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1.
In order to study the possible interactive effects of salinity and photoperiod on growth, feed conversion, and blood chemistry in juvenile halibut, 2,604 (initial mean weight 26.8 g ± 0.2 SEM) juvenile halibut were exposed to six different combinations of salinities (13, 21, or 27‰) and photoperiods [continuous light, C and simulated natural photoperiod (65°N), SNP] for 129 days. Improved (10–20%) growth and 10–24% higher feed conversion efficiency were observed at low and intermediate salinities compared to the high salinity groups. Improved feed conversion efficiency (20%) and temporary growth enhancing effects (10%) of continuous light were observed, but effects faded out as day length in the simulated natural photoperiod group increased. No interactive effects of photoperiod and salinity on growth feed conversion or measured blood chemistry variables (blood sodium, pH level, haematocrit, bicarbonate content, and total carbon dioxide). It is suggested that juvenile Atlantic halibut should be reared at low and intermediate salinities and at continuous light, as this will improve growth and increase feed conversion efficiency.  相似文献   

2.
The aim of the present study was to investigate the effects of different salinities (0‰, 6‰ and 12‰) and temperatures (23, 27 and 31 °C) on the food consumption, growth, blood biochemistry and haematocrit of Goldfish. After 45 days of exposure to different salinities and temperatures, Goldfish showed a good adaptation to these salinities and temperatures in terms of blood biochemistry (glucose and triglyceride) and haematocrit. Salinities (0‰ and 6‰) and temperatures (23 and 27 °C) did not affect the weight gain, specific growth rate, final biomass and feed conversion rates, but these parameters were significant (P<0.05) at 12‰ salinity and 31 °C temperature. Plasma total protein levels decreased with the increase in salinity (P<0.05), while they were independent of temperature. In conclusion, Carassius auratus, a freshwater stenohaline fish, showed good growth in saline waters with maximum 12‰ salinity and 31 °C temperature.  相似文献   

3.
We studied the effects of salinity on survival, growth, food conversion efficiency and plasma osmolality of juvenile Siganus guttatus in two independent experiments. In the first experiment, fish were transferred from 30 ‰ salinity to freshwater, 5, 10, 20 and 30 ‰ salinities for 192 h. No fish died when transferred directly from 30 ‰ to salinities >5 ‰. However, all fish died in the freshwater treatment. In the second experiment, survival, growth, feeding rate, food conversion efficiency and plasma osmolality of fish were analyzed during 6 weeks in salinities of 5, 10, 20 and 30 ‰ (control). At the end of this experiment, the final weight and the specific growth rate of fish were significantly greater at 10 ‰ than fish in all other treatments. Feeding rate increased significantly with decreasing salinity: 10 ‰ > 20 ‰ > 30 ‰. However, the food conversion efficiency was not significantly different between fish in any treatment. Plasma osmolality of fish in 20 and 30 ‰ salinity was significantly greater than fish reared at 10 or 5 ‰. A salinity of 13.95 ‰ (411.88 mOsmol/kg) was the point of isosmolality for juvenile S. guttatus.  相似文献   

4.
The giant freshwater prawn, Macrobrachium rosenbergii, is a species with a high commercial value in aquaculture. Two experiments were performed to determine the effects of salinities on the osmoregulation, growth and molting cycles of M. rosenbergii during growout. The first experiment was designed to determine whether these animals are capable of adapting to the changes in salinity seen in salinity intrusions in tropical deltas, with an incremental increase in salinity of 3‰ per day from 0‰ to 30‰ Haemolymph osmolality was rapidly regulated up to salinities of 15‰ , whereas animals conformed at higher salinities. The second experiment determined the growth, moulting cycle, osmolality, muscle water content and mortality during a 4‐month experiment at 0‰, 15‰ or 25‰ salinity. The weight gains in 0‰ and 15‰ were not significantly different and were comparable to the growth rates achieved in production farms with body mass increases of 2.6 and 2.3‐fold their initial body mass, respectively, after 4 months. The 25‰ group suffered from low growth, high mortality and a significantly lower moulting frequency. These data show that this species can be reared in brackish water up to 15‰, allowing for farming in the large areas impacted by salt water intrusions in tropical deltas.  相似文献   

