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).     

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.     

Growth and mortality of the narrowbarred Spanish Mackerel, Scomberomorus commerson (Lacepède), in Omani waters

Length composition data from quarterly catches of Omani narrowband Spanish mackerel, Scomberomorus commerson (Lacepède), landed between 1987 and 1995 were used to estimate the growth, mortality and exploitation parameters of the stock. Non-linear least square fitting provided a complete set of von Bertalanffy growth estimates: L _∞ = 173.6 cm fork length; K  = 0.28; and t ₀ = −0.86 years. There were no seasonal differences among the growth estimates. The instantaneous natural mortalities determined by three independent methods based on life-history parameters were 0.35, 0.64 and 0.77. Seasonal total mortalities were calculated by the length converted catch curve method for evaluating seasonal exploitation ratios ( E ). The E -values exceeded 0.4, indicating overexploitation during almost all the seasons studied. This was supported by the large reduction in the total landings of S . commerson from 27 762 t in 1988 to 3265 t in 1993.     

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.     

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.     

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 .     

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.     

Use of stable isotopes to distinguish farmed from wild Atlantic salmon, Salmo salar

Abstract –  Stable isotopes of carbon and nitrogen ( δ ¹³C and δ ¹⁵N) were examined in wild and aquaculture origin Atlantic salmon, Salmo salar , to evaluate their utility to identify escaped farmed fish. Samples of muscle tissue obtained from wild Conne River, Newfoundland, salmon were significantly more enriched in nitrogen ( δ ¹⁵N: mean = 12.75; SD ± 0.38‰) but depleted in lipid corrected carbon ( δ ¹³C': mean = −20.51; SD ± 0.23‰) by comparison with aquaculture specimens obtained from Bay d'Espoir, Newfoundland ( δ ¹⁵N = 10.96 ± 0.19‰;  δ ¹³C' = −19.25 ± 0.17‰) resulting in a complete separation of the two groups. Aquaculture specimens differed in δ ¹³C' from analyses of commercial salmon diet by 0.24‰, within the enrichment range associated with trophic transfers, while the δ ¹⁵N values in salmon muscle were enriched by 5.01‰. Although differences occurred in direct comparisons of white muscle and adipose tissue ( N  = 49), the average δ ¹³C' and δ ¹⁵N signatures varied in absolute amounts by only 0.5‰, supporting the use of adipose tissue as a nonlethal means to determine isotopic signatures of Atlantic salmon.     

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.     

Age,growth and maturation of the redbelly tilapia <Emphasis Type="Italic">Tilapia zillii</Emphasis> introduced into the Haebaru Reservoir on Okinawa-jima Island

ABSTRACT:   The age, growth and maturation of the redbelly tilapia Tilapia zillii introduced into the Haebaru Reservoir on Okinawa-jima Island were studied using 2197 specimens ranging from 7.3 to 168.0 mm standard length (SL). The spawning season was estimated to be from April to August, with a peak in April and May. The first maturation sizes of females and males were estimated to be 38.1 and 33.0 mm SL, respectively. The opaque zones in otoliths that form annually were found to correlate with the spawning season. Maximum ages of females and males were 7 and 6 years, respectively. The von Bertalanffy growth formulae were expressed as: L _t  = 99{1 − exp[−0.67( t  + 0.09)]} for females and L _t  = 155{1 − exp [−0.36( t  + 0.12)]} for males. Males grew to be larger than females from the first year onward. Populations of this species are characterized by early maturation life history parameters and are thought to adapt and become established quickly after being released into new water systems. Furthermore, extermination activity in winter is thought to be an effective strategy before the newly recruited fish begin breeding in the warmer months.     

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 surgically implanted dummy ultrasonic transmitters on physiological response of bighead carp Hypophthalmichthys nobilis

