Target strength estimation of black porgy Acanthopagrus schlegeli using acoustic measurements and a scattering model

ABSTRACT:   Black porgy are hatched and released in marine ranching areas in Japan, Korea and Taiwan to maintain fisheries resources in coastal areas. If acoustic methods are used for field surveys, target strength ( TS ) information on the species is needed to convert acoustic data to biomass density. Target strength of black porgy ( Acanthopagrus schlegeli ) 15.5–32.9 cm fork length (nine individuals) was measured at 38 and 120 kHz (split beam) by ex situ measurements (cage and fishhook methods) of living fish, a tethered method with shock-frozen fish, and an acoustic scattering model, the Kirchhoff ray mode (KRM) model based on fish morphology. The ex situ TS -to-fork length ( FL , cm) relationships were TS _38kHz = 20log₁₀ FL  − 64.6 ( r  = 0.77) and TS _120kHz = 20log₁₀ FL  − 65.2 ( r  = 0.70). The values for the KRM model were TS _38kHz = 20log₁₀ FL  − 64.8 ( r  = 0.88) and TS _120kHz = 20log₁₀ FL  − 65.4 ( r  = 0.80). The agreement between the ex situ measurements and the KRM model for the mean TS was very good. In contrast, the results for the tethered method ( TS _38kHz = 20log₁₀ FL  − 69.3 [ r  = 0.42]) differed markedly from the other two methods, perhaps because of the effects of the shock-freezing procedure in air. The results of the ex situ measurements and scattering model provide basic information for studying TS and conducting acoustic surveys of black porgy, even though the tethered method must be modified.     

Culture-based fisheries in non-perennial reservoirs of Sri Lanka: influence of reservoir morphometry and stocking density on yield

Abstract  Culture-based fish yield in non-perennial reservoirs of Sri Lanka was related to reservoir morphometry and stocking density. The reservoirs were stocked mainly with fingerlings of one Chinese and three Indian major carp species, common carp, Cyprinus carpio L., and the genetically improved farmed tilapia strain of Nile tilapia, Oreochromis niloticus (L.), at four pre-determined species combinations and a range of stocking densities [ SD (fingerlings ha⁻¹)]. Twenty-three reservoirs were harvested successfully at the end of the culture period of 2002–2003. Basic limnological and morphometric parameters, including shoreline development ( D _L ) and shoreline area ratio ( R _LA ), were estimated for each of the 23 reservoirs. Bray–Curtis similarity and non-metric multidimensional scaling using mean values of limnological data revealed that reservoirs could be ordinated into two major clusters, one with intact sample distribution due to similar trophic characteristics and the other with scattered sample distribution. Reservoirs in the cluster with similar trophic characteristics showed significant correlation ( P  < 0.05) between R _LA and total fish yield ( Y ). A multiple regression equation, Y  = −693 + 4810  R _LA  + 0.484 SD , was generated to estimate fish harvest in relation to SD .     

A pharmacokinetic study of flumequine in sea bass, Dicentrarchus labrax (L.), after a single intravascular injection

The pharmacokinetic properties of flumequine following a single intravascular injection (10 mg kg^–1 fish) were studied in sea bass, Dicentrarchus labrax (L.), 120 g held at 18 °C. The absorption half life ( t _1/2α) and the elimination half life ( t _1/2β) of the drug were calculated to be 1.05 and 10.71 h, respectively. Tissue penetration of flumequine seemed to be moderate because both the apparent volume of distribution of the drug at steady-state ( V _d(ss)) and the extensive apparent volume of the central compartment ( V _c) were found to be small (1.51 and 0.626 L kg^–1). The mean residence time ( MRT ) was short (09.73 h) and the total clearance (CL_T) of the drug was rapid (0.156 L kg^–1 h^–1).     

