Aquaculture

Environmental conditions can influence the physiology of marine organisms and have important implications for their reproductive performance and capacity to supply new recruits. This study examined the seasonal reproductive patterns of the coral Montipora capitata in habitats exposed to different sedimentation regimes. Although M. capitata is a main reef-building coral in the Hawaiian Archipelago, little is known about the gametogenic cycle and reproductive ecology of this important species. Our results indicate that gamete production in M. capitata is a resilient process; no differences in gamete development or fecundity were observed among sites with very different sedimentation regimes. The gametogenic cycle of M. capitata lasts between 10 and 11 months, with spawning occurring over 3-5 months during warmer months (May-September). Oocytes were found throughout the year, but spermatocysts were only found April-August. The largest increases in oocyte size occurred during February to May, the months when solar radiation increased rapidly. The largest variation in oocyte sizes was found during July and August; during this period individual colonies contained mature oocytes for immediate spawning and new oocytes being formed for spawning the next year. The capacity of M. capitata to reproduce in areas with high sedimentation is an interesting finding highlighting the potential of the species for acclimatization, adaptation, or both. Despite this optimistic finding, the management of terrestrial runoff and the restoration of habitat quality for corals remains a top priority to ensure the renewal and maintenance of coral populations.

Growth of several genetically improved Nile tilapia (GIFT or Genetically Improved Farmed Tilapia, FaST or Freshwater Aquaculture Center Selected Tilapia, SEAFDEC-selected) and domesticated red tilapia (BFS or Binangonan Freshwater Station, NIFI-red or National Inland Fisheries Institute red, HL or Hacienda Luisita) stocks were compared in controlled (tank) and uncontrolled farm conditions (lake-based cages) with unselected NIFI or Chitralada Nile tilapia as control. Specific growth rate differed significantly (P = 0.009) in tank-reared Nile tilapia stocks where GIFT grew best at 1.358%/ day followed by FaST (1.307%/day), control stock NIFI (1.257%/day) and SEAFDECselected (1.202%/day). Genetic effect explained 84.4% of the variance in growth of Nile tilapia in tanks. Although Nile tilapia growth in cages followed the same trend where GIFT grew best at 1.570%/day, no significant stock differences (P = 0.479) were noted. Meanwhile, red tilapia reared in either tanks or cages showed no significant stock differences in terms of growth. However, survival of the red tilapia stocks in cages differed significantly with HL having the highest percentage survival at 93.3%. The different growth responses of the Nile tilapia stocks especially under controlled (tank) farm conditions were largely due to genetic factors (stock differences).Under uncontrolled farm conditions, environmental factors were generally observed to have also affected the survival and to some extent, the growth of Asian Nile and red tilapia stocks.

Recirculating aquaculture systems may require an internal disinfection process to control population growth of pathogens and heterotrophic bacteria. Ozonation and ultraviolet (UV) irradiation are two technologies that have been used to treat relatively large aquaculture flows, including flows within freshwater systems that recirculate water. The objective of the present study was to evaluate the effectiveness of ozone application alone or ozone application followed by UV irradiation to reduce abundance of heterotrophic and total coliform bacteria in a water reuse system. Results indicate that when only ozone was applied at dosagesdefined by the product of the ozone concentration times the mean hydraulic residence time (Ct) -that ranged from 0.10 to 3.65 min mg/L, the total heterotrophic bacteria counts and total coliform bacteria counts in the water exiting the contact basin were reduced to, respectively, 3-12 cfu/mL (1.1-1.6 LOG 10 reduction) and 2-18 cfu/100 mL (1.9-3.1 LOG 10 reduction). Bacteria inactivation appeared to be just as effective at the lowest ozone ct dosage (i.e., 0.1 mg/L ozone after a 1 min contact time) as at the highest ozone ct dosage (i.e., 0.2 mg/L ozone after a 16.6 min contact time). As with our previous research on UV inactivation of bacteria, we hypothesize that the recirculating system provided a selection process that favors bacteria that embed within particulate matter or that form bacterial aggregates that provides shielding from oxidation. However, when ozonation was followed by UV irradiation, the total heterotrophic bacteria counts and total coliform bacteria counts in the water exiting the UV irradiation unit were reduced to, respectively, 0-4 cfu/mL (1.6-2.7 LOG 10 reduction) and 0-3 cfu/100 mL (2.5-4.3 LOG 10 reduction). Thus, combining ozone dosages of only 0.1-0.2 min mg/L with a UV irradiation dosage of approximately 50 mJ/cm 2 would consistently reduce bacteria counts to near zero. These findings were orders of magnitude lower than the bacteria counts measured in the system when it was operated without disinfection or with UV irradiation alone. These findings indicate that combining ozonation and UV irradiation can effectively disinfect recirculating water before it returns to the fish culture tank(s). #

Water column processes in undisturbed mangrove creeks and in creeks receiving effluent from shrimp farms in North Queensland, Australia, were studied. Small scale discharges into tidal creeks did not elevate dissolved nutrient concentrations compared with non-impacted creeks, but did elevate concentrations of particulate nutrients, chlorophyll and suspended solids proximal to the site of the effluent discharge. Rates of primary and bacterial production downstream from the discharge exceeded rates in the shrimp ponds because of the synergistic effects of turbulent mixing and eutrophication. In the lower reaches of the mangrove creeks and immediately offshore, standing stocks of particulate material and rates of primary and bacterial production were within the range of values found in non-discharge areas. Our results suggest that water column production by phytoplankton and bacteria strips nutrients from shrimp farm effluent and repackages them in more bioavailable forms.

