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1.
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2.
Regular weekly sampling of larvae with a Hensen net in the stationary stations on the main spawning grounds of the brackishwater herring population in the Gulf of Riga was carried out in 1947–2004. Probably due to the rapidly increasing anthropogenic eutrophication and the rising winter temperature the yearly abundance of herring larvae has significantly increased with a shift in the average abundance in 1972/1973. Correlation of the average number of herring larvae with the year-class strength was significant for the intermediate (10–16 mm, P < 0.05) and large (≥17 mm, P < 0.001) larval size groups. The monthly average air temperature in the period from January to March was the main environmental variable regulating the abundance of the year classes (P < 0.001). The dependence between the spawning stock biomass (SSB) and year-class abundance differed by climate periods. In the period of cold winters environmental conditions dominated in determination of the year-class abundance whereas the role of the SSB was nonsignificant (P > 0.05). In the period of milder winters the importance of the SSB in determination of the abundance of year classes considerably increased and it significantly correlated with the abundance of year classes (P < 0.05). The winter–spring temperatures and other climatic variables presumably control the abundance of the forming year-class during the period of the highest larval mortality mainly via the production of their food.  相似文献   

3.
The lipid content and fatty acids profile of different tissues of Holothuria tubulosa and H. polii were analyzed to assess the suitability of the central Mediterranean species as a potential marine resource for fatty acids, in particular omega-3 polyunsaturated fatty acids (n-3 PUFAs). Simultaneously, their important indices for human health were evaluated. Gonad and respiratory tree had the highest lipid content, while the body had the lowest values. The results showed significant differences between species and among the different portions analyzed. Internal tunic and longitudinal muscle of H. tubulosa exhibited the highest PUFA proportion (55.3 and 46.4%, respectively). Eicosapentaenoic acid (EPA, C20:5n-3) and arachidonic acid (ARA, C20:4n-6) were the most abundant PUFAs in both species, with a favorable n-3/n-6 ratio in all tissues. The atherogenic and thrombogenicity indices and hypocholesterolaemic/hypercholesterolaemic fatty acid ratio suggested the high-quality of this food, similar to the nutritional values of most popular fish.  相似文献   

4.
ＣＯＭＰＡＲＡＴＩＶＥＳＴＵＤＩＥＳＯＮＴＨＥＳＴＡＢＩＬＩＴＹＯＦＶＡＲＩＯＵＳＦＯＲＭＳＯＦＶＩＴＡＭＩＮＣＬｅｉＱｉｎｇｘｉｎ，ＬｉＡｉｊｉｅ，ＸｕＷｅｉ，ＲｅｎＺｅｌｉｎ（ＯｃｅａｎＵｎｉｖｅｒｓｉｔｙｏｆ　Ｑｉｎｇｄａｏ，２６６００３）ＣＯ...  相似文献   

5.
Edible coating is a novel food packaging technology for controlling the growth of spoilage bacteria and chemical changes in ready-to-eat food products. Fresh fish are highly perishable foodstuffs and are very susceptible to spoilage. A sodium alginate coating was used to maintain the quality of rainbow trout fillets in chilled storage over a period of 20 days. Fillet samples were coated with an aqueous solution of 3% sodium alginate and then stored at chilled temperature (4 ± 2°C). The control and coated samples were analyzed periodically (every 5 days) for microbial (aerobic plate count and psychrotrophic count), chemical (total volatile basic nitrogen, thiobarbituric acid, peroxide value), and sensory characteristics. The results indicated that the sodium alginate coating helped protect the quality characteristics of treated fresh fish fillets and prolonged the shelf life during chilled storage of rainbow trout fillets.  相似文献   