Comparison of horse mackerel and tilapia surimi gel based on rheological and <Superscript>1</Superscript>H NMR relaxation properties

ABSTRACT:   Horse mackerel and tilapia surimi were subjected to six different heat and pressure treatments in order to compare gelation characteristics of easy- and difficult-setting gels, that is, temperature dependence, by observing rheological properties and microscopic molecular mobility. The stress–relaxation and proton spin–spin relaxation time (¹H T ₂) of water were measured for all treated gels. Horse mackerel gel demonstrated higher elasticity, large distribution of the stress–relaxation process, and smaller water ¹H T ₂ than tilapia in both heat and pressure treatments. The water ¹H T ₂ was steeply increased in the pressure treatment at around 294 MPa for both fishes. In contrast, the ¹H T ₂ rarely changed in the heat treatment in spite of the considerable change in rheological properties. From the experimental results, it is considered that the gelation of horse mackerel (easy setting) surimi is induced by highly unfolding and re-aggregation of protein, which contributes to the formation of a strong network structure compared with tilapia in both heat and pressure treatments, and that pressure treatments hardly improve the gel strength of tilapia (difficult setting) surimi. The water ¹H T ₂ measurement was used effectively in order to study gelation characteristics of easy- and difficult-setting fish through observing its molecular dynamics.     

Pharmacokinetics of oxolinic acid in gilthead sea bream, Sparus aurata L.

This is the first study on the pharmacokinetic parameters of oxolinic acid (OA) in gilthead sea bream, Sparus aurata L. The kinetic profile of OA was studied after a single intravascular injection (20 mg kg⁻¹) in 100 g fish at 20 °C. The distribution half-life ( t _1/2α) and the elimination half-life ( t _1/2β) of the drug were found to be short (0.51 and 12.60 h, respectively). The drug penetration from the plasma to the tissues was adequate as the apparent volume of distribution of the drug at steady-state ( V _d(ss)) was found to be 2.11 L kg⁻¹. The mean residence time ( MRT ) of OA was short (14.25 h) and the total clearance rate ( Cl _T) of the drug was low (0.15 L kg⁻¹ h⁻¹). The bioavailability ( F %) of OA following oral administration (30 mg kg⁻¹) was also low (14%). Maximum values were observed for muscle at 0.5 h after injection, with levels declining as with subsequent sampling. At the first two time points (0.5 and 1 h) plasma levels of OA were higher than muscle, however, the reverse was evident for subsequent samples. Following oral administration, highest muscle levels were found at 16 h and, with the exception of the 24-h sampling, muscle OA concentrations were higher than plasma at all time points. The fast elimination of OA suggests short withdrawal times with reference to human consumption of treated fish.     

Effect of dietary lysine and methionine supplementation on growth, nutrient utilization, carcass compositions and haemato-biochemical status in Indian Major Carp, Rohu (Labeo rohita H.) fed soy protein-based diet

An 8-week feeding trial was conducted in flow through system to examine the effects of dietary supplementation of lysine and methionine on growth, nutrient utilization, haemato-biochemical status and carcass compositions in Indian major carp, rohu, Labeo rohita fingerlings (average weight 6.32 ± 0.06 g). Four experimental soy protein-based diets D ₀ (without lysine or methionine supplementation), D ₁ (lysine supplementation alone), D ₂ (methionine supplementation alone) and D₃ (both lysine and methionine supplementation) were fed to triplicate groups. l -Lysine and dl -methionine were added to the diets containing 550 g kg⁻¹ soybean meals at 4 and 7 g kg⁻¹ of dry diet respectively. Significant higher weight gain, specific growth rate (SGR), protein efficiency ratio (PER), dry matter retention, nitrogen retention, total ash retention, whole carcass protein, haemoglobin concentration, haematocrit value, total erythrocytic count, total leucocytic count, plasma glucose and plasma total protein and lower FCR, per cent lipid retention and whole body moisture content were observed in fish fed soya protein-based diet supplemented with both lysine and methionine than that of fish of other dietary groups at the end of 8 weeks feeding trial. Although fish fed diet supplemented with either methionine or lysine did not show any significant differences of growth performances, feed utilization, carcass composition and haemato-biochemical status, fish of both of these dietary groups showed significantly better growth performances, feed utilization, carcass composition and haemato-biochemical status than that of fish fed diet without lysine and methionine supplementation.     