The performance of Octopus bimaculoides juveniles from coastal areas of Baja California (Mexico) and reared in captivity was evaluated using Artemia salina as food source in three different treatments: Artemia enriched with either AlgaMac or Spirulina maxima and without enrichment. After 20 days, significant differences were found among treatments in terms of growth, which was significantly higher for juvenile fed AlgaMacenriched Artemia, followed by those fed unenriched Artemia. Moreover, far higher growth rates (0.74-0.88 mg day − 1 ) were obtained than those reported for other octopus species of the same size. Digestive enzyme activity during the experimental period (20 days) showed an oscillatory behavior, with a tendency to stabilize after day 15. Trypsin was the most important protease, though lipases and amylases were also present. The whole-body lipid content of the juvenile was apparently influenced by the lipid content in the food. The amino acid profile remained unaffected after juvenile were fed the different treatments; however, differences were found between the initial and final whole-body content of the juvenile, with relatively lower amounts of isoleucine, leucine and tyrosine, and relatively higher amounts of threonine, alanine and glycine after 20 days of feeding. The Artemia amino acid content of phenylalanine, isoleucine, leucine and valine was limited, and growth would likely be further promoted with a more suitable diet. Thus, O. bimaculoides is a promising species for commercial culture, and even though good results were obtained when fed Artemia, a more appropriate food source should be sought to obtain an amino acid profile that will maximize growth.

issues signals a clear warning for the future sustainability of this global industry. The linking together of global experts in the culture, capture and trading of crustaceans with pathologists, epidemiologists, ecologists, therapeutics specialists and policy makers in the field of food security will allow these issues to be better identified and addressed.

The objectives of this study were to determine the effects of the dietary docosahexaenoic acid (DHA) to arachidonic acid (ARA) ratio on the survival, growth, hypersaline stress resistance and tissue composition of black sea bass larvae raised from ¢rst feeding to metamorphic stages. Larvae were fed enriched rotifers Brachionus rotundiformis and Artemia nauplii containing two levels of DHA (0% and10% total fatty acids 5 TFA) in conjunction with three levels of ARA (0%, 3% and 6% TFA). On d24ph, larvae fed the 10:6 (DHA:ARA) treatment showed signi¢cantly (Po0.05) higher survival (62.3%) than larvae fed 0:0 (DHA:ARA) (27.4%). Notochord length and dry weight were also signi¢cantly (Po0.05) greater in the 10:6 (DHA:ARA) treatment (8.65 mm, 2.14 mg) than in the 0:0 (DHA:ARA) (7.7 mm, 1.65 mg) treatment. During hypersaline (65 g L À 1 ) challenge, no signi¢cant di¡erences (P40.05) were observed in the median survival time (ST50) between larvae fed 10% DHA (ST50 525.6 min) and larvae fed 0% DHA (ST50 518.2 min). The results suggested that black sea bass larvae fed prey containing 10% DHAwith increasing ARA within the range of 0^6% showed improved growth and survival from ¢rst feeding through metamorphic stages.

Viral haemorrhagic septicaemia virus (VHSV) has, in recent decades, been isolated from an increasing number of free-living marine fish species. So far, it has been isolated from at least 48 fish species from the northern hemisphere, including North America, Asia and Europe, and fifteen different species including herring, sprat, cod, Norway pout and flatfish from northern European waters. The high number of VHSV isolations from the Baltic Sea, Kattegat, Skagerrak, the North Sea and waters around Scotland indicate that the virus is endemic in these waters. The VHSV isolates originating from wild marine fish show no to low pathogenicity to rainbow trout and Atlantic salmon, although several are pathogenic for turbot. Marine VHSV isolates are so far serologically indistinguishable from freshwater isolates. Genotyping based on VHSV G- and N-genes reveals four groups indicating the geographical origin of the isolates, with one group representing traditional European freshwater isolates and isolates of north European marine origin, a second group of marine isolates from the Baltic Sea, a third group of isolates from the North Sea, and a group representing North American isolates. Examples of possible transfer of virus from free-living marine fish to farmed fish are discussed, as are measures to prevent introduction of VHSV from the marine environment to aquaculture.

The main objective of this work was the design of a high efficiency centrifugal surface aerator for fishponds. The proposed system has been designed to be used with photovoltaic panels as an energy supply. The work is presented in three papers, of which this is the first part. The objective was reached through a theoretical design of the rotor using the traditional mass transfer equations and the mechanical approach using the superficial similarities of aerators to axial flow pumps. A total of 23 different rotor configurations were tested. The configurations were defined by the type of propeller, the inlet and exit angles of the blades and the rotor's immersion percentage. Dimensional analyses was used to find the equations that describes the aerator's behavior.

