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1.
2004年夏季东海区渔业资源状况初析   总被引:6,自引:0,他引:6  
本文利用2000-2004年夏季东海渔业资源监测调查的资料,初步分析了2004年夏季东海区渔业资源状况。结果表明,2004年夏季监测海域的种类组成以带鱼、小黄鱼、太平洋褶柔鱼、黄、剑尖枪乌贼、刺鲳等为主,渔业资源种间结构较2003年同期略有改善。2004年春夏季水温较2003年同期偏高,有利于渔业生物资源的补充和生长,各类群和主要经济种类的渔获率显著提高,除银鲳外,带鱼、小黄鱼、刺鲳等资源状况趋好,预计伏季休渔结束开捕后,秋汛生产的渔况将好于2003年。  相似文献   

2.
2004年春季东海区渔业资源状况初析   总被引:1,自引:0,他引:1  
本文利用2000~2004年春季东海渔业资源监测调查的资料,初步分析了2004年春季东海渔业资源的状况。结果表明,2004年春季监测海域的种类组成以带鱼、小黄鱼、黄鲫、银鲳等为主,其比例呈现下降的趋势。所有种类的平均渔获率与2003年同期相比一下降了27.9%,为2000年以来最低。带鱼、小黄鱼、黄鲫等种类的渔获率也大幅下降。甲壳类、头足类的渔获率则有明显的上升。但从总体上来说,2004年春季的渔业资源状况为近来较差的一年。  相似文献   

3.
为了解黄渤海主要捕捞渔具对渔业资源的利用状况,2009年对张网、拖网和刺网等渔具类型的主要渔具种类开展了渔获结构和捕捞能力调查。结果表明,黄渤海的渔业生产以秋汛为主,张网、拖网和陷阱类渔具网目尺寸小,渔获选择I生差,大量捕捞小黄鱼0带鱼、蓝点马鲛和银鲳等传统经济鱼类当年发生的补充群体,幼鱼比例高。相比而言,刺网的网目尺寸大,渔获选择性强,渔获质量好,幼鱼比例低。建议将黄渤海渔具准入的最小网目尺寸暂定为5.5cm,待今后渔业资源结构发生变化和渔获上岸监管体系完善后再作分类调整。  相似文献   

4.
东海区夏、秋季大型水母分布区渔业资源特征分析   总被引:17,自引:2,他引:15  
丁峰元  程家骅 《海洋渔业》2005,27(2):120-128
本文根据1999~2004年的夏季和秋季东海区大型水母和渔业资源的状况,分析了大型水母分布区内的渔业资源特征。结果表明大型水母夏季主要分布于30°30′~33°00′N间,秋季主要分布于32°00′N以北海域,并呈现由夏季到秋季逐渐往北转移的趋势;2003年是大型水母数量最高的年份,该年水母主要分布区内的渔业资源种类数最少,CPUE最低,Margalef种类丰富度指数也最低;2003年夏季水母高发区内渔获种类的优势度也较其它年份发生了显著变化,优势种变为黄;2003年水母高发区内带鱼、小黄鱼和银鲳的当龄鱼较少,银鲳的肥满度增加,小黄鱼的肥满度降低,而带鱼的肥满度未发生显著变化。本文对水母高发区内渔业资源变化的原因进行了初步解释,并对水母的防治措施提出了初步的建议。  相似文献   

5.
深水张网是吕四渔场传统的作业方式,渔获量占江苏省海洋捕捞总量的比重较大。根据2004年4月~2005年11月吕四渔场深水张网渔业监测资料,结合渔业统计数据,分析了该渔业渔获物种类组成及其季节变化,以及主要经济鱼类渔获物种类组成和幼鱼比例。结果表明,各季节深水张网优势渔获物种类组成具有明显的季节变化特征,春季主要以小黄鱼、黄鲫、焦氏舌鳎和葛氏长臂虾为主,夏季为小黄鱼、黄鲫、焦氏舌鳎和银鲳,秋季为小黄鱼、焦氏舌鳎、棘头梅童鱼、灰鲳和银鲳,冬季为小黄鱼、焦氏舌鳎、棘头梅童鱼和斑鰶;小黄鱼和焦氏舌鳎是深水张网渔业常年优势渔获物。主要经济鱼类小黄鱼以6月份平均网产最高,但主要以幼鱼为主,2004年和2005年的平均体重分别仅0.81 g/ind和1.04 g/ind,幼鱼渔获尾数分别占到99.1%和99.8%,累计损害幼鱼尾数分别达1.84×107ind和2.37×107ind;银鲳平均体重3.22 g/ind和3.8 g/ind,累计损害幼鱼尾数分别为4.84×105ind和4.41×105ind。建议对深水张网渔业加强管理,可对该渔业提前一个月休渔,提高网囊网目尺寸,并强化管理力度。  相似文献   