The study assessed the effects of surgically implanted dummy ultrasonic transmitters on physiological response of bighead carp Hypophthalmichthys nobilis in April 2011. Before the surgery, 15 blood samples were extracted randomly from 195 bighead carp samples, and then the rest of the fish were divided into three groups: (1) control group, handing but no tagging, (2) sham group, surgical procedure without implantation of transmitter and (3) surgery group, surgical implantation of transmitters. In 3 h, 24 h, 7 days and 14 days after surgery, 15 fish were extracted randomly from the three groups, respectively, for sampling. Then the plasma samples were analyzed, and physiological measures of stress response (cortisol, glucose), tissue damage [alanine aminotransferase (ALT) and aspartate aminotransferase (AST)] and nutritional status [total protein, globulin, albumin, triglyceride, cholesterol, and alkaline phosphatase (ALP)] were compared. The result showed that there was no significant difference between sham and surgery groups in 3 h, 24 h, 7 days and 14 days after surgery. When compared to the control group, there were significant increases in concentrations of plasma cortisol, glucose, ALT, AST, total protein and globulin of sham and surgery groups in 3 h after surgery. After 24 h, the levels of plasma cortisol, ALT, AST, total protein, globulin and ALP were elevated in both sham and surgery groups, whereas the levels of plasma glucose had declined to normal level and plasma albumin, cholesterol and triglyceride were significantly decreased in both sham and surgery groups. After 7 days, the levels of plasma glucose, albumin and cholesterol continued to decline, while the level of plasma ALT, globulin and ALP had declined but still remained higher for sham and surgery groups than control group; however, the plasma total protein level had returned to normal. After 14 days, there was no significant difference between the three groups. The above results showed that surgical implantation of ultrasonic transmitters had indeed caused significantly negative effects on the physiological response of bighead carp. However, all the negative influences on stress response, tissue damage and nutritional status had disappeared in 14 days after surgery, and the presence of transmitters had no significant negative impact. Therefore, the bighead carp should be temporary cultured at least 14 days for the recovery of physiological response and then released into the free water for the ultrasonic telemetry research.     

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.     

Post-release mortality of bonefish, Albula vulpes, exposed to different handling practices during catch-and-release angling in Eleuthera, The Bahamas

Abstract  Bonefish, Albula spp., are popular sportfish that inhabit shallow nearshore environments in tropical and subtropical seas. Although catch and release is a common voluntary practice for anglers seeking bonefish, the post-release fate of bonefish is poorly understood. Gastrically implanted acoustic transmitters were used to assess the short-term (<48 h) and long-term (>48 h) post-release mortality of bonefish, Albula vulpes (Linnaeus), in Eleuthera, The Bahamas, subjected to gentle handling (quick retrieval, 0–15 s of air exposure and brief handling time) or rough handling (longer retrieval, 30–60 s of air exposure and extended handling time). Of the 12 fish captured and released, one was preyed upon by two lemon sharks, Negaprion brevirostris (Poey), within the first hour post-release, and this fish was handled roughly. The transmitter from another bonefish was found on the substratum 2 days post-release near the site at which the fish was originally caught. Of the remaining 10 fish, all were tracked and alive for at least 13 days and up to 24 days, suggesting that the negative impacts of catch-and-release angling that lead to mortality for bonefish likely occur within minutes post-release.     

Effects of radio-transmitter antenna length on swimming performance of juvenile rainbow trout

Abstract –  Technological advances have lead to the production of micro radio-transmitters capable of being implanted in fish as small as c . 5 g. Although the actual tags are small, transmitters are equipped with long antennas that can increase drag and tangle in debris. We examined the effects of radio-transmitter antenna length on the swimming performance of juvenile rainbow trout, Oncorhynchus mykiss , ( N  = 156, mean mass = 34 g, mean fork length = 148 mm). Although we tested a variety of different antenna lengths up to a maximum of 300 mm, only the longest antenna significantly impaired swimming performance relative to control fish ( P  < 0.001). There was no difference in swimming performance between the sham (surgery, but no transmitter) and the control fish (handled, but no surgery), suggesting that the surgical procedure itself did not negatively affect the fish. Regression analysis, however, indicated that there was a significant decrease in swimming performance associated with increased antenna length ( R ² = 0.11, P  < 0.001). In addition, when held in laboratory tanks, fish with the three longest antennas (150, 225 and 300 mm) frequently became entangled with the standpipe. We suggest that researchers, under the guidance of the tag manufacturer, trim antennas to the shortest possible length required to detect fish in their specific study area. Antenna length is clearly an important issue for small fish, especially for species that inhabit complex habitats where antennas may become entangled, and where fish must attain speeds near limits of their swimming capacity.     

Qualitative and quantitative changes of F<Subscript>o</Subscript>F<Subscript>1</Subscript>-ATPase in Japanese flounder and red sea bream associated with rearing temperatures

ABSTRACT:   Fast skeletal muscles of Japanese flounder Paralichthys olivaceus and red sea bream Pagrus major were examined for quantitative and qualitative changes of mitochondrial ATP synthase (F_oF₁-ATPase) in association with rearing temperatures. The specific activities of F_oF₁-ATPase from Japanese flounder reared at 10°C, 15°C and 25°C for 4 weeks were determined to be 81 ± 11, 74 ± 13 and 83 ± 11 nmol/min·mg mitochondrial protein, respectively. The corresponding activity from red sea bream reared at 8°C for 5 weeks was determined to be 65 ± 9 nmol/min·mg mitochondrial protein, which was higher than 33 ± 9 nmol/min·mg mitochondrial protein in fish reared at 23°C. The contents of α- and β-F₁-ATPase in total mitochondrial proteins were not significantly different between fish reared at different temperatures for the two fish species. However, the contents of β-F₁-ATPase in the total fast skeletal muscle extracts, prepared from Japanese flounder reared at 10°C, were 2.1- and 2.9-fold higher than those for fish reared at 15°C and 25°C, respectively. The corresponding content from red seabream reared at 8°C was 2.2-fold higher than that for fish reared at 23°C. Therefore, the changes in F_oF₁-ATPase depending on rearing temperatures were species-specific.     