Small-scale fisheries provide over half the world's wild-caught seafood, employ over 99% of its fishers, and are frequently promoted as a sustainable alternative to large-scale industrial fisheries. However, few studies have quantitatively examined how possible habitat impacts and non-target species composition vary across gears used in small-scale fisheries, as data are sparse and conservation efforts are largely focused on more iconic species. Here, we quantify and compare the ecosystem impacts of four fishing gears (lobster traps, fish traps, set gillnets, drift gillnets) used in small-scale fisheries of Baja California, Mexico, using at-sea observations and field experiments. Set gillnets had the highest overall impact on both non-target species and habitat, with discard rates higher than most industrial fisheries (34.3% by weight), and an estimated 19.2% of Eisenia arborea kelp and 16.8% of gorgonian corals damaged or removed within 1 m of the net path. Fish traps had the lowest discard rates (0.11%) while lobster traps and drift gillnets had intermediate discard rates (15.1% and 18.5% respectively). In contrast with gillnets, traps caused minimal immediate damage to gorgonian corals and rarely interacted with kelp. Results indicate that ecological impacts depend more on fishing gear type and habitat characteristics than the size of fishing vessels, calling into question broad generalizations that small-scale fisheries are inherently more sustainable than industrial fisheries. Our findings highlight the ecological impacts of artisanal gillnet fisheries as priorities for research, management, and conservation efforts in Baja California and other coastal areas.

Every sector of the livestock industry, the associated services and the wellbeing of both animals and humans are influenced by animal feeding. The availability of accurate, reliable and reproducible analytical data is imperative for proper feed formulation. Only reliable analysis can lead to the generation of sound scientific data. This document gives a comprehensive account of good laboratory practices, quality assurance procedures and examples of standard operating procedures as used in individual specialist laboratories. The adoption of these practices and procedures will assist laboratories in acquiring the recognition of competence required for certification or accreditation and will also enhance the quality of the data reported by feed analysis laboratories. In addition, ensuring good laboratory practices presented in the document will enhance the safety of the laboratory workers. The document will be useful for laboratory analysts, laboratory managers, research students and t...

The Kenyan aquaculture sector is broadly categorized into freshwater aquaculture and mariculture. Whereas freshwater aquaculture
has recorded significant progress over the last decade, the mariculture sector has yet to be fully exploited. The Kenyan
aquaculture industry has seen slow growth for decades until recently, when the government-funded Economic Stimulus Program
increased fish farming nationwide. Thus far, the program has facilitated the alleviation of poverty, spurred regional development,
and led to increased commercial thinking among Kenyan fish farmers. Indeed, national aquaculture production grew from 1,000
MT/y in 2000 (equivalent to 1% of national fish production) to 12,000 MT/y, representing 7% of the national harvest, in 2010. The
production is projected to hit 20,000 MT/y, representing 10% of total production and valued at USD 22.5 million over the next 5
years. The dominant aquaculture systems in Kenya include earthen and lined ponds, dams, and tanks distributed across the country.
The most commonly farmed fish species are Nile tilapia Oreochromis niloticus, which accounts for about 75% of production,
followed by African catfish Clarias gariepinus, which contributes about 21% of aquaculture production. Other species include
common carp Cyprinus carpio, rainbow trout Oncorhynchus mykiss, koi carp Cyprinus carpio carpio, and goldfish Carassius
auratus. Recently, Kenyan researchers have begun culturing native fish species such as Labeo victorianus and Labeo cylindricus
at the National Aquaculture Research Development and Training Centre in Sagana. Apart from limited knowledge of modern
aquaculture technology, the Kenyan aquaculture sector still suffers from an inadequate supply of certified quality seed fish and
feed, incomprehensive aquaculture policy, and low funding for research. Glaring opportunities in the Kenyan aquaculture industry
include the production of live fish food, e.g., Artemia, daphnia and rotifers, marine fish and shellfish larviculture; seaweed farming;
cage culture; integrated fish farming; culture of indigenous fish species; and investment in the fish feed industry.

This paper presents the design and construction of a smart and sustainable fish farm. The farm is based on the hybrid aquaculture concept that combines the advantages of the recirculation aquaculture system (RAS), the zero-water discharge (ZWD), and smart technology. The system’s smartness consists of using the latest technology, including monitoring and automation, ensuring zero water discharge, good water quality, reduced energy consumption, and high biosecurity. In addition, the system does not use chemicals in the aquaculture process. The paper describes the design of this system, including the hydraulic system, the smart monitoring system, the feeding regime, and the control of the biological parameters. Tests conducted in Tabuk, Saudi Arabia, showed high performance of this system with around 90% survival rate. In addition, observations showed the system’s capacity to maintain the water quality parameters within the optimal water quality ranges, reduce energy consumption, and ...

The Citarum River in West Java is the largest water supplier to the Saguling Dam, which plays a major role in electric power generation for the entire Java Island and is used for the aquaculture of marketed fish. To elucidate the extent of degradation in water quality and its causes in the Upper Citarum watershed, physical, chemical and biological parameters for water samples collected from various sites were analyzed. The results demonstrate large site-to-site variations in water qualities and pollutant loads derived from various human activities such as agriculture, cattle raising and the textile industry. To halt worsening conditions of the Citarum watershed, integrated mitigation efforts should be made, taking biophysical pollution mechanisms and local socioeconomic conditions into account.

