Final Total Length Research Articles

Rootstocks Modify Scion Architecture, Endogenous Hormones, and Root Growth of Newly Grafted ‘Royal Gala’ Apple Trees

‘Royal Gala’ apple scions (Malus ×domestica) were grafted onto 1-year-old rootstock stools of ‘M.9’ (M.9), ‘M.M.106’ (MM.106), ‘Merton 793’ (M.793), and ‘Royal Gala’ [R.G (control)] to elucidate how the dwarfing apple rootstock (M.9) modified scion architecture, the time from grafting when this started, and whether changes in scion architecture were explained by some endogenous hormones present within the scion. At the end of the first season of growth (April), the final length and node number of the primary shoot were similar for scions on M.9 and R.G. However, M.9 appeared to limit the number of secondary shoots formed on the primary shoot during summer. In addition, the proportion of secondary shoots that were actively extending in fall was lower for M.9; consequently, the final mean length of the secondary shoots was slightly shorter for M.9 compared with R.G. Collectively, these subtle effects of M.9 significantly reduced the final total shoot length of the scion compared with R.G. The final dry weight of the scion and root system was also lower for M.9 than MM.106, M.793, and R.G. The mean rate of indole-3-acetic acid diffusing from the apex of the primary shoot progressively declined from February onward irrespective of rootstock, whereas the mean concentration of zeatin riboside (ZR) in the xylem sap increased during the same period, and these events appeared to coincide with cumulative increases in the number of axillary growing points formed on the scion. Despite this general trend, M.9 had a greater concentration of ZR in the xylem sap during February compared with R.G, but the primary shoot on M.9 did not develop more axillary growing points, indicating that other endogenous hormonal signals were also involved in regulating scion branching. By March, M.9 lowered gibberellin A19 (GA19) concentration in the xylem sap of the scion significantly compared with R.G. We conclude that dwarfing apple rootstocks may limit root-produced GA19 supplied to shoot apices of the scion, where GA19 may be a precursor of bioactive gibberellin A1 required for shoot extension growth.

The effects of continuous photoperiod (24L:0D) on growth of juvenile barramundi (Lates calcarifer)

The efficacy of photoperiod manipulation to influence growth and developmental processes is well documented in a range of temperate aquaculture species. However, the application of such techniques with tropical species requires further investigation. This preliminary 20-day study investigated the influence of continuous photoperiod on growth of barramundi (Lates calcarifer). In addition, diel plasma melatonin profiles provided a physiological measure of how the endocrine system of barramundi responded to continuous photoperiod. Juvenile barramundi (1.33 ± 0.02 g) were held in recirculation systems under 12-h light: 12-h dark (12L:12D) or 24-h light (24L:0D) with a light intensity of 1,000 lux throughout the water column. Fish from both treatments grew to more than 14 times their original weight, with final weight (24L:0D = 21.59 ± 0.85 g; 12L:12D = 19.12 ± 0.55 g), total length (24L:0D = 12.67 ± 0.14 cm; 12L:12D = 11.96 ± 0.13 cm) and specific growth rate (24L:0D = 9.60 ± 0.05% bw day−1; 12L:12D = 9.14 ± 0.06% bw day−1) being significantly higher for fish grown on 24L:0D compared with 12L:12D. There were no significant differences in feed intake (24L:0D = 226.46 ± 6.27 g; 12L:12D = 219.02 ± 5.73 g) or feed conversion ratio (24L:0D = 0.71 ± 0.06; 12L:12D = 0.80 ± 0.07) between light treatments. Barramundi held under 12L:12D exhibited diel melatonin secretion, which peaked mid-dark phase (171.83 ± 4.81 pg ml−1) followed by a gradual decrease in base levels at the onset of illumination (68.61 ± 8.77 pg ml−1). When juvenile barramundi were subjected to 24L:0D, the amplitude of peak melatonin secretion was significantly suppressed during the subjective mid-dark phase (129.71 ± 2.36 pg ml−1). This preliminary study confirmed that barramundi respond to photoperiod manipulation in a similar manner to many temperate fish species, thus demonstrating the future potential use of artificial lighting to improve growth in this species commercially.