6.
人类识别到：海洋是对实现可持续发懈具有战略意义的一个新兴发展领域，海洋农牧化（Farming and Ranching of the Sea)的研究已成为21世纪海洋兰色革命挑战的主要对象，也将成为海洋时代研究的主要内容之一，我国于20世纪70年代中期正式提出海洋水产生产农牧化方向以来，已取得了可喜的成绩，但仍面临着一些问题。影响着我国海洋农牧化持续发展，海洋农牧化是海洋生物可持续利用的主要途径与模式，涉及一些深层次的理论研究问题，尚需探讨和思考，本文就我国海洋农牧化研究的有关问题作一些思考。  相似文献   

7.
The distribution and movement between habitats with growth of the hard clam Meretrix lusoria were examined by comparing the size–frequency distributions among 17 sites in the Shirakawa–Midorikawa Estuary of the Ariake Sea. This clam is a commercially important bivalve in Japan, and its annual catch is largest in the Ariake Sea. At the study sites, new recruits were abundant at river mouths, and density was strongly affected by the distance from coastal tidal rivers and streams. In contrast, adults were widely distributed on tidal flats, although density was low at many sites. At marine site Oda, the density of adults was higher than that of new recruits at all sites and higher than that of juveniles at most sites. These results indicate that this species moves from riverine sites to marine sites with growth. Moreover, the observed low density of adult clams may indicate overfishing. The active movement of M. lusoria across the fishing grounds complicates the sustainable resource management of this species. Therefore, further studies are needed for effective resource management of M. lusoria.  相似文献   

8.
Effects of virgin coconut oil (VCO) nanoemulsion stabilized by β-glucan and β-glucan solution at final β-glucan levels of 5–20% (based on solid weight of surimi) on croaker surimi gel were comparatively studied. Increases in breaking force, deformation, and fracture constant were found in surimi gel containing VCO nanoemulsion stabilized by 5% β-glucan, whereas a decrease in all properties was observed as the level of β-glucan in nanoemulsion increased. The addition of β-glucan solutions led to continuous decrease in breaking force, deformation, and fracture constant, compared to the control. Addition of both β-glucan stabilized nanoemulsion and β-glucan solutions resulted in decrease in viscoelastic moduli. Power law model represented viscoelastic behavior of all the gels. Expressible moisture content decreased, while whiteness increased with the addition of β-glucan-stabilized nanoemulsion, compared with gel containing VCO. However, both expressible moisture content and whiteness increased with the addition of β-glucan solutions, at all levels used. Addition of β-glucan-stabilized nanoemulsion resulted in finer gels compared to the control gel added with only VCO. Generally, overall likeness score increased for gel containing VCO nanoemulsion stabilized by 5% β-glucan. The surimi gel containing both medium chain fatty acids and β-glucan, functional ingredients, could be developed as a new product.  相似文献   

