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1.
The maternal transmission of a naturally occurring and non‐toxic minor isotope of strontium (84Sr) to the central otolith region of the progeny of a typical European freshwater fish species, brown trout, Salmo trutta f.f. L. was accomplished. The focus was to apply minimum doses of a non‐toxic solution at physiological salt concentration to minimise potential adverse effects on the fish. Female spawners were intraperitoneally injected with doses of 12.5 and 30.2 μg 84Sr kg?1 fish. Eggs were stripped and the resulting progeny were reared in a hatchery for about 1 year before sampling the otoliths. Strontium isotope ratios in the otoliths of the offspring were measured by cross‐sectional line scans using laser ablation‐multiple collector‐inductively coupled plasma mass spectrometry (LA‐MC‐ICPMS). Otolith cores of marked juveniles showed a significantly elevated 84Sr/86Sr ratio compared with control fish and to otolith regions created after hatching. Mass marking of cohorts of progeny from individually spiked brown trout with Sr isotopes is therefore possible for dispersal and migration studies without the necessity of handling eggs and applying other larval marking methods like immersion.  相似文献   

2.
The effectiveness of pelvic fin ray microchemistry of muskellunge, Esox masquinongy Mitchill, to identify stocked individuals along with the potential to identify naturally reproduced fish were evaluated. Fish and water samples were obtained from one hatchery and seven lakes with natural differences in water Sr:Ca to determine whether location‐specific environmental signatures were recorded in sectioned muskellunge pelvic fin rays, including fish of known environmental history. Water and fin ray Sr:Ca were strongly correlated. Six lakes in Illinois possessed Sr:Ca signatures that were distinct from the hatchery where muskellunge were raised, resulting in pronounced shifts in Sr:Ca across sectioned fin rays of stocked fish. Hatchery and lake‐specific Sr:Ca signatures were stable across years. Sixteen of 19 individual fish known to have been stocked based on PIT tags implanted at stocking were correctly identified as hatchery‐origin fish using fin ray core Sr:Ca. Results also indicated that the hatchery Sr:Ca signal can be retained for at least 7 years in fin rays of stocked fish. Fin ray microchemistry is a non‐lethal approach for determining environmental history of muskellunge that could be used to assess movement patterns in lake and river systems and the degree to which muskellunge populations are supported by natural reproduction and stocking.  相似文献   

3.
Fin ray biopsies are commonly used to age sturgeon, but the effects of fin ray biopsy on Siberian sturgeon Acipenser baerii swimming performance are unknown. Therefore, the effects of two fin ray biopsy methods on swimming performance of hatchery-reared, juvenile Siberian sturgeon were evaluated in this study. Treatment fish were subjected to one of two biopsy methods: removal of a 2- to 4-cm section from a marginal pectoral fin ray, or full removal of a marginal pectoral fin ray. Control fish were only subjected to a sham operation. A modified 2,936-l Brett-type swim tunnel was used to evaluate 10-min critical station-holding speeds (C SHS) and behavioral swimming characteristics of sturgeon immediately after fin ray biopsies were carried out. Fish sizes (range 65- to 84-cm fork length) were comparable among treatments. Mean 10-min C SHS (mean ± SE) were 113 ± 3.4, 109 ± 2.5, and 111 ± 2.8 cm s?1 for the segment removal treatment, full removal treatment, and control treatment, respectively. ANOVA indicated that the two methods had no significant effect on the 10-min C SHS of Siberian sturgeon compared to the control treatment. Results indicate that fin ray removal has no effect on Siberian sturgeon swimming performance.  相似文献   

4.
Abstract The potential to discriminate between wild and hatchery trout [Salmo trutta f. fario L. and Oncorhynchus mykiss (Walbaum)] by chronological microchemical patterns of different otolith regions was tested. Central and rim regions of otoliths were analysed for life stage specific elemental patterns of strontium (Sr), sodium (Na) and calcium (Ca) as well as of 87Sr/86Sr ratios using laser ablation inductively coupled plasma mass spectrometry (LA‐ICP‐MS). Classification to life stage specific habitats was achieved with 100% accuracy by 88Sr/43Ca, 23Na/43Ca and 87Sr/86Sr ratios resulting in a discrimination of hatchery fish from wild fish. 87Sr/86Sr ratios and Sr concentration in otoliths were positively correlated with the ratio and amount in the water. Na content in otoliths did not directly reflect the concentration in the water, although the 23Na/43Ca ratio in otoliths contributed to the discrimination. Clear differences in otolith chemistry were found for fish experiencing different geological units or a groundwater‐fed environment in a hatchery. Natural chronological microchemical patterns in otoliths proved to be a valuable tool for discriminating wild and hatchery fish without the necessity to use marking methods. LA‐ICP‐MS is well suited for this application because of its limited need for sample preparation, its potentially high sample throughput and the possibility of simultaneous measurement of multiple elemental and isotopic fingerprints.  相似文献   

