Fisheries Sciences

Viral haemorrhagic septicaemia (VHS) was diagnosed in rainbow trout in the UK in May 2006. VHS virus (VHSV) was isolated from fingerlings showing typical histopathological lesions at a single rainbow trout farm site experiencing high mortality. The virus was confirmed as VHSV by serological and molecular biological tests. Phylogenetic analysis based on the complete glycoprotein gene sequence revealed that the isolate was closely related (99% nucleotide identity) to several Danish isolates from 1991 to 2000 and was assigned to VHSV genogroup Ia. The pathogenicity of the isolate was determined in infection experiments using rainbow trout fry. Following waterborne challenge, cumulative mortalities reached 96.67-100% by 12 days post-infection. This represents the first isolation of a pathogenic freshwater VHSV in the UK.

The golden cownose ray, Rhinoptera steindachneri, was one of the most abundant species landed in artisanal elasmobranch fisheries in the northern Gulf of California (Baja California and Sonora) and Bahía Almejas, Mexico during 1998-1999. In the northern Gulf of California, R. steindachneri was most frequently observed during summer months (11.4% of elasmobranch landings, catch per unit effort (CPUE) = 6.8 individuals/vessel trip) and was rare during winter (0.1%, CPUE = 0.1). In Bahía Almejas, its relative abundance was greater during August (5.2%) than June (0.3%), a trend also evident in CPUE (August = 1.2, June = 0.1). The mean size of R. steindachneri landed in the Gulf of California was 64.3 ± 12.8 (SD) cm disc width (DW). Median size at maturity for Gulf of California specimens was similar for females (70.2 cm DW) and males (69.9 cm DW). Fecundity was found to be one offspring per female, with parturition estimated to occur from late June-August. Size at birth was estimated at 38-45 cm DW after a gestation period of approximately 11-12 months. Greater maximum sizes (to 104 cm DW) and embryo sizes (to 43 cm DW) were observed in Bahía Almejas. The large size at maturity, low fecundity, and long gestation period determined for R. steindachneri indicate that this species could be particularly susceptible to overexploitation.

Since the beginning of the 21st century, electronic monitoring (EM) has emerged as a cost-efficient supplement to existing catch monitoring programmes in fisheries. An EM system consists of various activity sensors and cameras positioned on vessels to remotely record fishing activity and catches. The first objective of this review was to describe the state of play of EM in fisheries worldwide and to present the insights gained on this technology based on 100 EM trials and 12 fully implemented programmes. Despite its advantages, and its global use for monitoring, progresses in implementation in some important fishing regions are slow. Within this context, the second objective was to discuss more specifically the European experiences gained through 16 trials. Findings show that the three major benefits of EM were as follows:

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 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.

Porcine circovirus type 2 (PCV2), a small single-stranded DNA virus, was initially discovered in 1998 and is highly prevalent in the domestic pig population. Disease manifestations associated with PCV2 include postweaning multisystemic wasting disease (PMWS), enteric disease, respiratory disease, porcine dermatitis and nephropathy syndrome (PDNS), and reproductive failure. Although these clinical manifestations involve different organ systems, there is considerable overlap in clinical expression of disease and presence of lesions between pigs and within herds. It is now widely accepted that PCV2 can be further subdivided into different types, of which PCV2a and PCV2b are present worldwide and of greatest importance. This review will focus on PCV2-associated lesions in different organ systems.

Behavioural observations in the field of male Mediterranean damselfish Chromis chromis were combined with molecular analyses, using bi-parentally and maternally inherited markers, to investigate reproductive success patterns of alternative reproductive tactics (ARTs) in terms of number of eggs sired and number of females contributing to each nest. Cuckoldry was observed in every nest sampled, with at least two and up to seven sneaker males per nest. The nesting male, however, always significantly fertilized the greater number of eggs (on average 49%) in each clutch, whereas each sneaker fertilized around 7% of the clutch. The average number of females whose eggs were fertilized by nesting males was 6·76 (range 2-13), while each sneaker on average fertilized the eggs of 1·74 (range 1-8) females. Using this sibship reconstruction, some of the factors involved in the regulation of the dynamic equilibrium of reproductive success were investigated between the two ARTs shown by C. chromis...