A preliminary study on the use of mannan oligosaccharides (MOS) in freshwater crayfish, Astacus leptodactylus Eschscholtz, 1823 juvenile diets

The effects of dietary mannan oligosaccharides (MOS) on the survival and growth of Astacus leptodactylus juveniles were evaluated. Experimental diets were prepared by using supplementation of 0 (Control), 1.5, 3.0, and 4.5 g MOS kg−1 commercial trout larvae diet containing 43 g kg−1 protein and 15.74 g kg−1 lipid. A. leptodactylus juvenile with an average total length of 3.6 ± 0.46 cm (TL) and average weight of 1.25 ± 0.43 g was stocked in 0.2-m2 aquariums at a rate of 50 crayfish/m2 and reared for 60 days at 22.8°C. The experiment consisted of four treatments with three replicates each. Each aquarium contained ten crayfish. Crayfish juvenile fed with 0, 1.5, 3.0, and 4.5 MOS attained 6.15 ± 0.49, 5.94 ± 0.29, 7.34 ± 0.39, and 5.94 ± 0.27 cm final total length and 50, 56.67, 46.67, and 50% survival rates, respectively. Moreover, molting frequencies in 0, 1.5, 3.0, and 4.5 g kg−1 MOS groups were detected as 44.44, 61.11, 83.33, and 38.88%, respectively. At the end of the experiment, a general enhanced growth performance (P 0.05) in percentage moisture, protein, and ash (wet-weight basis) in the tail meat of A. leptodactylus juvenile among treatments (diet) that averaged 82.3, 16.1, and 1.2%, respectively. However, lipid value was significantly different among the diets P < 0.05), with values between 0.13 and 0.32. From the current results, it could be advised to use MOS at the rate of 3.0 g kg−1 in A. leptodactylus juvenile diets.

Culture of Pinfish at Different Stocking Densities and Salinities in Recirculating Aquaculture Systems

AbstractThere is great demand for marine baitfish in U.S. coastal states. The supply of marine baitfish in the United States is almost completely wild caught, and this fishery is seasonal and inconsistent. Aquaculture may be able to consistently supply marine baitfish for anglers. Two experiments were conducted to evaluate the effects of stocking density and salinity on the growth and survival of pinfish Lagodon rhomboides cultured in recirculating aquaculture systems. For the stocking density experiment, juvenile pinfish were stocked (50, 200, 400, and 600 fish/m3) into 1,600‐L circular tanks in three identical recirculating systems with a salinity of 27 g/L and were cultured for 82 d. Mean survival was not statistically different among densities and ranged from 94.3% to 99.18%. Daily growth of pinfish ranged from 0.35 to 0.39 g·fish−1·d−1. Mean percent weight gain ranged from 624% to 690% and followed a density‐dependent trend. Final total length followed a density‐dependent pattern, with each increasing density exhibiting statistically significant decreases in length. Mean feed conversion ratio (FCR) ranged from 1.70 to 1.89. In the salinity experiment, juvenile pinfish were stocked at a density of 120 fish/m3 into 1,600‐L tanks within four identical recirculating systems and were cultured for 65 d. Treatment salinities were 9 or 27 g/L; each salinity level was maintained in two systems. Two size‐classes were stocked separately into two tanks within all four systems, resulting in four replicates per treatment. Mean survival was not significantly different among treatments and ranged from 98.2% to 99.9%. Mean percent weight gain ranged from 234% to 284%, with no significant differences between salinities. Mean FCR ranged from 2.5 to 3.1 and did not significantly differ between salinities, although fish in the small size‐class converted feed more efficiently than those in the large size‐class. Pinfish show great potential as a new aquaculture species and can be successfully cultured in recirculating systems at stocking densities of 600 fish/m3 and at a salinity as low as 9g/L.