5.
Toxicity of aflatoxin B1 (AFB1) was investigated in juvenile hybrid sturgeon Acipenser ruthenus ♂ × A. baeri♀, an important coldwater finfish farmed in China and other countries. Seven experimental diets (Diet A–G) containing different levels of AFB1 (0, 1, 5, 10, 20, 40 and 80 μg kg?1 diet) were fed to juvenile sturgeon weighing 10.53 ± 0.17 g kg?1 to determine its effect on survival, growth, feed consumption, hematocrit, liver histology as well as muscular and hepatic toxin accumulation. The experiment lasted for 35 days and was conducted in two periods of 25 and 10 days each. No external changes or unusual behaviour was observed in the fish fed diets with AFB1. Mortality was observed in fish fed with highest levels of AFB1 (80 μg kg?1– Diet G) from day 12 onwards. After 25 days, fish fed the diet of 80 μg AFB1 kg?1 showed significant lower survival (50 ± 5.77%) followed by those fed 40 μg AFB1 kg?1 diet (80 ± 5.77%) and 20 μg AFB1 kg?1 diet (86.66 ± 3.33%). No significant difference was observed in specific growth rate (SGR) or hepatosomatic index (HSI) between groups. Hematocrit was significantly higher in the fish fed the diet of highest AFB1. The fish were weighed at day 25 in some treatments (Diets F and G) because of high mortality. However, feeding was continued for another 10 days to observe mortality or behavioural changes if any in the other groups. After 35 days, survival in the fish fed Diet F (40 μg AFB1 kg?1) was 40% and those fed Diet E (20 μg AFB1 kg?1) was 36.2%. Significant histopathological changes including nuclear hypertrophy, hyperchromasia, extensive biliary hyperplasia, focal hepatocyte necrosis and presence of inflammatory cells were observed in the liver of fish fed high levels of aflatoxin (40 and 80 μg kg?1). AFB1 accumulation in fish muscle and liver increased with increased dietary AFB1 levels. It could be confirmed that 10 μg AFB1 kg?1 diet was the maximum allowable level in hybrid sturgeon diet.  相似文献   

6.
Abstract –  We used laser ablation inductively coupled plasma mass spectrometry line scans to determine the elemental composition of otoliths, pectoral fin rays and scales of Arctic grayling. Elemental signatures of otoliths and pectoral fin rays effectively provide life-history information on individual fish, important for management of grayling, and potentially all freshwater teleosts. Bulk elemental signatures measured in the otoliths and fin rays were highly correlated to the stream chemistries where the fish were captured. A surprising result of this study was that fin rays showed the strongest relationship with water chemistry for strontium. Scale strontium concentrations were not correlated to water chemistries suggesting that other physiological mechanisms, or remobilisation, may be influencing the deposition of trace elements within scales. Linear discriminant function analyses for otolith and fin ray elemental signatures (and intriguingly also for scales) separated fish from different rivers for all three structures; thus, this technique can be used effectively as a means to discriminate origin of capture.  相似文献   

7.
Effective species management often requires understanding patterns of movement and habitat use. A common approach in identifying where individuals reside relies upon chemical tracers from the environment that are incorporated into an individual's tissues. For fish, isotopes in their otoliths, specifically the portion of their otolith formed during their larval stage, have been used to identify the natal origin. Complicating this work, however, is the fact that during this life stage, there is a shift in the source of isotopes deposited onto the growing otolith from maternally to environmentally derived. The objective of this study was to identify the portion of the otolith representing this transition to environmentally derived isotopes so as to accurately investigate questions of natal origin for a threatened population of fall Chinook salmon (Oncorhynchus tshawytscha). We exposed developing larvae to four treatments that differed in terms of their water strontium isotope ratio (87Sr/86Sr) and used change-point analysis of otolith 87Sr/86Sr and strontium to calcium ratio (Sr/Ca) to identify the otolith radius corresponding to the transition to environmentally derived isotopes. Our results indicated this transition occurred, on average, at 132 μm (87Sr/86Sr; ±50 μm standard deviation) and 127 μm (Sr/Ca; ±29 μm) from the otolith core, which corresponded to the developmental time between hatching and exogenous feeding. A substantial proportion of our otoliths (i.e., 61%) did not show convergence between otolith and water 87Sr/86Sr by the end of the 113-day experiment, which was likely due to the dietary contribution of marine-based feed. Therefore, we were unable to recommend an otolith radius to target for the purposes of reconstructing natal origin apart from being beyond approximately 130 μm.  相似文献   