The effects of stocking density of tilapia Oreochromis niloticus with the inclusion of silver carp Hypophthalmichthys molitrix were evaluated in the C/N-CP prawn Macrobrachium rosenbergii farming system in triplicate. Management practices were same for all treatments. Bamboo side shoots were posted vertically into the pond bottoms as a periphyton substrate. A locally formulated and prepared feed containing 15.44% crude protein with a C/N ratio 15 were applied twice daily in all ponds. Maize flour was supplied in water for raising the C/N ratio 20 in all treatments. Water quality parameters, except transparency and chlorophyll a, did not differ significantly (P > 0.05) among the treatments. The periphytic abundance and biomass differed significantly (P < 0.05) among the treatments and even among different months. Although the individual harvesting weight, individual weight gain, and SGR were significantly higher (P < 0.05) in the T 10000 treatment compared to T 15000 and T 20000 treatments, respectively, the gross and net yields of tilapia were significantly higher (P < 0.05) in the treatment T 20000 followed by T 15000 and T 10000 treatments resulting in higher combined gross and net yield of both prawn and tilapia (16.05 and 16.92%, 32 and 33.59% from the later two treatments, respectively) with a higher economic return (BCR 0.53) during a 122-day culture period. As a whole, the study revealed that prawn, tilapia, and silver carp with a stocking density at 30,000,

This paper proposes using a control function to correct for endogeneity in recreation demand models. The control function approach is contrasted with the method of alternative specific constants (ASCs), which has been cautiously promoted in the literature. As an application, we consider the case of travel cost endogeneity in the demand for Great Lakes recreational fishing. Using data on Michigan anglers, we employ a random utility model of site choice. We show that either ASCs or the control function can correct for travel cost endogeneity, although we find that the model with ASCs produces significantly weaker results. Overall, compared with traditional approaches control functions may offer a more flexible means to eliminate endogeneity in recreation demand models.

In the last years pejerrey culture has been developed in an intensive form using circular tanks. Employing this system is possible to obtain fish of commercial size but the production costs are high making this activity not profitable. An alternative to re-duce costs is to rear pejerrey employing a mix system using cages in natural lagoons and a posterior culture in tanks until commercial size (250g). In a first step, pejerrey fish hatched and reared for 25 days at IIB-INTECH aquaculture facilities were transferred to floating cages of 16 m3 (50 fish/m3) placed at Lacombe Lagoon (Chascomús County). Af-ter 11 months, and only eating natural food, these fish had a total length (TL) of 15 ± 0.19 cm and a weight of (W) 25.27 ± 1.5 g. During this period of time the mean sur-vival was 18 %. Then, 400 fish were transported to the IIB-INTECH and placed in an out-door tank of 20.000 liters with an open water flow system and a salinity of 15 g/L. They were fed twice a day to satiation with ar...

A theoretical model linking the production of salmon, mussels and seaweed in floating, enclosed units is based on field data, laboratory tests and literature data. First step is the production of 300 metric tons of salmon in 12 production units of 500 m3 each and a total water flow of 60 m3 min. . Using a standard high energy dry feed with a feed conversion factor of 1, a production of 300 metric tons of salmon is calculated to produce 15 metric tons of nitrogen (N) and 2 .4 metric tons of phosphate (P), of which 13 metric tons of N and 0 .7 metric tons of P are dissolved. Outlet water is transferred from the salmon units to 12 closed units (500 m3 each) with blue mussels. A standing stock of 112 .5 metric tons of mussels (WW) is necessary to filtrate 60 m3 min-'. If all particles are filtrated through the mussels, 25% of the nitrogen is accumulated as increased biomass. 25-30% is released as faeces and 45-50% as dissolved matter. Particles are removed by a sedimentation trap. Outlet water from the 12 mussel filter units, containing 13 .9 metric tons of dissolved N (0 .9 metric tons from the mussels), is transferred to closed units (1000 m 3) with seaweeds. Concentration of N is calculated to 0 .44 g N m_3 and hydraulic retention time in the seaweed production unit is 4 hours. With a DW of 20% (4% N of DW) and an estimated growth rate of 10% d-' during the production period, a standing stock of 45 metric tons (FW) of seaweed is theoretically needed to bind up all dissolved N from the salmon and mussel production .

Paphia malabarica is an important clam species, which has formed vast beds in the Kalbadevi estuary (Shirgaon creek) and Kajali estuary (Bhatye creek), Ratnagiri. They are exploited here commercially throughout the year for local as well as external markets due to the heavy demand. This study was undertaken to assess seasonal variations in the quality of the meat of clams by estimating the condition index and percentage edibility. Higher values were recorded during the monsoon (June–August). A rapid decline was observed in the edibility values from November onwards. Higher condition index and percentage edibility were recorded from June to November, indicating the high quality of clam meat.

A total 67 strains were isolated from five different stations of Aksu River. Total aerobic bacteria number in the river was determined as 2 x 10 7 CFU/mL and fecal coliforms were determined >1100 MPN/100 mL. Strains of Enterobacteriaceae (66 isolates), representative of the human and animal commensal flora, and Pseudomonas sp. (1 isolate) were selected for antibiotic susceptibility testing. Among the isolates, 67,2% were Escherichia coli, 29,8% Klebsiella spp., 1,5% Citrobacter spp., and 1,5% Pseudomonas spp. Eleven antibiotics (Meropenem, Cefoxitin, Ceftazidime, Ceftriaxone, Imipenem, Sulbactam/Cefoperazone, Cefazoline, Cefotaxime, Aztreonam, Ampicillin/Sulbactam, Penicillin G) were used for determination of antibiotic resistance of isolates. Multiple antibiotic resistances were determined in 27 isolates (40%) and they were resistant to five or over antibiotics and 49,3% of the isolates were found to be β-lactamase producing.