Utilização de farinha de silagem de pescado em dietas para o jundiá na fase juvenil

Neste trabalho, foram avaliados o desempenho e o rendimento de carcaça em juvenis de jundiá Rhamdia quelen, alimentados com farinha de silagem química de rejeitos de pescado em substituição à levedura de cana, em dietas à base de ingredientes vegetais (dieta controle). Os 135 animais (peso médio inicial de 48,11±5,54g) foram distribuídos em cinco tratamentos com três repetições ao acaso. Cada unidade de observação foi composta por um tanque circular (1000 litros) abastecido com 200 litros de água, com temperatura controlada, em um sistema fechado de criação contendo nove animais cada. Os peixes foram alimentados durante 75 dias, duas vezes ao dia, na proporção de 10% da biomassa total. Foram testadas dietas contendo: 0, 12,5, 25, 37,5 e 50% de farinha de silagem. Os resultados indicaram um efeito quadrático (P&lt;0,05) da inclusão de farinha de silagem de pescado sobre o peso final, o ganho em peso, o comprimento total e a taxa de crescimento específico. A inclusão de 30- 33%- da farinha de silagem química de rejeitos de pescado na dieta proporcionou melhor desempenho para juvenis de jundiá, não afetando a sobrevivência e a qualidade de água.

Farelo de canola na alimentação de alevinos de carpa-capim (Ctenopharyngodon idella V.)

One hundred fry with 1.33 mean weight and 5.06cm mean length distributed in twenty 50-liter aquarium, with 5 fish each, were used in a completely randomized plotted experiment, with 4 replications, to evaluate the effects of soybean meal (SM) protein replacement by canola meal (CM) protein in diets for grasscarp fry ( Ctenopharyngodon idella V.). Five substitution levels of SM protein by CM protein (0.00%, 20.00%, 40.00%, 60.00% and 80.00%) corresponding to 0.00%, 8.04%, 16.10%, 24.10% and 32.15% diet-included CM were used. Isoproteinic, isocalcic and isophosphoric meals were given during 28 days, while physical and chemical parameters were monitored. The results of the investigation as for performance characteristics revealed that weight gain, relative growth rate, protein efficiency rate, feed conversion, survival rate and cost of diet/kg weight gain were not affected, while final weight (Y=2.39190 + 0.01327X - 0.00019X 2 , r 2 = 0.78), total length (Y= 6.15270 + 0.01195 X - 0.00016X 2 , r 2 = 0.86) and total length increase (Y= 1.10340 + 0.01198 X - 0.00016X 2 , r 2 = 0.86) suffered quadratic effects. Physical and chemical parameters remained within appropriate level range. The substitution level of 35.79% SM protein by CM protein or diet inclusion CM of 14.40% presented the best performance for grasscarp fry.

Comparison of Two Environmental Regimes for Culture of Australian Snapper, Pagrus auratus, Larvae in Commercial‐scale Tanks

Abstract The performance of Australian snapper, Pagrus auratus, larvae from 4 to 33 days posthatch (dph) under two environmental rearing regimes was evaluated in 2000‐L commercial‐scale larval rearing tanks (N = 3 tanks/treatment). The treatments were the following: (1) a varying regime of salinity (20–35 ppt), temperature (24 C), and photoperiod (12 light [L] : 12 dark [D] to swim bladder inflation and then 18L : 06D) and (2) a constant regime of salinity (35 ppt), temperature (21 C), and photoperiod (14L : 10D). The final total length (TL) and wet and dry weights (mean ± SEM) of larvae grown in the varying regime were greater (15.6 ± 0.5 mm; 42.4 ± 3.4 mg wet weight; and 7.3 ± 0.6 mg dry weight) than those of larvae grown in the constant regime (11.1 ± 0.2 mm; 12.9 ± 0.8 mg wet weight; and 2.1 ± 0.2 mg dry weight). By 33 dph, larvae in the varying regime were fully weaned from live feeds to a formulated pellet diet and were suitable for transfer from the hatchery to a nursery facility. In contrast, larvae in the constant regime were not weaned onto a pellet diet and still required live feeds. Neither survival (Treatment 1, 14.2 ± 3.0% and Treatment 2, 13.3 ± 1.9%) nor swim bladder inflation (Treatment 1, 70.0 ± 17.3% and Treatment 2, 70.0 ± 11.5%, by 13 dph) was affected by rearing regime. The incidence of urinary calculi at 7 dph was greatest initially in the varying regime; however, by 19 dph, when larvae were 8.0 ± 0.28 mm TL, very few larvae in this treatment had urinary calculi. In contrast, many larvae in the constant regime had developed urinary calculi and this continued until the end of the experiment. The incidence of urinary calculi was not associated with larval mortality. Extrapolation of the snapper larval growth curves for the constant larval rearing regime predicts that a further 15–18 d, or approximately 1.5 times longer, will be required until these larvae attain the same size and development of larvae reared in the varying regime.

