Econometric model of viability/profitability of octopus (<Emphasis Type="Italic">Octopus vulgaris</Emphasis>) ongrowing in sea cages

The interest in diversifying aquacultural production with new species is evident, preferably with species with a high commercial value and whose consumption is not geographically limited. In this sense, octopus would be a good choice. The present work, therefore, presents an economic-financial analysis of the commercial viability of octopus ongrowing in the Mediterranean, paying special attention to the one- or two-cycle approach. Viability–profitability equations are developed for analysing economic parameters associated with production. To estimate the investment, an offshore ongrowing installation was designed comprising 150 cages containing 30,000 individuals. Growth was estimated for the two strategies: (A) Two consecutive cycles per year (2CY), each lasting 3.5 months from October to June. Initial weight was 0.7 kg, and the mean final weight was 2.7 kg. (B) One growth cycle per year (1CY) beginning in November or December and finishing in April or May, starting with the same weight individuals (0.7 kg) and giving individuals with a final weight of 3.65 kg. The highest costs, the most important from an economic point of view, are feed (38.57 and 40.03%, respectively), fixed assets (25.26 and 17.47%, respectively), juveniles (16.65 and 23.02%, respectively), and in fourth place salaries (14.34 and 15.60%, respectively). The equations obtained for the variables NPV (Net Present Value) and IRR (Internal Ratio of Return) are the following: 1 cycle per year (1CY), NPV = −489,088 − 1.45 K − 1,439,823 C _F − 1,477,890 C _J − 1,460,627 C _O + 1,432,386 SP, IRR = 0.1328 − 7.82 × 10⁻⁸ K − 0.0416 C _F − 0.0437 C _J − 0.0427 C _O + 0.0412 SP. 2 cycles per year (2CY), NPV = −404,431 − 1.46 K − 2,118,410 C _F − 2,121,221 C _J − 2,144,755 C _O + 2,129,223 SP, and IRR = 0.0952 − 6.95 × 10⁻⁸ K − 0.0586 C _F − 0.0588 C _J − 0.0588 C _O + 0.0613 SP. The NPV and IRR values estimated with the econometric equations for each option using the initial variables confirm that 1CY has a higher NPV (3,013,569 €) and IRR (12.27%) than 2CY, with an NPV of 2,396,708 € and IRR of 10.39%. In both cases, octopus ongrowing is economically viable, although 1CY is the most favourable system.     

Characterization of Pseudomonas aeruginosa associated with diseased postlarval abalone in Shenzhen, China

Outbreaks of mass mortality of postlarval abalone, Haliotis diversicolor supertexta, have occurred in south China since 2002 and have forced many abalone farms to close. About 30 representative bacterial strains were isolated from a sample of five diseased postlarval abalone, taken 25 days post-fertilization during an outbreak of postlarval disease in Shenzhen, China, in October 2006. Bacterial challenge tests showed that the predominant strain, designated as strain 22, was highly virulent to postlarvae with an LD₅₀ value of 7.8 × 10⁴ colony forming units (CFU) ml⁻¹, while four of the other isolates were weakly virulent with LD₅₀ values ranging from 1 × 10⁶ to 1 × 10⁷ CFU ml⁻¹, and the remaining 25 isolates were classified as avirulent with LD₅₀ values greater than 1 × 10⁸ CFU ml⁻¹. By means of API 20NE and 16S rDNA and ITS sequencing analyses, strain 22 was identified as Pseudomonas aeruginosa. Antibiotic susceptibility tests showed that strain 22 exhibited around 75% of susceptibility to 16 various antibiotics tested. The results of this study show P. aeruginosa as one of the bacteria involved in the mortality of abalone postlarvae in Shenzhen, China.     

Influence of poultry meal, meat meal or soybean meal inclusion on weight gain and production characteristics of Australian snapper Pagrus auratus