9.
  • 1. Dolphins are often claimed to compete with fisheries, including through removal of substantial biomass. To calculate the biomass removed by fisheries and the degree of resource overlap with dolphins in a coastal area of Greece, estimates of dolphin abundance based on photographic capture–recapture were combined with an assessment of fishing effort and catch.
  • 2. The estimated total biomass consumed annually by local dolphin populations – 15 short‐beaked common dolphins and 42 common bottlenose dolphins – was 15.5 and 89.8 tonnes, respectively. The total biomass removed by the local fishing fleet (307 fishing boats) was 3469.2 tonnes, i.e. about 33 times greater than that removed by dolphins.
  • 3. Dolphins removed 2.9% of the total biomass, fisheries 97.1%. Nine purse seiners (representing only 3% of the active fishing fleet) were responsible for 31.9% of biomass removal. Similarity of biomass composition between dolphins and fisheries was expressed by a Pianka index of 0.46 for common dolphins and 0.66 for bottlenose dolphins.
  • 4. Overlap differed according to fishing gear. Common dolphin overlap was higher with purse seiners (0.82), and lower with beach seiners (0.31), bottom trawlers (0.11) and trammel boats (0.06). There was virtually no overlap with longliners (0.02). Bottlenose dolphin overlap was higher with trammel boats (0.89) and bottom trawlers (0.75), and lower with longliners (0.38), purse seiners (0.24) and beach seiners (0.18). There was minimal overlap (0.12) between the two dolphin species.
  • 5. This study suggests that ecological interactions between dolphins and fisheries in this coastal area have minor effects on fisheries. Conversely, prey depletion resulting from overfishing can negatively affect dolphins. Fisheries management measures consistent with national and EU legislation are proposed to ensure sustainability and to protect marine biodiversity. Copyright © 2010 John Wiley & Sons, Ltd.
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10.
Antimicrobial peptides (AMPs) are a diverse group of small polypeptides that can inhibit the growth of microbes; the investigation of their cytotoxicity is critical before they can be considered for use. The purpose of the present study was to examine the cytotoxicity of apidaecin at different concentrations (0.0, 10.0, 20.0, and 30.0 μg/ml) on tilapia, Oreochromis niloticus, primary intestinal epithelial cells in vitro through cells morphology observation, methylthiazolyldiphenyl-tetrazolium bromide (MTT) conversion assay, and cellular viability assay. The lactate dehydrogenase (LDH) activity, cytosolic free Ca2+ concentration, and phospholipase A2 (PLA2) activity of primary cells treated with/without apidaecin were also determined. No significant differences (P > 0.05) in MTT assay and viability were found between the treated and the control cells. LDH activities were slightly increased when treated with apidaecin for 24 h compared with the control (19.97 ± 1.24 U/l), but not significantly (P > 0.05). When treated with 20.0 μg/ml apidaecin for 24 h, the concentrations of cytosolic free Ca2+ was the highest among all the treatments (133.65 ± 9.65 nmol/l), but not the difference was not significant when compared with the control (P > 0.05). Similar results were found for the activity of cytosolic PLA2. The current results indicate that apidaecin did not show significant cytotoxicity to primary epithelial cells within 30.0 μg/ml and that it can be used as a new candidate for infection control in fish culture.  相似文献   

11.
In the present study, black cumin oil in the rates of 0.00 % (the control), 0.10 %, 0.40 %, 0.70 %, 1.00 % and 1.30% was added to rainbow trout feed for 144 days. After the feeding process, trout were harvested and stored at 2 ± 1°C in ice, and changes in chemical, microbiological, and sensory parameters were examined periodically. According to sensory analyses, black cumin oil used in fish meat did not cause a perceptible sensory change for all groups. Chemical analyses showed that the addition of black cumin oil to fish feed led to higher total volatile basic nitrogen content in the fish flesh. During the storage period, the highest peroxide values were observed in the groups with 1.0% and 1.3% black cumin oil added, and the lowest were in the groups with 0.0% and 0.1% added oil. The highest microbial count value was observed in the control group.  相似文献   

12.
The daily mortality rates of North Sea herring early‐stage larvae are found to vary over decades. Larval abundance data were used with a spatio‐temporal oceanographic model to reconstruct temperature histories of the observed larvae. The histories were used in conjunction with a temperature‐based growth model to estimate larval age. Mean daily mortality rates were then estimated for the four spawning components (Downs, Banks, Buchan and Orkney/Shetland) using the vertical life table approach, which considers instantaneous abundances across all ages rather than following distinct cohorts. All spawning components, but especially Downs (in the south), exhibited a steady rise in mortality associated with increasing population size. In addition, the three northern components shared a distinct trend in mortality that was significantly correlated with ambient water temperatures experienced by the larvae during the respective time periods after hatching. This trend was also significantly negatively correlated with the residuals of the whole stock‐recruitment relationship. These findings were generally robust to assumptions about growth and hatch length of larvae. The compensatory increase in productivity in the late 1980s and poor recruitment since 2000 coincide with changes in the mortality of larvae younger than 30 days post hatch and covary with larval density and temperature. Thus we suggest that the mortality of early‐stage larvae does impact on the population dynamics in North Sea herring in its current productivity regime, implying a critical period in the determination of year class strength.  相似文献   

