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题名: 长江国华鲟繁殖群体结构特征和数量变动趋势研究
作者: 常剑波
答辩日期: 1999
导师: 曹文宣
专业: 水生生物学
授予单位: 中国科学院水生生物研究所
授予地点: 中国科学院水生生物研究所
学位: 博士
关键词: 中华鲟 ; 繁殖群体 ; 产卵量 ; 水声学 ; 荧光标记 ; 长江
摘要: 中华鲟主要生活在我国黄渤海和东海人陆架,具有溯河洄游习性,其繁殖群体见于我国的长江和珠江。长江中华鲟繁殖群体的数量较多,特别是在其产卵场所在的四川江段,70年代的年平均捕捞量达40t左右,是重要的渔业对象。1981年以后,由于葛洲坝水利枢纽的修建,长江中华鲟繁殖群体被阻隔在中、下游江段,加上过度捕捞等因素的影响,其种群的繁衍受到了一定的威胁。为此,1983年以后,国家完全禁止了对中华鲟繁殖群体的商业捕捞;1984年以后,每年还从葛洲坝坝下江段捕捞中华鲟成熟亲鱼进行人工催产,并将孵出的幼鲟放流以弥补自然繁殖的不足。为检验评价上述保护措施的效果,1996-1999年间,作者对葛洲坝水利枢纽修建以来中华鲟繁殖群体结构的历史资料进行了深入的理论分析,并开展了葛洲坝坝下江段中华鲟繁殖群体数量估算和中华鲟人工繁殖放流效果评价的研究,取得了如下结论:1.90年代以后,中华鲟繁殖群体的长度、重量和年龄均比80年代及葛洲坝水利枢纽修建前有所增加,其中雄鱼比雌鱼表现得更显著。此外,繁殖群体的雌雄性比和性腺发育成熟个体的比例在1990年以后也呈现逐年上升的趋势。2.目前中华鲟华鲟的产卵场位于葛洲坝坝下至庙嘴之间约2km的江段。该江段相对安静的环境、合适的底质条件为其产卵活动小受十扰、所产卵粒的正常发育,以及避免完全被敌害鱼类吞食提供了可能。此外,该江段水位、流速,以及含沙量等水文条件能满足中华鲟自然繁殖的需要。3.在葛洲坝坝下江段的产卵场,中华鲟在1年中至少有1次集中的产卵活动,57.14%的年份有2次以上集中的产卵活动。不同年份的产卵活动最早开始于10月13日,最晚开始于11月7日。有2次以上集中产卵活动的年份,最迟在11月18曰还可以有产卵活动发生。4.根据底层鱼类食卵量估算,葛洲坝坝下江段中华鲟1次繁殖活动的产卵量在857.4-4148.5万粒之间,约等于13-64尾雌鱼的繁殖规模。由于产卵场范围狭小、敌害鱼类密度高,加之受精卵密集、孵化时间长,中华鲟所产卵粒的90%以上都被敌害鱼类所吞食。5.中华鲟繁殖群体包含有上年度和当年进入长江的两个股群,前者的性腺已经发育成熟,后者的性腺则未发育成熟。根据捕捞样本中性腺未发育成熟个体的比例,及其与上年度捕捞量的关系,估算出1981-1990年间。中华鲟繁殖群体的年补充量在822-1650尾之间。6.根据1990年以来繁殖群体雌雄性比的上升趋势,估计其在200l年达到最大值,以后将逐年下降,至2019年与期望值相一致。相应地其资源量自1990年开始逐年下降,至2019年达到最小值,年资源量将维持在400尾左右。7.利用水声学方法估算出1998年度,在葛洲坝坝下江段产卵场,产卵前中华鲟亲鱼数量约为282尾,产卵后调查只有81尾。庙嘴以下至古老背之间13km江段在产卵前估计约有746尾,产卵后只有约366尾。产卵亲鱼分布水深为4.0-19.0m,其中71.19%分布水深超过9.0m。8.根据荧光标记放流估算,全长8-10cm人工放流个体占长江口中华鲟幼鱼的数量比为:1996年放流5900尾,占1997年中华鲟幼鱼资源的1.71%;1997年放流8000尾,占1998年中华鲟幼鱼资源的比例少于1.89%:1998年放流20000尾,占1999年中华鲟幼鱼资源的3.03%。9.由于长江中华鲟的种群已经很难靠自然繁殖维持,目前人工放流又尚不足以弥补自然繁殖减少的损失,今后除应继续加强对繁殖群体的监测管理和增加人工放流数量外,还应着手栖息生境的恢复和重建以满足其自然繁殖的需要,并研究建立全人工繁殖种群以减少对自然种群的破坏。
英文摘要: The Chinese sturgeon, Acipensor sinensis, an anadromous fish, lives mainly in the continent shelf of the Yellow China Sea and East China Sea, and spawns in the Yangtze River and Pearl River. The abundance of the spawning stock in the Yangtze River is obviously higher than in the Pearl River. In reaches of the river within Sichuan province, where the spawning grounds existed, the sturgeon was one of the most important commercial fishing species with an annual output of about 40 tons in 1970s. Unfortunately, since the building of the Gezhouba hydraulic project in 1981, the migration of the fish to spawn in the upper reaches of the river has been blocked. Because of the loss of most of spawning grounds, the overfishing and other environmental stressors, A. sinensis has become endangered. Thus, since 1983 commercial fishery of this species has been prohibited in order to protect its natural resources. And ever since 1984, artificially propagated larvae and juveniles have been released annually into the Yangtze River for the stock enhancement. In order to understand the value of the above conservation measures, the author analyzed the detailed historical data of the spawning stocks, and estimated the population sizes of spawning stocks. The successness of released artificially reproduced young fish was then evaluated. 1. After the building of the Gezhouba Dam, the increases in average total length, body weight and age of the fish have been observed in spawning stocks, with much more significant increase in male sturgeons. Moreover, female-male ratio and percentage of gonad matured individuals (PGMI) have increased drastically in spawning stocks each year since 1990. 