Two experiments were done to evaluate the effects of poultry meal (PM), meat meal (MM) or solvent-extracted soybean meal (SBM) inclusion on the performance of Australian snapper Pagrus auratus. In each experiment, test feeds were formulated with similar contents of digestible protein (DP) and digestible energy (DE) using previously determined digestibility coefficients for this species. In experiment 1, groups of snapper (initial weight 14 g) were fed 4 feeds containing 360, 480, 610 or 730 g kg⁻¹ PM; 3 feeds containing 345, 320 or 500 g kg⁻¹ MM; 3 feeds containing 420, 600 or 780 g kg⁻¹ SBM. In experiment 2, groups of snapper (initial weight 87 g) were fed 3 extruded test feeds that contained combinations of PM, MM, SBM or blood meal (BM) which replaced all but 600, 250 or 160 g kg⁻¹ of fishmeal in respective diet formulations. Both experiments included a proprietary extruded aquafeed (COM) to benchmark fish performance. In experiment 1, weight gain was highest in snapper fed feeds containing 360, 345 or 420 g kg⁻¹ of PM, MM or SBM, respectively, and was similar (P > 0.05) to snapper fed the COM feed. Nonetheless, weight gain and protein retention efficiency tended to decrease as the amount of each test ingredient was increased. Relative feed intake was not affected by the inclusion level of PM, MM or BM, but declined significantly in snapper fed diets containing 600 or 780 g kg⁻¹ SBM. Feeding behaviour indicated fish found these feeds unpalatable. In experiment 2, the harvest weight of snapper fed the 3 extruded test feeds was similar (P > 0.05), but lower than snapper fed the COM feed (i.e. 234 vs. 256 g). Feed conversion ratio (FCR) was best in snapper fed the COM feed (FCR = 1.53); however, the FCR of snapper fed feeds containing 160 (FCR = 1.66), 250 (FCR = 1.70) or 600 g kg⁻¹ fishmeal (FCR = 1.60) was not different (P > 0.05). Australian snapper will readily accept feeds containing high levels of PM, MM or SBM and feeds containing these ingredients will support rapid weight and protein gain with little affect on whole body composition. In combination, these feed ingredients were able to replace all but 160 g kg⁻¹ of fishmeal in an extruded test feed. As such, they serve as valuable alternatives to fishmeal and extend the manufacturing options available to aquafeed producers.     

Chromosome set manipulations in the black carp

The mollusc-eating black carp (Mylopharyngodon piceus) has economic and health-care potential for biological control of nuisance aquatic molluscs. The present study investigates the production of gynogenetic-monosex and triploid-sterile populations of black carp. The goal was to provide a method which would eliminate unwanted biological and environmental impacts of introducing this exotic species into areas with nuisance mollusc infestation. Meiotic gynogenesis was induced by inseminating black carp eggs with UV-irradiated (800 Jm⁻²) sperm of common carp (Cyprinus carpio) or Japanese ornamental (koi) carp. Diploidy was restored through retention of the second polar body (2PB), by shocking activated eggs at 1–8 min post-fertilization (embryological age of 0.07–0.57τ₀, a parameter defined by the cell cycle duration) at 1 min intervals, with heat-shocks (41.0±1.0 °C for 1 min) or pressure-shocks (7500–7600 psi for 1.5 min). Highest survival was found when embryos were heat-shocked 1.5–4.5 min post-fertilization (0.10–0.25τ₀). The highest survival of free-swimming larvae from pressure-shocked eggs, was achieved at 7500 psi at 1–2 min post-fertilization (0.08–0.16τ₀). Triploidy was induced by retention of 2PB following normal fertilization. Batches of 30 000 eggs were fertilized with intact sperm and pressure-shocked (6000–8500 psi for 1.5 min) 2 min post-fertilization (0.15–0.16τ₀). The highest survival of triploid swim-up larvae was 5.1% in eggs shocked with 7500 psi. In random samples of individual larvae taken from each treatment, triploidy was analysed by cytofluorometry of the cellular DNA content. In DNA analysis performed in fingerlings (N≥15), 50% of the fish were triploids.     

Dietary protein requirement for fingerling Channa punctatus (Bloch), based on growth, feed conversion, protein retention and biochemical composition

An 8-week feeding trial was conducted in a flow-through system (1–1.5 L min⁻¹) at 27°C to determine dietary protein requirement for Channa punctatus fingerlings (4.58 ± 0.29 g) by feeding six isocaloric diets (18.39 kJ g⁻¹, gross energy). Diets containing graded levels of protein (300, 350, 400, 450, 500 and 550 g kg⁻¹) were fed to triplicate groups of fish to apparent satiation at 09:00 and 16:00 h. Maximum absolute weight gain (AWG; 8.11 g fish⁻¹), specific growth rate (SGR; 1.82%) and best feed conversion ratio (FCR; 1.48) were recorded in fish fed diet containing 450 g kg⁻¹ protein, whereas protein efficiency ratio (PER; 1.52), protein retention efficiency (PRE; 25%), energy retention efficiency (ERE; 78%) and RNA/DNA ratio (3.01) were maximum for the group fed dietary protein at 400 g kg⁻¹. Second-degree polynomial regression analysis of AWG, SGR and FCR data against varying levels of dietary protein yielded optimum dietary protein requirement of fingerling between 462.24 and 476.72 g kg⁻¹, whereas the regression analysis of PER, PRE, ERE and RNA/DNA ratio data showed a lower protein requirement of 438.28–444.43 g kg⁻¹ of the diet. Considering the PER, PRE, ERE and RNA/DNA ratio as more reliable indicators, this protein requirement is recommended for developing quality protein commercial feeds for C. punctatus fingerlings.     