6.
延长拖网伏季休渔期的渔业资源养护效应   总被引:1,自引:1,他引:0       下载免费PDF全文
海洋伏季休渔制度是当前中国最主要的渔业资源管理制度之一,并在实践中得到不断调整与完善,新的海洋伏季休渔制度已于2017年发布实施。为论证新制度延长拖网休渔期的渔业资源养护效应,本研究依据2015—2017年每年5月东海区拖网大面定点调查资料,利用Ricker动态综合模型,从拖网的渔获结构特征和带鱼(Trichiurus japonicus)的种群动力学过程视角开展了相应的量化分析研究。研究结果表明, 5月拖网利用主体为带鱼和小黄鱼(Larimichthys polyactis),带鱼和小黄鱼的性成熟比例分别为92.04%~95.57%和13.82%~29.55%,幼鱼比例分别为74.94%~88.90%和0.03%~4.19%;带鱼种群经过4.5个月的休渔,其单位补充量资源量、单位补充量渔获量和平均渔获质量与3.5个月休渔期相比较,分别增加了7.04%、8.96%和20.78%。以上结果表明,提前并延长拖网休渔期,东、黄海主要经济渔业资源带鱼与小黄鱼的产卵群体和幼鱼得到进一步保护,资源增殖效果随着休渔期的不断延长而增加,新制度的休渔时间设置更趋合理。但由于开捕后的带鱼与小黄鱼渔获仍主要以当龄鱼为主,有必要同时配套执行现已颁布的最小网目尺寸和开捕标准等其他渔业资源管理措施,以确保伏季休渔制度主导下的渔业资源养护效果能真正得到巩固,渔业资源的种群结构能够得到切实好转与不断合理化。  相似文献   

7.
东海区延长伏季休渔期渔业资源增殖效果分析   总被引:2,自引:0,他引:2  
为评价2017年东海区延长伏季休渔期的渔业资源增殖效果,依据2014—2017年每年5月上旬和8月下旬东海区拖网大面定点调查资料,分析了2017年和2014—2016年的8月下旬(休渔后期)的渔业资源密度、资源结构和资源补充能力的同比差异,以及5月上旬和8月下旬的资源密度环比差异。结果表明,总渔业资源、鱼类及3种典型资源种带鱼(Trichiurus japonicus)、小黄鱼(Larimichthys polyactis)、银鲳(Pampus argenteus)的资源密度同比和环比均以2017年为高;2017年资源密度相对增长率鱼类甲壳类头足类;2017年休渔后期主要经济种类的生物量或尾数合计比例均高于2014—2016年,生态优势种更为集中;以带鱼、小黄鱼和银鲳为代表种的休渔后期资源补充数量和单位亲鱼量补充量均以2017年为最高。研究认为,东海区延长伏季休渔期具有渔业资源增殖效果,其中对鱼类的贡献最大;但现有休渔制度对渔业资源仅起到短期暂养的养护作用,延长休渔期的渔业增产效果仅仅限于当年。  相似文献   

8.
南黄海族小黄鱼昼夜渔获率差异的统计学分析   总被引:4,自引:2,他引:2  
利用2004年度东海区重点渔场底曳拖网渔业资源监测资料,从中选用小黄鱼网次渔获率作为指标值,应用LSD方法对南黄海族小黄鱼昼夜渔获率差异进行了统计学分析,以揭示小黄鱼昼夜的活动规律。结果表明,小黄鱼在不同的洄游阶段昼夜网次间渔获率无显著性差异,昼夜无垂直移动现象,常年处于底层,为典型的底层鱼类;在利用底曳拖网船进行渔业资源调查时,无需修正昼夜网次间小黄鱼的渔获率,用获取的调查数据即可估算资源量。  相似文献   