8.
Ammonia is a metabolite of aquatic organisms which might reach deleterious levels in intensive fish farms. The aim of the present study was to determine median lethal concentrations (96‐h LC50) of total ammonia nitrogen (TA‐N) on marbled spinefoot rabbitfish (Siganus rivulatus) and chronic effects of TA‐N on survival, growth and behaviour of juvenile rabbitfish over a 50 day period. In the first experiment, fish were exposed to 0, 2, 4, 6, 8, 10, 12, 14, 16, 18 and 20 mg L?1 TA‐N for 96 h and survival evaluated. In the second experiment, 12 fish were stocked per 50‐L tank and treated with one of 0, 2, 4, 6, 8, 10 and 12 mg L?1 TA‐N with three replicate tanks per treatment. Survival and growth were determined and histopathological alterations of gills due to chronic ammonia exposure were studied by light and electron microscopy. The 96‐h LC50 values were 16–18 mg L?1 TA‐N. In the chronic exposure experiment, fish reared in water with 0 mg L?1 TA‐N had 100% survival and had 50% weight increase in 50 days. Fish at 2 and 4 mg L?1 TA‐N all died whilst fish in 6, 8, 10 and 12 mg L?1 TA‐N survived and grew albeit less than in treatment 0 mg L?1. Gills from ammonia treated fish displayed severe histological and ultrastructural alterations including hyperplasia, hypertrophy and fusion of secondary lamellae, aneurysms and presence of pleomorphic altered cells. Chronic exposure to ammonia is deleterious to marbled spinefoot rabbitfish and low concentrations of ammonia appear to kill the fish in <50 days whilst fish can survive for more than 50 days at concentrations between 6 and 12 mg L?1 TA‐N.  相似文献   

9.
Calcein (CAL) from 50 to 250 mg/l and alizarin complexone (ALC) from 100 to 300 mg/l were used for double immersion marking of juvenile qingbo Spinibarbus sinensis. With the exception of the scales, double immersion for 24 h produced detectable double marks in otoliths (sagittas and asterisci), barbs, fin rays (dorsal, pectoral, ventral, anal, and caudal), and fin spines (dorsal, pectoral, ventral, and anal) after 90 days in a laboratory growth experiment. Green fluorescent rings produced by CAL were considerably closer to the inside of the bony structures (including otoliths, barbs, fin rays, and fin spines) than red fluorescent rings produced by ALC. Sagittas, asterisci, and barbs showed acceptable fluorescent marks at higher concentrations (250 mg/l CAL and ≥ 200 mg/l ALC, ≥ 200 mg/l CAL and 300 mg/l ALC, 150–250 mg/l CAL and 250–300 mg/l ALC, respectively). Fin rays and fin spines treated by 200 mg/l CAL and 250 mg/l ALC and 250 mg/l CAL and 300 mg/l ALC simultaneously had both acceptable CAL and ALC marks. There was no statistically significant difference on the survival or growth of marked fish compared to the controls throughout the experiment (p > 0.05). The results suggest that double immersion with CAL and ALC is suitable for double mass-marking of juvenile S. sinensis, and these double marks are useful in the experimental development of biological research or restocking methodologies.  相似文献   