Effect of dietary niacin on growth and body composition of two Indian major carps rohu, <Emphasis Type="Italic">Labeo rohita</Emphasis>, and mrigal, <Emphasis Type="Italic">Cirrhinus mrigala</Emphasis> (Hamilton), fingerlings based on dose–response study

An 15 week two set of feeding experiments were conducted to determine the dietary niacin requirement of Indian major carp fingerlings Labeo rohita and Cirrhinus mrigala, using casein gelatin–based diet. In both experiments, six isonitrogenous (40%) and isoenergetic (15.35 kJ g⁻¹) test diet, with graded levels of niacin (0–50 mg kg⁻¹ dry diet) in gradation of 10 mg kg⁻¹ dry diet, were formulated. In first experiment, fingerling of L. rohita (4.20 ± 1.22 cm; 0.632 ± 0.67 gm) were randomly stocked, in triplicate groups, in 55-L indoor polyvinyl flow-through system (1.5 L min⁻¹) and fed experimental diet at 0800 and 1600 h. Maximum live weight gain (1214%), feed conversion ratio (1.55) and protein efficiency ratio (1.60) were recorded at 30 mg dietary niacin diet. In second experiment, C. mrigala (4.50 ± 1.25 cm, 0.665 ± 0.88) were stocked in same setup. At the end of experiments, maximum live weight gain (1248%), FCR (1.47) and PER (1.70) occurred at 30 mg dietary niacin diet. However, the weight gain, FCR and PER data were analyzed by polynomial regression analysis indicating the requirement of niacin for L. rohita at 36.69, 33.06 and 32.0 mg kg⁻¹, respectively, and for C. mrigala at 35.19, 28.69 and 27.70 mg kg⁻¹ of dry diet, respectively. Whole body composition also showed significant (P < 0.05) differences among each other. On the basis of regression analysis of growth data, it is recommended that the diet for fingerlings should contain niacin at 33 and 30 mg kg⁻¹ dry diet for L. rohita and C. mrigala, respectively.     

Cod CGRP and tachykinins in coeliac artery innervation of the Atlantic cod, <Emphasis Type="Italic">Gadus morhua</Emphasis>: presence and vasoactivity

The presence and vasoactive effects of native calcitonin gene-related peptide (CGRP), substance P (SP), and neurokinin A (NKA) were studied on isolated small branches of the coeliac artery from Atlantic cod, Gadus morhua, using immunohistochemistry and myograph recordings, respectively. Immunohistochemistry revealed nerve fibers containing CGRP- and SP/NKA-like material running along the wall of the arteries. CGRP induced vasorelaxation of precontracted arteries with a pD₂ value of 8.54 ± 0.17. Relaxation to CGRP (10⁻⁸ M) was unaffected by l-NAME (3 × 10⁻⁴ M) and indomethacin (10⁻⁶ M) suggesting no involvement of nitric oxide or prostaglandins in the CGRP-induced relaxation. SP and NKA (from 10⁻¹⁰ to 3 × 10⁻⁷ M) contracted the unstimulated arteries at concentrations from 10⁻⁸ M and above in 42% and 33%, respectively, of the vessels. It is concluded that the innervation of the cod celiac artery includes nerves expressing CGRP-like and tachykinin-like material, and that a vasodilatory response to CGRP is highly conserved amongst vertebrates while the response to tachykinins is more variable.     