Temperature-dependent index of mitotic interval τ0 in greenling Hexagrammos otakii

ABSTRACT:   The aim of this study was to establish effective procedures for chromosome manipulation in greenling Hexagrammos otakii Jordan et Starks, which has enormous aquacultural potential. To accomplish this, temperature-dependent measurements of the mitotic intervals (τ₀) were carried out. The τ₀ in this fish was determined by averaging the duration of the first and third embryonic divisions at temperatures ranging 5–25°C. At higher temperatures, eggs developed faster and underwent more identical development. For greenling, τ₀ were 341.1 ± 3.60 min at 5°C, 275.5 ± 4.53 min at 10°C, 189.7 ± 6.93 min at 15°C, 99.2 ± 8.27 min at 20°C and 34.2 ± 8.74 min at 25°C. There were strong, negative correlations between the τ₀ and water temperatures at all temperatures studied ( Y  = −79.3 X  + 425.3, R ² = 0.9968, where Y is the mitotic interval and X is the temperature).     

In vitro hydroxylation of vitamin D3 and 25-hydroxy vitamin D3 in tissues of Atlantic salmon Salmo salar, Atlantic mackerel Scomber scombrus, Atlantic halibut Hippoglossus hippoglossus and Atlantic cod Gadus morhua

The in vitro metabolism of ¹⁴CD₃ and ³H25OHD₃ was investigated in different tissues from Atlantic salmon Salmo salar , Atlantic mackerel Scomber scombrus , Atlantic halibut Hippoglossus hippoglossus and Atlantic cod Gadus morhua . The tissues analysed were liver, kidney, head kidney, gills, spleen and intestine. The metabolites were extracted in methanol–chloroform and separated by normal-phase high-pressure liquid chromatography (HPLC) followed by scintillation counting. Identification of the metabolites was by comigration with standards on normal and reversed-phase HPLC systems and by protein-binding assays. All tissues from all species analysed produced hydroxylated derivatives identified as 25OHD₃, 24,25(OH)₂D₃ and 1,25(OH)₂D₃. In addition, some unidentified derivatives were recorded, one probably being 25,26(OH)₂D₃. Organs producing great amounts of one metabolite also produced considerable amounts of the other possible derivatives, suggesting a lower degree of specificity in fish organs than in human organs. The predominating metabolite was 24,25(OH)₂D₃ in all organs from salmon and mackerel during incubation with ¹⁴CD₃ and within most organs from all species during ³H25OHD₃ incubation. The latter observation probably results from the need for decreasing rather than increasing the calcium absorption in these species, which live at least some periods of life in a marine environment.     

Age and growth of Sebastes vulpes in the coastal waters of western Hokkaido, Japan

ABSTRACT:   Age and growth of Sebastes vulpes collected from the coastal waters of western Hokkaido were studied. Observation of the otolith margin verified that annuli (outer margins of the opaque zone) were produced chiefly from July to August. This period was associated with parturition and the birth season. The maximum age estimated by the surface method was 12 years but the oldest fish was aged at 35 years by the cross-section method. The surface method was inadequate for aging of S. vulpes older than 6 years because of the underestimation of age. No significant difference was found in the parameters of the growth equations between both sexes. The von Bertalanffy growth curve combined for both sexes was as follows: SL _t  = 358.6(1 − exp^{−0.156( t +0.820)}), where SL _t is standard length (mm) at age t (after parturition in years). It seems likely that S. vulpes grows slowly and lives longer than previously thought.     

Effects of Aeration, Alum Treatment, Liming, and Organic Matter Application on Phosphorus Exchange between Soil and Water in Aquaculture Ponds at Auburn, Alabama

Application of readily-oxidizable organic substrate to laboratory soil-water systems and fish ponds caused anaerobic conditions in bottom soil and water, and concentrations of soluble reactive phosphorus (SRP) increased. Aeration of ponds increased total phosphorus (TP) concentrations by suspending soil particles in the water, but SRP concentrations declined because of increased oxy- genation of bottom water and soil, Alum [Al₂(SO₄)₃·14H₂O] treatment of ponds reduced SRP and TP concentrations in ponds, but the low concentration of alum used, 20 mg/L, had little residual effect on phosphorus concentration. Application of agricultural limestone at 0.2 kg/m² to ponds with soil pH of 5.5 and Ca²⁺ concentration of 5 mg/L did not affect SRP and TP concentration. Unless pond soils were anaerobic at their surfaces, a condition not acceptable in thermally-unstratified fish ponds, soils released little phosphorus to the water. Strong adsorption of phosphorus by soils in intensive ponds with feeding is beneficial, because removal of phosphorus by aerobic soils is a control on excessive phytoplankton growth. In fertilized ponds, phosphorus must be applied at frequent intervals to replace phosphorus removed from the water by soils.     

