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991.
利用原养鳗池进行刀额新对虾池塘淡化饲养试验。育苗场应在山苗前约10d内将育苗池池水的相对密度从1.018逐步淡化到1.008,使之与养殖池池水的相对密度一致。放苗时水温温差不超过2℃。虾苗入池1d内保持池水相对密度(1.008)不变,之后逐步淡化,直到完全成为淡水。试验中池水盐度的降幅分别为每天0.0005、0.001和0.002,以缓慢淡化为好。本试验取得了产量1080-1530kg/hm^2,成活率40%-58%,投入产出比1:1.62-1:1.95的较好成果,为推广刀额新对虾的淡水池养提供了可行的技术路线。 相似文献
992.
993.
Atlantic sturgeon (Acipenser oxyrhynchus), which are bottom dwelling and migratory fish, experience environmental hypoxia in their natural environment. Atlantic sturgeon,
acclimated to either 5 or 15°C, were subjected to a 1 h severe (<10 mm Hg) hypoxia challenge in order to document their physiological
responses. We measured hematological parameters, including O2 transport (hemoglobin, hematocrit), ionic (chloride, osmolality), and metabolic (glucose, lactate) variables under normoxic
conditions (~160 mm Hg), immediately following a 1 h exposure to hypoxic water, and following a further 2 h of recovery from
this challenge in normoxic water. In a second experiment, we assessed the opercular beat frequency before, during, and after
hypoxic exposure. Hemoglobin concentrations and hematocrit were significantly different between fish held at 5°C vs. 15°C
and also significantly different between normoxia prior to hypoxia and following recovery. Plasma lactate concentrations increased
following hypoxia at both temperatures, indicative of an increase in anaerobic metabolism. In contrast, a significant increase
in plasma glucose concentrations in response to hypoxia only occurred at 5°C, suggesting different fuel demands under different
temperatures. Changes in opercular beat frequency (OBF) were dependent on temperature. At 5°C, OBF increased upon exposure
to hypoxia, but returned to pre-exposure levels within 35 min for the remainder of the experiment. During hypoxia at 15°C,
OBF increased very briefly, but then rapidly (within 20 min) decreased to levels below control values. Following a return
to normoxia, OBF quickly increased to control levels. Overall, these findings suggest that Atlantic sturgeons are relatively
tolerant to short-term and severe hypoxic stress, and the strategies for hypoxia tolerance may be temperature dependent. 相似文献
994.
Hei-Zhao Lin Yong-Jian Liu Jian-Guo He Wen-Hui Zheng & Li-Xia Tian 《Aquaculture Research》2007,38(15):1605-1611
The aim of this study was to investigate the effects of different oils on growth performance and lipid metabolism of the grouper, Epinephelus coioides. Five experimental fish meal‐based isonitrogenous and isolipidic diets were formulated containing either 5.5%‐added fish oil (FO), soybean oil (SBO), corn oil (CO), sunflower oil (SFO) or peanut oil (PO). Each diet was fed to triplicate groups of 20 fish (initial body weight 13.2±0.02 g) grown in seawater at 28.0–30.5 °C for 8 weeks. Fish were fed twice a day to visual satiety. No significant differences in the survival, weight gain, specific growth rate, feed conversion ratio, protein efficiency ratio or hepatosomatic index were found between fish fed the FO or vegetable oils (VO) diets. Dietary lipid sources did not affect whole‐body composition among grouper fed the various diets. Muscle of fish fed the FO diet had significantly higher levels of 14:0, 16:0, 16:1n‐7, 20:5n‐3[eicosapentaenoic acid (EPA)] and docosahexaenoic acid (DHA)+EPA (except for PO fed fish) compared with those of fish fed VO diets. However, the levels of 18:1n‐9, 18:2n‐6 and DHA/EPA ratios in the muscle of fish fed FO diet were significantly lower than those of fish fed the VO diets. The liver of fish fed the FO diet had significantly higher levels of 18:0, 20:5n‐3, 22:6n‐3, n‐3 highly unsaturated fatty acids and DHA+EPA than those of fish fed the VO diets, whereas increases in 18:1n‐9, 18:2n‐6 and mono‐unsaturated fatty acid levels were observed in the liver of fish fed the VO diets. 相似文献
995.
996.
Masashi Ando Shintaro Mizuochi Yasuyuki Tsukamasa Ken -Ichi Kawasaki 《Fisheries Science》2007,73(3):705-712
ABSTRACT: Changes in meat firmness and structure of cultured yellowtail at several storage temperatures, from −1.5°C to 10°C, were compared. Firmness decreased less at −1.5°C and 10°C than at the other temperatures. During storage at temperatures from −0.5 to 4.0°C, expansion of intercellular space, which indicates weakening of the connecting force between muscle cells, began to increase after 8 h storage, and the ratio of space to the whole area increased by 3.4–4.9 times after 24 h of storage. However, at −1.5°C and 10°C, the increase of intercellular space was suppressed, and the ratio was 2.4–2.6 times, even after 24 h storage. Collagen fibrils connecting muscle cells disintegrated after 24 h storage at all storage temperatures. Conversely, in 10°C storage, the fine structure of muscle, except for collagen fibrils, was maintained better than at other storage temperatures. These findings indicate that −1.5 and 10°C storage could maintain fish-meat quality for longer periods than storage at −0.5, 1.0, or 4.0°C, the normal refrigeration temperature. 相似文献
997.
