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Abstract  Experiments were carried out to test the dependence of anatomical hooking location on terminal rig configuration, and identify strategies by which hook ingestion can be minimised to reduce post-release mortality of angled yellowfin bream, Acanthopagrus australis (Günther). Eighty-five anglers targeted yellowfin bream using different designs and sizes of circle and J hooks and recorded technical, environmental and biological data for each landed fish. Considerably fewer fish (16.6 and 8.5%, respectively) ingested hooks than those hooked in the mouth (82.1 and 88.6%), and a greater percentage of J hooks were ingested than circle hooks or a J hook modified with a 15-mm horizontal bar. Irrespective of hook type, the rate of ingestion also declined with increasing hook weight and decreasing fish size. In cage experiments, significantly more hooks baited with natural soft baits (e.g. intestines and cephalopods) were ingested than those baited with artificial baits, crustaceans or teleosts, while in the field fewer hooks were ingested using artificial bait (e.g. bread and pellets) than terrestrial animals, teleosts, crustaceans, teleost or terrestrial animal intestines, cephalopods or polychaetes. Similarly, rigs with floats, short traces or a sinker only on the hook, along with angling in environments with at least some current reduced ingestion. Based on this study, anglers targeting yellowfin bream should be encouraged to use circle or modified J hooks and, regardless of the hook design, the largest hook size possible attached to short traces or a sinker only and hard baits.  相似文献   
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团头鲂幼鱼饲料中α-亚麻酸、亚油酸的适宜含量   总被引:1,自引:0,他引:1  
在半纯化饲料配方的基础上,分别设计6个α-亚麻酸含量(0.02%、0.55%、1.08%、1.60%、2.13%、2.65%)、6个亚油酸含量(0.86%、1.29%、1.73%、2.16%、2.59%、3.03%),以亚麻籽油、玉米油、棕榈油调节饲料中α-亚麻酸、亚油酸的含量,配制等氮等能(粗蛋白质含量为30.09%,粗脂肪含量为6.87%)的12种半纯化试验饲料,探讨团头鲂幼鱼[初始均重为(59.5±0.5)g]饲料中α-亚麻酸、亚油酸的适宜含量。养殖试验分为α-亚麻酸和亚油酸试验2部分,均设6组,每组4个重复,每个重复20尾,养殖周期为85 d。结果表明:在α-亚麻酸试验中,依据回归方程计算得到,在饲料α-亚麻酸含量分别为1.32%、1.33%时,团头鲂幼鱼具有最大的特定生长率和最小的饲料系数;0.02%组的脏体指数显著低于除1.08%组外的其他各组(P0.05),肥满度、肝体指数各组间无显著差异(P0.05);0.02%组血清总胆固醇、甘油三酯含量显著高于0.55%、1.08%组(P0.05),1.60%组血清高密度脂蛋白含量显著高于0.55%、2.13%组(P0.05),0.02%组血清低密度脂蛋白含量显著高于其他各组(P0.05)。在亚油酸试验中,依据回归方程计算得到,在饲料亚油酸含量分别为2.02%、2.03%时,团头鲂幼鱼具有最大的特定生长率和最小的饲料系数;3.03%组的肝体指数显著低于其他各组(P0.05),肥满度、脏体指数各组间无显著差异(P0.05);1.29%组血清总胆固醇含量显著高于1.73%组(P0.05),0.86%组血清甘油三酯含量显著高于1.73%组(P0.05),1.29%组血清高密度脂蛋白含量显著高于0.86%、3.03%组(P0.05),各组血清低密度脂蛋白含量无显著差异(P0.05)。以特定生长率、饲料系数作为主要评价指标,结合部分血清生化指标和形体指标,得到适合团头鲂幼鱼快速生长、维持鱼体正常健康的饲料中适宜的亚麻酸、亚油酸含量分别为1.32%~1.33%、2.02%~2.03%。  相似文献   
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平鲷胚胎发育及仔,稚,幼鱼的形态观察   总被引:4,自引:0,他引:4  
本文介绍以人工繁殖所获得的平鲷受精卵进行孵化,培育的结果。连续观察并描述该种鱼的胚胎发育过程及仔、稚、幼鱼的形态。  相似文献   
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The insulin-like growth factor I (IGF-I) cDNA (GenBank Accession No. AY247412) of triangular bream (Megalobrama terminalis) was expressed for the first time in Escherichia coli. To construct the expression plasmid, the IGF-I cDNA was subcloned into prokaryotic-expressing vector pGEX-4T-1. The E.coli JM109 was transformed with the recombinant plasmid pGEX-4T-1-IGF-I, and the transgene expression was observed after being induced with isopropyl-β-D-thiogalactoside (IPTG). The results of SDS polyacrylamide gel electrophoresis (SDS-PAGE) and Western blotting indicated that the recombinant fusion protein had immune activity and the molecular weight was about 47 kDa. The results of SDS-PAGE and thin layer scanning showed that the yield of fusion protein had been enlarged with prolonging time. When the time of induced expression was 1, 2, 3, 4, 5, and 6 h, the expression amount was approximately 1.4, 4.3, 8.1, 11.3, 16.3 and 18.8% of total bacterial protein respectively.  相似文献   
