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研究于2021年11—12月,设置12条考察路线,采用同步目视考察法,对包含长江干流江西段、鄱阳湖和赣江下游的江西水域长江江豚数量和分布开展了考察,结合历史资料,探讨了该水域长江江豚种群数量和分布规律及江湖迁徙关系。结果显示, 11月考察观测到长江江豚217群次、454头次, 12月考察观测到长江江豚236群次、569头次,受水位和天气等环境条件影响,两次考查观察到的长江江豚数量差异显著(t=–2.23, P<0.05)。11月和12月江豚分布规律基本一致:长江江西段,江豚主要分布在湖口石钟山-彭泽三号洲水域;鄱阳湖适宜水深范围水域都有长江江豚分布,其中吴城望湖亭-渚溪河口、都昌船厂-黄金咀-三山-瓢山水域是江豚高密度分布区;赣江下游,长江江豚分布在扬子洲渔业村附近水域。两次考察目击率分别为1.00和1.08次/km,均高于往年调查结果,由此推测,鄱阳湖长江江豚种群数量可能有所增长。鄱阳湖通江水道蛤蟆石-石钟山水域,两次考察分别仅发现3头和2头长江江豚,推测调查期间长江江豚在长江干流和鄱阳湖之间的迁移行为较少,未来需进一步管控江湖迁移水域的人类活动,促进江湖迁移。吴城望湖亭-渚溪... 相似文献
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土壤农杆菌转化的长春花冠瘿细胞培养 总被引:17,自引:0,他引:17
以土壤农杆菌C58诱导的长春花冠瘿组织与从长春花茎、叶外植体诱导的愈伤组织进行比较,发现冠瘿组织在生长、总吲哚生物碱含量及药用成份阿吗碱含量等方面都优于愈伤组织。测定了光照、温度、蔗糖浓度及外加L-色氨酸前体等,对长春花冠瘿细胞的生长、总生物碱及阿吗碱含量的影响,为长春花冠瘿细胞培养生产吲哚生物碱的实际应用研究提供理论依据。 相似文献
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鄱阳湖及其周围水域的双壳类包括一新种 总被引:6,自引:0,他引:6
一、前言 鄱阳湖位于长江中游,江西省的北部,面积约为3,350平方公里,是我国最大的淡水湖泊。湖的东北部有乐安江,东南部有信江,南部有赣江及旴江,西部有修水和博阳河等注入湖中。湖在北部的湖口处与长江相通。湖水的深度有显著的季节变化,一般在6—7月水位最高,水深约3—8米,11—2月水位最低,水深约1—3米。常水期间,湖口附近水位较长江为高,湖水由此排入长江,仅在湖的枯水期或长江特大洪水时,才接纳一部分长江水量。因此,它对长江水量的调节不及洞庭湖大,它的淤塞也较洞庭湖慢。该湖及其附 相似文献
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Efficacy of releasing captive reared broodstock into an imperilled wild Atlantic salmon population as a recovery strategy 总被引:4,自引:0,他引:4
The strategy of releasing captive reared adult Atlantic salmon Salmo salar into the Magaguadavic River, New Brunswick, Canada, to spawn, was not an effective tool for rebuilding a seriously depressed wild population. The fish were first generation progeny from wild parents, and had spent their entire lives in captivity in either sea or fresh water. No differences in movement or behaviour patterns were observed between freshwater and seawater reared groups. Fish released in the lower river early (35 to 80 days prior to the natural spawning period) moved into a lake low in the system, and most stayed there near the commercial hatchery where they had been reared from egg to smolt. During the spawning season, none moved to the upper river reaches where most spawning habitat exists. Most broodstock released in the upper river reaches near the time of spawning stayed there during the spawning period. The following year few to no Atlantic salmon fry were found, and most appeared not to be offspring of released adults. 相似文献
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Yellowstone cutthroat trout (YCT), Oncorhynchus clarki bouvieri, that spawn in the outlet of Yellowstone Lake show two potamodromous migration patterns, fluvial and allacustrine. The main purpose of this study was to determine whether those fluvial and allacustrine YCT represent reproductively isolated stocks. Redd surveys indicated spawning occurred during about 5 consecutive weeks between late May and mid-July 1993–1995. Lake fish (N=6), defined as radiotagged YCT that entered Yellowstone Lake after the spawning period (i.e. allacustrine pattern), were found in the river between the lake outlet (river kilometer [Rkm] 0) and Rkm 20.0 during spawning. Probable lake fish (N=28; tagged YCT that were last detected near the lake outlet) were found between Rkm 0 and Rkm 22.5 during spawning. River fish (N=4; tagged YCT that remained in the river when annual tracking concluded in fall, i.e. fluvial pattern) were found between Rkm 1.1 and Rkm 18.0 during spawning. Fidelity to spawning areas used between consecutive years was suggested by one of five lake fish and the single river fish for which data were available. Spatial overlap in spawning and a lack of temporal separation between the life-history types during spawning suggested that fluvial and allacustrine YCT were not reproductively isolated. Radiotagging, as well as visual observations made annually from boats during April and May, indicated fluvial YCT overwintered downstream from Rkm 14 and were few, probably on the order of 10% of all YCT that spawned in the Yellowstone River. 相似文献