Worldwide, populations of catadromous eels are in decline. Knowledge on downstream migration patterns is needed to mitigate damage caused by hydroelectric stations. Silver eel migration and its relation with environmental factors were investigated using data from a fishery located in the lower reaches of a large catchment (110 000 m 2 ). Migration days, indicative of different proportions (50%, 75% and 95%) of the annual run of eels (i.e. represented by the annual catch), were predicted using discriminant analyses. Efficiency of prediction was 58-95% depending on the proportion of the run targeted. The onset of migration was correlated with sunshine hours, August temperature and discharge. Julian days (i.e. photoperiod) was significantly correlated with migration days, indicating between-year similarity in the dynamics of the runs. The size of migrants varied within the migration season, reflecting differences in their initial spatial distribution.

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 onset of downstream migration of European eels is accompanied by a cessation of feeding and the start of sexual maturation which stresses the link between metabolism and sexual maturation, also suggesting an important role for exercise. Exercise has been tested with eels in swim tunnels and was found to stimulate the onset of sexual maturation. In this study, we have investigated the interplay between migration and maturation in the field during the downstream migration of female silver eels. Temporal changes in migratory status and sexual maturation among silver eels of the upstream Rhine River system over 3 months of the migration season (August, September and October) were determined in biometrical parameters, plasma 17b-estradiol and calcium levels, oocyte histology and gonadal fat levels. Furthermore, the ecological relevant parameters age as determined by otolithometry and health aspects indicated by haematocrit, haemoglobin and swim-bladder parasite load were measured. Silver eels were estimated to be 14 years old. A strong temporal progression in migratory stage was shown over the months of downstream migration. Catches probably represented a mix of reproductive migrants and feeding migrants of which the ratio increased over time. Furthermore, this study confirmed our hypothesis linking the migratory stage to early maturation as indicated by enlargement of the eyes, oocyte growth and fat deposition in the oocytes, exactly the same changes as found induced by exercise but not ruling out environmental influences. Migrants show extensive fat uptake by the oocytes, probably stimulated by the swimming exercise. In addition, at least 83% of the silver eels in this spawning run may have suffered from negative effects of swim-bladder parasites on their swimming performance.

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.

Analyses of long-term data are an important component of climate-change research because they can help further our understanding of the effects of climate change and can help establish expectations for biological responses to future climate changes. We used macroinvertebrate data to assess whether biological trends associated with directional climate change could be detected in routine biomonitoring data from Maine, North Carolina, and Utah. We analyzed data from 8 long-term biomonitoring sites that had 9 to 22 y of data, and focused on thermal-preference metrics based on coldand warm-water-preference trait groups. The thermal-preference metrics were derived primarily from weighted-average or generalized-linear-model inferences based on data from each state database and are region specific. Long-term trends varied across sites and regions. At some sites, the thermal-preference metrics showed significant patterns that could be interpreted as being related to directional climate change, whereas at others, patterns were not as expected or were not evident. The strongest trends occurred at 2 Utah sites that had §14 y of data. At these sites, cold-water taxa were negatively correlated with air temperature, and, when years were grouped into hottest-and coldest-year samples, were strongly reduced in the hottest-year samples. Results suggest that thermal-preference metrics show promise for application in a biomonitoring context to differentiate climate-related responses from other stressors.

There is both a fundamental and applied need to define expectations of changes in aquatic ecosystems due to global changes. It is clear that programs using biological indicators and referencebased comparisons as the foundation for assessments are likely to make increasingly erroneous decisions if the impacts of global change are ignored. Global changes influence all aspects of water resource management decisions based on comparisons to reference conditions with impacts making it increasingly problematic to find an ''undisturbed'' water body to define acceptable conditions of ecological integrity. Using a more objective scale for characterizing reference conditions that is anchored in expectations for what would be attainable under