9.
东海区带鱼底拖网昼夜渔获率差异的统计分析   总被引:3,自引:1,他引:2  
以2004年和2005年东海区重点渔场底拖网渔业资源监测资料,从中选取带鱼渔获率作为指标值,并将昼夜不同网次渔获率分成4组,应用最小显著性差异法(LSD)对东海区带鱼昼夜渔获率进行了统计学分析,以揭示带鱼昼夜的活动规律,并利用样本均值的95%置信区间法估算带鱼昼夜渔获率的差异程度,为东海区渔业资源大面定点调查带鱼昼夜网次间渔获率的差异修正提供量化指标。结果表明,东海区带鱼昼间与夜间的渔获率具有统计学上的显著性差异,昼间的渔获率显著地高于夜间的渔获率,带鱼昼间栖息于底层和近底层,夜间垂直移动到中上层;使用拖网规格为100◇×4 m/88 m、网囊网目为25 mm的调查网具,2004年昼间和夜间带鱼渔获率均值的95%置信区间分别为:220.89±12.94和128.23±10.75;2005年昼间和夜间带鱼渔获率均值的95%置信区间分别为:176.28±20.63和105.23±9.71;取2年带鱼昼夜差异程度的平均值,最保守的估计是昼间网次的渔获率均值是夜间的1.69倍。本研究从统计学分析角度证实了以往的无量化的带鱼昼夜渔获率存在差异的观察结果,推断了带鱼具有昼夜垂直移动的习性,其意义在于利用LSD法可以分析其它鱼种的昼夜栖息特征并提供昼夜渔获率均值差异程度的量化指标。  相似文献   

10.
东海区主要经济鱼类开捕规格的初步研究   总被引:14,自引:1,他引:13       下载免费PDF全文
根据1997-2000年东海区底拖网渔、№资源调查资料,以Beverton—Holt模型的单位补充量渔获最方程估算东海区18种主要经济鱼类的最适开捕年龄。运用von Bertalanffy,丰长方程估算最适开捕体长。结合鱼类生长的拐点年龄、临界年龄和初届性成熟年龄的体长,以及各鱼种实测最小性成熟体长,确定开捕规格。结果表明,目前东海区产量较高的带鱼(Trichiurus japonicus)和小黄鱼(Larimichthys polyactis)的建议开捕规格分别应为体长230mm和170mm。调整后的开捕规格与旧开捕规格相比,带鱼、短尾大眼鲷(Priacanthus macracanthus)、灰鲳(Pampus cinereus)、自姑鱼(Argyrosomus argentatus)均有所增大,小黄鱼、银鲳(Pampus argenteus)的开捕规格有所减小,变化较小的有蓝点马鲛(Scomberomorus niphonius)、日本鲭(Somber japonicus)、慌圆鲹(Decapterus maruadsi)等。建议以这18种主要经济鱼类为指标种类,制定新的法定开捕体长和幼鱼比例检查措施,实现东海区渔业资源的可持续利用。  相似文献   

11.
12.
The environmental processes associated with variability in the catch rates of bigeye tuna in the Atlantic Ocean are largely unexplored. This study used generalized additive models (GAMs) fitted to Taiwanese longline fishery data from 1990 to 2009 and investigated the association between environmental variables and catch rates to identify the processes influencing bigeye tuna distribution in the Atlantic Ocean. The present findings reveal that the year (temporal factor), latitude and longitude (spatial factors), and major regular longline target species of albacore catches are significant for the standardization of bigeye tuna catch rates in the Atlantic Ocean. The standardized catch rates and distribution of bigeye tuna were found to be related to environmental and climatic variation. The model selection processes showed that the selected GAMs explained 70% of the cumulative deviance in the entire Atlantic Ocean. Regarding environmental factors, the depth of the 20 degree isotherm (D20) substantially contributed to the explained deviance; other important factors were sea surface temperature (SST) and sea surface height deviation (SSHD). The potential fishing grounds were observed with SSTs of 22–28°C, a D20 shallower than 150 m and negative SSHDs in the Atlantic Ocean. The higher predicted catch rates were increased in the positive northern tropical Atlantic and negative North Atlantic Oscillation events with a higher SST and shallow D20, suggesting that climatic oscillations affect the population abundance and distribution of bigeye tuna.  相似文献   

