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1.
Levels of the selenium-containing imidazole compound selenoneine and overall organic selenium were measured in the muscle of fishes by speciation analysis. The method involves monitoring 82Se levels by liquid chromatography inductively coupled plasma mass spectroscopy using a gel filtration column. Selenoneine levels were found to be highest in swordfish muscle (concentration 2.8 nmol/g tissue). The selenoneine contents of bigeye tuna, Pacific bluefin tuna, albacore, yellowfin tuna, and alfonsino muscle were 1.3–2.6 nmol/g tissue. In muscle of these fishes, most organic selenium (9–42%) was present as selenoneine. In other fish species, such as Pacific sardine, greeneye, skipjack, Pacific mackerel, horse mackerel, red sea bream, and Japanese barracuda, selenoneine levels were 0.1–1.4 nmol/g tissue, accounting for 3–34% of organic selenium. In contrast, muscle of Japanese conger, Japanese anchovy, chum salmon, Pacific saury, white croaker, and marbled sole contained levels of selenoneine below the level of detection (<0.05 nmol/g tissue). Mercury and selenium contents were 0.01–5.12 nmol/g tissue and 1.4–19.1 nmol/g tissue. The Se-to-Hg molar ratio varied from species to species, ranging from 1 for swordfish to 217 for marbled sole.  相似文献   

2.
This paper provides data concerning biochemical composition of milt of two sturgeon species, Siberian sturgeon bred in aquaculture facility of Inland Fisheries Institute in North Poland and sterlet (from two different populations from Danube and Odra). Milt plasma of Siberian sturgeon and sterlet, when compared to teleost fish, is characterized by much lower osmolality (up 70 to 96 mOsm kg−1) and protein concentration (0.24–0.58 g l−1). In spite of the presence of an acrosome and acrosin the antiproteinase activity of seminal plasma was low (12.79–25.40 U l−1). Activities of arylsulfatase and β-N-acetylglucosaminidase were found in spermatozoa. This agrees with the presence of an acrosome in sturgeons sperm. Similarly to mammals, these enzymes are also present in milt plasma. We determined a range of enzymatic activities from the minimal (seminal plasma) to the maximal damage (supernatants obtained after freezing-thawing without cryoprotectant). Activities of arylsulfatase, β-N-acetylglucosaminidase, lactic dehydrogenase and acid phosphatase were released from spermatozoa after freezing-thawing. For this reason they are good potential candidates as a markers of cryoinjury to sperm acrosome and midpiece. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

3.
The abundance of sulphate-reducing bacteria (SRB) was investigated in the coastal marine sediments along the coast of Japan and South Korea. Sediment samples were collected from fish and shellfish farms between 2006 and 2008. As non-fish farming reference sites, sediments were also collected from highly eutrophic bays, a highly sulphidogenic saline lake, and the deep sea. A quantitative real-time PCR analysis that targeted the gene coding for a portion of the α-subunit of dissimilatory sulphite reductase (dsrA) was performed to assess the abundance of the SRB in the sediments. Between 2.8 × 107 and 2.5 × 109 copies of the dsrA gene per gram dry sediment were detected. There was no relationship between dsrA gene copy number and total bacterial count in the sediments, whereas organic matter contents (particulate organic carbon and nitrogen, ignition loss and chemical oxygen demand) and acid-volatile sulphide contents were significantly correlated with the dsrA copy number. The data presented demonstrate that organic enrichment of sediment may influence the abundance of SRB communities in coastal marine sediments and that the cell density of SRB may be used as a biological indicator for assessing pollution levels in sediments of marine fish farms.  相似文献   

4.
The spawning season and grounds of red sea bream in Hiuchi-nada, the central part of the Seto Inland Sea, were described using a new method based on monoclonal antibodies for identifying Pagrus major eggs, and the daily egg production (standardized by the incubation time and survival rate) was estimated. At the peak of spawning (May), the ranges of sea temperature, salinity, and chlorophyll a where red sea bream eggs occurred were 14.8–17.4°C, 32.0–33.0, 0.5–4.4 μg/L, respectively. The main spawning grounds of the red sea bream were confirmed as being the areas near the Geiyo Islands, Misaki Peninsula, Saijyo, Niihama. The spatial spread of red sea bream eggs increased with the egg developmental stage. The ranges of daily egg production in 2005 and 2006 were 0.3–19.3 and 0.2–6.7 × 109 eggs/day, respectively. In Hiuchi-nada, aquaculture farms are located close to the spawning grounds, and the potential spawning population from the aquaculture farms equaled or exceeded that of the estimated spawning population obtained by the egg production method. Red sea bream eggs in Hiuchi-nada might be produced by both wild and aquaculture-based spawning populations.  相似文献   

