| The construction and operation of The Three Gorges Dam and The first phase of the Jinsha River hydroelectric Project(comprised of Xiangjiaba Dam and Xiluodu Dam) have changed the original environment in the upper Yangtze River. Between those two water conservancy projects are located the national nature reserve of rare and endemic fishes in the upper Yangtze River which is lotic environment and the three gorges reservoir is lentic environment. The decrease of lotic environment has a great influence on survival of fish which like lotic environment and hatching drifting eggs. Gobioninae which spawns drifting eggs is an important fish group in the upper Yangtze River, including a variety of endemic fish which are unable to be effectively protected. Their survival are threatened by water conservancy project. Whether Gobioninae which spawns drifting eggs is able to adapt the change of the environment in the upper Yangtze River, and their habitat selection strategy and breeding conditions are urgently needed to be researched.To understand the influence of impoundment of the first phase of the Jinsha River hydroelectric Project, the survey of fish resources and ichthyoplankton was carried out in the mainstream of upper Yangtze River, including the composition and distribution of fish and ichthyoplankton, the fish habitat selection strategy of the upper Yangtze River, and the relationship between fish breeding activity and environment factor.. The main results which would provide the scientific basis for the fish protection in the upper Yangtze River, especially the Gobioninae fish which spawns drifting eggs were as follows:1. The fish resources investigations were carry out in Yibin, Jiangjin and Fuling section in the upper Yangtze River in March, June, September and December, 2014-2015. The results showed 106 species(subspecies) fish were collected, belonging to 6 orders, 16 families, among them 28 endemic species and 4 species were exotic fish. Cyprinidae fish was dominant families, including 60 species fish, the second was Cobitidae include 13 species. Gobioninae including 17 species was the highest number in the subfamily, followed by Cultrinae with 16 species. Yibin, Jiangjin and Fuling section respectively had 91, 93 and 69 fish species, The Jaccard’s similarity index of Yibin and Jiangjin section was 76.92%, Fuling and Jiangjin section was 70.53%. The CPUE of Yibin, Jiangjin and Fuling section were 2.53, 3.68, 3.19 Kg/boat per day. Analyzed The analysis of Shannon Wiener diversity index, Margalef richness index and Simpson dominance index of the three sections, showed that Yibin were both the highest, Fuling were the lowest, but for three sections there were no significant difference of diversity index(P > 0.05). The main catches of the upper Yangtze River were Pelteobagrus vachelli, Hypophthalmichthys molitrix, Coreius heterodon, Rhinogobio typus, Saurogobio dabryi, Coreius guichenoti, Ctenopharyngodon idellus etc.2. The fish resources surveys showed that Gobioninae fish accounted for 32.8% of the total weight of fish catches and 37.9% of the total number.of catched species. After impoundment of the first phase of the Jinsha River hydroelectric Project, the population of Coreius guichenoti declined in the below-dam section of the upper Yangtze River, the spawn grounds of Coreius guichenoti were above-dam, but there was still a small amount of Coreius guichenoti larvae below the Xiangjiaba Dam. The length and weight of Coreius heterodon were not significantly different. The distribution of Gobioninae without obvious regularity, but the distribution of 0 + age juveniles of some Gobioninae which spawned drifting eggs had certain regularity. 0 + age Coreius guichenoti juveniles mainly distributed in the lotic environment in the upper Yangtze River. Coreius heterodon juveniles began to leave the Three Gorges reservoir between September and December. The larvae could be found in both three sections after December. Rhinogobio typus juveniles began to leave the reservoir around September. Rhinogobio cylindricus juveniles were collected in Jiangjin and Fuling section in autumn and winter, and could be found in Yibin in the spring of second year. Rhinogobio cylindricus juveniles were mainly distributed in Fuling section.3. The surveys of fish eggs and larvae were carried out in Jiangjin section from May 5 to July 10, 2011-2015. According to the results, there were at least 58 species of fish spawning in the mainstream of upper Yangtze River. The mainstream of the upper Yangtze River was the important spawning ground for fish. The dominant groups include Gobioninae, Cultrinae, Cobitinae, Balitorinae, Gobiobotinae and four Chinese major carps etc. Based on the estimated, the quantity of eggs runoff the Jiangjin section during The quantity of larvae runoff the Jiangjin section during 5 years were 31.23×108, 30.85×108, 4.36×108, 1.03×108and 1.62×108 ind., respectively. From 2011 to 2015 average daily density of ichthyoplankton were 10.14, 8.75, 1.68, 2.45 and 3.87 ind./100m3, respectively. Among them, average daily density of fish eggs were 3.37, 2.08, 0.81, 2.24 and 3.35 ind./100 m3, respectively. The quantity rate of eggs of Pseudolaubuca engraulis, Rhinogobio typus and Gobiobotia filifer were increased, meanwhile the quantity rate of eggs of Coreius heterodon and Leptobotia were decreased. The quantity