Diferentes fontes protéicas na alimentação de alevinos de curimba (Prochilodus lineatus V.)

Different proteic sources were evaluated for curimba fingerlings ( Prochilodus lineatus ) to check performance and economical viability for fingerlings with an average weight of 10.47 ± 2.11g and a total initial length of 8.85 ± 0.64 cm, distributed in a completely randomized design with four treatments and four replications, in sixteen 1,000L ponds. Soybean meal + fish meal (SM + FM); soybean meal (SM); SM + canola meal (SM + CM) and SM + dry yeast (DY), with inclusion levels of FM, CM and DY of 19.60%, 32.00% and 39.20% respectively, corresponding to 50.55%, 48.19% and 61.30% of crude protein substitution by FM, CM and DY respectively, were used. There were no significant differences (P > 0.01) for survival and ration R$/gain kg between treatments. The fishes fed with SM + FM, SM and SM + CM showed values of final weight and total length with differences between them (P > 0,01), but higher than those that received SM + DY. For weight gain the fishes fed with SM + FC showed values higher than SM + DY, but both treatments did not show differences (P > 0,01) of SM + FM or SM. The proteic efficiency rate and apparent feed conversion of fishes that received SM + DY were lower than (P < 0,01 and P < 0,05 respectively) SM + FM or SM + FC, however SM showed similar values in all treatments. Water temperature was below the recommended one, the pH remained within the adequate levels and electrical conductivity was below the levels that were recorded in ponds. It was concluded that protein sources constituted by SM + FM; SM + CM or only SM provided the best performance however all alternative tested sources may be given to curimba fingerlings

Influence of ration level and rearing temperature on hepatic GHR1 and 2, and hepatic and intestinal TRα and TRβ gene expression in late stages of rainbow trout embryos

The study examined whether the early life‐history temperature experience of rainbow trout Oncorhynchus mykiss embryos affects subsequent growth and expression of growth‐related genes in the growing‐up juveniles in response to variations in ration levels. Embryos were reared in a Heath incubator at either 8·5° C (E8·5) or 6·0° C (E6·0) until hatching, at which time they were transferred to grow‐up tanks supplied with water at 8·5° C. At swim‐up, the late stage embryos were subsequently fed a salmonid starter diet at levels of 5, 2 or 0·5% of live body mass per day. The body mass and proximate composition of the juveniles was examined when yolk absorbance was complete (21 days after the fish commenced feeding). Quantitative RT‐PCR was used to examine the expression of mRNA encoding for growth hormone receptors 1 and 2 (GHR1 and GHR2) in the liver, and the two isoforms of thyroid hormone receptor (TRα and TRβ) in the liver and intestinal tract. Final body mass and total length, liver and intestinal masses, and total lipid content of the E8·5 treatment group were directly related to increased ration size. These variables in the E6·0 treatment group fed the 5% ration were significantly lower than for the comparable E8·5 treatment group, suggesting an effect of embryo rearing temperature on the subsequent growth of these late stage embryos as they undergo the transition from embryo to early juvenile. Intestinal TRα and TRβ mRNA abundance was directly related to ration size in the E8·5 treatment group, but not in the E6·0 treatment group. Conversely, hepatic TRα and TRβ mRNA abundance was significantly affected by ration size only in the E6·0 group, with TRβ and TRα abundance showing direct and inverse relationships with ration size, respectively. Hepatic GHR1 mRNA abundance was significantly and directly related to ration size in both the E8·5 and E6·0 treatment groups, but there were no differences in the abundance of hepatic GHR2 mRNA among any treatments.