Carillo, M., Bromage, N., Zanuy, S., Serrano, R., and Prat, F., 1989. The effect of modifications in photoperiod on spawning time, ovarian development and egg quality in the sea bass (Dicentrarchus labrux L.). Aquaculture, 81: 351-365. Under simulated natural conditions female sea bass (Dicentrurchus labrax) in eastern Spain (latitude 4O"N and longitude 0" ) spawned over a 6-8-week period in February and March, with 0044-8486/89,'$03.50 0 1989 Elsevier Science Publishers B.V. M. CARRILU) ET AL.

As alternative farming methods, we investigate growth, haematological, biochemical and immunological parameters of European sea bass (Dicentrarchus labrax) farmed in submersible cages in order to compare physiological status under different rearing conditions and to validate the efficacy of submersible technology in solving several of the substantial problems that exist in surface-based fish farming as heavy storms, algal and jellyfish blooms and attacks by predators. The study was conducted in 2008 in the Gulf of Castellammare (NW Sicily, Mediterranean Sea) in two submerged and two surface cages filled with 75.000 D. labrax (initial weight: 28.2 ± 4.3 gr), for each cage. No significant differences were shown in specific growth rate between the two groups, even if, fish cultured in submerged cage reached the largest size. Results from biochemical and haematological parameters examined indicated higher welfare state in fish cultured in submerged cages. Fish reared in surface cages showed a significantly higher blood cortisol and glucose levels and haematocrit value than those of submerged cages. Also lysozme and haemolytic activity, used as indicators of immunocompetence in fish exposed to stress, lead us to suppose that submergence could have a positive effect on some components of innate immune system of cultured fish. Results of this study suggest mariculture in submerged net cages a promising system that allows to minimize stress and therefore that favours animal welfare.

A model of the multibeam echosounding process was developed. This model has now been used as the basis for the application of a model inversion technique, with the aim of analyzing midwater multibeam echosounder data, for fisheries applications.

At-sea distributions of large scyphozoan jellyfish across the Irish Sea were studied using visual surface counts from ships of opportunity. Thirty-seven surveys were conducted along two[100 km long transects between Ireland and the UK from April to September in 2009 and 2010. Five species were recorded but only Aurelia aurita and Cyanea capillata were frequently observed. The first formal description of the seasonal changes in the abundances and distributions of these two species in the study area is provided. The highest densities of these species were more likely to be found *30 km offshore, but large aggregations were present both in coastal and offshore waters. Evidence for aggregations of medusae along physical discontinuities was provided by coupling jellyfish observations with simultaneous records of environmental parameters. The value of surveys from ships of opportunity as cost-effective semi-quantitative tools, to develop local knowledge on jellyfish abundance, distribution, and phenology is discussed.

ObjectiveDespite widespread concern over exploitation of the European Union&#39;s fish stocks, dietary guidelines in the UK continue to recommend two portions of fish per week. The present study sought to investigate whether health and/or sustainability are motivating factors when purchasing and consuming fish and whether there are sociodemographic trends.DesignA structured, self-completion postal questionnaire exploring consumers’ attitudes towards purchasing fish, their dietary intake, stated purchasing behaviour and sociodemographic information.SettingNottinghamshire, UK.SubjectsAdults from 842 households randomly selected from the electoral register.ResultsOver half of the participants (57·0 %) were aware of the health benefits of fish consumption and reported health as a primary motivator for purchasing fish; however, only 26·8 % actively sought to purchase fish from a sustainable source (e.g. Marine Stewardship Council (MSC) certified fish). Only 30·6 % of participants met cur...

Atlantic salmon (Salmo salar L.) smolts (mean weight 66 g) in freshwater were exposed to three replicate levels of carbon dioxide (CO 2 ) partial pressures for 60 days in an open flow system: 2 mm Hg (6 mg l À 1 ; control), 5 mm Hg (16 mg l À 1 ; medium) and 7 mm Hg (24 mg l À 1 ; high) at constant pH. Water temperature was 7 -9 jC and oxygen concentration higher than 9 mg l À 1 . All groups were transferred to 34x seawater on day 60 and kept there for 150 days. No significant differences in weight and length were found between groups during the freshwater and seawater period. While mean cellular haemoglobin (in the high group) and plasma chloride (in the medium and high group) were significantly lower than that of the control group during the freshwater period, no significant differences between groups were observed in mean haemoglobin concentration, haematocrit, or gill Na + ,-K + -ATPase activity. Increased nephrocalcinosis and contents of Ca in the kidney in response to increasing water CO 2 levels were observed at day 58. After 4 weeks in seawater, pH in muscle and whole body ash, Ca, P and Zn content were all significantly higher in 0044-8486/03/$ -see front matter D Aquaculture 215 (2003) 301 -319 fish exposed to elevated CO 2 levels during the freshwater period. This indicates that freshwater CO 2 levels affected tissue mineral content after transfer to seawater. D