5.
Abstract. The growth of the aquaculture industry and the general awareness of the environment have increased the concern of' the environmental impact from aquaculture.
As fish farms are open systems, all material that is not harvested as fish is released to the environment. The most important effluents are solid particles like feed and faeces, dissolved substances like nutrients and excretion products, and antibacterial agents.
The effect of these substances varies with their nature and quantity and with local conditions. Production and biomass of phytoplankton seem to be little influenced. The benthic community beneath and close to the cages is often altered. At poorly flushed sites the sea-bed may be anoxic and methane and hydrogensulphide are released from the sediments. Wild fauna, like fish, otters and birds are attracted to the farms.
The respiration and excretion of the fish directly influence water quality. Usually the oxygen tension is somewhat reduced in the net cages, while the concentration of ammonia is elevated in the net. Such conditions are assumed to influence fish growth and health.
Most of the antibiotic agents used in fish farming are persistent and may remain in high concentrations in the sediments up to one year after medication. The frequency of resistant bacteria in the sea-bed is normally increased, and there is a temporary drop in sediment metabolism after medication. Wild fish have been found to have high residues of antibiotic agents.
The organic loading of the sea-bed, the evolution of resistant bacteria and residues in the wild flsh are considered to be the most severe environmental impact of aquaculture. These are all associated with effluent of large particles, and thus mainly restricted to the site area.  相似文献   

6.
We investigated the usefulness of acceleration loggers in aquaculture by examining net-cage use and metabolic rates in red sea bream, Pagrus major. First, the fish’s metabolic rate (mg O2 kg−1 min−1) was measured with the logger in a swim tunnel at designated water velocities. We found that metabolic rate could be expressed by using a linear regression model of the activity rate index (unitless min−1) derived from acceleration data. Using this equation, the field metabolic rates of three fish in a net cage were monitored and were estimated at 14.1–15.0 kcal kg−1 day−1. The results suggested that 15–19% of energy from satiation feeding ration was consumed for metabolism and activity in the net cage. The loggers showed orderly net-cage use by the fish. Tagged individuals used the whole cage from surface to bottom, but individual fish that preferred the surface area rarely used the bottom, and vice versa. Metabolic rate increased significantly with distance of the fish from their preferred depths. The logger provided information on the physiological and behavioral responses of fish in a given breeding system, and its use should contribute to the design of practical aquaculture systems.  相似文献   

7.
To determine the fate of organic matter derived from fish cage aquaculture, carbon and nutrient cycling processes in waters and sediments, and water circulation, were examined at two fish cage farms of different size and utilizing different food types, on Sulawesi and Sumatra islands, Indonesia. Mass balance models of C, N and P were constructed to assess the pathways of waste utilization and dispersal. At the smaller farm in Sulawesi (64.5 m2 cage area; 3 t annual net production) using pelleted food, there was proportionally less waste (≈ 40% of total C input) than at the larger Sumatran farm (2432 m2 cage area; 9 t annual net production) using trash fish (≈ 70% of total C input) as food. At the small farm, the mass balance and hydrographic models indicated a maximum dispersal area of 1180 m2, equivalent to 18 times the farm area. Within this area, 30% of total organic matter input (farm waste + fixed phytoplankton carbon) was buried in sediments with 30% mineralized in the water-column and 40% mineralized in the seabed. At the larger Sumatran farm, the models indicated a maximum dispersal area of 29  220 m2, roughly 12 times the farm area. Within this area, 30% of total organic matter input (farm waste + natural pelagic input) was buried in sediments with 50% mineralized in the water-column and 20% mineralized on the seabed. There was some evidence of benthic enrichment at both farms, mostly as enhanced dissolved nutrient release, but sulfate reduction accounted for < 25% of total C flux, and denitrification/ammonium oxidation accounted for only 4–17% of N lost from sediments. There was no clear evidence of impact with distance from the cages at either farm. Phytoplankton gross primary production accounted for 60–77% of the total organic input to the receiving environment, suggesting that the relative importance of fish cage wastes must be assessed against natural inputs of organic matter.  相似文献   