Effects of vitamin A palmitate, β-carotene and retinoic acid on the growth and incidence of deformities in larvae of red sea bream Chrysophrys major

The effects of vitamin A palmitate (VAP; 2.7, 27 and 165 mg/100 g diet),&#x0D; β-carotene (βC; 1, 9 and 50 mg/100 g diet) and retinoic acid (RA; 2.8, 28 and 166 mg/100 g diet) on the incidence of deformities in red sea bream (Chrysophrys major) larvae were examined using zein-based micro-bound diets during 15 days. Growth (final body weight, weight gain and total length) and survival rate were affected by the increasing supplementation of these compounds. The abnormalities observed in the larvae included the compression or apparent fusion of the segments in the notochord and mouth deformities. Compression/apparent fusion of the segments was detected mainly in vertebrae of the hemal zone, affecting the total length of larvae. Incidence of these deformities increased with increasing levels of VAP,&#x0D; βC and RA in the diets, but a significantly higher percentage of affected vertebrae was observed in the larvae fed the diets containing RA. The effect of βC was unclear in the present experiment, since only the highest concentration caused significant incidence. The results of this study show that dietary vitamin A may be related to the vertebral deformities in red sea bream larvae.&#x0D;

The influence of dietary protein and energy levels on growth, survival and thyroid hormone (T3 and T4) composition of Lates calcarifer larvae

Two growth trials were conducted to determine the effects of different dietary protein (450–550 g kg−1) and energy contents (18–22 MJ kg−1) on growth, survival and carcass thyroid hormone (T3 and T4) levels of barramundi (Lates calcarifer) larvae. Larvae fed diets containing 21 and 22 MJ kg−1 dietary energy performed consistently better than those fed diets containing 18 and 19 MJ kg−1 dietary energy in terms of final dry weight and total length, while those fed 20 MJ kg−1 had intermediate values for both the parameters. No effects of dietary protein level were discernable from the physical parameters measured; however, larvae fed diets containing the lowest protein and energy combination (450 g kg−1 protein/18 MJ kg−1 energy) had significantly lower carcass T4 levels than larvae in all other treatments, except for those fed the 500 g kg−1 protein/18 MJ kg−1 diet, which had an intermediate value. The results indicate that the optimum diet for L. calcarifer larvae from 14 to 28 days after hatch should contain 500 g kg−1 protein and a minimum of 21 MJ kg−1 dietary energy. Carcass T4 content was influenced by macronutrient inclusion level, and correlated significantly with growth, described by the total length. Reduced T4 levels may indicate a depressed larval status in this species.

Refúgios artificiais coloridos e o desempenho e sobrevivência de alevinos de Leporinus macrocephalus (Garavello &amp; Britsky, 1988)

O presente experimento foi realizado no Laboratório de Aqüicultura da Universidade Estadual de Maringá com o objetivo de avaliar o desempenho e a sobrevivência de alevinos de Leporinus macrocephalus alojados em aquários de vidro com capacidade para 12L, com ou sem refúgios artificiais de diferentes colorações. Foram utilizados 240 alevinos com peso inicial de 0,20 ± 0,06g por um período de 28 dias. Os animais foram distribuídos em um delineamento inteiramente casualizado com seis tratamentos (sem refúgio e com refúgios de cor verde, vermelha, azul, marrom e branca) e quatro repetições. As variáveis analisadas foram peso, comprimento total, sobrevivência, fator de condição e uniformidade do lote. Ao fim do experimento, verificou-se que as variáveis peso, comprimento e fator de condição não diferiram entre os tratamentos com e sem refúgio. Houve maior índice de sobrevivência com a não utilização de refúgio e com refúgios de cor vermelha e verde (P &lt; 0,05) do que quando utilizado o de cor azul. O emprego de refúgios de cor branca proporcionou lotes mais uniformes (P &lt; 0,05) do que os refúgios de cor marrom e verde. Portanto, ao se utilizarem refúgios coloridos no cultivo de piavuçu, recomenda-se preferencialmente as cores brancas e vermelhas, cujos resultados foram satisfatórios e semelhantes ao tratamento sem refúgio.