rate of four Chinese major carps eggs was relatively stable, only significant decreased in 2013. Because the first phase of the Jinsha River hydroelectric Project trapped sediment, the transparency after 2013 was significantly higher than that before 2012. Although other environmental factors had significant difference, but there was no regularity before and after impounded. It was employed Classical Correspondence Analysis(CCA) to analyze the relationship between every day density of each fish eggs and environment factors. The results showed the most groups were significantly related to water flow, flow diurnal variation, water temperature and transparency. Leptobotia breeding need high water temperature and flow, four Chinese major carps breeding requirements of water flow and flow diurnal variation were higher, and Gobioninae breeding requirements were different.4. The spawning number of Gobioninae from 2011 to 2015 in Jiangjin section of the upper Yangtze River was compared. The results showed that there were certain differences of spawning between different species of the Gobioninae in the upper Yangtze River. There was no significant decline on the occurrence rate of Coreius heterodon eggs During Five years, but quantity rate of Coreius heterodon eggs decreased significantly in 2015. The occurrence rate and quantity rate of Rhinogobio typus eggs were increase after 2014. Rhinogobio cylindricus spawning occurred every year, but the quantity rate was low. Small size Gobioninae, like Saurogobio dabryi and Squalidus argentatus occurrence rate increased significantly; Rhinogobio ventralis eggs only appeared in 2013. The quantity of total Gobioninae eggs runoff Jiangjin section during 2011-2015 were about 19.06×107, 13.17×107, 4.55×107, 22.90×107 and 29.28×107, respectively. From 2011 to 2015 average daily density of Gobioninae eggs were 0.47, 0.36, 0.13, 0.61 and 0.81/100 m3, respectively. The average daily density of Gobioninae eggs in 2013 was significantly lower than those in other years(P < 0.05), other years had no significant difference. From 2011 to 2015 average daily density of Coreius heterodon eggs were 0.39, 0.26, 0.09, 0.29, 0.14 ind./100 m3, the average daily density of 2013 was significantly lower than those in other years except 2015(P < 0.05), the average daily density of 2015 was significantly lower than that in 2011(P < 0.05). The Generalized additive model(GAM) was used to analyze the relationship between Coreius heterodon spawning or not and environment factors. The results showed that Coreius heterodon whether spawning or not was significantly related with transparency, dissolved oxygen, conductivity and flow(P < 0.01) and there was no significant correlation with flow diurnal variation and water temperature and p H. From 2011 to 2015 average daily density of Rhinogobio typus eggs were 0.03, 0.06, 0.02, 0.30, 0.41 ind. / 100 m3, respectively, the average daily density of Rhinogobio typus eggs in 2014 and 2015 was significantly higher than the average density from 2011 to 2013. GAM results showed that Rhinogobio typus spawning were significantly related to transparency(P < 0.01); and related to the water temperature(P < 0.05).The average daily density of Rhinogobio cylindricus eggs from 2011 to 2015 were respectively 0.041, 0.030, 0.013, 0.005, 0.034 ind. / 100 m3, the annual average daily density had not significant difference. Squalidus argentatus egg discovered only in 2013-2015, eggs average daily density were 0.008, 0.003, 0.160, ind. / 100 m3, respectively. In 2011-2015, the average daily density of Saurogobio dabryi eggs were 0.005, 0.010, 0, 0.010 and 0.064, ind. / 100 m3, respectively.5. Comparing the morphological characteristics of Gobioninae eggs which collected from 2011 to 2015, showed that the egg diameter and membrane diameter of Coreius heterodon was significantly bigger than other Gobioninae fish(P < 0.05), the average egg diameter and membrane diameter of Rhinogobio typus and Rhinogobio cylindricus was significantly bigger than the Squalidus argentatus and Saurogobio dabryi, the average egg diameter and membrane diameter of Rhinogobio ventralis was between Rhinogobio cylindricus and Squalidus argentatus. The Gobioninae spawning grounds were located according to the developmental stage of egg and velocity when catching the egg. Coreius heterodon spawning grounds were mainly distributed in six sections, the position of the spawning grounds was different in different years, but mainly located in the two sections from Baisha to Yangshi and from Rongshan to Zhaoya. Rhinogobio typus spawning grounds mainly distributed in four sections before 2013 and Rhinogobio typus spawning grounds were scattered after 2014, but mainly distributed in the Zhuyang to Rongshan section. The position of Rhinogobio cylindricus spawning grounds was different in each year. Rhinogobio ventralis spawning grounds located in Zhutuo and Hejiang two sections in 2013. Saurogobio dabryi spawning grounds located in 4 sections. Squalidus argentatus spawning grounds located in 2 sections.The fish resources and fish breeding in the upper Yangtze River had significant changed before and after the impoundment of the first phase of the Jinsha River. Effective protection and monitoring of fish resources were needed in the upper Yangtze River. |
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