8.
An eight-week feeding trial has been conducted to determine the optimum ration for Indian major carp, Labeo rohita, fingerling (4.10 ± 0.30 cm, 0.55 ± 0.16 g) by feeding a purified diet (40% CP; 3.61 kcal g−1 GE) at six levels, 2, 4, 6, 8, 10, and 12% of body weight per day, at 0800 and 1600 h, in triplicate, to 20 fish per trough fitted with a water flow-through system. Highest weight gain, best feed conversion ratio (FCR), best specific growth rate (SGR%), and highest protein efficiency ratio (PER) were evident for rations of 6–8% body weight. Second-degree polynomial regression analysis for FCR, PER, protein, and energy retention data indicated the break-points occurred at 6.55, 6.75, 6.80, and 6.95% bw per day, respectively. Significant (P < 0.05) differences between body composition were observed for fish fed different rations. Maximum body protein content was recorded for 6% and 8% rations. A linear increase in body fat content was evident with increasing ration. Body moisture and ash content remained non-significantly (P > 0.05) low for higher rations, however. On the basis of these results it is recommended that feeding in the range 6.5–7.0% bw per day corresponding to 2.6–2.8 g protein and 23.49–25.31 kcal energy per 100 g of the diet per day is optimum for growth and efficient feed utilization of Labeo rohita. Results for 2–4% rations (0.8–1.6 g protein and 7.23–14.46 kcal energy) suggest these amounts approximate to the maintenance requirement of this fish.  相似文献   

9.
European sea bass, Dicentrarchus labrax, is one of the main species cultured in Europe. In this study, non-invasive techniques such as visible-near infrared spectroscopy and dynamometric analysis were used to discriminate concrete tank–cultured sea bass from sea cage–cultured sea bass. A total of 198 samples were collected at six time points from 3 Italian fish farms. A partial least squares analysis was conducted on individual animals at 48 and 96 h post-mortem to determine whether textural and spectral parameters can discriminate between concrete tank– and sea cage–reared sea bass. The results of this analysis demonstrated that spectral measurements better discriminate individual animals at 48 h post-mortem (87% in the independent test) with respect to 96 h post-mortem (66.7% in the independent test). Differences in texture were observed between the two groups of fish, but the texture changed in the time. The texture in sea cage–cultured fish showed higher values of measured force (N) with respect to fish reared in concrete tanks at 48 h post-mortem. Instead, opposite results were observed at 96 h post-mortem. Fillet colour were influenced by both farm and rearing condition.  相似文献   

10.
In South China, certain problems exist in some of aquaculture pond ecosystems, where the concentrations of total phosphorus are high in the sediment but the concentrations of phosphate are low in the overlying water. It is very important and necessary to isolate and screen some phosphate-solubilizing bacteria (PSB) that can adapt to the pond environment for enhancing the utilization of phosphorus in the aquaculture systems. To reach the objective, one PSB, named g6, was isolated using modified Pikovskaya and Pikovskaya medium. By 16S rDNA sequencing analysis and BIOLOG auto-identification system, this strain was identified as Pantoea stewartii subsp. stewartii. After 144 h strains cultivation in liquid National Botanical Research Institute’s phosphate growth medium, its activity resulted in accumulations of soluble phosphate 543 mg l−1. Based on the aquaculture pond ecosystems in South China, effects of temperature, salinity, and pH on g6’s growth were also conducted under indoor culture conditions. Results indicated that Pantoea stewartii subsp. stewartii g6 could tolerate wide range of temperature 15–35°C, salinity 5–35‰, and initial pH 6–10. The results showed that g6 had high solubilization efficiency in vitro and could be expected to adapt well to different aquaculture pond environments, based on culture results.  相似文献   

11.
The diet composition and fish preference of piscivorous Eurasian otters (Lutra lutra) were studied in two fish farm systems in Hungary using spraint (otter faeces) analysis during two wintering periods. The primary food source of otters in both fish farms was fish (97–99% of biomass). The main fish prey was small-sized, below 100 g in weight (96% in both areas), while fish prey above 500 g comprised only 0.1–0.4% of the diet. The bulk of the otters’ diet consisted of less-valued species, especially non-native Prussian carp (Carassius auratus gibelio). Consumption of commercial fish species ranged between 15 and 31% of the total diet. Otters preferred fish below 100 g in weight (Ivlev’s electivity index, E i = 0.65–0.70), and showed a lesser preference for (or avoided) fish above 100 g in weight (E i = −0.37–1.00). With regard to species distribution, otters preferred small (below 100 g) grass carp (Ctenopharyngodon idella), zander (Sander lucioperca), pike (Esox lucius), Prussian carp, topmouth gudgeon (Pseudorasbora parva), while they consumed common carp (Cyprinus carpio), the most important commercial species, proportionally to its abundance in the environment (E i = −0.18–0.29).  相似文献   