Farinha de vísceras de aves em rações para a tilápia do Nilo (Oreochromis niloticus L.) durante a fase de reversão sexual

Neste trabalho, objetivou-se avaliar o desempenho, a sobrevivência e a efetividade de reversão de larvas de tilápia do Nilo (Oreochromis niloticus L.) alimentadas com rações contendo níveis crescentes de inclusão de farinha de vísceras de aves (FVA). Utilizou-se 500 larvas de tilápia do Nilo com dois dias de idade, distribuídas em um delineamento inteiramente casualizado com cinco tratamentos e cinco repetições, sendo a unidade experimental constituída por um aquário de 30 L com 20 larvas. Foram elaboradas cinco rações com cinco níveis de inclusão de FVA ( 0; 20; 40, 60% e 60% mais lisina sintética). Foram elaboradas rações isocalóricas, isocálcicas, isofosfóricas e isoprotéicas, com 60mg de a-metiltestosterona/kg, 38,6% de proteína digestível e 3.700 kcal de energia digestível/kg, de modo que a ração com inclusão de lisina foi isoaminoacídica para lisina em relação à ração sem a inclusão de FVA. O arraçoamento foi realizado quatro vezes ao dia, ad libitum. Ao final, foram avaliadas as médias de peso final (PF), comprimento total (CT), sobrevivência (SO) e efetividade de reversão (ER). Foi observado aumento linear no PF e CT com o aumento da inclusão da FVA na ração, enquanto, para SO, a ração sem FVA foi inferior às demais. As rações sem inclusão de FVA e com 20% de inclusão de lisina proporcionaram PF e CT médios inferiores e somente a ração sem FVA foi inferior para SO. Conclui-se que a FVA pode ser utilizada em rações para a tilápia do Nilo durante a reversão sexual.

Embryonic and larval development of striped sea bream (Lithognathus mormyrus L 1758)

Development of the embryonic and yolk-sac larvae of striped sea bream (Lithognathus mormyrus) was investigated. The average egg and oil globule diameters were 0.71±0.1286 mm and 0.18±0.1344 mm, respectively. The morula, gastrula, and neurula stages, somite formation, and hatching occurred 2:10, 5:15, 8:45, 9:45, and 21:15 hours after fertilization. The total length, yolk- sac volume, oil globule volume, digestive tube length, otolith diameter, head length, eye diameter, preanal and postanal lengths of newly hatched larvae were 1.74±0.03 mm, 0.12±0.008 mm3, 0.003±0.0002 mm3, 0.47±0.02 mm, 54±8 μm, 299±11 μm, 157±8 μm, 911±0.3 μm, and 827±0.03 μm. When the mouth opened 40 h after hatching, these measurements were 2.87±0.014 mm, 0.003±0.001 mm3, 0.001±0.0001 mm3, 0.61±0.015 mm, 134±8 μm, 376±10 μm, 221±13 μm, 1.02±0.03 mm, and 1.84±0.03 mm. During the first 18 hours, the larvae reached 84% of its final total length, the yolk sac was 65% absorbed, and the oil globule was 62% absorbed. Statistical analysis showed negative allometry for the relationships between total length and yolk-sac volume (r2 = 0.88) and total length and oil globule volume (r2 = 0.76), and positive allometry for the relation- ship between total length and digestive tube length (r2 = 0.89).

Dietary l-tryptophan and tank colour effects on growth performance of rainbow trout ( Oncorhynchus mykiss) juveniles reared in a recirculating water system

The aim of the present study was to evaluate the possible anti-stressful effect of dietary tryptophan supplementation on growth of juvenile rainbow trout ( Oncorhynchus mykiss) reared in different background colour using recirculating water system. Therefore, rainbow trout (4.7 g ± 0.02) were reared for 11 weeks in black, light blue and white tanks and fed either a commercial diet (CD) or the same diet supplemented with tryptophan (2 g 100 g −1 diet). Rearing in black tanks led to reduced final weight and total length, lower food consumption, food conversion ratio and body protein, while no differences were observed between fish reared in light blue or white tanks. Feeding the fish tryptophan supplemented diet resulted in depressed growth, increased food consumption and food conversion ratio, decreased body protein and increased body lipid, reduced liver total lipids and a marked increase in hepatosomatic index (least in fish reared in white tanks). It is concluded that rearing on a black background was stressful for rainbow trout juveniles, while the dietary level of tryptophan used failed as a stress-releasing factor and probably evoked an amino acid imbalance.