5.
Salinity has been proven to have a significant effect on the growth and survival of anadromous fish species; however, there is a paucity of information regarding its effect on euryhaline marine species. Experiments were conducted to examine the effect of hyposalinity on the osmoregulation and growth of juvenile spotted grunter, Pomadasys commersonnii (Lacépède). Although the spotted grunter is considered to be a strong osmoregulator, growth performance and survival was compromised below isosmotic concentrations. The growth rate, condition and food conversion of fish in low salinity (5‰) were lower than in either isosmotic (12‰) or hyperosmotic (25‰ and 35‰) conditions. Mortality was also significantly higher at 5‰. From these results, it is concluded that P. commersonnii can be successfully cultured in salinities ranging from 12‰ to full-strength sea water (35‰).  相似文献   

6.
The Brazilian flounder, Paralichthys orbignyanus, is a promising candidate for aquaculture, especially due to the euryhalinity demonstrated experimentally for large juveniles (3 g) and sub-adults. Flounder are observed in estuaries and were already reared in fresh and salt water, however little is known with respect of salinity tolerance during their early development. The objective of this work was to evaluate the effects of salinity from fertilization to juvenile settlement. Three experiments were conducted to evaluate the effects of salinity. In trial 1 adult flounder were captured in the wild, transferred to the laboratory and induced to spawn. The gametes were hand striped, split in four samples and fertilized with water at 10, 15, 25, and 35‰. Eggs were considered fertilized when the first cell divisions were observed under the microscope. For the trial 2 newly hatched larvae were reared in four salinities (5, 10, 20, and 30‰) and their growth and survival were observed until metamorphosis. In trial 3 larvae and juvenile of different ages (6, 16, 30, 45, and 60 dah — days after hatching) were evaluated for their tolerance to fresh water. Although the fertilization rate was directly proportional to salinity, hatching was successful only in full salt water. Larvae did not survive in low salinity water (5‰) longer than 6 days, whereas growth was improved when larvae were reared at 20 and 30‰. Young larvae cannot survive in salinities below 4‰, but at 30 dah juvenile presented 100% survival in fresh water. The present findings demonstrate the need for high salinity water (30–35‰) for the successful reproduction and incubation of P. orbignyanus eggs. Flounder can be reared successfully at intermediate salinities (20‰) during larviculture, but at lower salinities (5 and 10‰) their survival and growth are impaired. However, immediately after flounder metamorphose into juveniles they survive even in fresh water, demonstrating the strong euryhalinity of this species even at early stages of development.  相似文献   

7.
To investigate the interactive effects of temperature and photoperiod on the growth performance, feeding parameters and muscle growth dynamics in juvenile Atlantic halibut (Hippoglossus hippoglossus L.), a total of 1212 juvenile halibut, including 383 tagged fish (mean initial weight of tagged individuals: 17.6 ± 0.3 g SE), were reared under a simulated natural light regime for Bergen (60°25′N) or continuous light at 9, 12 and 15 °C from 3 December 2007 until 11 March 2008. The mean weight and growth rate were significantly higher at 12 and 15 °C than at 9 °C. In addition, significantly higher mean weight and growth rate were observed in halibut reared under continuous light at a low temperature, indicating an interactive effect of temperature and photoperiod on growth performance. No effect of temperature or photoperiod was found with respect to feed conversion efficiency, whereas a higher feed consumption at increasing temperature and a higher overall daily feeding rate at continuous light at a low temperature were observed. Indications of continuous light having a stronger effect at low temperatures on muscle growth dynamics were found. A difference in the size class distribution of fibre diameter was found between photoperiod treatments at 9 °C, suggesting that continuous light resulted in elevated hypertrophic growth at low temperature. This may suggest that the increased growth rate found at continuous light at 9 °C may be a result of hypertrophic growth in juvenile halibut.  相似文献   