10.
The influence of stocking density (1, 2, 4, 6 and 8 kg m?2) was investigated on haematological parameters, growth and fin erosion of great sturgeon (Huso huso) juveniles for a period of 8 weeks. The mean weight of fish at the start of trial was 93.13±1.04 g. After 8 weeks of rearing, the mean weight was 362.4, 319.7, 267, 242.1 and 211.1 in densities 1–8 kg m?2 respectively. The results of this study showed that growth parameters, including condition factor, weight, weight gain, feed conversion ratio, specific growth rate and body weight increase, had a statistically significant difference among treatments (P<0.05). A significant difference (P<0.05) was observed in haematocrit, but the other haematological parameters, including red blood cells, white blood cells (WBC), haemoglobin concentration, mean corpuscular haemoglobin, mean corpuscular volume, mean corpuscular haemoglobin concentration and differential WBC count, showed no significant effect with stocking density (P>0.05). At the end of the experiment, stocking density had no significant effect on plasma cortisol and glucose concentration. The fin length (dorsal, anal, ventral, pectoral and caudal) of fish was measured to calculate the fin index. According to this index, dorsal, anal, ventral and pectoral fins showed no significant difference among treatments (P>0.05), but the erosion of the caudal fin was significantly different between fish held on 6 and 8 kg m?2 (P<0.05). These results showed that rearing density has a major effect on the growth indices of H. huso. Unlike many other fish, great sturgeon exhibited lower stress responses to high stocking density. This indicates that they are more tolerable to rearing conditions in high stocking densities. With respect to the various effects that density causes on growth, fin erosion and physiological and haematological parameters, better understanding of these phenomena considering different levels of density could have a beneficial impact on many rearing steps of this species.  相似文献   

11.
This study aimed to evaluate the effect of low salinity on the water quality, microbial flocs composition and performance of Litopenaeus vannamei juveniles reared over 40 days in a zero‐water‐exchange super‐intensive system at 0, 2, 4 and 25 g L?1. At 0 g L?1, the mortality was total at the 26th day, and consequently, these salinity data were not included in the statistical analysis. Among the water quality parameters, only pH and the total suspended solids concentration were significantly influenced by salinity. However, a trend towards intensification of the nitrification processes was observed as the salinity increased, with the lowest ammonia and the highest nitrite and nitrate concentrations found at 25 g L?1. The concentrations of ciliates and flagellates diminished and increased, respectively, with the increase in salinity. Diatoms predominated at 25 g L?1, whereas at 2 and 4 g L?1, chlorophytes were more abundant. Microbial floc crude protein content was reduced with the increase in salinity, whereas ash content demonstrated the inverse trend. The best overall growth performance and survival were observed at 25 g L?1. However, satisfactory productivity was also found at 4 g L?1, suggesting the viability of rearing L. vannamei at low salinity under zero‐water‐exchange conditions.  相似文献   

12.
Immersion of 1‐day‐old Silurus asotus (Linnaeus) larvae in 50, 100 or 200 μg L?1 oestradiol‐17β for 15 days altered gonad differentiation and gonadal morphology. The survival of the group immersed at the highest dose (200 μg L?1) was reduced significantly (86%), whereas survival of the groups immersed at the lower doses was as high as that of untreated controls (94%). The sex ratio of the untreated group was close to 1:1 (female–male); however, the incidence of females was significantly higher in groups immersed in doses of 50, 100 and 200 μg L?1, i.e. 86%, 92% and 99.4%, respectively. Ovarian morphology of feminized individuals was different to that of the controls; the ovary was morphologically rather similar to testis although it contained fully matured oocytes. Morphological changes in genital organs were also noted in fish exposed to oestradiol‐17β the shape and size of genital papilla were intermediate between those of normal male and female. During a 4‐month growth trial after the exposure, the feminized fish showed significantly improved growth performance over normal genetic males (P < 0.05), although the growth was not equal to that of normal genetic females (P < 0.05).  相似文献   

13.
  1. Statistical fisheries data are usually obtained during landings, through rapid fish classification and their categorization under the trade names given to species or groups of species. However, species classification is often difficult, particularly concerning elasmobranchs whose fins and heads have been removed, leading to labelling errors.
  2. The aim of this paper is to identify the ray species composition landed in south‐east Brazil, providing identification strategies to support a plan for more efficient labelling and management.
  3. Samples were obtained from artisanal fleet landings, between November 2012 and May 2014. For taxonomic identification of whole or processed animals (n = 279, belonging to 10 species), morphological, metric, and molecular techniques were employed. The common name used by fishermen was more related to the location where they lived than the fishing gear used.
  4. Morphometric analyses resulted in pectoral fin to length and weight conversion equations of whole individuals for each species, and 10 variables were found to be diagnostic of each genus.
  5. A genetic identification, based on sequencing of the mitochondrial genes cytochrome b and cytochrome oxidase I, was applied to verify morphological identification. A dichotomous key that allowed ray identification at the species level from pectoral fin morphology was developed. The approach was field tested and deemed adequate, leading to a robust monitoring strategy for estimating the biomass of specific landed rays.
  相似文献   