Organization and promoter analysis of a tiger shrimp Penaeus monodon single WAP domain-containing protein gene

The main function of the single whey acidic protein domain (SWD)-containing protein in shrimp is unknown. To elucidate the function of the SWD-containing protein in vivo, the SWD-containing protein gene was isolated and characterized. A 9.3-kb shrimp SWD-containing protein gene, and a 3.9-kb 3′-flanking region. The shrimp SWD-containing protein gene contained three exons and two introns. Different fragments of the shrimp SWD-containing protein 5′-flanking region were transfected into HeLa cells. The promoter activities were assayed by basal human chorionic gonadotropin (HCG), luteinizing hormone-releasing hormone (LRH), and gonadotropin-releasing hormone (GnRH) treatments. The in vitro actions of the SWD-containing protein promoter expression pattern were studied by transfection of an SWD-containing protein promoter (1 kb)-driven green fluorescent protein (GFP) encoding the GFP cDNA transgene into the HeLa cell line, which was then microinjected into zebrafish Danio rerio embryos. These results indicate that the shrimp SWD-containing protein promoter might play an important role in gene regulation of sex hormones in mammalian cell lines and in gene regulation of developmental stages in zebrafish.     

Differences in fatty acid composition of egg capsules from broodstock spotted babylon, <Emphasis Type="Italic">Babylonia areolata</Emphasis>, fed a local trash fish and formulated diet under hatchery conditions

This study is the first attempt to condition broodstock Babylonia areolata using formulated diets under hatchery conditions. Samples of spotted babylon egg capsules from broodstock fed either a formulated diet or a local trash fish, carangid fish (Seleroides leptolepis) for 120 days were analyzed for proximate composition and fatty acid composition. The formulated diet contained significantly higher levels of arachidonic acid (20:4n − 6; ARA), eicosapentaenoic acid (20:5n − 3; EPA) and docosahexaenoic acid (22:6n − 3; DHA) than those of the local trash fish. The formulated diet also had significantly higher ratios of DHA/EPA and (n − 3)/(n − 6) PUFA than those of local trash fish but not for the ARA/EPA ratio. The compositions of egg capsules produced from broodstock fed formulated diet contained significantly more ARA, EPA and DHA compared to broodstock fed the local trash fish. The ARA/EPA and DHA/EPA ratios in egg capsules were significantly higher in the trash fish—fed group compared to those fed the formulated diet. However, (n − 3)/(n − 6) PUFA ratios in egg capsules produced from broodstock fed the formulated diet did not differ significantly compared to those from broodstock fed the local trash fish. The relatively low DHA/EPA, ARA/EPA and (n − 3)/(n − 6) ratios in the egg capsules produced from the formulated diet—fed broodstock B. areolata suggested that this diet is inferior, when compared to the traditional food of trash fish.     

Changes in metabolic enzymes,cortisol and glucose concentrations of Beluga (<Emphasis Type="Italic">Huso huso</Emphasis>) exposed to dietary methylmercury

In this paper, effects of dietary methylmercury (MeHg) on several blood biochemical parameters including GLU (glucose), LDH (lactate dehydrogenase), AST (aspartate aminotransferase), ALT (alanine aminotransferase), ALP (alkaline phosphatase) and cortisol were investigated in the Beluga sturgeon (Huso huso). Beluga juveniles were fed for 32 days on four diets containing MeHg (control: 0.04 mg kg⁻¹; low: 0.76 mg kg⁻¹; medium: 7.88 mg kg⁻¹; and high 16.22 mg kg⁻¹ treatment). Significant increases (P < 0.05) were observed in all biochemical parameters, except ALP levels, which decreased significantly (P < 0.05) compared to the control group with either dose- or time-dependent effects. These results suggest that long-term dietary MeHg exposure may affect metabolic enzyme activity and glucose levels in Belugas. These findings provide useful information for environmental and fishery officials to apply in future decisions for managing fish resources in Caspian Sea.     

Serum biochemical characteristics of Beluga, Huso huso (L.), in response to blood sampling after clove powder solution exposure

In order to investigate the effect of anesthesia on serum parameters, Beluga, Huso huso (L.) were blood-sampled immediately without anesthesia (control) or subjected to following anesthesia procedure: 40, 120, and 240 s exposure to 3,000, 700, and 500 mg l⁻¹ clove solution, respectively. Blood samples were collected after these periods, when fish were immobile and reached stage 4 anesthesia. Results showed that cortisol and glucose levels were significantly high in 700 and 500 but not 3,000 mg l⁻¹ group compared to control. Serum lactate levels were significantly high in 500 mg l⁻¹ group compared to control group. Lactate levels were not significantly differed between control, 3,000, and 700 mg l⁻¹ groups. There were no significant differences in serum levels of cholesterol, total protein, lactate dehydrogenase, aspartate aminotransferase, alanine aminotransferase, Na⁺, Cl⁻, K⁺, and Ca²⁺. Results suggest that rapid anesthesia with higher dose is better than slow anesthesia with lower dose for blood sampling in Beluga.     