8.
Effects of salinity on the growth, survival, superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX) and sodium‐potassium adenosine triphosphatase (Na+K+‐ATPase) activities of juvenile golden pompano Trachinotus ovatus were studied under a laboratory condition. Experimental fish were reared at the salinities of 10‰, 18‰, 26‰ and 34‰ for 30 days. Growth and survival of juvenile golden pompano were significantly affected by the rearing salinity. Fish reared at 34‰ achieved the highest specific growth rate, while the highest survival was obtained when fish were cultured at the salinity of 26‰. The highest GPX activity was obtained when fish were cultured at 26‰, and the lowest GPX activity was observed when fish reared at 34‰ salinity. The SOD activities of fish reared at 18‰ and 34‰ were significantly higher than those reared at 10‰ and 26‰. The lowest of Na+K+‐ATPase activity was obtained in fish reared at 34‰, while the highest Na+K+‐ATPase activity was obtained when fish reared at 18‰. Results from present study indicate that juvenile golden pompano can be reared above 18‰ without sacrificing fish survival, and the best growth can be achieved when fish is reared at the salinity of 34‰. The salinity of 10‰ may be too low for juvenile golden pompano as the growth, survival and SOD activity were reduced.  相似文献   

9.
Abstract. Field-caught fry of the common wolfish, Anarhichas lupus L., and the spotted wolffish, A. minor Olafsen, were reared on a commercial dry pellet. Both species experienced the same environmental conditions, including an annual fluctuation in temperature from 5·8 to 13·7°C. The spotted wolffish reached 1·58 kg in 2 years from hatching, more than four times the weight of common wolffish (0·37kg). Analysis showed that for both species the specific growth rate decreased with increasing fish size and increasing temperature. Estimates, based upon optimum conditions, indicate that the spotted wolffish would reach a total wet weight of 5 kg (<7°C) in 2 years from hatching, and the common wolffish (7–9°C) a total wet weight of 2·5kg within that same period. Female common wolffish matured at a weight above 0·5kg, whereas those of the spotted wolffish matured at a weight above 2·5kg. The spotted wolffish had a significantly higher fillet proportion (∼50%) than the common wolffish (∼45%) and a significantly lower hepato-somatic index (3·7% and 5% respectively).  相似文献   

10.
We investigated the growth of juvenile common snook (Centropomus undecimalis) reared at 25°C and 28°C and salinities of 0.3, 15, and 32 g L?1. Total length, weight, RNA/DNA, and protein/DNA ratios were determined after 90 days of experiment. Higher growth was observed at 28ºC compared with 25°C, at the same salinity. At 28°C and 15 g L?1 salinity, the weight (25.14 g) of juveniles was twice that of the juveniles reared at the lower temperature. At different salinities, only higher temperature affected growth, with higher weight values obtained at 15 g L?1 in comparison with 0.3 and 32 g L?1. Length was similar at 0.3 and 15 g L?1. The RNA/DNA ratio was greater in juveniles reared at a salinity of 15 g L?1 when compared with 0.3 and 32 g L?1. This study shows that the combination of higher temperature and intermediate salinity promotes better growth of common snook juveniles.  相似文献   

11.
A study was performed to examine the effects of salinity on water quality, fish performance, carcass composition and haemato‐biochemical parameters in juvenile meagre, Argyrosomus regius. Fish (5.0 g) were stocked in fibreglass tanks at four salinity levels: 8‰, 16‰, 24‰ and 32‰, and fed a pelleted diet (47/17 protein/lipid) for 56 days. Results indicated that the growth, feed utilization, carcass composition and haemato‐biochemical parameters of meagre gradually improved with the increase in salinity up to 24‰ and then significantly (p ≤ .05) decreased at 32‰. The survival per cent showed a significant decrease when A. regius exposed to 8‰ salinity. An improvement with 32%, 47% and 34.1% of FCR, protein productive value and energy utilization was detected at 24‰ compared with 8‰ salinity respectively. The highest content of protein and the lowest of lipids were recorded in fish carcass at 24‰ compared with the opposite trend at 8‰ salinity. The 24‰ salinity treatment exhibited the highest value of haemoglobin (4.9 g/dl) and the lowest ratio (0.73) of albumin/globulin. The serum total protein, albumin and globulin were significantly higher at 24‰ and 32‰ salinity than those at 8‰ and 16‰ salinity groups. These findings indicate that 24‰ salinity level might be the best for meagre.  相似文献   