2. At present, the spawning ground of the Chinese sturgeon is located within a 2-km area between the Gezhouba Dam and Miaozui of the river. The condition of water level, flow, and sediment charge of this section meet the requirements of natural propagation of the fish. Moreover, a comparatively stable environment and a rough riverbed of this area may enable mature sturgeons to spawn, and the fertilized eggs to develop and not to be eaten totally by benthic fish. 3. The spawning activity of A. sinensis population occurs at least once a year, and two or three occasions of the spawning activities within a year have also been observed in 57.14% of the years when the spawning was investigated. The earliest date of spawning activity was recorded from 13th, October to 7th, November in different years. If twice or more of the activities were noted, the latest recorded was 18th, November. 4. According to the amount of eggs eaten by benthic fish, it is estimated that there are 8.574 to 41.485 million eggs in a spawning activity in the spawning ground below the Gezhouba Dam, and correspondingly 13 to 64 spawners. However, because of the narrowness of the spawning area, the abundance of predators, the high density of eggs, and the long period of incubation, more than 90% eggs were eaten by benthic fish. 5. The spawning stock of the Chinese sturgeon is consisted of two groups: one coming into the river in the previous year of a particular sampling year and the gonad matured in the sampling year, and another into the river in the sampling year with immature gonad. On the basis of the relationship between the PGMI in catches of a sampling year and the number of fish obtained in the previous year, the annual recruitment of spawning stock was estimated to be 822 to 1650 individuals during the period from 1981 to 1990. 6. According to the increasing trend since 1990, the female-male ratio may reach its maximum in 2001, and then decrease annually and finally reach its expected value in 2019. The population size of the spawning stock has reduced since 1990, and this trend may continue until 2019 when the minimum spawning population observed. A size of about 400 individuals would then remain afterwards. 7. By means of underwater acoustics method, it is evaluated that in 1998 about 282 spawners of the Chinese sturgeon might exist prior to the spawning in the spawning area. But, the actual number found was only 81 individuals after the completion of the spawning activity. In a 13-km section between Miaozui and Gulaobei, there might be 746 individuals of Chinese sturgeon before the spawning, and then only 366 individuals remained after the spawning. The spawners can stay in depth of water ranging from 4.0 to 19.0 m, but 71.19% of them prefer the depth greater than 9.0 m. 8. The artificially stocked juveniles were assessed with fluorescent mark-recapture data obtained from 1995 to 1998. Ranging from 8 to 10 cm in total length, 5900 artificial juveniles were released in 1996, which accounted for 1.71% of the juveniles in the estuary of the Yangtze in 1997. In 1997, with the release of 8000 juveniles, the percentage of released individuals to the capture should be less than 1.89% in 1998 in the estuary. In 1998, 20000 juveniles were released, accounting for 3.03% of the juveniles in estuary in 1999. 9. The population of A. sinensis can hardly be maintained only by natural reproduction. And until now, the artificial release of juveniles is also insufficient to compensate the loss of the natural reproduction. In order to protect the fish in the future, several measures should therefore be taken into consideration, including the strengthening of the spawning stock management, the increase of artificial release of juveniles, the restoration of natural spawning habitats, and the establishment of fully artificial stocks.
语种: 中文
内容类型: 学位论文
URI标识: http://ir.ihb.ac.cn/handle/342005/12532
Appears in Collections:中科院水生所知识产出(2009年前)_学位论文

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长江国华鲟繁殖群体结构特征和数量变动趋势研究.常剑波[d].中国科学院水生生物研究所,1999.20-25
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