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The likelihood that fish will initiate spawning, spawn successfully, or skip spawning in a given year is conditioned in part on availability of energy reserves. We evaluated the consequences of spatial heterogeneity in thermal conditions on the energy accumulation and spawning potential of migratory bull trout (Salvelinus confluentus) in a regulated river–reservoir system. Based on existing data, we identified a portfolio of thermal exposures and migratory patterns and then estimated their influence on energy reserves of female bull trout with a bioenergetics model. Spawning by females was assumed to be possible if postspawning energy reserves equaled or exceeded 4 kJ/g. Given this assumption, results suggested up to 70% of the simulated fish could spawn each year. Fish that moved seasonally between a cold river segment and a warmer reservoir downstream had a greater growth rate and higher propensity to spawn in a given year (range: 40%–70%) compared with fish that resided solely in the cold river segment (25%–40%). On average, fish that spawned lost 30% of their energy content relative to their prespawn energy. In contrast, fish that skipped spawning accumulated, on average, 16% energy gains that could be used toward future gamete production. Skipped spawning occurred when water temperatures were relatively low or high, and if upstream migration occurred relatively late (mid‐July or later) or early (early‐May or earlier). Overall, our modeling effort suggests the configuration of thermal exposures, and the ability of bull trout to exploit this spatially and temporally variable thermal conditions can strongly influence energy reserves and likelihood of successful spawning. 相似文献
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A. H. Weatherley †† P. A. Kaseloo M. D. Gare J. M. Gunndr †† B. Llpicnik 《Journal of fish biology》1996,48(4):675-685
Many lake trout Salvelinus namaycush spawn in shallow areas along windswept shores. However, precise determination of time and location of spawning is limited by its nocturnal occurrence, and possibly by some postulated, but unproven, spawning in deep water by certain populations. In White Pine Lake, Ontario, a well-studied experimental lake, lake trout spawn in two shallow locations where some direct observation is possible. Radiotelemetry apparatus was used in 1991 to obtain records of the electromyograms (EMGs) produced by muscle activity in one adult male and one adult female lake trout, captured from the lake before their reproductive period and returned to the lake at the beginning of the spawning period. Both fish survived, though only the male was detected as active over the main spawning site, where it showed evening EMG activity patterns indicating considerable activity. At other times of day, when not located over the spawning site, but present elsewhere in the lake, the male's EMG (i.e. muscle) values were considerably reduced. At the cessation of the spawning period, the transmitter-equipped male's EMG record showed no further pattern indicative of high activity during what had formerly been the daily spawning period. The female was tracked as she moved around the lake, but based on both her location and level of EMG activity, is thought not to have spawned. In 1992, a second male was captured, equipped with a transmitter and released again. This fish failed to show spawning activity but, as with the 1991 female, moved fairly considerable distances in the lake. In one instance, in a swim of short duration (6 min), well away from the spawning grounds, this fish displayed EMG activity levels resembling those of the high activity of spawning. The results obtained appear to demonstrate that EMG telemetry could be used to assess the level of muscular activity occurring in lake trout, especially in relation to reproductive behaviour, and when they cannot be directly observed. 相似文献
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本文是对已达性成熟年龄的池养和江河雌性草鱼产卵前后卵巢组织学结构的研究。实验结果证明草鱼是一次产卵类型。经人工催产后的雌性草鱼,由于亲鱼的成熟程度存在个体间的差异,有的全产,有的部分产。在湘江天然产卵场捕得的雌性草鱼,也有全产和部分产的。人工催产全产后的卵巢组织学结构是Ⅰ、Ⅱ时相,部分产后的卵巢组织学结构是Ⅰ、Ⅱ和Ⅳ(Ⅳ+、Ⅳ++)时相,已达满熟阶段但未经人工催产的卵巢组织学结构是Ⅰ、Ⅱ和Ⅳ(Ⅳ+++)时相,以上都未发现有处于Ⅲ时相的卵母细胞。从江河天然产卵场捕得的全产、部分产和尚未产卵的雌性草鱼的卵巢组织学结构,与上述结果一致。证实由Ⅲ时相到Ⅳ时相是同步性的。5月全产后的雌性草鱼,其卵巢组织学结构在6-9月内处于第Ⅱ期,没有新的Ⅳ时相卵母细胞。因此,夏季全产后的雌性草鱼,不可能在当年夏季或秋季完成由Ⅱ-Ⅲ-Ⅳ时相的发育程序。草鱼的卵巢成熟系数在繁殖季节只出现一次高峰。