12.
The rate of metamorphosis of larvae, duration of larval stages and carapace lengths of postlarvae were measured in the common prawn, Palaemon serratus, reared in 30 different combinations of temperature and salinity. Temperature varied from 13°C to 29°C and salinity from 13‰ to 43‰. When salinity.was 13‰, this species was able to metamorphose at a temperature of 21°C. For salinities of 19‰, 25‰, 31‰, 37‰ and 43‰, the temperature range over which metamorphosis occurs extends from 17°C to 25°C. The equation of Van't Hoff can be adapted to calculate the relation between the rearing rate, which is the converse of the duration of larval stages, and the water temperature. The Q10 values vary from 1.39 minimum at a salinity of 37‰ to 2.28 maximum at 31‰. Neither the effect of temperature (at 0.1%) nor that of salinity (at 1%) is significant for the carapace lengths of postlarvae.Tridimensional models of the combined effects of temperature and salinity on the rate of metamorphosis and on the number of metamorphosed postlarvae appearing daily were constructed for this species.  相似文献   

13.
There is a particular interest in Mexico for the grow-out and breeding in captivity of the native oyster Crassostrea corteziensis. However, there is a lack of knowledge of the effect of temperature and salinity on the feeding physiology that maximizes the growth and eventually achieves the maturation of C. corteziensis. Our aim was to evaluate the filtration and clearance rates, oxygen consumption, ammonium excretion rates, assimilation efficiency, and scope for growth of the oyster C. corteziensis acclimated during 2 weeks to different combinations of temperature (23, 26, 29, and 32 °C) and salinity (20, 30, 40, and 50 psu). Oysters were fed with a standard suspension of the microalga Chaetoceros muelleri as total particulate matter, which was supplied at 4.2 L h?1 into 10 1-L tanks used as experimental chambers. The results showed that filtration and clearance rates increased with increasing temperature and decreased with increasing salinity, with the highest values obtained at 29 °C and 20 psu. Ammonium excretion and, to lesser extent, oxygen consumption matched with the variations in the feeding rate. The values of the scope for growth (SFG) suggested that C. corteziensis is able to grow out in all combinations of temperatures and salinities tested in this work. However, the SFG decreased at higher salinity (50 psu) in both extreme temperatures (23 and 32 °C), with highest value occurring at intermediate temperature and the lowest salinity. The SFG increased with increasing temperature and decreased with increasing salinity, which was explained by the increase in the feeding rates and ammonium excretion, coupled with higher absorption efficiency of the food. We concluded that higher filtrations and scope for growth of oysters occurred at 29 °C in brackish-water (20 psu) rather than in marine-water conditions. The results obtained can be considered highly useful information for aquacultural management of this oyster species, and useful to establish suitable sites to enhance their cultivation and maximize the growth of C. corteziensis.  相似文献   

14.
Despite larval robustness characterized by the absence of metamorphosis and readiness for exogenous feeding based on commercial feed, the spotted wolffish (Anarhichas minor) displays highly variable survival at first-feeding. In this study, we investigated the use of three dietary concentrations of protein hydrolysates (PH, pre-digested proteins) (0, 10 and 20%) when newly hatched juvenile wolffish were held at three different rearing temperatures namely, 5, 8 and 12 °C to determine whether digestion of protein was a limiting factor for fish growth and survival. Final weights for fish at 5, 8,and 12 °C at day 60 were respectively 0.35, 1.19 and 2.02 g. Mean specific growth rates were 1.97, 4.01 and 4.88%/day and survival rates were 49.8, 53.4 and 33.2% respectively. No significant effects of PH were observed on growth or survival at any time during the experiment. However, as a general trend, fish survival was always higher when the diet contained 20% PH. We suggest that the degree of hydrolysis of the PH used may have been insufficient to induce specific digestive enzyme stimulation for promoting larval growth. Moreover, precocious ontogeny of the digestive system may have precluded any significant effect of using dietary protein hydrolysates. Our results are discussed in comparison with metamorphic species which characteristically display incomplete development of the digestive system.  相似文献   