Growth, survival, haemolymph osmolality and organosomatic indices of the western king prawn (Penaeus latisulcatus Kishinouye, 1896) reared at different salinities

The growth, survival, haemolymph osmolality and organosomatic indices of the western king prawn, Penaeus latisulcatus, (2.95±0.26 g mean initial weight), were measured when reared at 10, 22, 34 and 46 ppt salinity for 60 days. Mean final weight, total length and specific growth rate (SGR) of the prawns were highest at 34 ppt. Rearing at different salinities did not alter moult increments and intermoult periods of the prawns. One hundred percent mortalities were observed at 10 ppt.Survival was highest at 22 ppt and food conversion ratios were significantly lowest (P<0.0.5) in prawns cultured at 22 and 34 ppt. Haemolymph osmolality increased with the increase in medium salinity and physiological age of the prawns. Isosmotic points calculated from regression between haemolymph and medium osmolality were 28.87, 29.46 and 31.73 ppt at 0, 20 and 60 days of culture, when body weights were 2.95±0.26, 4.02±0.47, 5.79±0.64 g respectively. After 60 days of culturing, hepatopancreatic moisture levels increased with the increase in salinity, whereas tail moisture levels remained unchanged. Wet and dry hepatosomatic indices were highest at 22 ppt. Wet tail muscle index was highest at 34 ppt, whereas dry tail muscle index did not change by any salinity levels. The results suggest that the optimum salinity range for rearing western king prawns ranges from 22 to 34 ppt and 10 ppt was unsuitable for culture.

Design, Analysis, Manufacture, and Test of Shallow Water Pressure Vessels Using E-Glass/Epoxy Woven Composite Material for a Semi-Autonomous Underwater Vehicle

Six E-glass/Epoxy shallow water composite pressure vessels with effective length of 45.72 cm and inner diameter of 33.02 cm were designed, analyzed, manufactured, and tested for an external hydrostatic design pressure of 1.14 MPa that corresponds to a depth of 91m in ocean. Composite pressure vessels were designed as composite cylinders fabricated by roll-wrapping and enclosed by two flat plug-supported end-caps due to their ease of manufacturing and cost-effectiveness. The plug-supported end-caps had a combination of tapered contour and initial radial clearance to account for bending and shear stresses in composite cylinders at the end-cap locations. Buckling and stress finite element analyses were performed for the design of the pressure vessels. An eigenvalue buckling analysis was performed to determine a bifurcation buckling pressure (2.51MPa) and a modal shape of the structure for a wall-thickness of 7.72 mm based on 32 layers of 0.2413 mm thick each. These results were then used to perform a nonlinear buckling analysis. The nonlinear buckling pressure was determined to be 1.42 MPa yielding a buckling pressure factor of safety of 1.25. Stress analysis was performed to investigate the stress response of the structure with the wall-thickness of 7.72 mm under the design pressure. Maximum stress and strain criteria were used and stress and strain factor of safety of 11.95 and 17.17 were achieved, respectively. The composite pressure vessels were made of plain weave E-glass/Epoxy fabric. A comparative study of various materials property modeling for woven materials was performed and reported in this work. The three-dimensional Crimp model was explained and employed in this investigation to model the effective properties of a woven composite material, and the results were compared with other existing models. In addition, general guidelines to model the effective properties of woven hybrid materials are also provided. Tube roll-wrapping with wet-laying technique was used to fabricate the pressure vessels. This technique consisted of several steps, namely set-up preparation, fabric impregnation, fabric rolling, shrink taping, curing and cooling, and post-processing. The total time of manufacturing was 7 h for each pressure vessel. The final products needed minor machining. The final total length, inner diameter, and thickness of the manufactured pressure vessels were 49.53 cm, 33.02 cm, and 8.23 mm, based on 32 cured layers, respectively. An average fiber volume fraction of 55% and an average porosity content of 5% was achieved. The fiber waviness due to the fiber migration during the manufacturing under the cylinder compaction was in the order of the waviness of the woven material due to its weave undulation. End-caps were designed using Aluminum 6061-T6 employing Von Mises criterion. The end-caps have seven holes, which are used to place the connectors and a vacuum bolt. The stress factor of safety of 4.2 was achieved for the end-caps. Aluminum 6061-T6 end-caps with 2.9 cm thickness were fabricated. An axial washer and two radial O-rings were used to seal the pressure vessel/end-caps interfaces. The pressure vessels and end-caps were assembled using six tie-rods. Six pressure vessels were tested at the external hydrostatic design pressure of 1.14 MPa inside a high-pressure water-filled chamber. The pressure vessels were intact and no leakage was observed. The pressure vessels were strain gauged during the testing to compare the experimental and finite element analysis results of axial and hoop strains at the mid-length as well as the vicinity of the end-caps for composite cylinders, and excellent agreements were achieved.