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Substantial interannual variability in marine fish recruitment (i.e., the number of young fish entering a fishery each year) has been hypothesized to be related to whether the timing of fish spawning matches that of seasonal plankton blooms. Environmental processes that control the phenology of blooms, such as stratification, may differ from those that influence fish spawning, such as temperature‐linked reproductive maturation. These different controlling mechanisms could cause the timing of these events to diverge under climate change with negative consequences for fisheries. We use an earth system model to examine the impact of a high‐emissions, climate‐warming scenario (RCP8.5) on the future spawning time of two classes of temperate, epipelagic fishes: “geographic spawners” whose spawning grounds are defined by fixed geographic features (e.g., rivers, estuaries, reefs) and “environmental spawners” whose spawning grounds move responding to variations in environmental properties, such as temperature. By the century's end, our results indicate that projections of increased stratification cause spring and summer phytoplankton blooms to start 16 days earlier on average (±0.05 days SE) at latitudes >40°N. The temperature‐linked phenology of geographic spawners changes at a rate twice as fast as phytoplankton, causing these fishes to spawn before the bloom starts across >85% of this region. “Extreme events,” defined here as seasonal mismatches >30 days that could lead to fish recruitment failure, increase 10‐fold for geographic spawners in many areas under the RCP8.5 scenario. Mismatches between environmental spawners and phytoplankton were smaller and less widespread, although sizable mismatches still emerged in some regions. This indicates that range shifts undertaken by environmental spawners may increase the resiliency of fishes to climate change impacts associated with phenological mismatches, potentially buffering against declines in larval fish survival, recruitment, and fisheries. Our model results are supported by empirical evidence from ecosystems with multidecadal observations of both fish and phytoplankton phenology. 相似文献
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The river Ingdalselva, which drains to the Trondheims fjord, has no local salmon population due to an impassable waterfall 500 m upstream from the outlet. In the period 1994–97, a total of 31 mature Atlantic salmon (19 females and 12 males) from the rivers Orkla (1994–96) and Vigda (1997) were radio-tagged and released in the river Ingdalselva before spawning. The main goal of the project was to find out whether the fish would stay and spawn in the river, and if the observations during the spawning period could be used to indicate where spawning had taken place. Some fish left the river shortly after release, but 77% of the fish stayed in the river during the spawning period in October. Most of the females (74%) spawned in the river, including multi-sea winter salmon of approximately 10 kg. Some fish remained at the site of the release, while others migrated downstream to hiding places where they stayed until spawning. Long distance upstream migrations were not observed. The observations of the fish during the spawning period were used to identify spawning areas. Electrofishing for salmon fry in the spawning areas the following year in all cases produced fry, and in two of the years salmon fry were also found in areas where no spawning activity had been registered. Radio-tracking was an efficient method for determining whether transplanted salmon would remain in a `new'n river during the spawning season and for locating spawning areas, particularly when the fish were tracked daily. 相似文献
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太湖产乔氏短吻银鱼于3月中旬至5月末产卵。卵具粘性。集中在有沉水植物着生的湖湾内产卵。生殖周期短,一年可达性成熟。繁殖力强。在水温14.5—25.0℃时,仔鱼在受精后118小时23分孵出。终生以浮游动物为食。生长较缓慢,接近一年才达上市规格。其寿命只一年,产卵后不久死亡。保护其产卵基质——沉水植物,以及适当地扩大银鱼网的网目,是关键的增殖措施。