14.
This study was conducted to determine the effects of dietary α‐ketoglutarate (AKG) supplementation on the antioxidant defense system and gene expression of heat shock protein (HSP) 70 and HSP 90 in hybrid sturgeons Acipenser schrenckii ♀ × A. baerii ♂ exposed to ammonia‐N stress. A 2 × 3 factorial experiment was arranged, in which each diet (0%, 1% AKG) was randomly assigned to 0.25 (control) 5 and 10 mg L?1 ammonia‐N groups with three replicate aquaria for each 72 h. The 10 mg L?1 ammonia‐N significantly increased serum ammonia concentrations and intestinal Gln concentrations and GS activity compared with the 0.25 or 5 mg L?1 ammonia‐N groups. The intestinal Gln concentration and GS activity increased, and the serum ammonia concentration decreased, in fish given dietary supplementation of 1.0% AKG compared with fish given diets without AKG. Superoxide dismutase (SOD) and glutathione peroxidase (GPx) activity in serum, gills and intestines decreased when fish were exposed to 5 or 10 mg L?1 ammonia‐N, and their activity increased in fish given diets with 1% AKG. Catalase in the serum and gills decreased when fish were exposed to 5 or 10 mg L?1 ammonia‐N and increased in fish given diets with 1% AKG. The 10 mg L?1 ammonia‐N or 1% AKG supplementation increased HSP 70 and HSP 90 gene expression in the liver. The increased activity of antioxidant enzymes, and increased HSP 70 and HSP 90 gene expression in fish fed diets containing 1% AKG suggested higher tolerance to ammonia‐N stress.  相似文献   

15.
Experiments were designed to determine the effects of temperature and salinity on the virulence of Edwardsiella tarda to Japanese flounder, Paralichthys olivaceus. In the temperature experiment, a two‐factor design was conducted to evaluate the effects of both pathogen incubation temperature and fish cultivation temperature on pathogen virulence. E. tarda was incubated at 15, 20, 25 and 30±1°C, and the fish (mean weight: 10 g) were reared at 15, 20 and 25±1°C respectively. The fish reared at different temperatures were infected with the E. tarda incubated at different temperatures. The results of a 4‐day LD50 test showed that temperature significantly affected the virulence of E. tarda (P<0.01) and the interaction between the two factors was also significant (P<0.01). For fish reared at 15°C the virulence of E. tarda was the highest at 25°C of pathogen incubation, followed by 20, 15 and 30°C. When the fish rearing temperature was raised to 20 and 25°C, the virulence of E. tarda incubated at all temperatures increased. Isolation testing demonstrated results similar to those of LD50. The higher rearing temperature increased the proliferation rate of the pathogen in fish. In the salinity experiment, the incubation salinity of E. tarda was at 0, 10, 20 and 30 g L?1, respectively, and the fish with mean weight of 50 g were cultured in natural seawater of 30 g L?1. The results of one‐way anova in 4‐day LD50 test showed that incubation salinity significantly affected virulence. Virulence was lower when the salinity of the incubation medium was at 0 and 30 g L?1, higher at 10 and 20 g L?1. The results of isolation test were in accordance with those of LD50. At 20 g L?1E. tarda had a faster proliferation rate than that at 10 g L?1.  相似文献   

16.
We evaluated the effects of chloride concentration on the clinical pathology in juvenile Atlantic sturgeon, Acipenser oxyrinchus oxyrinchus (Mitchill), following semi‐static exposures to 1 mg L?1 nitrite for 96 h. In spring water naturally low in chloride (5 mg L?1), plasma nitrite concentrated to more than 40× environmental levels resulting in a severe methaemoglobinemia characterized by torpid behaviour, 30‐fold increase in methaemoglobin fraction, anaemia, leucopenia and hyperkalaemia. Loss of intracellular water and potassium to extracellular space may have resulted in hyperkalaemia and haemodilution. Fish survived nitrite exposure, but 60% of torpid fish died following capture and tissue sampling. Fish acclimated to 10‐fold higher chloride content (55 mg L?1) did not concentrate nitrite in the plasma above environmental levels or develop methaemoglobinemia, but did exhibit similar haematology and plasma chemistry changes. Plasma nitrite returned to preexposure levels by 14 days following nitrite exposures, but severity of clinical pathology changes persisted or increased, suggesting that Atlantic sturgeon have reduced capacity to recover from methaemoglobinemia. Fish that survive methaemoglobinemia may be susceptible to mortality from the cumulative effects of intoxication, handling and other stresses for two or more weeks following nitrite remediation. Chloride buffering in aquaculture systems reduces the toxic effects of nitrite accumulation.  相似文献   