12.
Spinefoot rabbitfish, Siganus rivulatus, is an economically important species of herbivorous fish that is relatively easy to rear and thus considered to be suitable for aquaculture. Juveniles are generally reared in nursery systems before being stocked into growout cages or ponds. We report here our evaluation of the effects of stocking density on the survival, growth, feed efficiency and condition index of S. rivulatus juveniles in nursery tanks. The experiment was conducted in a recirculating system of twelve 52-l aquaria connected to a biological filter and a sand filter. Juvenile fish (average weight 6.5 g) were stocked into aquaria at four stocking densities (10, 20, 30, and 40 fish/aquarium) with three replicate aquaria per treatment. Diet was provided at 3% body weight daily divided into two feedings. Fish were weighed weekly for 8 weeks and the diet increased accordingly. Survival was greater than 95% in all treatments, with no significant differences observed among treatments. There were also no differences in specific growth rate (SGR 2.12–2.27) of the fish among treatments. Growth rate was linear during the 8 weeks in all treatments, and harvested biomass increased proportionally to stocking density (198, 401, 600 and 785 g per increasing stocking density, respectively). Feed efficiency (FE 0.67–0.71) of the fish did not vary significantly among treatments. The coefficient of variation was high (35–41%) among the harvested fish, but it also did not differ significantly among treatments. The final condition indices of the fish in all treatments were similar to each other but significantly greater than the initial values (P < 0.05). The results suggest that there is no apparent effect of stocking density at the levels tested on the survival and growth of juvenile rabbitfish.  相似文献   

13.
The present status of contamination by heavy metals, and the impact of cage culture on sediments at the Uranouchi Inlet, Kochi Prefecture, Japan, were investigated from two stations influenced by intensive aquaculture and a control station, during May–July 2006. The moisture content of the sediments at the aquaculture stations was over 65%, and the organic matter was always over 100 mg/g dry wt. In contrast, the highest moisture content and organic matter at the control station was 45.5% and 62.9 mg/g dry wt, respectively. Concentrations of zinc (Zn) (178 ± 4.8 mg/kg dry wt) and copper (Cu) (125 ± 1.2 mg/kg dry wt) were highest at the aquaculture stations. Lead (Pb) was highest (50.7 ± 0.77 mg/kg dry wt) at the aquaculture station though it was as high as 33.2 ± 0.77 mg/kg dry wt at the control station. One-way ANOVA showed that the differences in concentrations of Zn and Cu in sediments from the aquaculture and control stations were highly significant (P = 0.01), whereas Pb showed no such trend. Occurrence of a large fraction of labile Zn (56.1%) and Cu (40.3%) in these sediments warrants attention. Although factors other than metals may explain the distribution observed, the information presented here may be useful in predicting long-term effects of heavy metal contamination from aquaculture in the marine environment.  相似文献   

14.
张玉平  刘金金  张芬 《中国水产科学》2020,27(12):1448-1463
为综合评估上海地区池塘沉积物环境质量状况,2016-2019年对上海地区36个养殖场池塘采集沉积物样品360个,检测和分析沉积物中总氮（TN）、总磷（TP）、总有机碳（TOC）及重金属Cu、Zn、Pb、Cd、Cr、Hg和As含量。研究结果表明,池塘0~10 cm层和10~20 cm层沉积物中TN、TP、TOC及各重金属均值分布无显著差异（P>0.05）,0~20 cm层沉积物（干重）中TN、TP和TOC平均含量分别为（873.37±352.45）mg/kg、（685.66±199.66）mg/kg和（6.62±3.05）mg/g,三者相关性显著。综合污染指数法和有机指数法评价结果表明,池塘沉积物中氮和有机物质的累积量较低,磷累积量相对较高,均低于其他地区高产池塘。池塘沉积物中Cr、Cd、Cu和Hg样品超标率分别为6.42%、3.21%、4.13%和1.38%,Zn、Pb和As无超标现象。地质累积指数、潜在生态危害指数法和一致性沉积物质量基准评价结果表明,上海地区池塘沉积物中重金属整体上处于清洁等级、低潜在生态危害状态,预测不会引发生物毒性效应。  相似文献   