Influence of the larval rearing technique on morphological and productive traits of European sea bass (Dicentrarchus labrax L.)

The productive performances and morphological traits of 60 000 Dicentrarchus labrax L. weighing 2.4 ± 0.6 g and obtained from intensive rearing were compared with 60 000 sea bass of the same age (110-day-old) weighing 2.1 ± 0.7 g obtained from a fish farm using the mesocosm technique during the larval phase. The trial lasted throughout the fattening period until harvest. Fish from the mesocosm system (SB-II) had a better final survival rate (69%) in comparison to those obtained from the intensive larval system (64.2%) (SB-I). No significant differences emerged between the two groups concerning the specific growth rate (SGR) or the feed conversion ratio (FCR). Although the weights were the same as the SB-I group, the final total length result was higher in the SB-II group (P < 0.0001). As for the other morphological traits, the standard length was significantly higher in the SB-II fish, while the maximum body depth showed similar values in the two batches. The greatest abdominal circumference was recorded in SB-I fish.

An Evaluation of Six Internal Anchor Tags for Tagging Juvenile Striped Bass

Abstract Six types of internal anchor tags were compared for retention, legibility, and durability in tagging juvenile (age-0) striped bass Morone saxatilis. Tank-reared striped bass (120–200 mm total length) were tagged with coded wire tags and one of six types of internal anchor tags (500 fish each tag type and two groups of controls). The types of internal anchor tags used were as follows: Floy streamer FM-84 (currently in use by the U. S. Fish and Wildlife Service); Floy streamer with protective sheath (modified FM-84), Floy streamer with a monofilament leader and sheath (FM-89SL), modified Hallprint T687, Hallprint monofilament IEX WAD, and Hallprint T-bar IEX NOR. The Hallprint T-bar IEX NOR and the Floy FM-84 tags caused significantly higher 2-week and 6-month mortality. Final fish total length was different among tag types and tagger groups; however, final fish size was not correlated with either variable after adjusting for initial fish size. Tags were also mounted on polyvinyl chloride pipes and...

Effects of salinity and dietary DHA (22:6 n - 3) content on lipid composition and performance of Penaeus kerathurus postlarvae

A two-way ANOVA experiment was designed to study the effects of salinity and dietary docosahexaenoic acid (DHA; 22:6n-3) on lipid composition and performance of postlarvae from the marine shrimp Penaeus kerathurus (Forskal, 1775). Shrimp were reared from 1- to 8-d-old postlarvae at 35 and 25‰S with Kelko-enriched Artemia sp. [20.0 μg (n-3) HUFA mg−1 dry weight; 9.1 μg DHA mg−1 dry weight] and nonenriched Artemia sp. [14.2 μg (n-3) HUFA mg−1 dry weight; 0.3 μg DHA mg−1 dry weight]. Dietary DHA content did not affect either total length or survival but influenced the nutritional status represented by condition indices (triacylglycerol/total polar lipid and triacylglycerol/free cholesterol) of 8-d-old postlarvae at the end of the experiment. Culture salinity affected final total length and condition indices but did not show any effect on survival in the different experimental treatments. The interaction of dietary DHA and culture salinity was not significant for total length and survival but was significant for both condition indices used. P. kerathurus 8-d-old postlarvae showed better growth, survival and nutritional condition when reared at 35‰S and when fed on Kelko-enriched Artemia sp., but the differences with postlarvae from other treatments were very poorly marked. The results demonstrate that 8-d-old postlarvae may have sufficiently developed osmoregulatory capabilities to resist 25‰S under good conditions, although (n-3) HUFA-enriched diets may also enhance osmotic stress resistance, general performance and disease resistance.