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We have studied the seasonal relationship between growth and circulating growth hormone (GH), hepatic GH-binding and plasma insulin-like growth factor-I immunoreactivity in gilthead sea bream,Sparus aurata. The seasonal increase in plasma GH levels preceded by several weeks the summer increase in growth rates. In contrast, a marked increase in hepatic GH-binding with a high degree of endogenous GH occupancy was found during the period of maximum growth which suggests an enhanced sensitivity of liver to GH action. Thus, circulating levels of immunoreactive IGF-I, probably derived from the liver in response to GH action, were positively correlated with growth throughout the experimental period although a consistent relationship between growth and circulating GH was not found. In spite of this, we consider that, in gilthead sea bream, as in several other teleosts, the availability of endogenous GH can limit growth. Thus, under environmental conditions of suboptimal growth, a single intraperitoneal injection of recombinant rainbow trout GH (rtGH) induced over the dose range tested (0.75, 1.5, 3 μg g BW−1) an increase in plasma IGF-I-like immunoreactivity comparable to that seen during the period of maximum growth.  相似文献   
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Two bacterial strains, Lactobacillus fructivorans, isolated from sea bream (Sparus aurata) gut, and Lactobacillus plantarum, isolated from human faeces, were administered simultaneously, during sea bream development, using Brachionus plicatilis and/or Artemia salina as vectors. The probiotic treatment significantly affected gut colonization. To test the probiotic influence on stress responsiveness, sea bream fry, 47 days post-hatching (p.h.), were subjected to pH stress (from 8.6 to 6.3) and cumulative mortality, cortisol levels and HSP70 gene expression were analysed. Cortisol was selected, since under stress conditions its level increases. HSP70 was selected with consideration of its wide involvement in response to a great number of injuries, and because it protects cells probably by binding and refolding damaged proteins. The results obtained indicated that the administration of probiotic to sea bream fry induced higher HSP70 levels, indicating a greater potentiality to respond to the harmful conditions possibly present in fish farms. This hypothesis is supported by the fact that the levels of cortisol found were significantly lower (P < 0.05) in both groups under probiotic treatment. When pH was used as a stressor, it induced a higher cumulative mortality in the control; the mortality was found to be significantly lower in both treated groups. Interestingly, a significant increase (P < 0.05) in HSP70 gene expression was observed in all stressed groups. These results suggest an improvement in tolerance to acute stress of fry fed with probiotics.  相似文献   
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The nucleotide sequences of DNA fragments amplified by polymerase chain reaction (PCR) from four different genomic regions of nine red sea bream iridoviruses (RSIVs) isolated from different species of fish, different areas and in different years in Korea were compared with the reported reference sequences. One isolate, RSIV Namhae, showed 100% homology to the reference sequences, while the other eight isolates, which appeared to contain identical nucleotide sequences, showed 96.6–98.9% homology with reference sequences depending upon the target regions of PCR gene amplification. However, differences in nucleotide sequences were not apparent between the RSIVs isolated in different locations, in different years or in different host species. We also cloned and sequenced the 3′ end flanking region (K1) of the DNA polymerase (DPOL) gene using the cassette ligation-mediated PCR method. This sequence was 4436-bp long and possessed two open reading frames (ORF-1 and ORF-2) oriented in opposite directions. The putative proteins encoded by these two ORFs could not be characterized by comparison with the proteins of other species in the data banks. The presence of the ribonucleotide reductase small subunit (RNRS) gene at the 3′ end of the K1 region allowed us to determine that these two genes, RNRS and DPOL, are separated 5508 bp and oriented in the same direction in the genome of RSIV. Moreover, it is of interest that a PstI-restriction fragment, of which the sequence but not the location within the RSIV genome had previously been reported, is located at nucleotide positions from 1096 to 2054, extending from within the ORF-1 region, spanning the intervening sequence between ORF-1 and ORF-2, and extending into the ORF-2 region. Various repeating sequences up to 86 bp were present at the 3′ ends of ORFs, especially within the nucleotide sequences at the 3′ terminus of ORF-2. No similarities were detected when the DNA sequences of the K1 region were compared to the DNA sequences of a repetitive element in the genome of other iridoviruses.  相似文献   
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