The inability of Ghana's capture-based fisheries to meet national demand has placed aquaculture in an advantageous position to satisfy this supply deficit. The majority of fish farmers in Ghana, however, resort to local feed mixtures, occasionally in combination with commercial aquafeeds, demonstrating that the sector has not yet reached its full potential in terms of production volumes and efficiency. Fish meal is available in limited quantities and is prohibitively expensive in Ghana, making it essential to develop suitable complete and supplementary diets using low-cost and locally available plant by-products for use in fish grow-out facilities, particularly in tilapia production, which accounts for over 80 % of aquaculture production. This review thus identifies local agro-industrial byproducts with potential use in fish feeds based on their nutritional composition, total annual production, competition for and seasonal availability and dynamics of these products as well as prices. The effects of dietary inclusions of these by-products on fish growth and feed utilisation are also reviewed. Based on the published works and other practical information reviewed, these by-products represent huge potentials as alternative aquafeed protein sources because of their abundance, very affordable prices and healthy nutritional profiles for fish growth. Although this review focuses on Ghana, it can also be of direct benefit to fish farmers, feed manufacturers, researchers and the policy-makers in other regions of the world where these crops and their resulting by-products are produced in commercial quantities.

For most marine aquaculture species, one of the main bottlenecks is the stable production of high quality juveniles. The high and unpredictable mortality in the first weeks after hatching of marine fish larvae remains a challenging problem that needs to be solved. The severity of the problem differs between species, but cannot be considered adequately solved for any species. Both scientific evidence and experience in hatcheries for a variety of fish, shrimp and shellfish species are accumulating as support for the hypothesis that detrimental fishmicrobe interactions are the cause of these problems. Host-microbe interactions in reared fish are still poorly understood, except for a few pathogens, and empirical data of the quality required to test this hypothesis, are lacking. This article provides an overview on the current knowledge of the microbial environment of fish larvae, including methodological aspects to characterize the microbial community (both using culture-dependent and culture-independent methods). Further, the current knowledge of the immunology of fish larvae is reviewed, including recent advances in the understanding of toll-like receptors, inflammatory cytokines, mast cells and piscidins, and the ontogeny of the adaptive immune system. Finally, we provide an overview of the state of the art with respect to steering of microbial communities associated with fish larvae-both steering of community composition and of its activity (e.g. by quorum sensing interference).

Effects of heavy metals [copper (Cu), zinc (Zn), chromium (Cr), nickel (Ni), manganese (Mn), iron  (Fe), Aluminum (Al), cadmium (Cd), mercury (Hg), stannum (Sn), and lead (Pb)] present in Tubruk harbor (polluted site) comparing to Umm Hufayan lagoon water (control) on liver and kidney performance of Mugil cephalus captured from both sites were investigated. For this purpose, surface water samples of both chosen sites were compared in terms of heavy metals concentrations, pH, and dissolved oxygen. Mullet fish were captured from both sites and blood samples were taken from the fish and sent to the lab for liver and kidney function tests. The results showed that heavy metals levels were significantly higher in Tubruk than those in Umm Hufayan lagoon. Additionally, significantly higher total protein and albumin levels were found in the blood serum of M. cephalus of Umm Hufayan, compared to Tubruk harbor fish samples; however, higher levels of bilirubin (BR), alanine transaminase (ALT), ...

A pen culture system of the mud crab, Scylla serrata was introduced in Mtwapa mangrove creek with the aim of finding an alternative source of income and food for the local communities, who practice artisanal fishery in the creek. Other objectives were to motivate the interaction between scientists and the community through technology transfer, and to collect scientific data necessary for maintenance and management of the culture system. Pen construction took place from October 2000 - January 2001. The pen was located in the intertidal area and measured 800 m2. It was constructed and fenced using uzio (fish trap) material made of mangrove poles and wood. Stocking of the pen with seed crabs occurred from February- May 2001. Local sources was used to obtain a total of 1697 crab seeds which were measured (carapace length and width), weighed and sexed before stocking. The crabs were fed with trash fish obtained from a local fish processing plant. Feeding was conducted once daily, prefera...

Kenya has a great potential for aquaculture growth by producing additional volumes of fish to fill the growing gap in national fish supply, as wild fish catches continue to decline. In order to balance the shortfall between fish production and high increase in demand, the Kenyan government drafted a fiscal policy measure in the form of Economic Stimulus Program (ESP) to stimulate economic growth in the industry. Despite increased aquaculture adoption and subsequent increase in fish supply in the country, little is known about consumer preference of farmed fish products that ultimately may hinder optimization of production and marketing of the aquaculture sub-sector. This study examined factors influencing consumer preferences and marketing trends in the demand for Nile tilapia (Oreochromis niloticus) and African catfish (Clarias gariepinus) in Kirinyaga and Vihiga Counties in Kenya. A total of 153 questionnaires were administered to 95 and 58 respondents in Kirinyaga and Vihiga coun...

