| Datengxia Water Control Project is the last link of cascade development of Hongshui River.Its completion represents that the development and utilization of water resources in the Pearl River has reached a new height.It not only brings great convenience to people,but also blocks the circulation of water areas,changes the local natural ecological environment and brings difficulties to the protection of biological resources.Squaliobarbus curriculus is the main economic fish in the Pearl River Basin.Its living habits are similar to those of the four major fish.It is suitable to be the object of the impact of the dam on fish.From June 2020 to September 2021,1066 samples of Squaliobarbus curriculus were collected in the upstream and downstream of Datengxia Water Control Project in Guiping City,Guangxi Province to study the breed and growth characteristics of Squaliobarbus curriculus,so as to explore the impact of project on the Squaliobarbus curriculus and provide reference for subsequent fishery resources protection.The main results are as follows:1.The age range of Squaliobarbus curriculus in Datengxia area is 1 ~ 5 years old,the dominant age group above the dam is 1 year old,accounting for 54.6%,followed by 2years old,accounting for 32.8%;The dominant age group under the dam is the first age group,accounting for 54.7%,followed by the second age group,accounting for 33.6%.There is no significant difference in the age composition structure of Squaliobarbus curriculus in the upstream and downstream of the project.2.The standard length range of Squaliobarbus curriculus above the dam is 84 ~410mm,the average standard length is 218.6 ± 66.3 mm,the weight range is 9.2 ~ 1266.6g,and the average weight is 225.06 ± 197.73 g;The individual standard length under the dam is 54 ~ 389 mm,the average standard length is 212.2 ± 55.1 mm,the weight range is3.0-1059.6 g,and the average weight is 201.58 ± 164.47 g.The body weight of Squaliobarbus curriculus above the dam is significantly higher than that under the dam,and the standard length is higher than that under the dam.The proportion of small individuals under the dam is relatively high,and the proportion of large individuals above the dam is relatively high.There are significant differences in the relationship between standard length,weight and age of Squaliobarbus curriculus above and under the dam.The fitting result of relationship of standard length and weight above the dam:W=8.13E-6×SL3.1303,under the dam: W=1.03E-5×SL3.0958.The individuals of Squaliobarbus curriculus in the upstream and downstream of the dam grow at an allometric rate.The individual Squaliobarbus curriculus above the dam has a larger weight per unit standard length.Fitting von Bertalanffy equation results as followed.Above the dam: Lt=396.28(1-e-0.5014(t+0.1786)),Wt=518.23(1-e-0.5014(t+0.1786))3.1303;Under the dam: Lt=429.82(1-e-0.3552(t+0.5363)),Wt=642.00(1-e-0.3552(t+0.5363))3.0958.The apparent growth index((?))of Squaliobarbus curriculus above the dam is 4.90 and that under the dam is 4.82.The L∞ and W∞ of upstream Squaliobarbus curriculus were 396.3mm and 518.64 g respectively;The L∞ and W∞ of downstream Squaliobarbus curriculus were 429.82 mm and 640.41 g respectively.The standard length and weight of individuals under the dam are greater than those above the dam.There is an inflection point of body weight growth of Squaliobarbus curriculus in Datengxia area,which is 2.1 years old above the dam and 2.6 years old under the dam.3.The sex ratio of Squaliobarbus curriculus in Datengxia area is 1.36:1,the ratio above the dam is 1.71:1,under the dam is 1.03:1.The number of female fish under the dam is much larger than that of male fish.The proportion of female sexually mature individuals of Squaliobarbus curriculus above the dam was the highest in June,and the proportion of female sexually mature individuals of Squaliobarbus curriculus above the dam was the highest in July.The breeding season under the dam was slightly later than that above the dam.The average maturity coefficient above the dam was 5.58,which was significantly higher than that under the dam of 4.26.The first sexual maturity age above the dam of the male is 1.93,and the first sexual maturity standard length is 264.3 mm.The first sexual maturity age of female above the dam is 1.92,and the first sexual maturity standard length is 254.4 mm;The first sexual maturity age under the dam of the male is 2.38,and the first sexual maturity standard length is 275.2 mm.The first sexual maturity age of female under the dam is 2.14,and the first sexual maturity standard length is 257.9 mm.Individuals above the dam reach sexual maturity earlier than those under the dam,and their standard length is slightly smaller when they reach sexual maturity. |
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