Growth,diet, and reproduction of Eurasian perch <Emphasis Type="Italic">Perca fluviatilis</Emphasis> L. in Lake Varese,northwestern Italy

No data have previously been reported on Eurasian perch Perca fluviatilis L. in Lake Varese. In this study, the growth, diet, and reproductive biology of the Eurasian perch population were investigated with the aim of providing information that may serve as a basis for efficient resource management. A total of 240 specimens were caught during the monthly sampling campaign from November 2006 through October 2008. The length-to-weight relationships were W _t = 8.4 × 10⁻³ L _t^3.10 (males) and W _t = 4.1 × 10⁻³ L _t^3.36 (females). The parameters for the von Bertalanffy growth function for pooled sexes were L _∞  = 33.17 cm, k = 0.20 year⁻¹, and t ₀ = −1.34 year. Perch in Lake Varese spawn from April through May. Sexual maturity is reached when males are 2 years old, in females mostly when they are 3 years old. Relative fecundity (F _rel) and absolute fecundity (F _abs) were assessed for females. Fecundity values were similar to data reported for other European populations: females of age 2+ F _rel = 102,457 ± 12,275, age 3+ F _rel = 131,767 ± 5,891, and age 4+ F _rel = 131,252 ± 15,555. Perch diet spectrum was wide and somewhat characterized by season. Perch in Lake Varese feed on macroinvertebrates, mainly Chironomidae and Chaoborus, zooplankton, and juvenile rudd Scardinius erythrophthalmus.     

Effect of ethanolic extract of propolis on growth performance and plasma biochemical parameters of rainbow trout (Oncorhynchus mykiss)

This study was conducted to evaluate the effect of ethanolic extract of propolis (EEP) on growth performance and plasma biochemical parameters of rainbow trout (Oncorhynchus mykiss). Graded levels of EEP [0 (control), 1, 2, and 4 g kg⁻¹ diet] were fed to trout juveniles (mean weight 7.73 ± 0.17 g) for 10 weeks. Dietary EEP supplementation regardless of inclusion level significantly improved the specific growth rate of fish. Similarly, supplemental EEP generally improved the feed efficiency ratio and protein efficiency ratio, but no significant differences were observed between the 1 g kg⁻¹ EEP group and the control group. In addition, dietary EEP supplementation generally increased the plasma superoxide dismutase, lysozyme, total antioxidant capacity, glutathione peroxidase, and catalase activities, but decreased the plasma malondialdehyde level. The plasma triglycerides level was significantly lower in the 1 or 4 g kg⁻¹ EEP group as compared with the control group. Dietary EEP supplementation generally decreased the plasma aspartate aminotransferase and alanine aminotransferase activities, but increased the hepatic aspartate aminotransferase and alanine aminotransferase activities. These results indicate the potential to use the EEP as a growth promoter, hepatoprotective agent, and immunostimulant for rainbow trout.     

Molecular cloning of cDNA of mammalian and chicken II gonadotropin-releasing hormones (mGnRHs and cGnRH-II) in the beluga (<Emphasis Type="Italic">Huso huso</Emphasis>) and the disruptive effect of methylmercury on gene expression

Two gonadotropin-releasing hormone (GnRH) isoforms were identified in the beluga (Huso huso) brain by cDNA sequencing: prepro-mammalian GnRH (mGnRH) and prepro-chicken GnRH-II (cGnRH-II). The nucleotide sequences of the beluga mGnRH and cGnRH-II precursors are 273 and 258 base pairs (bp) long, encoding peptides of 91 and 86 amino acids, respectively. To investigate the effect of methylmercury (MeHg) on GnRH gene expression, animals were fed with four diets containing increasing levels of MeHg (0 mg kg⁻¹ [control]; 0.76 mg kg⁻¹ [low]; 7.8 mg kg⁻¹ [medium]; 16.22 mg kg⁻¹ [high]) for 32 days. The effects of MeHg on brain GnRH mRNA levels were evaluated by real-time PCR. A significant decrease in brain mGnRH and cGnRH-II mRNA levels were detected in fish receiving high dietary MeHg dose compared to controls on day 11 (P < 0.05). On day 18 and 32, all treatment groups had significantly lower brain mGnRH and cGnRH-II mRNA levels compared to the control group (P < 0.05). These findings demonstrate a disruptive role of MeHg on the level of brain mGnRH and cGnRH-II mRNAs in immature beluga.