取含有小鼠重金属螯合蛋白(mMT)基因启动子及人生长激素(hGH)基因的鱼样品,以Qiagene核酸纯化技术对鱼组织DNA进行纯化。常规PCR检测显示,mMT启动基因和hGH基因的PCR产物分别为240bp和130bp,与设计相符。PCR产物的核酸测序结果证实其扩增产物具特异性。地高辛-PCR(Dig-PCR)标记反应显示,2个基因均产生1条Dig标记的特异产物带。Dig-PCR-ELISA检测敏感性试验显示,对mMT启动子和hGH基因的检测敏感性可达10^-3,与常规PCR结合琼脂糖胶电泳检测方法相比,检测敏感性可提高至100-1000倍。试验证明,针对mMT和hGH基因所建立的Dig-PCR-ELISA技术特异可靠。 相似文献
998.
The effects of acetylcholine (ACh) on the action potential and twitch force of atrial tissues isolated from 15 tilapia (Oreochromis nilotica × O. aureus) were studied by means of conventional microelectrode techniques. In isolated whole atrium or sinoatrial tissue, scattered pacemaker-like cells with spontaneous diastolic depolarization were found mainly near the sinoatrial junction but also occasionally throughout the atrial wall. However, most of the atrial cells recorded were myocardial fibers as judged by a stable diastolic potential and a markedly reduced action potential duration (APD) in response to low concentrations of ACh (0.1–1 M). The shortening in APD in atrial myocardial fibers was correlated with a significant fall in twitch force in the atrial preparations. ACh at high concentrations (10–300 M) decreased moderately the APD and the slope of diastolic depolarization of the pacemakers and prolonged the spontaneous cycle length but did not induce hyperpolarization. The negative chronotropic action of ACh was competitively inhibited by atropine, a muscarinic antagonist. The means (± SEM) negative logarithm of the dissociation constant (pKb or pA2 value) for atropine against the ACh action on muscarinic receptors were 9.10 (± 0.13) (n = 6), similar to those values obtained in mammalian atria. The present findings indicate that while the negative inotropic effects of ACh in tilapia atria are comparable to those observed in mammalian hearts, unique electrophysiological responses to ACh exist in different types of tilapia atrial cells. 相似文献
999.
Wataru Doi Than Than Lwin Masashi Yokota Carlos Augusto Strüssmann Seiichi Watanabe 《Fisheries Science》2007,73(2):331-340
ABSTRACT: Sexual maturity, morphological sexual dimorphism, and reproduction of the goneplacid crab Carcinoplax vestita were investigated in Tokyo Bay, Japan, from November 2002 to October 2003. The puberty molt in males was evidenced by changes in the relative size of the chelipeds and merus of the walking legs, and was estimated to occur at a size range of 13.20–18.85 mm carapace length. Post-pubertal females were identified by the relative size of the abdomen and puberty was estimated to occur at a size range of 12.81–15.46 mm carapace length. Sexual dimorphism in C. vestita was observed in all features that showed secondary sexual characteristics. Monthly changes of gonad index in males, and of seminal receptacle index and occurrence of sperm plugs in females were synchronized, and indicated that mating was intense in spring. Ovaries began developing in March. Ovigerous females were found in all months except December, but were clearly more abundant between August and October. Fecundity ranged from 7800 to 57 000 mature oocytes per female per batch and was highly correlated with body size. The results suggest that some females may spawn more than one batch per year. 相似文献
1000.
Noriyuki Takai Noriyuki Hirose Takuya Osawa Kazuyuki Hagiwara Takahito Kojima Yuji Okazaki Tomohiro Kuwae Toru Taniuchi Kiyoshi Yoshihara 《Fisheries Science》2007,73(3):593-608
ABSTRACT: It is important to clarify trophic dynamics in marine ecosystems for management of the fishing ground. Organic carbon sources and trophic position of pelagic fishes in the coastal waters of the south-eastern Izu Peninsula, Japan, were examined on the basis of carbon and nitrogen stable isotope distributions. The δ13 C of the fishes was mostly distributed from −19 to −16‰ for nektonic fishes (13 species of adults and immatures) and planktonic fishes (10 species of larvae and juveniles), close to the δ13 C values of particulate organic matter and planktonic decapods. These δ13 C signatures for the inhabitants of the water column were in contrast with the high δ13 C values (mainly −16 to −13‰) for demersal fishes of Scorpaeniformes and benthic polychaetes collected in the surf zone. These results indicate that nektonic and planktonic fishes depend on phytoplankton for carbon supply. The δ15 N signatures suggest that the trophic position ranged 3.1–4.5 for the nektonic fishes and 2.9–3.7 for the planktonic fishes, premised on trophic level 3 for larval Japanese anchovy Engraulis japonicus . Thus, planktivorous fishes should be mainly assigned to trophic levels 3 and 4 in this area. 相似文献