Perish legally and ecologically: the ineffectiveness of the minimum landing sizes in the Mediterranean Sea

Abstract  Minimum landing size (MLS) is one technical measure used to manage fisheries with the aim of allowing enough juveniles to survive and spawn. In this study the practical and ecological efficiency of the MLSs set by European Union (Regulation 1967/2006) and Greek legislation for 13 fish species caught with five gears in the Ionian Sea was tested using length measurements from 22 382 individuals. The percentage of individuals with lengths smaller than MLS was estimated. In addition, MLSs were compared against length at 50% maturity ( L ₅₀) and the percentages of individuals caught per species and gear with lengths smaller than the L ₅₀ were also estimated. The mean percentage of individuals caught with lengths smaller than MLS ranged from 5.9% for longliners to 42.6% for beach-seiners, showing the practical inefficiency of this measure. In addition, all MLS were smaller than the corresponding L ₅₀ and L ₅₀ − SE values and across species the mean percentage of the immature individuals caught was very high, ranging from 55% for longliners to 92% for beach-seiners, indicating that the vast majority of the individuals caught did not have the chance to spawn even once. Thus, the existing MLSs are ecologically inefficient for sustainable management.     

Age,growth and age at sexual maturity of fan ray <Emphasis Type="Italic">Platyrhina sinensis</Emphasis> (Batoidea: Platyrhinidae) in Ariake Bay,Japan

Abstract:   Age, growth and sexual maturity of the fan ray Platyrhina sinensis in Ariake Bay, Japan were determined from specimens collected from May 2002 to September 2006. Age determination was conducted by vertebral centrum analysis using soft X-radiography. Annual band pair deposition was determined by marginal increment and edge analyses. The von Bertalanffy growth model best described the overall pattern of growth for both males and females (males L _∝  = 455.2, k  = 0.56, t ₀ = −1.09; females L _∝  = 555.8, k  = 0.28, t ₀ = −1.77; L _∝ is the theoretical asymptotic total length in mm, k is the growth rate coefficient and t ₀ is the theoretical time at zero length). Parameter estimates suggest that females attain a larger asymptotic total length and grow more slowly than males. The observed maximum ages were 5 years for males and 12 years for females. Age at 50% sexual maturity was 2.1 years for males and 2.9 years for females. The results indicate that this species is relatively fast-growing, short-lived and early maturing compared with many batoid species.     

A comparison of gastrically and surgically implanted telemetry transmitters in shovelnose sturgeon

Abstract  Transmitter retention and the effects gastrically and surgically implanted telemetry transmitters had on condition and mortality of shovelnose sturgeon, Scaphirhynchus platorhynchus (Rafinesque), >450-mm fork length were examined. Four, 35-day trials were conducted with approximately equal numbers of control fish, fish receiving dummy transmitters gastrically and fish receiving dummy transmitters surgically. Four sturgeon expelled gastrically implanted transmitters during the observation period. Two mortalities occurred among fish receiving gastrically implanted transmitters during the study period and one mortality was recorded for control fish. No mortalities were recorded for fish receiving surgically implanted transmitters. Condition change (Δ K _n ) was significantly different between fish receiving surgical implantation (mean Δ K _n  ± SE; −5.17 ± 0.94), fish receiving gastric implantation (−2.98 ± 0.72) and control fish (−0.65 ± 1.09). Surgical transmitter implantation is recommended for telemetry studies on shovelnose sturgeon because of increased transmitter expulsion and occurrence of mortality in fish receiving gastric implantation.     