Rainbow trout (Oncorhynchus mykiss) from a Danish mariculture system (a total of 166 fish) and from a freshwater system (a total of 40 fish before transfer to the marine system) were investigated for the presence of nematode larvae through a 1 year cycle. Correspondingly, wild fishes (a total of 160 fish) (cod, whiting, saithe, haddock, hake, flounder, turbot, common sole, lemon sole, witch, plaice, herring, mackerel, garfish, angler fish, and European eel) obtained from the same geographic region were examined. Morphological and molecular techniques were applied for diagnosis. No nematode larvae were recovered from the aquacultured fish. In contrast, anisakid larvae (Anisakis simplex) occurred frequently in wild fishes (body cavity and musculature) although at varying intensity. Other anisakid species (Pseudoterranova decipiens and Contracaecum sp.) were also found in the wild fishes but at lower frequency. Examination of the stomach content from the cultured trout confirmed that aquacultured fish preferentially feed on pelleted dry feed although algae, invertebrates and small fish occurred in a few cases. The background for the absence of nematode larvae in maricultured rainbow trout (low infection risk due to feeding using heat-treated feed without any infective parasite larvae) and the implications for food safety issues (lower likelihood of infected fish from mariculture systems) are discussed.

In this study, we demonstrate how an event that is initially frightening to Atlantic salmon is turned to a positive stimulus through habituation and associative learning. The study was carried out in four commercial sized tanks (5 m 3) with near industry densities ([550 fish, 16 kg m-3), using a delay conditioning procedure with an aversive flashing light as the conditioned stimulus and food reward as the unconditioned stimulus. By using video image analysis of the distribution of the fish in the tanks, the changes in behaviour from trial to trial could be documented in great detail. The current study documents the change in behaviour across the individual conditioning trials, clearly showing the step-by-step nature of the transition. The salmon needed more than 26 trials to become fully habituated to the flashing light but showed clear anticipatory behaviour already after about 19 trials. This demonstrates that the learning process is a combination of habituation and associative learning.

Proper nutrition at first feeding in marine fish larvae is an important factor for successful larval rearing. However, live prey used to feed marine finfish larvae lack essential fatty acids requiring commercial hatcheries to enrich live prey to provide a balanced diet. Currently, the many commercially available enrichments for live prey present considerable differences in their formulas, and compositions of essential nutrients. Since nutritional requirements are species-specific it is necessary to define those enrichments most appropriate for each species in terms of larval development and quality. This study aimed to evaluate the effect of six enrichments on Senegalese sole larval performance including growth, digestive system development and skeletogenesis, to determine whether any of these products are more suitable for Senegalese sole larval rearing. From 8 to 37 days post hatching (dph), larvae were fed Artemia nauplii previously enriched with six different formulae: Easy Selco© (INVE, ES), Easy Selco© (INVE) half diluted with olive oil (ES/2), Multigain© (BioMar, MG), Red Pepper© (Bernaqua, RP), Aquagrow Gold© (ABN, AGG) and Aquagrow DHA© (ABN, AGD), with the last two being diluted by a third with olive oil. The dietary treatments significantly affected larval growth and performance; larvae fed Artemia enriched with AGG presented significantly higher final dry weight (2.0 ± 0.4 mg), growth and intestinal maturation than larvae fed ES-enriched Artemia (final dry weight: 1.1 ± 0.3 mg). Larvae fed the AGG treatment also were those most advanced in metamorphosis and ossification processes. Larvae fed ES/2, RP, AGD and MG treatments presented intermediary values for all these parameters. No significant effect of the dietary treatments was detected in final survival and incidence of skeletal deformities. We conclude that, among the enrichments tested, AGG is the most appropriate for larvae of Senegalese sole. Commercial products for Artemia enrichment affect growth performance, digestive system maturation, ossification and incidence of skeletal deformities in Senegalese sole (Solea senegalensis) larvae.

A continuous cell line, designated FG-9307 was derived from gill tissue of the flounder Paralichfh~s oliuaceus and has been propagated for 96 passages over 3 years. The cells grew well in the temperature range of 20-25"C, but had a reduced growth rate at 30°C and did not grow at 35°C. At 15"C, the cells grew very slowly but could be maintained for one or two months without medium replacement. The diploid chromosome number of the cells at the 10th passage was 48, which was identical with those of the embryonic cells of the fish. However, the chromosome number varied greatly at the 57th passage, ranging from 38 to 102 with a bimodal distribution, a large distribution peak at 48 and a smaller one at 46. The cells were not susceptible to infectious pancreatic necrosis virus. 0 1997 Elsevier Science B.V.

Serious production losses have occurred in shrimp producing countries around the world, principally due to poor rearing environments and pathogenic disease. In response to this, shrimp farmers are changing their culture methods. To understand the source and sink of nutrients which affect pondwater quality and effluent impact, the nitrogen, phosphorus and solids budget have been constructed for water exchange systems. These budgets reveal the contribution of the pond bottom soil to the accumulation of sediment and phosphorus and its potential contribution of nitrogen to the pond system. A survey of shrimp farm water quality and management practices in southern Thailand has also been completed. This reveals a high proportion of farms using low water exchange methods of shrimp culture but without the ability to maintain suitable water quality in the production ponds. Shrimp production in these systems is variable due to high incidences of disease and slow growth rates. The pond processes that might cause this are suggested and potential methods for their amelioration are discussed. Alternative culture systems such as lined ponds, low salinity rearing and recirculation farms are described in relation to their potential for remediating problems within the shrimp culture industry.