Globally, harmful algal blooms (HABs) caused by marine phytoplankton pose a significant threat to human health and result in enormous economic loss. Many strategies have been implemented for their detection, management, and control. One such instrument is the red-tide acoustic sensing system (RASS) which utilizes a backscattered acoustic signal to detect microalgal cells in the water column, proving to be a cheap and easy tool for the HABs detection. In the current study, five RASSs were deployed at fish farms located in HAB-occurring areas of South Korea during the summer of 2018, and their performance examined for the HABs detection. From 26 July to 6 August 2018, the dinoflagellate Cochlodinium polykrikoides was the most abundant HAB species across all locations. A standard curve between the relative received level (RRL) of acoustic intensity as measured by RASS and cell densities of HAB species was constructed (R 2 = 0.846) and was successfully applied to quantify the HAB cell density. The RRL values noticeably increased from July 25, 2018 and decreased from August 1. The RRL values corresponding to warning level of HABs (≥ 100 cells mL −1) were not measured after August 5. The highest 22 RRL was recorded on July 29, which corresponded to 2,782 cells mL −1. To evaluate the efficacy and accuracy of the RASS, a significant correlation (R 2 = 0.997) between HAB cell abundance and backscattered acoustic signals was confirmed. Results from our study show that the RASS can produce accurate, real-time bloom data, providing significant advantages for the warning of HABs.

Reducing overfishing and recovering overfished fish stocks is a challenging and important global problem. Rebuilding targets are essential ingredients for guiding overfished stocks to recovery. Having robust estimates of rebuilding targets is likely a necessary condition for effective long-term management of fishery resources. In this paper, we show how Bayesian model averaging can be applied to estimate rebuilding targets under alternative hypotheses about stock–recruitment dynamics. Using alternative hypotheses about stock–recruitment dynamics and environmental variation is important because using only a single hypothesis can lead to substantially different reference points and policy implications. The alternative hypotheses are augmented with prior information collected from meta-analyses of stock–recruitment data to construct a set of age-structured production models. We illustrate our approach using three overfished New England groundfish stocks. We fit alternative model likeli...

The trypsin-inhibitory activity of the serum of five cultured fish species, halibut (Hippoglossus hippoglossus L.), turbot (Scophthalmus maximus L.), arctic char (Salvelinus alpinus L.), rainbow trout (Oncorhynchus mykiss, Walbaum) and brown trout (Salmo trutta L.) was investigated. Individual fish were bled and the serum trypsin-inhibitory activity analysed using an arginine-aniline dye ester as colorimetric substrate. Results for the five species indicate that levels of 2-macroglobulin-like activity decrease significantly (P<0•05) from halibut through turbot, brown trout, char and finally rainbow trout with the lowest levels. Analysis of the total trypsin binding capacity indicates a ranking with decreasing concentration of char, turbot, halibut, brown trout and rainbow trout. Significant di#erences occurred only in certain cases, brown and rainbow trout were significantly (P<0•05) lower than char, and rainbow trout was significantly (P<0•05) lower than turbot. The results indicate that halibut and turbot possess a higher level of 2-macroglobulin-like activity than the other species in the study, whereas char had the highest total trypsin-inhibitory level.

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,

We use six decades of catch-at-age data for perch (Perca fluviatilis) and pike (Esox lucius) in Windermere (UK) to estimate age-and sex-specific population sizes, natural mortalities and catchabilities in both species. Population sizes are estimated by fitting age structured population models to the catch-at-age data using standard maximum likelihood methods. We validate our methods using data simulations, and use our estimates of vital rates (natural mortality, recruitment and catahability) to address important aspects of fisheries biology. ...

We compared three proportional back-calculation methods for scales using data sets for pumpkinseeds Lepomis gibbosus and golden shiners Notemigonus crysoleucas from 10 southern Quebec lakes, and we validated back-calculations by comparing them with observed lengths at lime of annulus formation. Ordinary least-squares regression (OR) was compared with geometric mean regression (GMR) for describing bodyscale relationships. Although minor differences were detected in body-scale regressions among lakes, pooling data across lakes yielded linear bodyscale relationships with very high r2. Differences between OR and GMR body-scale relationships were negligible in both species. Likewise, all back-calculation methods produced equivalent results. Back-calculated lengths generally corresponded well with observed lengths in all pumpkinseeds age-classes and in golden shiners older than 1 year. Observed lengths were often greater than back-calculated lengths for age-1 golden shiners. Our results, indicating little or no difference among methods, contradict recent reviews claiming substantial disagreement among methods. Tighter body-scale relationships in our data sets than in previous studies appear to explain this contradiction. We suggest that light body-scale relationships are attainable for many species, obviating concern over which proportional back-calculation method is chosen.