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The reproductive biology ofBarbus holubi, B. kimberleyensis, Labeo capensis andL. umbratus was examined in a large reservoir on the Orange River, South Africa. The findings are integrated into the existing knowledge on largeBarbus andLabeo species, which coexist in most river systems in Africa and Asia.LargeBarbus spawn on gravel beds within the river channel during floods in spring or summer. In continuously flowing regulated rivers, time of spawning is governed by water temperatures. They have moderate fecundity; large eggs, incubation time of several days and the larvae are initially immobile with large yolk sacs. In the impoundment, they spawn in the inflowing regulated river withB. kimberleyensis spawning four to six weeks later than the more cold-tolerantB. holubi, the dominant largeBarbus. Survival is generally good and the juveniles disperse throughout the lake, but unseasonal release of cold water from an upstream impoundment may cause poor reproductive success.In contrast,Labeo species generally spawn on newly flooded ground, usually leaving the main river channel. Spawning may or may not be preceded by a longitudinal migration. Labeos are relatively fecund with small (30%Barbus size) eggs which hatch quickly and the larvae swim in bursts up into the water column before sinking down again.L. capensis does not require a longitudinal spawning migration and breeds throughout the lake, depending on local conditions. Large temporal variation in gonadal development within the population can result in more than one spawning. Dispersal within the lake is poor.L. umbratus uses larger inflowing tributaries for spawning thanL. capensis and its juveniles have a much greater power of dispersal. Early dependence on external feeding and undependable occurrence of conditions for spawning and juvenile feeding makes for variable reproductive success. 相似文献
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Brandon S. Harris Carl R. Ruetz III Travis J. Ellens Anthony D. Weinke Bopaiah A. Biddanda 《Zeitschrift fur angewandte Ichthyologie》2020,36(5):547-558
Recent advancements in telemetry have allowed managers and researchers to conduct comprehensive studies on the movement ecology of lake sturgeon (Acipenser fulvescens), a species of conservation concern in most of the Laurentian Great Lakes basin. In Michigan waters of Lake Michigan, drowned river mouth systems (a protected lake-like habitat that connects a river to lake) support 4 of 11 remaining lake sturgeon populations. One of those remnant populations is supported by the Muskegon River, a drowned river mouth system consisting of both Muskegon Lake and the Muskegon River. The objectives of this 6-year telemetry study were to determine whether adult lake sturgeon occupied the Muskegon River system outside of the spawning season (defined as March to July), to quantify their use of the system annually, and to identify and characterize patterns in occurrence. A total of 21 adult lake sturgeon implanted with acoustic transmitters were passively monitored throughout the year during 2012–2017. Eighty-two percent of tagged fish at large were detected ≥1 day in the Muskegon River system annually, and tagged lake sturgeon were frequently detected during both spawning and non-spawning time periods. Residency index (i.e., no. detection days/365 days) values indicated that adult lake sturgeon were not only detected throughout the year but that they occupied the Muskegon River system for an average of 130 days each year (residency index = 0.36 ± 0.05 SE) during our most spatially intensive acoustic monitoring in 2016–2017. Additionally, 24% of tagged lake sturgeon were primary residents (i.e., residency index >0.5) of the Muskegon River system in both years. Adult lake sturgeon followed 1 of 3 patterns of occurrence based on individual detection histories, and those patterns varied temporally and by the relative amount of use (i.e., high, medium, and low). Our findings build on previous research that found drowned river mouth systems in Lake Michigan can be important nursery habitats for juvenile lake sturgeon by showing that these habitats also can be used extensively by adult lake sturgeon throughout the year. 相似文献