15.
RNA concentrations and enzyme activities are often used as indices of recent growth in fish, but few studies have used both methods to assess the same fish. This study measured RNA concentrations and ornithine decarboxylase (ODC) activity in muscle tissue of juvenile Atlantic salmon (Salmo salar) to compare their usefulness for reflecting specific growth rates, and to determine whether either growth index was influenced by diel variations or time of feeding. Three groups (n = 54 in total) were fed 1.5% of body weight in commercial pellets in four feedings per day. One group was fed only in the morning (0830–1230h), one in the afternoon (1430–1830h), and one in the morning and afternoon (0830–1830h). At the end of ten days, fish were sampled at three times (0130h, 1030h, 1630h) over a single 24h period. Correlations to specific growth rate were slightly higher for RNA concentrations than for ODC activity, but both were highly significant. RNA and ODC activity were also correlated to each other. These results suggest that RNA concentration and ODC activity, taken together, can be used to monitor changes in both the numbers and activity of ribosomes. For RNA concentrations, there was no evidence of an effect of diel variations or the time of feeding. For ODC activity, a significant diel effect (all feed schedules combined) was detected if one non-growing fish was excluded from the analysis; activity of the enzyme was slightly higher in the sample taken at night (0130h) than in the two daytime samples. Contribution no. 8, Catamaran Brook Habitat Research Project  相似文献   

16.
Changes in fatty acid metabolism in Atlantic salmon (Salmo salar) induced by vegetable oil (VO) replacement of fish oil (FO) and high dietary oil in aquaculture diets can have negative impacts on the nutritional quality of the product for the human consumer, including altered flesh fatty acid composition and lipid content. A dietary trial was designed to investigate the twin problems of FO replacement and high energy diets in salmon throughout the entire production cycle. Salmon were grown from first feeding to around 2 kg on diets in which FO was completely replaced by a 1:1 blend of linseed and rapeseed oils at low (14–17%) and high (25–35%) dietary oil levels. This paper reports specifically on the influence of diet on various aspects of fatty acid metabolism. Fatty acid compositions of liver, intestinal tissue and gill were altered by the diets with increased proportions of C18 polyunsaturated fatty acids and decreased proportions of n-3 highly unsaturated fatty acids (HUFA) in fish fed VO compared to fish fed FO. HUFA synthesis in hepatocytes and enterocytes was significantly higher in fish fed VO, whereas β-oxidation was unaltered by either dietary oil content or type. Over the entire production cycle, HUFA synthesis in hepatocytes showed a decreasing trend with age interrupted by a large peak in activity at seawater transfer. Gill cell prostaglandin (PG) production showed a possible seasonal trend, with peak activities in winter and low activities in summer and at seawater transfer. PG production in seawater was lower in fish fed the high oil diets with the lowest PG production generally observed in fish fed high VO. The changes in fatty acid metabolism induced by high dietary oil and VO replacement contribute to altered flesh lipid content and fatty acid compositions, and so merit continued investigation to minimize any negative impacts that sustainable, environmentally-friendly and cost-effective aquaculture diets could have in the future. Abbreviations: FO - fish oil; HUFA - highly unsaturated fatty acids acids (carbon chain length ≥C 20 with ≥3 double bonds); LO - linseed oil; RO - rapeseed oil; VO - vegetable oil. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

17.
To assess the impact of aquaculture activities, we measured the primary production, total sediment oxygen consumption, and benthic nutrient flux at two aquaculture farms (sea squirt and oyster) and one reference site. The estimated primary production in the water column ranged from 19–169 mmol C m−2 d−1. Total sediment oxygen consumption rates ranged from 58 to 328 mmol m−2 d−1, 1.1 to 40 mmol m−2 d−1 for nitrogen, 0.17 to 3.0 mmol m−2 d−1 for phosphate, and 7.3 to 74 mmol m−2 d−1 for silicate. The average total sediment oxygen consumption at the longline farms was >2.5 times higher than the reference site. Nitrate was significantly removed by denitrification at the longline farms in July and September and ranged from −5.4 to −0.09 mmol m−2 d−1, which is higher than for other coastal sediments. The benthic fluxes of nitrogen and phosphate at longline farms were up to 16 and six times higher than at the reference site, respectively. The average nitrogen requirements of the primary producers were 9.3 mmol m−2 d−1 at the sea squirt farm, 7.0 mmol m−2 d−1 at the oyster farm, and 13.5 mmol m−2 d−1 at the reference site, corresponding to 88, 316, and 27.2% of the nitrogen supplied by benthic fluxes, respectively. Our results suggest that benthic nutrient fluxes at longline farms are a major nutrient source for primary production in coastal waters.  相似文献   