An enzyme-histochemical study concerning the localization of steroid glucuronide production in the reproductive organs of African catfish, Clark gariepinus. Aquaculture, 63: 89-96. In ovaries of the African catfish, Clarias gariepinus, uridine diphosphoglucose dehydrogenase (UDPGD) and 3b-hydroxysteroid dehydrogenase (3B-HSD) appear in the granulosa of postovulatory follicles. In testes, both enzymes are present in interstitial cells. The combined presence of UDPGD and 3j?-HSD points to the formation of steroid glucuronides at these sites. Interstitial cells between the tubules of the seminal vesicle also show 3/3-HSD activity, both in captive fish and fish from nature. However, in these interstitial cells UDPGD activity was restricted to a few cells in the seminal vesicle of fish from nature. The latter enzyme was furthermore demonstrated in the epithelium of the seminal vesicle tubules, its activity being weaker in captive fish. Thus, in the seminal vesicle, glucuronidation of steroids may take place in interstitial cells, and it cannot be excluded that this process can also take place in the epithelium of the tubules.

Abstract
Blood cockles Tegillarca granosa culture in natural habitat is one of the way to increase national
production in addition to harvesting natural resources today, but culture in pond is rare to Malaysia.
Many factors need to be considered before the study of blood cockles in the pond is to be carried out. The
presence of plankton as a food source is a key factor in obtaining optimal blood cockles growth. The
study was conducted in two ponds with different treatments. Pond one used commercial probiotic for
water treatment and pond two was as a control. Fertilization was carried out weekly while water
exchange was carried out monthly. Measurement of water quality and chlorophyll a content were
performed once a month. As a result of 12 month of culture, blood cockles from pond one average length
was 22.85+1.80mm and for pond two average length was 25.36+3.00mm. Blood cockles length growth
rate for pond one was 0.66mm/month while for pond two was 0.99mm/month.
Keywords: Tegillarca granosa, growth performance, water quality, blood cockles

Two sets of adaptive trials were performed to determine the effects of size grading and batch grading on size heterogeneity in cultured Macrobrachium rosenbergii raised in the Coconut Garden channels of Kuttanad, Southern India. In the first set of trials, postlarvae were batch graded on the basis of their hatching order, segregated and grown separately as first-hatched and second-hatched groups. In the second set of trials, postlarvae were size graded as jumpers and laggards and were grown in separate channels. The average weight attained by prawns after 10 months of culture was highest for jumpers (83.11 g) and lowest for the prawns from the firsthatched group (43.76 g). The percentage of males was highest in the population of jumpers (58.23%). Highest production was recorded in the channel stocked with postlarvae from the second-hatched group (103.4 kg ha À1) and lowest production was obtained from the first-hatched group (63.74 kg ha À1). The proportions of undesirable small males were highest among laggards and the first-hatched group: 24.8% and 15.1% respectively. The level of heterozygosity within morphotypes was also high in these groups. Jumpers attained good growth by the end of culture but, because of their low survival rate, this approach was not economically feasible. However, higher production and survival in the secondhatched group improved economic viability. Thus, for better results, stocking with later-hatched groups would be more appropriate than stocking with the first-hatched group.

The objective of this present study is to determine the optimum concentration for glutathione in the cryopreservation of seurukan fish (Osteochilus vittatus) spermatozoa. A completely randomized design (CRD) was used with 6 treatments and 3 replications. The Seurukan fish sperm was diluted in extender with a ratio of 1:20 (sperm: extender), then glutathione was added at a concentration of 0, 10, 20, 30, 40 and 50 mg L À1. Next, the sperm thawed at 39e40 C for 3 min and mixed with 100 eggs which were randomly selected. The success of the fertilized egg was observed 6 h after fertilization, while the hatching rate was examined 60 h after fertilization. The ANOVA test showed that the addition of glutathione significant affected the sperms motility, fertility and hatching rate of seurukan fish Osteo-chilus vittatus eggs (P < 0.05). By segregation the fresh sperm, a higher sperm motility rate was recorded with an addition of 30 mgL À1 of glutathione (63.00 ± 5.89), however, this value was not significantly different from using concentration of 10 and 20 mg L À1. A higher fertilization rate was produced using glutathione concentration of 50 mg L À1 (51.33 ± 17.01); however, it was also not significantly different from the concentration of 20, 30 and 40 mgL À1. In addition, a higher hatching rate was also recorded using glutathione concentration of 50 mg L À1 (40.33 ± 12.89), this value was not significantly different from using 40 mgL À1 glutathione. Hence, a conclusion was drawn that the optimum concentration of glutathione is 40 mg L À1 of diluent.

In the present investigation, the effect of sub lethal concentration of the garlic aqueous extract on fish Channa punctatus were studied after 24 hrs, 48 hrs, 72 hrs and 96 hrs exposure respectively. Different concentrations of garlic (10 ppm/lit, 15 ppm/lit) used against Protein content of fish and results showed the gradual decrease in the protein content, ranging (106.14 – 91.65 mg/gm) for 10 ppm/lit for (24 hrs – 96 hrs) and (103.90-88.13 mg/gm) for 15 ppm/lit respectively