13.
GH-transgeniccoho salmon (Oncorhynchus kitsutch) juveniles were fed diets containing 3,5,3-triiodo-L-thyronine (T3; 30 ng/g fish) or 6-n-propyl-2-thiouracil (PTU; 20 ug/g fish), to assess the effect of these drugs on the physiology, growthand survival in comparison with untreated transgenicand non-transgenic salmon. After 84 days, food intake, feed efficiency, survival, growth, hepato-somatic index (HSI), viscera-somatic index (VSI), plasma L-thyroxine (T4), T3and growth hormone (GH) levels,and cranial morphological abnormalities were determined. Growth of transgenic salmon was significantly faster than the nontransgenic salmon,and was increased by exogenous T3and reduced by PTU. Food intake of transgenic salmon was higher than that of the nontransgenic group, but was reduced by exogenous PTU administration. Food conversion efficiency of transgenic salmon was lower than that of nontransgenic salmon,and also was increased by T3 but reduced by PTU in the transgenic fish. The survival rate in all transgenic groups was significantly higher than that of nontransgenic,and transgenic T3and PTU treatment groups showed higher survivals than the transgenic-control group. The HSIand VSI of the transgenic fish were higher than the nontransgenic fish;and both parameters in the transgenic salmon were increased by PTU, but reduced by T3. The plasma T4 level in transgenic salmon was approximately 1.5-fold higher relative to the nontransgenic fish, whereas no difference was observed among the transgenic groups. Plasma T3 levels in transgenic salmon were also approximately 2-fold higher relative to the nontransgenic fish. However, the plasma T3 level in transgenic animals was increased by exogenous T3 administration, but was reduced by exogenous PTU to that observed in nontransgenic salmon. The plasma GH level of transgenic fish was higher than that of the nontransgenic salmon,and the level was increased by the exogenous T3, whereas exogenous PTU did not reduce significantly GH levels in transgenic salmon. Transgenic fish also displayed cranium, jawand opercular abnormalities typical of the effects of this gene construct incoho salmon, indicating that some imbalance in growth processes has been induced. However, these abnormalities (especially cranial disruptions) were diminished by administration of exogenous PTU. In conclusion, exogenous T3and PTU treatments can induce hyperthyroidismand hypothyroidism, respectively,and have inverse effects on growthand skeletal abnormalities of transgenic salmon constitutively expressing GH.  相似文献   

14.
《国际渔业》1999,(6):19-19
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15.
ABSTRACT

Developing an understanding of economic variance (risk) is critical when evaluating alternative aquaculture production technologies. This article assesses the efficacy of employing a quantitative stochastic analysis technique to support technology selection decision making by undertaking a case study investment assessment of three alternative production expansion strategies (offshore sea-pens, land-based RAS growout and larger post-smolt) for the Tasmanian salmon industry. Results demonstrate that salmon aquaculture is undertaken with considerable underlying levels of economic risk, expansion offshore probably represents the lowest initial capital investment and greatest economic return, and that levels of financial uncertainty increase with land-based RAS production. The study highlights stochastic modeling provides significant “added-value” over single-point deterministic analysis and that developing an appreciation of the input variability is a key component in critically evaluating alternative production technologies.  相似文献   

16.
用放在海水池塘中的８个陆基围隔（５０ｍ×５０ｍ×１８ｍ），研究中国对虾（Ｐｅｎａｅｕｓｃｈｉｎｅｎｓｉｓ）与不同密度海湾扇贝（Ａｒｇｏｐｅｃｔｅｎｉｒａｄｉａｎｓ）投饵混养的放养方式、生产力和极限放养量。对虾体长（２８５±０１６）ｃｍ，扇贝壳长（１１０±０１２）ｃｍ，放养密度分别为６０尾／ｍ２和０，１５，４５，７５粒／ｍ２，用投饵和施肥（鸡粪和化肥）饲养。结果表明，扇贝密度为０和１５粒／ｍ２时，对虾的成活率无显著差异。混养（扇贝１５粒／ｍ２）时对虾的出塘体长、体重和产量分别比单养高２５％，３８％和６５％；当扇贝密度高于１５粒／ｍ２时，对虾的平均体长、体重和产量随扇贝密度的增加而显著减少（Ｐ＜００５）。扇贝密度为１５和７５粒／ｍ２时，其产量由４７０ｋｇ／ｈｍ２增至１２３６ｋｇ／ｈｍ２；当扇贝密度高时，去壳后湿重占体重的百分数从（４２８４±３４４）％降至（３７８８±４２６）％。扇贝的极限放养量为６００～８００ｋｇ／ｈｍ２，适宜放养密度为１０～１５粒／ｍ２。  相似文献   

