中国水产科学2017，Vol.24Issue(3)：425-431,7.DOI:10.3724/SP.J.1118.2017.17095
从连续到偶发:中华鲟在葛洲坝下发生小规模自然繁殖
From continuous to occasional: Small-scale natural reproduction of Chinese sturgeon occured in the Gezhouba spawning ground, Yichang, China
摘要
Abstract
The critically endangered Chinese sturgeon (Acipenser sinensisGray), a large anadromous fish, is strictly protected in Chinese waters, where it is deemed to be a national treasure. Mature individuals enter the Yangtze River estuary from July to August, before entering their spawning ground the following year from Octo-ber to November. Historically, sturgeon spawned in the upper reaches of the Yangtze and lower reaches of the Jinsha Rivers, but construction of Gezhouba Dam (the first dam in the Yangtze mainstream) blocked this migratory route. A relatively stable spawning ground has since developed below this dam. From 1982, the Yangtze River Fisheries Research Institute has conducted annual monitoring of natural breeding of sturgeon within the newly formed spawning ground. Between 1982 and 2013, sturgeon spawned annually, though both fecundity and fre-quency of reproduction declined. Whereas the number of mature fish arriving at the spawning ground annually exceeded 2000 individuals in the early 1980 s (near the closure of Gezhouba Dam), it also dropped to fewer than 100 individuals in recent years. Prior to impoundment of the Three Gorges Reservoir (1984?2003), sturgeon spawned on average 1.8 times per year, though this decreased to 1.1 times during impoundment (2004?2012). Al-though controlled propagation and augmentation of sturgeon stocks has been performed from as early as 1983, both mark-recapture and molecular genetic identification reveal more than 90% of juvenileA. sinensis within the Yangtze estuary originated from natural reproduction. Thus, it is critical that natural reproduction of the fish may be maintained in the only knowing spawning ground.Though there was an apparent interruption in sturgeon spawning between 2013 and 2015 at this only known spawning ground, we report a resumption of spawning in 2016, during which time 67 egg (or egg membrane) and 22 larval sturgeon were collected by bottom draft-net, and 454 eggs were found in the stomachs of 10 egg-preying fishes. Underwater camera observations also revealed five sites with fertilized sturgeon eggs adhering to the sub-stratum. The spawning ground was 300 m downstream of the Dajiang power plant (Gezhouba Dam). Spawning likely occurred during the early morning of November 24; estimated fecundity was less than two million; water temperature at the time of spawning was 19.7℃; and the flow and water level were 6610 m3/s and 39.7 m, respec-tively.Recent monitoring indicates the Chinese sturgeon has changed from being a "continuous" to an "accidental" spawner, and that this is likely to continue. Increased water temperature was probably the main reason for the failed spawning between 2013 and 2015, as the Three Gorges Reservoir significantly altered water temperature within the middle reach of the Yangtze River, but other factors, such as navigation, waterway regulation, over-fishing and environmental pollution, have also reduced environmental quality at the spawning ground and may have contributed to spawning failures. Without effective environmental management, the natural population of Chinese sturgeon is at high risk of extinction.In 2015 the Ministry of Agriculture issued the "Chinese Sturgeon Rescue Action Plan" to protect Chinese sturgeon, which introduced severalin-situ conservation programs, such as artificial restocking, habitat manage-ment and restoration, and the prohibition of fishing. Artificial restocking of Chinese sturgeon would also be im-proved by increasing the number and size of released individuals, thereby increasing their survival. In the middle and lower reaches of the Yangtze River, port, waterway, shipping and other construction projects should be man-aged to avoid any negative impact on the habitat and migration of Chinese sturgeon. In particular, environmental protection of Hubei Yichang Chinese Sturgeon Natural Reserve needs strengthening to maintain the hydrological conditions of spawning grounds. Additionally, improvement and rebuilding of Chinese sturgeon spawning grounds would facilitatein situ-protection of Chinese sturgeon.关键词
中华鲟/洄游/自然繁殖/葛洲坝/产卵场Key words
Acipenser sinensisGray/migration/natural reproduction/Gezhouba Dam/spawning ground分类
农业科技引用本文复制引用
吴金明,王成友,张书环,张辉,杜浩,刘志刚,危起伟..从连续到偶发:中华鲟在葛洲坝下发生小规模自然繁殖[J].中国水产科学,2017,24(3):425-431,7.基金项目
国家自然科学基金项目(31602160) （31602160）
公益性行业(农业)科研专项(201203086) （农业）
国家自然科学基金应急管理项目(51641909). （51641909）