15.
Physiological responses of pink abalone Haliotis corrugata were determined under different temperature and salinity conditions. Oxygen consumption rate was not affected by temperature and salinity. Ammonium excretion of pink abalone was inversely related to salinity. The O:N ratio indicated that abalone maintained in lower salinities had an interval of 4.9–7.7, which is indicative of a protein‐dominated metabolism, whereas the O:N in 35‰ was 28.8–35.5 for both temperatures, suggesting that carbohydrates were used as energy substrate. Haemolymph osmolality of abalone exposed to 20 and 24 °C was slightly hyperiso‐osmoconformic in salinity ranges of 20–35‰. The results of this study suggested that for optimized culture, pink abalone should be cultivated at 24 °C at a salinity of 35‰.  相似文献   

16.
盐度对杂交东方鲀存活和摄食的影响   总被引：1，自引：0，他引：1  
采用盐度骤变和渐变的方法,研究了盐度0、5‰、10‰、15‰、20‰、25‰、30‰、35‰、40‰、45‰、50‰、55‰、60‰共13个梯度对菊黄东方鲀(♀)×红鳍东方鲀(♂)杂交F1代存活和摄食的影响。研究表明,盐度从30‰骤变到15‰～50‰时,杂交F1存活率最高,显著高于盐度0、5‰、10‰、55‰和60‰梯度的存活率(P<0.05),其中盐度10‰的梯度中杂交F1代存活率约为33.3%,而盐度0、5‰、55‰和60‰梯度的存活率均低于1%;盐度5‰～50‰为杂交F1可摄食盐度,其中20‰～35‰是最佳摄食盐度。盐度渐变时,盐度5‰～50‰梯度中杂交F1代存活率最高,显著高于盐度0、55‰和60‰梯度的存活率(P<0.05),其中盐度0的梯度中杂交F1代存活率最低,约为12%;盐度0～60‰为杂交F1可摄食盐度,其中盐度20‰、25‰、30‰、35‰和40‰时,杂交F1摄食率无显著差异,在盐度30‰时摄食量和摄食率均达到最大。表明,菊黄东方鲀(♀)×红鳍东方鲀(♂)杂交F1代是广盐性鱼类,对盐度适应能力较强,而且适应盐度渐变的能力强于盐度骤变。  相似文献   

17.
Juvenile sablefish, Anoplopoma fimbria (mean length 15.5 ± 1.9 cm, mean weight 68.5 ± 4.8 g), were used to evaluate the effects on growth, oxidative stress, and non-specific immune responses by changes of water temperature (8, 10, 12, 14, 16, 18, and 20 °C) and salinity (100 (35.0), 90 (31.5), 80 (28.0), 70 (24.5), 60 (21.0), 50 (17.5), and 40% (14.0) (‰)) for 4 months. The growth performance was significantly increased at the temperature of 12 and 14 °C, and the feed efficiency was notably decreased at the temperature of 18 °C. The growth performance and feed efficiency were also significantly decreased at low salinity. The antioxidant responses such as superoxide dismutase and catalase were significantly increased by the high temperature and decreased by the low salinity. The immune responses such as lysozyme and phagocytosis were elevated by the temperature of 18 °C and decreased by the salinity of 50%. The results of this study indicate that the growth performance of juvenile sablefish, A. fimbria, is influenced by the temperature and salinity, and the excessive temperature and salinity levels can affect the antioxidant and immune responses.  相似文献   

