls were significantly influenced (p = 0.035) by culture method. This study clearly demonstrated the benefits of pearl production using panel nets compared to the traditional chaplet-based system used by the majority of pearl farmers in Fiji and throughout the Pacific. Pearls production using panel nets will provide better returns with higher profit margins for pearl farmers but requires greater outlay for infrastructure and labour that may be beyond the scope of most pearl farmers in Fiji and the Pacific. A detailed cost–benefit analysis of the two husbandry options would be beneficial to pearl farmers. Statement of relevance This paper presents novel new information showing that grafted P. margaritifera cultured using panel nets produced pearls with fewer ‘circles’ and of higher quality and value than oysters cultured using chaplets. The potential benefits to pearl farmers of pearl production using panel nets compared to the more traditional chaplet-based system are clear and the results of this study support improved pearl quality and income for pearl farmers in the Pacific.

The native tropical seaweed Kappaphycus alvarezii from the Indo-Pacific region has been introduced in many countries because it is the main source of raw material for the carrageenan industry. In Brazil, K. alvarezii aquaculture is allowed in 300 km of the southeastern coast. The aim of this study was to analyze the risk of invasion of this species along the entire Brazilian coast to design public policies and to minimize environmental risks associated with aquaculture. The risk analysis was based on: K. alvarezii suitability models (GARP and MAXENT), coral reef presence, substrate preferences for establishment, and the probability of occurrence of nine species of herbivores that are potential feeders. An invasibility index was created from these parameters and published data of field experiments were used for calibration. The maximum values of suitability corresponded to regions with low temperature ranges, low nitrate availability, high irradiance, and high salinity. Three invasion risk classes were established. The areas of high risk are the eastern and northeastern regions, where the main Atlantic coral reefs are found. This is a priority area for global marine conservation. K. alvarezii introduction is not recommended in this area and the cultivation of native species must be prioritized. The area of medium risk is mainly in the northern region, where local field scale experiments are recommended before widespread introduction. The area of low risk is the southeastern region, where K. alvarezii farming has been established since 2004 with no evidence of invasion. However, considering the high capacity of acclimation of this species, permanent monitoring is recommended, even in areas having a low risk of invasion. Statement of relevance We state the relevance of our paper in commercial aquaculture since we presented a consistent environmental risk analysis for K. alvarezii that according to FAO is the most cultivated seaweed in the world. Our aim is to contribute for development of sustainable seaweed aquaculture, subsiding data to minimize environmental risks associated with K. alvarezii introduction. This kind of analysis also can be adapted to other countries. Our results indicate safe areas to extend K. alvarezii cultivation, areas where the native seaweed should be cultivated and with those conclusions encouraging the expansion of the commercial seaweed aquaculture and highlight for high environmental risks in coral reef areas.

This paper describes a two-year study of spatial and temporal patterns and processes in the benthos in response to the removal of salmon cages from a sheltered coastal embayment, coupled with the simultaneous reintroduction of cages at an adjacent location. Significant recovery was evident at the fallowed site in the first six months; however, the macrofaunal assemblage remained impacted at the conclusion of the study. By comparison, the reintroduction of a fully operational farm overwhelmed the macrobenthic community within three months, with anoxic and near-azoic conditions developing. Both removal and reintroduction of the farms triggered alternating oscillations of geochemical and biological variables, which were attributed to effects on sediment chemistry from organic loading, ‘boom and bust’ cycles of opportunistic taxa in response to food supply, and the associated variations in metabolic potential. The study also revealed interesting spatial dynamics in the benthos and some useful indicators of different stages of recovery and re-impact. It is concluded that farm reintroductions should aim to gradually increase production; allowing time for the benthos to adapt to the additional organic flux, and be maintained at a level that avoids macrofaunal collapse. The sediment's ability to cope with organic inputs from fish farming, and hence the duration of the recovery period, is contingent on the organic load in each farming cycle and the extent to which the sediment community is allowed to recover. Understanding the influence of each of these on sediment processes is important for sustainable long-term management of farming operations.

Offshore production system is predicted to increase in the near future driven by the lack of coastal space and lower environmental impacts. The aim of this paper has been to evaluate the economic performance of offshore production system respect to inshore one, by comparing net present value (NPV), discounted payback time (DPBT) and internal rate of return (IRR) of two Italian mariculture farms that produce European sea bass. Results showed a better economic profitability of offshore farm, even if sensitivity analysis revealed that financial indicators of both aquaculture production systems have been very sensitive to market condition changes. So, offshore production system could represent an opportunity for fish farmers to increase their profitability, obtaining a more sustainable production and avoiding possible conflicts with other human activities in coastal areas.