Acoustic characterization of biological backscatterings in the Kuroshio-Oyashio inter-frontal zone and subarctic waters of the western North Pacific in spring

The acoustic characteristics of biological backscattering in the western North Pacific were studied to verify expert knowledge on species composition in the echosigns. The survey was conducted in the Kuroshio-Oyashio inter-frontal zone and the subarctic waters in April 2003. The species composition of backscatterings was identified by using midwater trawl, Isaacs-Kidd midwater trawl and Bongo net. The differences of mean volume backscattering strengths between 120 and 38 kHz (ΔMVBS₁₂₀₋₃₈) were calculated for the backscatterings. Six types of backscatterings were classified based on the results of net samples and the ΔMVBS₁₂₀₋₃₈. The ΔMVBS₁₂₀₋₃₈ of each group was as follows: copepods 13.7–17.3 dB, krill 11.6–15.3 dB, Japanese anchovy −1.6 to 1.1 dB, a myctophid, Diaphus theta −0.8 dB, sand lance 6.1 dB and larvae and juveniles of pelagic and mesopelagic fish −9.6 to −4.0 dB. The results suggest that biological backscatterings in the Kuroshio-Oyashio inter-frontal zone and subarctic waters of the western North Pacific in spring can be characterized by using ΔMVBS.     

Age and growth of alfonsino Beryx splendens from the Kanto District, central Japan, based on growth increments on otoliths

ABSTRACT:   Age and growth of alfonsino Beryx splendens (Lowe) were studied using counts of presumed daily incremental growth rings on the transverse section of otoliths of fish collected from the Kanto District, central Japan. Microstructural growth increments were observed from the core to the outermost margin of the broadest of approximately 50 branches formed on the surface of an otolith. Of 98 otoliths examined, 46 were readable. The number of increments and fish lengths ranged from 448 (218 mm fork length [FL]) to 3701 (411 mm FL). The ages of these fish were estimated to be 1 year, 2 months and 10 years, 2 months, respectively, assuming that an increment was formed daily. The von Bertalanffy growth equation combined for males and females was expressed as follows: L _t  = 542 {1 −  exp  [−0.133( t  + 2.00)]}, where L _t is fork length (mm) at yearly age t . The results of the present study were compared with those of other researchers who had studied alfonsino from central Japan.     

Effects of entrance design on catch efficiency of arabesque greenling traps: a field experiment in Matsumae, Hokkaido

ABSTRACT:   A field experiment was conducted in the Matsumae area of Hokkaido, Japan, during June and July 2002, to investigate the effects of different entrance designs on the catch efficiency of fish traps by fishing with commercial traps (entrance inclination angle [α] = 37°; funnel length of entrance [ L _f ] = 22 cm) and experimental traps. The experimental traps were of the same size and similar design as commercial traps, with different entrance inclination angles (trap E1: α = 46°; E2: α = 27°; E3: α = 0°; all L _f  = 22 cm) or funnel lengths (E4: α = 37°, L _f  = 8 cm). In total, 2200 fish during 200 trap hauls were captured. The catch was significantly higher using both traps E2 and the commercial trap than with trap E3 ( P  < 0.05), and the catch of trap E2 was higher than that of the commercial trap. There were no significant differences in mean fish body length or the frequency distributions of body length among trap types (E1, E2, E3 and commercial). The funnel length of the entrance also affected the catch of traps. Trap E4 had significantly higher catches than the commercial trap ( P  = 0.04) when traps were deployed for a 1-day soak time. Fish body length frequency distributions did not differ between trap E4 and the commercial trap. The results showed that catch can be greatly affected by trap entrance designs.     

Genetic characterization of a spontaneous green-type pigmentation mutant of Porphyra yezoensis and the significance of using heterozygous conchocelis in nori farming

ABSTRACT: In order to characterize the spontaneous green-type pigmentation mutant of Porphyra yezoensis , growth and contents of photosynthetic pigments were compared with those of the wild type in gametophytic blades. The growth of the green mutant was slower than that of the wild type. The content of phycoerythrin was markedly lower in the green mutant than in the wild type. For genetic analysis, the green mutant was crossed with the wild type. In the cross, the heterozygous conchocelis (the wild-type color) produced many sectored F ₁ gametophytic blades, which were composed of both parental colors. The segregation ratio by counting the wild-type sectors and the green-type sectors of the F ₁ blades was approximately 1 : 1. This suggests that the green mutant is governed by a single recessive gene. All the monospore germlings from the sectored F ₁ gametophytic blades that originated from the heterozygous conchocelis developed into single-colored blades with either the green color or the wild-type color. The advantages of using heterozygous conchocelis (hybrid conchocelis) and monospores from F ₁ gametophytic blades that originated from the heterozygous conchocelis in commercial farming of Porphyra yezoensis are detailed and discussed.     