Comparative efficacy of MS-222 and benzocaine as anaesthetics under simulated transport conditions of a tropical ornamental fish Puntius filamentosus (Valenciennes)

There is a growing commercial interest in the fish, Puntius filamentosus , in the ornamental fish trade in India and elsewhere. The trade is, however, hampered by severe mortalities during transport of the fish owing to insufficient data available on the use of anaesthetics. To resolve this problem, we evaluated the efficacy of two anaesthetics, MS-222 and benzocaine, in sedating P. filamentosus in simulated transportation experiments and used stress response parameters such as cortisol and blood glucose levels to perform assessments. We observed that MS-222 at 40 mg L⁻¹ and benzocaine at 20 mg L⁻¹ were sufficient to induce sedation for 48 h. Above these concentrations, both the anaesthetics adversely affected the fish and resulted in mortalities. Both anaesthetics significantly lowered the blood cortisol and glucose levels compared with the unsedated controls. Importantly, the anaesthetics treatment significantly lowered the post-transport mortality in the fish. The results of the study show that MS-222 and benzocaine could be used as sedatives to alleviate transport-related stress in P. filamentosus to improve their post-transport survival and hence reduce economic loss.     

Age, growth and reproductive characteristics of round scad Decapterus maruadsi in the waters off west Kyushu, the east China Sea

ABSTRACT:   The purpose of this study was to determine the growth and reproductive characteristics of round scad Decapterus maruadsi in the East China Sea. The characteristics regarding growth and reproduction of round scad based on otolith reading and gonad histology, respectively, were estimated. The von Bertalanffy's growth model for round scad was estimated as follows:
FL _t  = 342[1 − exp{−0.55( t  + 0.58)}], (1 <  t  < 7)
where FL _t is fork length (mm) at age in years t . The maturation stage of the ovary was observed by histological techniques. June was the main spawning period; the maturation and migratory nucleus stage of the oocyte was observed when the gonad somatic index value was approximately greater than 4.     

Growth and mortality of the catfish, Hemisynodontis membranaceus (Geoffroy St. Hilaire), in the northern arm of Lake Volta, Ghana

Estimates of growth and mortality of the catfish, Hemisynodontis membranaceus (Geoffroy St. Hilaire), in Lake Volta were obtained from length composition data compiled in 1995 and 1996. The von Bertalanffy growth function (VBGF) estimates were: L _∞=44.5 cm standard length; K= 0.62 year⁻¹; and t ₀=−0.23 years. Natural mortality rate, M , was 1.20 year⁻¹. Total mortality rate, Z , was computed as 4.39 year⁻¹ and the exploitation ratio ( E = F / Z ) was 0.72. Although the fish is estimated to have longevity of about 5 years, those exploited are normally less than 2 years of age, which is indicative of growth over-fishing. In order to arrest over-exploitation of the species, there is a need to establish 'lake reserves'. In addition, the fisheries management should be devolved from the state to the local level to compel fishermen to take greater responsibility for the sustainability and conservation of the fisheries.     

Linear models to predict the digestible lipid content of fish diets

Values for the digestible contents of nutrients in diets and feed ingredients are of utmost importance in nutritional strategies for fish. Prediction from dietary composition would eliminate lengthy, tedious and demanding digestibility experiments with fish. Apparent digestible lipid (DL) content [range 7.6–353.4 g kg⁻¹ dry matter (DM)] in compound diets can be predicted with high accuracy ( n  = 610; studies =127; fish species = 34; R ² = 0.9515; RMSE = 16.9504) from dietary crude lipid (CL) content (range 12.0–388.7 g kg⁻¹ DM) by the linear regression equation DL =−2.7303 + 0.9123 CL. Validation of this equation against 65 values from 15 independent studies presented R ² and mean prediction error (MPE) values of 0.9947 and 0.0671, respectively. The corresponding equation for 37 individual feed ingredients evaluated in 24 studies with 18 fish species ( n  = 180) was found to be DL = −1.5824 + 0.8654 CL ( R ² = 0.9717; RMSE = 8.3765). However, validation of the latter is currently hampered by a lack of independent values.