18.
The combined effects of temperature and salinity on larval survival and development of the mud crab, Scylla serrata, were investigated in the laboratory. Newly hatched larvae were reared under 20 °C temperature and salinity combinations (i.e. combinations of four temperatures 25, 28, 31, 34 °C with five salinities 15, 20, 25, 30, 35 g L−1). The results showed that temperature and salinity as well as the interaction of the two parameters significantly affected the survival of zoeal larvae. Salinity at 15 g L−1 resulted in no larval survival to the first crab stage, suggesting that the lower salinity tolerance limit for mud crab larvae lies somewhere between salinity 15 and 20 g L−1. However, within the salinity range of 20–35 g L−1, no significant effects on survival of zoeal larvae were detected (P>0.05). The combined effects of temperature and salinity on larval survival were also evident as at low salinities, both high and low temperature led to mass mortality of newly hatched larvae (e.g. 34 °C/15 g L−1, 34 °C/20 g L−1 and 25 °C/15 g L−1 combinations). In contrast, the low temperature and high salinity combination of 25 °C/35 g L−1 resulted in one of the highest survival to the megalopal stage. It was also shown that at optimal 28 °C, larvae could withstand broader salinity conditions. Temperature, salinity and their interaction also significantly affected larval development. At 34 °C, the mean larval development time to megalopa under different salinity conditions ranged from 13.5 to 18.5 days. It increased to between 20.6 and 22.6 days at 25 °C. The effects of salinity on larval development were demonstrated by the fact that for all the temperatures tested, the fastest mean development to megalopa was always recorded at the salinity of 25 g L−1. However, a different trend of salinity effects was shown for megalopae as their duration consistently increased with an increase in salinity from 20 to 35 g L−1. In summary, S. serrata larvae tolerate a broad range of salinity and temperature conditions. Rearing temperature 25–30 °C and salinity 20–35 g L−1 generally result in reasonable survival. However, from an aquaculture point of view, a higher temperature range of 28–30 °C and a salinity range of 20–30 g L−1 are recommended as it shortens the culture cycle.  相似文献   

19.
The physiological responses to different environmental salinities were assessed in juveniles of large yellow croaker Pseudosciaena crocea. This species shows a good capacity to adapt to comparatively low environmental salinities by evaluating some physiological responses, i.e. superoxide dismutase (SOD), acid phosphatase (ACP), alkaline phosphatase (AKP) and lysozyme (LZM) in the liver, spleen, gill and kidney respectively. Growth and survival at salinity 5‰, 10‰ and 25‰ were better than those at salinity 15‰ and 20‰. No significant differences in ACP, AKP, SOD and LZM in the liver were observed among different salinity treatments; SOD, AKP and LZM in the spleen among different treatments only showed significant differences at the beginning or the 2nd week; in the gill, no significant difference of AKP and LZM were observed during the whole experiment, SOD among different treatments showed significant difference at the beginning and the 8th week, and ACP only showed significant difference at the end of the experiment; in the kidney, significant differences in ACP, AKP and SOD among different salinities were merely observed at the end of experiment, and LZM showed significant difference among different treatments at the 2nd week. Overall, some slight stress responses were observed, but few significant differences were observed between low salinity and normal salinity, especially the growth and physiological functions were not influenced by low salinity, i.e. 5‰ and 10‰. We conclude that juvenile large yellow croaker is tolerant to low salinity and shows a potential for low salinity culture.  相似文献   

20.
Full scale experiments in tanks were conducted to elucidate the effect of photoperiod regime, dietary fat level and stocking density on growth in spotted wolffish. The study showed that continuous light (LD24:0) did not give a higher final mean weight or faster overall growth rate in spotted wolffish compared to constant 8 h light and 16 h darkness (LD8:16). However, there were indications that the fish needed time to adapt to a new photoperiod regime. The feeding experiment indicated a negative relation between dietary fat level and growth, where fish given 15% fat in the diet had a 13% higher final mean weight compared to fish on a diet with 20% fat. However, no conclusions could be made. The final mean weight was 10% higher at 25 kg/m2 compared to 40 kg/m2, indicating a negative impact of high stocking density on spotted wolffish.  相似文献   

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