Kinetics of Nitrogen Excretion by Cultured Flounder Paralichthys olivaceus

This study was undertaken to quantify the rate of nitrogen excretion by the cultured Japanese flounder as a function of body weight and water temperature. Measurements of the did rate of nitrogen excretion for the cultured flounder were made at mean water temperature of about 16, 19, and 23 C. The excretion rate of nilmgen was estimated by adding the nitrogen excreted in the forms of ammonia and urea nitrogens. The diurnal pattern in the excretion rate of nitrogen was governed mainly by the feeding time. The proportions of excreted ammonia to total nitrogen were 77.9% at 16 C, 84.5% at 19 C, and 83.2% at 23 C. The average was 81.9%. The relationship between the body weight and excretion rate of nitrogen ( E_N , mg N/fish per h) is expressed as E_N =α,.W', where α, = nitrogen excretion rate at temperature 0 . The parameter α, is dependent on water temperature, such that α, =α₂₀ Q₀₁^(0–200) where α₂₀= nitrogen excretion rate at 20 C, and Q₀₁, = temperature coefficient. The values of the kinetics parameters for the cultured flounder were found to be γ = 0.57, α₂₀= 0.060, and Q₀₁= 1.12.     

Nutritional evaluation of waste date fruit as partial substitute for soybean meal in practical diets of juvenile Nile tilapia, Oreochromis niloticus L.

The potential of waste date meal (WDM; low-quality date palm, Phoenix dactylifera L.) as a carbohydrate source in formulated diets for Nile tilapia was evaluated. Four isocaloric-practical diets (15.7 kJ g⁻¹) were formulated incorporating WDM at 0, 100, 200 and 300 g kg⁻¹ levels as partial substitutes for soybean meal (SBM). These were designated D₀ [284 g crude protein (CP) and 383 g carbohydrate (CHO) kg⁻¹ diet], D₁ (279 g CP and 446 g CHO kg⁻¹ diet), D₂ (207 g CP and 495 g CHO kg⁻¹ diet) and D₃ (175 g CP and 578 g CHO kg⁻¹ diet). Each diet was fed to three replicate groups of 30 fish [20.20 ± 0.09 g (±SE)] for 75 days. No feed-related mortality was observed during the entire experimental period. Final body weight (FBW) and specific growth rate (SGR) in the different treatments were statistically not significantly different ( P  > 0.05). Protein efficiency rate (PER) was lowest in diet D₀ and increased with decrease of SBM content (D₁–D₃). A significant increase in whole body lipid content was recorded in fish fed diets D₂ and D₃. Results showed that WDM could be a substitute for SBM up to 300 g kg⁻¹ in practical Nile tilapia diets without compromising growth.     

Testing in situ avoidance reaction of vendace, Coregonus albula, in relation to continuous artificial light from stationary vertical split-beam echosounding

Abstract  The in situ avoidance reaction of vendace, Coregonus albula L., in relation to continuous artificial light in terms of a scaring device was tested by split-beam echosounding. The tests were carried out in the mesotrophic Bigge Reservoir (Germany) in November 2007 and 2008 using a Simrad EK 60 echosounder (120 kHz). An underwater lamp with light turned on and off was lowered to 30 m water depth at four sampling sites. No reaction of vendace was observed for the sampled references (light off), but strong avoidance behaviour by swimming mainly downwards was observed when the light was turned on. The light avoidance reaction was confirmed by the volume backscattering strength ( S _v) and calculated fish densities (fish ha⁻¹). The mean fish densities for the samples carried out with light turned on were lower (268 fish ha⁻¹, ±409 SD, n  =   32) than for the references with light turned off (5028 fish ha⁻¹, ±2317 SD, n  =   56). The related median values (33 and 3726 fish ha⁻¹, respectively, n  =   88) differed significantly (Mann–Whitney test, P  = <0.001). In conclusion, artificial light has great potential to scare pelagic vendace from areas near the bottom outlets of reservoirs to prevent entrainment losses.