6种大型海洋掠食性鱼类胃含物角质颚分类研究

为了研究大型海洋掠食性鱼类胃含物中角质颚的分类效果,于2017年10月,2018年3、5和11月,收集了南大西洋、中东太平洋和西印度洋海域的大型海洋掠食性鱼类的36个胃并分析其残留角质颚的形态。对采集的角质颚形态侧视图和顶视图进行种类鉴定,建立检索表,提取椭圆傅里叶描述子(EFDs)系数进行聚类分析。结果显示,通过对胃含物角质颚形态进行种类鉴定,共发现头足类2目10科17种。根据角质颚形态分类检索分析,17种头足类角质颚形态种间差异明显。枪形目(Teuthoidea)的13种头足类角质颚喙部形态分别为三角形和等腰三角形,侧壁为近似菱形,翼部发达;八腕目(Octopoda)的4种头足类角质颚有喙部发育,侧壁近似长四边形,有翼部发育。角质颚形态信息聚类分析在目级别区分效果显著。通过对胃含物角质颚形态进行分类研究,不仅可佐证胃含物头足类的识别,而且丰富了胃含物头足类的鉴定内容,也为大型海洋掠食性鱼类胃含物头足类分类鉴定体系奠定基础。     

Weight–length relationships of 33 demersal fish species from Azores archipelago

Weight–length relationships are presented for 33 fish species of Azores archipelago. This work is the first reference on weight–length parameters of 16 species. Samples were collected between the years of 1999 and 2003 using longline at depths ranging from a few meters to 1200 m. The parameters of a and b of the equation W = aL^b were estimated. The b values of the species caught ranged from 2.701 for Lepidopus caudatus to 3.677 for Centroscymnus crepidater. Whenever possible, the b values for the species obtained both in this study and some of the previously reported in the Portuguese waters were compared.     

鱼食性与肠道菌群关系的初步研究

对淡水养殖池中的乌鳢、鲢鱼、鳊鱼、鲫鱼不同食性鱼的后肠菌群进行了定性、定量分析,结果表明:四种鱼的后肠壁和后肠内容物都是厌氧菌总数远大于好氧菌总数;后肠内容物菌数远大于后肠壁菌数;不同的鱼,后肠壁的好氧菌总数差别很大,而厌氧菌总数差别不大;后肠内容物中的厌氧菌总数和好氧菌总数为:乌鳢>鲫鱼>鲢鱼>鳊鱼;而后肠壁细菌含量与食物没有明显的关系;后肠内容物和后肠壁中的双歧杆菌数为:乌鳢>鲫鱼>鲢鱼>鳊鱼。表明后肠内容物中的细菌总数、后肠内容物和后肠壁中的双歧杆菌数都与食性相关。大肠杆菌、肠球菌和乳酸菌在后肠的分布没有规律,说明它们与食物相关性不强。     

闽东北外海渔场中上层鱼类探捕调查研究

为了减轻福建近海的捕捞压力，打破灯光围网作业生产的被动局面，解决闽南－台湾浅滩渔场在春夏汛灯围淡季作业问题，于１９８９￣１９９１年５￣９月，对该渔场的中上层鱼类进行生产性探捕。在专业生产调查中，从统计的渔获量和其它方面，取得了较好的经济效益和社会效益，这期间表明：闽东北外海渔场中上层鱼类有开发利用价值，不仅为福建灯光围网作业开创一条新路，而且为今后重点开发该渔场提供科学依据。     

Recruitment patterns of six species of cyprinid fishes in the lower River Trent, England

Abstract – Fisheries data were collected for six species of 0-group cyprinid fishes from eight sites in the lower reaches of the River Trent, England, between May and October 1999 inclusive, using a micromesh seine net. Recruitment and growth patterns were observed via monthly length–frequency histograms and estimations of mean length. In the cases of roach and dace, growth was approximately linear through the summer, before declining in September and October. In the cases of chub and gudgeon, and to a lesser extent bream and bleak, however, there were suggestions of multiple recruitment events. It is argued that some of the fish species examined in the present study adopt fractional or protracted spawning strategies in the lower River Trent.     

Eulerian views of layered water currents, vertical distribution of some larval fishes, and inferred advective transport over the continental shelf off North Carolina, USA, in winter

Currents that effect the shoreward transport of the larvae of estuarine-dependent fishes spawned in winter in Onslow Bay, North Carolina, USA, were driven by winds and pressure gradients, and influenced by the Gulf Stream. Aside from storms, winds over the continental shelf in Onslow Bay blew predominantly alongshore with velocities approaching 14 m s^-1 during February and March 1986, and January and February 1989. Water masses and currents observed at two current-meter moorings, one at mid-shelf and the other on the outer shelf, reflected the onshore (or offshore) advection of interior water in compensation for the offshore (or onshore) advection of wind-driven surface water. Winds and currents reversed direction approximately every 4 to 6 days. The larvae of Atlantic menhaden, Brevoortia tyrannus , spot, Leiostomus xan- thurus, and Atlantic croaker, Micropogonias undulatus , were most abundant in 17–19^oC and 20–21^oC water of the outer shelf and Gulf Stream fronts. There was little indication of diel vertical migration; larval Atlantic menhaden were most abundant in mid- and surface water, while spot and Atlantic croaker were most abundant in mid- and deep water. Given this distribution, the inferred advective transport of larvae was at times onshore, but at other times it was offshore. Within a spawning season, the prevalence of either reciprocation could determine the number of larvae that reach coastal inlets.     

Hypoxia-based habitat compression of tropical pelagic fishes

Large areas of cold hypoxic water occur as distinct strata in the eastern tropical Pacific (ETP) and Atlantic oceans as a result of high productivity initiated by intense nutrient upwelling. We show that this stratum restricts the depth distribution of tropical pelagic marlins, sailfish, and tunas by compressing the acceptable physical habitat into a narrow surface layer. This layer extends downward to a variable boundary defined by a shallow thermocline, often at 25 m, above a barrier of cold hypoxic water. The depth distributions of marlin and sailfish monitored with electronic tags and average dissolved oxygen (DO) and temperature profiles show that this cold hypoxic environment constitutes a lower habitat boundary in the ETP, but not in the western North Atlantic (WNA), where DO is not limiting. Eastern Pacific and eastern Atlantic sailfish are larger than those in WNA, where the hypoxic zone is much deeper or absent. Larger sizes may reflect enhanced foraging opportunities afforded by the closer proximity of predator and prey in compressed habitat, as well as by the higher productivity. The shallow band of acceptable habitat restricts these fishes to a very narrow surface layer and makes them more vulnerable to over‐exploitation by surface gears. Predictably, the long‐term landings of tropical pelagic tunas from areas of habitat compression have been far greater than in surrounding areas. Many tropical pelagic species in the Atlantic Ocean are currently either fully exploited or overfished and their future status could be quite sensitive to increased fishing pressures, particularly in areas of habitat compression.     

Nitrogenous waste excretion and accumulation of urea and ammonia inChalcalburnus tarichi (Cyprinidae), endemic to the extremely alkaline Lake Van (Eastern Turkey)

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.     

Nearshore fish assemblages associated with introduced predatory fishes in lakes

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22种海水鱼中ACEI的制备及其化学修饰

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