The effects of temperature, salinity, irradiance and pH on the growth of Fibrocupsu juponicu (Raphidophyceae) were examined to determine how environmental factors affect the distribution of this species. Optimal growth was observed at temperatures of 15-25 c, salinities of 25-35 parts per thousand (ppt), irradiances of 60-140 pmol quanta/m2 per s and pH between 7.5-8.5. Growth did not occur at temperatures helow 10 C or above 30 C nor at salinities below 15 ppt. Fibrocupsu juponicu grew when subjected to irradiances of 20-180 pmol quanta/m2 per s, and could tolerate a pH range of 6.5-8.5.

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.

Habitat features influence the ecological interactions and spatial distribution of fish species. For example, water transparency and macrophyte cover, as well as their interaction, can strongly influence predation risk and mortality. Tethering trials were conducted in Lake St. Pierre (Quebec, Canada) to assess the effects of water transparency and macrophyte cover on the mortality risk of eight abundant fish species; Brown Bullhead (Ameiurus nebulosus), Mooneye (Hiodon tergisus), Emerald Shiner (Notropis atherinoides), Golden Shiner (Notropis crysoleucas), Blacknose Shiner (Notropis heterolepis), Spottail Shiner (Notropis hudsonius), Trout-perch (Percopsis omiscomaycus), and Yellow Perch (Perca flavescens). Kaplan-Meier survival curves showed that mortality risk varied substantially among three groups of species having high, intermediate, or low survival rates. Species with spines appeared to have higher survival rates, consistent with the notion that spines deter predators. Cox regression models showed that mortality risk for six of the eight species was influenced by water transparency or an interaction of transparency with macrophyte cover. Mortality risk was generally greatest at low transparency. Variation in water transparency may generate spatial heterogeneity in fish abundance, either through direct effects, such as local reduction in prey numbers by predation, or indirect effects, such as behavioural avoidance of risky areas by prey.

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.

An individual-based model of nesting smallmouth bass, Micropterus dolomieu, is used to predict the effects of water level fluctuations on reproductive success. The model simulates daily nest site selection, spawning, nest guarding, and development and survival of eggs, embryos, and larvae until dispersal. The model was configured for Brownlee Reservoir, Idaho-Oregon. Each reservoir bank is represented as a rectangular grid of cells, with each cell characterized by an assigned slope, substrate, and elevation, and by a water depth that varied daily. Nest site (cell) selection is determined from a habitat suitability index (HSI) based on substrate, slope, and depth. Development of young is temperature-dependent. Mortality of young occurs via attrition, abandonment by the guarding male, and probabilistic whole-nest catastrophe. Simulations were performed that used observed data for 1991 to 1996. Model predicted nest habitat selection and egg-to-dispersal survival rates were similar to observed values. Additional model simulations showed that: (1) nest habitat selection was best predicted when depth, slope, and substrate were considered together rather than singly, (2) egg-todispersal survival was related to the magnitude of water level fluctuations during the peak spawning period, (3) relating mortality to HSI values resulted in lower survival, while relating growth to HSI values resulted in higher survival, and (4) spawning habitat is not limiting in Brownlee Reservoir. Suggestions for future monitoring of reservoir-based smallmouth bass populations are discussed.

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

Canine peritoneal larval cestodiasis (CPLC) is a poorly understood disease of dogs caused by asexual multiplication of larval Mesocestoides spp. tapeworms. In this study, we examined the descriptive statistics and survival characteristics of 60 dogs diagnosed with CPLC from 1989 to 2009. Clinically affected dogs presented with ascites (60%), anorexia/weight loss (42%), vomiting (23%), diarrhea (9%) and tachypnea (9%), while subclinical infections (22%) were incidentally detected, typically during ovariohysterectomy or neuter. Survival at 6 months and 1 year post-diagnosis were 72.3% and 60.5%, respectively, and survival was not affected by sex or age. Using Cox proportional hazard analyses, we determined that the most significant factors influencing survival were the severity of clinical signs at the time of diagnosis and application of an aggressive treatment strategy after diagnosis. Dogs that were not treated aggressively were >5 times more likely to die than dogs that were treated with a combination of surgery/lavage and high doses of fenbendazole.