17.
The efficacy of copper sulphate (CuSO4) against the early stages of an experimental acute infection of Flavobacterium columnare in channel catfish (Ictalurus punctatus) was evaluated. Fish were challenged, by waterborne exposure to F. columnare in an ultra‐low flow‐through water delivery system, and treated with CuSO4 at 4.2 and 2.1 mg L?1 at 5.5 h post challenge for 4 h. Bacterial challenged non‐treated fish acted as a positive control and non‐challenged non‐treated fish acted as a negative control. Fish challenged with F. columnare and treated with CuSO4 at 4.2 and 2.1 mg L?1 post challenge had mortalities of 6.4% and 18.3%, respectively, compared with the positive control, which had 90.2% mortality. The mortality of challenged fish treated with CuSO4 at 4.2 and 2.1 mg L?1 was significantly different from the positive control. There was no significant difference between the mortalities of the 4.2 and 2.1 mg L?1 treatments. The results suggest that CuSO4 has clear therapeutic value against columnaris infections.  相似文献   

18.
Of 32 structures examined in the white sucker, annulus formation is potentially suited for age determination only on the dermethoid, frontal, lacrimal and rib bones, pectoral fin rays and body scales. Ages assigned by annulus counts on each of the above-noted structures, except scales, were in total agreement. Scale annulus counts were accurate determinants of age in slow-growing riverine stocks, but not in faster-growing lake fish using the same river for reproduction. A linear correlation (r=+0.978) between pectoral fin ray radii and standard length regardless of growth rate, and confirmed by tag-recovery data, permits the accurate back-calculation of white sucker growth using annuli formed on this structure.  相似文献   

19.
A 12‐week growth trial was conducted with gibel carp Carassius auratus gibelio (initial weight: 2.69 g) to evaluate the effects of dietary n‐3 highly unsaturated fatty acids (n‐3 HUFA) on growth performance and tissue fatty acid composition. Five diets of different n‐3 HUFA levels from 0 to 17 g kg?1 diet were supplemented at 80 g kg?1 dietary lipid by including fish oil (FO) at 0, 25, 50, 75 and 100% of supplemental lipid. The remainder was coconut oil. The results showed that fish fed FO25 and FO50 obtained highest specific growth rate and lowest with FO0. Feed efficiency was highest at FO100 and lowest at FO0. Apparent digestibility coefficient of lipid increased with increasing dietary n‐3 HUFA. The fish fed FO0 diet had the lowest thiobarbituric acid reactive substance in serum and muscle and highest moisture and lowest lipid content in viscera. Fatty acid compositions of muscle and liver were correlated with dietary fatty acids. Fish muscle concentration of 20:5n‐3 increased with increasing dietary n‐3 HUFA while the concentration of 22:6n‐3 was distinctly reduced in FO0 group. It suggested that 4 g kg?1 n‐3 HUFA in diet could permit gibel carp normal growth performance and provide considerable n‐3 HUFA in fish muscle. Excessive n‐3 HUFA showed impact on growth performance of gibel carp.  相似文献   

20.
This study compared the effects of dietary l ‐carnitine and ploidy on growth performances and fatty acid content in rainbow trout (Oncorhynchus mykiss). Fish [initial body weight (BW) = 30 g] reared under high density (50 kg biomass m?3) were hand‐fed in triplicate (3 tanks treatment?1, 34 fish tank?1) twice a day, with three nutritionally identical diets containing 15, 200 or 530 mg l ‐carnitine kg?1 of diet. No significant growth differences were observed over a 56‐day grow‐out period, during which BWs increased threefold. Growth performances and survival were not significantly affected by either ploidy or dietary l ‐carnitine content, although daily growth index showed an increasing trend (2.52–2.65% day?1) with increasing dietary l ‐carnitine. Body l ‐carnitine content increased significantly with dietary l ‐carnitine content. Diploid fish had higher plasma ammonia (716–725 μmol L?1) and osmolality (297–303 mOsm) levels than triploid trout (523–649 μmol L?1 and 285–291 mOsm, respectively). l ‐carnitine, ploidy and their interaction showed to affect significantly the concentration of several fatty acids. Palmitoleic (16:1), oleic (18:1) and erucic (22:1) acids showed lower concentrations, while the eicosadienoic (20:2n‐6) and arachidonic (20:4n‐6) acids were elevated in liver of triploid fish. Eicosapentaenoic acid (22:5n‐3) was significantly higher in fish fed 200 mg than in fish fed 15 mg l ‐carnitine.  相似文献   

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