18.
The environmental impact of a well-established fish farm has beeninvestigated in surface sediments of the Ligurian Sea in order to assess thebiodeposition, bacterial community structure and dynamics at a mature stage oforganic enrichment.The Biopolymeric carbon (BPC) fraction of organic matter and phytopigmentconcentrations displayed very high values beneath the fish cages. In particularlipid, carbohydrate and chlorophyll-a concentrations werehigher in farm sediment while protein concentrations did not show significantchange between farm sediment and control.Benthic bacteria were closely related to organic enrichment and their densitywas three times higher (up to 3 × 1010 cellsg–1) in stations beneath the cages being positivelycorrelated with BPC (n = 10, p < 0.05) and lipid (n = 10, p < 0.05)concentrations. Colony forming units (CFU) counts of heterotrophic bacteriaindicate a shift in the relative importance of the gram negative bacterialfraction, displaying the predominance of theCytophaga/Flexibacter-like bacteria (CBF), as well as theoccurrence of pathogenic bacteria (such as Vibrio) insediments beneath the farm. In contrast, Gram positive bacteria were moreprevalent in control site where they represented up to 90% of total isolates.Aminopeptidase activity displayed higher values in sediment beneath the cages,whereas the enzymatic activity per bacterial cell was lower. These data suggesta functional stress of bacterial degradation rates and represent a potentialvaluable environmental index of imbalance between supply and removal of organicmatter in eutrophicated environments.Data presented in this study also suggest that either the biochemicalcomposition of sedimentary organic matter as well as the selected microbialvariables may represent useful tools for evaluating the effects of organicenrichment due to fish farming and could be proposed as new environmentalindices of aquaculture impact on marine sediment.  相似文献   

19.
Vitellogenin (Vtg) has proven to be a sensitive and simple biomarker in determining sex, sexual maturity, and xenoestrogenic effects in fish. Thus, our investigation has been focused on identification, partial characterization, and quantification of grey mullet (Mugil cephalus) Vtg through the use of a variety of biochemical and immunological analytical techniques. Mullet is considered both a promising aquaculture candidate and an important species for improving sediment quality in polyculture systems. In the first part of this work, grey mullet Vtg was purified from plasma of 17β-estradiol (E2)-induced male fish by a one-step chromatographic protocol, and partially characterized. Specific polyclonal antibodies were then raised against the mullet Vtg, and both an indirect ELISA and an optical immunosensor were set up and validated to quantify plasma Vtg. The indirect ELISA and the optical immunosensor assay developed showed linear measuring in the range 56.8–1047.1 ng mL−1 and 70–739 ng mL−1 Vtg concentrations in standard solutions, respectively. The results obtained suggest that the indirect ELISA allows Vtg detection over a wide dynamic range, thus resulting more suitable for rapid and sensitive sample screening. Therefore, we suggest that the direct immunosensor is a promising tool which needs more investigation to improve the sensitivity.  相似文献   

20.
Abstract

Modern aquaculture is a relatively new activity among Nepalese farmers and a small contributor to the economy. Given the abundance of water resources and fish species, rising demand for fish, and its high profitability, aquaculture has potential for future expansion if it is given appropriate attention from the government. In Nepal, productivity in aquaculture is much lower compared to other countries in the region, which suggests that there is potential for increased fish production through technological progress and improvement in farm‐level technical efficiency. However, no formal analysis has yet been conducted to assess the productive performance of Nepalese aquaculture and its potential for future improvement. Against this background, this paper examines the technical efficiency and its determinants for a sample of fish pond farms from the Tarai region of the country using a stochastic production frontier involving a model for technical inefficiency effects. The estimated mean technical efficiency is 77%, with intensive farms being more efficient than extensive farms. The adoption of regular fish, water, and feed management activities has a strong positive effect on technical efficiency.  相似文献   

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