Journal of Dalian Ocean University  2023, Vol. 38 Issue (3): 494-503 DOI: 10.16535/j.cnki.dlhyxb.2022-234 |
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| Spatial and temporal characteristics and influencing factors of larvae and juveniles of Siniperca in the Anqing section of the Changjiang River |
| LI Jiasheng，FANG Di’an，XU Dongpo*，TANG Yue，DING Longqiang，HUANG Zhongjia，REN Peng
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| 1.College of Wuxi Fisheries，Nanjing Agriculture University，Wuxi 214081，China；2.Changjiang River Downstream Fisheries Resources and Environmental Science Observation Station，Ministry of Agriculture and Rural Affairs，Freshwater Fisheries Research Center，Chinese Academy of Fishery Sciences，Wuxi 214081，China；3.National Demonstration Center for Experimental Fisheries Science Education，Shanghai Ocean University，Shanghai 201306，China；4.Chinese Academy of Agricultural Sciences，Beijing 100081，China |
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Abstract In order to understand the status of resources of larval and juvenile Siniperca in the Anqing section of the Changjiang River, and to explore the spatio-temporal characteristics and influencing factors, an larval and juvenile fish resource survey was carried out from April to August, 2018 to 2020. The results showed that the first appearance time of Siniperca larvae was April 29th (2018), April 30th (2019)and May 5th (2020), indicating a delayed occurrence time of resources of larval and juvenile Siniperca. The cumulative occurrence time of larvae and juveniles in 2018, 2019 and 2020, was 44 days, 54 days and 68 days respectively. The occurrence frequency was 40.74% (2018), 55.67% (2019) and 69.39% (2020). The cumulative number of larvae and juveniles collected in 2018, 2019 and 2020, was 175, 313 and 404, respectively, exhibiting a time-dependent increasing trend.During the investigation, the occurrence time of peak abundance of larvae and juveniles was from July 14th to August 6th in 2018, July 16th to July 27th in 2019, and June 18th to July 20th in 2020. The corresponding average abundance was 0.073, 0.051, and 0.044 ind./m3 in 2018, 2019 and 2020, showing a time-dependent decreasing trend. Affected by hydrological dynamics, the spatial distribution of larval and juvenile drifting density in the Anqing section was different, showing the characteristics of the left bank (0.056 ind./m3) >the right bank (0.046 ind./m3) >the center of the river (0.026 ind./m3). Spearman correlation analysis showed that the abundance of larvae and juveniles was positively correlated with the flow, water level and water temperature (P<0.05), and significantly negatively correlated with the transparency (P<0.05). The temporal dynamic characteristics of larvae and juveniles abundance were consistent with the seasonal variation pattern of flow and water temperature. The results of this study reveal that the optimum water temperature for the reproduction and spawning of Siniperca is 25.6 to 29.2 ℃ during the investigation, and the change of water temperature gradient stimulates the occurrence of breeding events in Siniperca. The annual increase of the absolute number of larval and juvenile fish reflects that the annual supplement of Siniperca fish species in the Anqing section has been steadily enhanced, and the situation of resource recovery is improving.
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Published: 12 July 2023
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