Atlantic salmon fry (0+) sampled from the River Alta exhibited only minor differences in stomach content weights and feeding rates throughout diel periods, but feeding rates were generally lowest at night. In contrast, salmon parr (1+ to 3+) had large diel fluctuations in stomach content weight, with the largest weights usually being recorded during the night and early morning. Accordingly, their feeding rates were highest at night. This nocturnal feeding pattern was consistent throughout all sampling occasions, and appeared to reflect a persistent feeding periodicity in the salmon parr. The daily food consumption rates of both fry and parr were highest during midsummer and decreased towards autumn. 1999 The Fisheries Society of the British Isles

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).

Growth rates and longevities were estimated for five major fishery species of parrotfishes (“uhu”) at Oahu, Hawai’i. All species grew rapidly with von Bertalanffy growth formula k values ≥0.4·year−1. Longevities were found to range broadly among the three small species, 4 years in Calotomus carolinus and 6 and 11 years in Scarus psittacus and Chlorurus spilurus, and to 15–20 years in Scarus rubroviolaceus and Chlorurus perspicillatus for the two large species. Age reading and growth curves for the latter two large species were validated using bomb radiocarbon dating. Median ages at sexual maturity as females (AM50) and at sex change (from female to terminal phase male, AΔ50) were estimated using logistic models. Sexual maturation occurred at 1–2 years for the small species and at 3–3.5 years in the large species. AΔ50 estimates ranged from 2 to 4 years in the small species and were about 5 and 7 years in S. rubroviolaceus and C. perspicillatus, respectively. Estimated milestones poo...

Visual surveys are conducted to rapidly estimate population densities of stream fishes, often without calibration against more established or more widely used methods to determine precision and accuracy or to correct for potential biases. We compared population density estimates from a visual survey (VS) point quadrat method widely used in Hawaii with estimates from "in hand" individual and batch mark-recapture (BMR) methods. Visual survey sampling and individual mark-recapture (IMR) sampling were conducted in three watersheds that represent gradients of land use and prevalence of nonnative poeciliid fishes on the Island of Hawaii. Focusing on adult O'opu Nākea Awaous stamineus, VSs were conducted prior to IMR events to allow direct comparisons of results independent of location and time. Density estimates of O'opu Nākea from VS and IMR samplings were strongly correlated, although VS estimates were generally higher and underrepresented exceptionally large fish. Batch mark-recapture estimates of O'opu Nākea densities were conducted for comparison with VSs at 13 sites across the archipelago. Estimates of VSs were not significantly different from BMR estimates. Estimates of VSs also exhibited less variance than did BMR estimates across sites. General linear models showed that the relationship between VS and IMR estimates varied significantly among watersheds but not seasons and that land use was associated with a greater mismatch between VS and BMR estimates of population density. These findings indicate that visual surveys using a point quadrat method are an efficient and accurate approach for estimating the abundance of small benthic fishes, such as O'opu Nākea, in wadeable streams and that obtaining absolute densities or size distributions from VS methods would benefit from a calibration with IMR not BMR estimates.

Many changes occur in the biochemical composition of microalgae in response to stress conditions. In the present study, two nitrogen-stressed Chlorella minutissima strains (MACC 360 and 452) were placed in media containing a range of nitrogen concentrations (7-700 mg L −1 N). Biomass, chlorophyll a and b, carotenoid, protein and lipid concentrations were monitored over 15 days. There was lower biomass accumulation in nitrogen-deficient treatments while lipid yields increased to 40-46% DW in response to nitrogen deficiency. Chlorophyll concentrations initially recovered in response to the nitrogen spike with maximum concentrations recorded on days 6-8 and decreased thereafter as nitrogen became limiting. In comparison, proteins recovered faster with maximum concentrations recorded on day 4. Carotenoid concentrations did not increase in response to the nitrogen spike.