17.
Juvenile stellate sturgeon Acipenser stellatus were intraperitoneally injected with estradiol-17β (E2; 0 and 5 mg/kg fish) to investigate the possibility of sex reversal and also determine the changes in biochemical parameters. Five-month-old fish (40.9 ± 1.1 g) were injected every 3-week interval during a 190-day trial. At the termination of the experiment, final weight and other growth parameters including weight gain and specific growth rate, hepatosomatic and viscerosomatic indices were not affected by repetitive injection of E2. Hematological features of E2-treated fish showed significant reductions in number of red blood cells, hemoglobin concentration, hematocrit value and mean corpuscular hemoglobin (P < 0.05), but no significant changes were observed in number of white blood cells, mean corpuscular volume and mean corpuscular hemoglobin concentration (P > 0.05). Calcium, phosphorus, glucose, triacylglycerol, cholesterol, total protein and estradiol concentrations were significantly increased in fish injected with E2 (P < 0.001). Plasma progesterone and testosterone levels were noticeably lower in fish injected with 5 mg/kg E2 rather than the control fish (P < 0.001). Histological observations of gonads showed that all fish injected with 5 mg/kg E2 apparently feminized, while 66.6 % of the control group was female. These results revealed that the injection of E2 is an effective method for feminization of stellate sturgeon without having significant inhibitory effects on growth and survival.  相似文献   

18.
In order to understand the processes affecting early survival of the Japanese anchovy Engraulis japonicus population in the Seto Inland Sea, we examined the monthly fluctuations in the abundance and survival rates from eggs to recruits (15-day-old larvae, 13?mm in standard length fish, defined as 1-month-old fish) during their main spawning season from 1980 to 2007. The abundance of the yolksac larvae positively correlated with the abundance of eggs, but the abundance of recruits did not significantly correlate with the abundance of yolksac larvae. These results imply that the survival rate during the egg stage is relatively stable, but that the rate during the larval stage is variable. Of the three most recent decades (1980s, 1990s and 2000s), the abundance of recruits was highest in the 1980s. The decrease in the abundance of recruits after the 1990s can be considered to have occurred through a decline in survival rate during the larval stage because there were no significant differences in egg abundance, yolksac larval abundance, and survival rates during the egg stage in the three decades of the study period.  相似文献   

19.
世界海胆Sea Urchin(Echinoidea)主要产地概况   总被引：4，自引：1，他引：3  
据FAO统计,2003年世界主要国家和地区的海胆总产量为72,514t,其中智利为42,284t、日本为12,574t、美国7,731t、加拿大为6,951t、俄罗斯为2,207t。我国2004年出口日本240多t。日本既是海胆生产大国也是世界海胆消费的最大市场,在日本海胆如同高档的金枪鱼、咸鲑鱼籽一样颇受人们的青睐。  相似文献   

20.
This study assessed the performance of L. alexandri postlarvae (2 days after hatching) with different diets (Artemia and Panagrellus redivivus), food amounts (C300-C500-C700), and feeding frequencies (F1-F3-F6) in two experiments lasting 10 days. The best performing food type, Artemia and Artemia with P. redivivus, presented the highest survival rates as well as fish with the greatest weight, length, and specific growth rate (SGR). In the second experiment with Artemia, the weight, length, and SGR presented significant differences, increasing with higher amounts of prey. The best performance was obtained from a daily diet (F1) with the greatest amount of prey (C700).  相似文献   

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