13.
Previously, we reported 10 PEGE types of 85 tilapia Streptococcus agalactiae(GBS), which shifted from Streptococcus iniae in China, by using PEGE method. Presently, larger and more representative tilapia GBS were isolated, for the ?rst time in China, to characterize their serotypes and genetic diversities more precisely than had done before. 168 GBS strains were distributed in ?ve provinces of China, in which Guangdong, Guangxi and Hainan were the major ones, holding36.9%(62/168), 37.5%(63/168) and 19.6%(33/168), respectively. Serotypes, Ia, Ib and III, were observed in these strains and the most predominant one was Ia(95.2%), which mainly distributed in Guangdong, Guangxi and Hainan. Ia initially occurred in 2009, it shoot up to 32.1% in 2010,but decreased to 16.1% in 2011 before went up to 45.2% in 2012. Ib sporadically occurred during2007–2011, III onlyoccurred in 2012. 14 different PFGE types, including 4 new types(N, O,P and Q), were observed, in which B, D, F and G were the predominant types, holding 83.9%(141/168) of the total GBS strains. Ia corresponded to 11 PFGE types(A–H, N–P), in which type D predominated(51%). Ib represented 3 genotypes(I, J and Q) and III harbored only 2genotypes(N and F). Type N and Fsynchronously presented in Ia and III. In summary, the genetic diversity of tilapia GBS varied by serotypes and changed with geographical locations and years.Although Iastillpredominated, new rareserotypeIII alreadyoccurred in China.  相似文献   

14.
Growth hormone (GH) and reproduction: a review   总被引:5,自引:0,他引:5  
Interaction between growth and reproduction occurs in many vertebrates and is particularly obvious at certain stages of the life cycle in fish. Endocrine interactions between the gonadotropic axis and the somatotropic axis are described, the potential role of GH being emphasised. A comparative analysis of these phenomena in mammals, amphibians and fish, suggests a specific role of GH in the physiology of puberty, gametogenesis and fertility. It also shows the original contribution made by studies on the fish model in this field of investigations.  相似文献   

15.
16.
Protein and amino acid composition of the mantle of juvenile O ctopus vulgaris (Cuvier, 1797) during fasting for 27 days were determined. Average protein content of octopus mantle was of 711.19 ± 46.80 g kg?1 DW, and it decreased with increasing fasting days. The non‐essential amino acids content was higher (486.18 ± 11.08 g kg?1 protein) than essential amino acids (425.82 ± 9.15 g kg?1 protein) at the start of the experiment (unstarved animals). The results suggest that the amino acid profile of the mantle where the most abundant amino acids are Arg, His, Lys, Gly, Leu and Pro could indicate a prolonged fasting condition (>20 days) or poor nutrition of O . vulgaris. This study supports the idea of using mantle for metabolic needs of starved O . vulgaris suggesting that the degradation pathway of amino acids to pyruvate and tricarboxylic acid cycle intermediates was favoured contrary to the degradation pathway of ketogenic amino acids. Special considerations should be taken concerning Thr, Ile, Ser, Ala, Asx (Asp, Asn), Glx (Glu, Gln) (because of their fast intake) and Lys and His (due to their stable contents) during a prolonged period of fasting.  相似文献   

17.
In this experiment, a feeding trial was performed to determine the effects of fructooligosaccharide (FOS) on growth performance, digestive enzyme activity and immune response of Japanese sea bass, Lateolabrax japonicus juveniles (initial weight 38.3 ± 0.5 g), and the fish were examined following feeding with six levels of FOS (0, 0.5, 1, 2, 4 and 6 g/kg) for 28 days. Significant enhancement of weight gain (WG) and specific growth rate (SGR) was found in fish fed 1 g/kg FOS incorporated diets (p < .05), while the feed conversion ratio (FCR) in the 1, 2 g/kg FOS groups reduced significantly compared with the control (p < .05). Besides, the crude lipid in the 4, 6 g/kg FOS groups increased significantly compared with the control (p < .05). On the other hand, the erepsin and lipase activities significantly elevated in intestine of fish fed 2 g/kg FOS (p < .05) and the lysozyme activity in serum of fish fed 2 g/kg FOS were significantly higher than that in the control (p < .05). Moreover, the alkaline phosphatase activities in serum of fish fed 0.5, 1, 2 g/kg FOS were significantly higher than in control (p < .05). Regression analysis showed that the relationships between dietary FOS levels and either SGR, FCR, erepsin or lysozyme activities were best expressed by regression equations, and the optimal inclusion levels are 1.37, 1.80, 3.06, 3.11, 1.93 and 1.80 g/kg for SGR, FCR, erepsin, lipase, lysozyme and total superoxide dismutase activities, respectively. Overall, this study revealed that FOS incorporated diets could beneficial for L. japonicus culture in terms of increasing the growth, digestion and immune activities. Under the present experimental condition, the optimal supplementary level of FOS in the diet of L. japonicus is 1–3 g/kg.  相似文献   

18.
The endemic, anadromous cyprinidChalcalburnus tarichi is the only fish species known to occur in alkaline Lake Van (Eastern Anatolia, Turkey). EightC. tarichi were maintained individually in Lake Van water (17 – 19°C; pH 9.8; 153 mEq·I–1 total alkalinity; 22 total salinity) and tank water samples analyzed for 24 h in 2 to 4 h intervals. At zero time, < 1µM ammonia was present and urea was undetectable in the tank water; at 24 h, total ammonia and urea made up 114±32 and 35±25µM, respectively. Over the experimental period, ammonia-N and urea-N excretion averaged 1041±494 and 607±169moles·kg–1 fish·h–1, respectively. The extent of urea excretion was highly variable between specimens. Uric acid excretion was not detectable.Urea was present at high concentrations in all tissues and plasma (25 – 35moles·g–1·ml–1) of freshly caughtC. tarichi; total ammonia content of the tissues was by a factor of 1.9 (liver) to 3.0 (brain) lower. High arginase activity (2.4±0.2 U·min–1·g–1) was detected in the liver ofC. tarichi but ornithine carbamoylphosphate transferase, a key enzyme of the ornithine-urea-cycle, was absent. Ureagenesis is likely through degradation of arginine and/or uricolysis. High glutamine synthetase activity (11±0.6 U·min–1·g–1) and low ammonia content in brain suggest that, like other teleosts,C. tarichi has an efficient ammonia detoxification in the brain, but in no other tissue.Nitrogenous waste excretion at alkaline pH is discussed. The ability ofC. tarichi to excrete high levels of ammonia at extremely alkaline pH is unique among teleosts studied so far. The mechanism of ammonia excretion under Lake Van conditions remains to be elucidated.  相似文献   

19.
Two gonadotropins (GtH; Qa and Qb) were purified by gel filtration and ion exchange chromatography from the pituitaries of Indian walking catfish (Clarias batrachus). The presence of GtH during purification was assessed by in vitro oocyte maturation and in vivo steroidogenic activity, and their identities were determined by elution profiles, molecular weight, biological activities and yield. The molecular weights of Qa and Qb were 37 and 42 kDa, respectively, and composed of distinct subunits (Qa: 20 and 14 kDa and Qb: 26 and 18 kDa). Polyclonal antibodies raised against Qa immunostained Qa, Qb and pituitary GtH cells. A competitive Qa‐ELISA was developed whose sensitivity was 6.25 ng mL?1 (1.25 ng well?1) with intra‐ (3.5%) and inter‐ (12.4%) assay coefficients of variation. Displacement curves parallel to the standard were obtained with plasma and pituitary extracts of catfish, Qb and carp GtHII. The assay was validated by measuring the plasma Qa levels after LHRH treatment and in relation to ovarian growth in the female catfish during different reproductive phases. Based on the results, Qa and Qb corresponded to fish LH and FSH respectively. The findings will increase the knowledge of the mechanisms controlling fish reproduction and identification of sensitive phases in fish in captivity for hormonal manipulation.  相似文献   

20.
Tetrahymena is a protozoan parasite, which infects guppy, Poecilia reticulata Peters, and causes substantial economical losses in commercial farms worldwide. Studies of guppy infected by Tetrahymena require standardized infection protocols. The LD50 for Tetrahymena infection of guppies by intraperitoneal (IP) injection was calibrated, and the level obtained was 946 parasites per fish. Guppy infection with Tetrahymena by immersion, imitating the natural route of infection via the integument, was studied under normal or stress conditions. Exposure to cold and netting (CNI) and to cold only (CI) followed by immersion exposure to 10 000 Tetrahymena per mL resulted in 22.5% and 19.2% mortality, respectively, as compared to 14.2% and 10% in groups that were netted only (NI) or non‐stressed (I). Histopathology revealed that immersion infection resulted in a systemic infection. Lysozyme levels, measured 3 weeks after infection, were significantly higher in the CNI group (288 μg per mg protein) compared with CI‐, NI‐ and I‐treated groups (94.5, 64 and 62.3 μg mg?1, respectively). There was no evident parasite immobilization activity in body homogenates, suggesting no development of acquired immunity. Re‐infection by IP injection revealed no increase in protection in any of the treatment groups, mortality range of 56.3–75%, higher than in the non‐exposed control (40.6% mortality).  相似文献   

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