| The Gymnocypris przewalskii is the dominant species in Qinghai Lake and its watershed,a unique economic fish in Qinghai Lake,which is at the core of the ecosystem of Qinghai Lake,and is also one of the few fish in the carp family that can adapt to the high cold water environment.Because Qinghai Lake grows in alpine areas,the living water body is high-salt and high-alkali environment,and the nutrients are scarce,so the growth rate is extremely slow.In recent years,due to the impact of human activities and overfishing,the resources of G.przewalskii have declined sharply and are almost depleted,and the construction of water conservancy facilities has destroyed the original river channels,destroyed natural spawning grounds,and due to climate change,the number of rivers entering the lake in Qinghai Lake has plummeted to less than 10 at present.At present,with the implementation of measures such as fish breeding,breeding and stocking,and the construction and restoration of migratory passages in the lake,the resources of G.przewalskii are gradually increasing,and the population is in the growth stage,but it has not yet recovered to the historical peak.The G.przewalskii is a migratory fish in the river,and the Quanji River is its important spawning field distribution channel,which has an important impact on the resource replenishment of G.przewalskii.In this paper,the specific habitat parameters of the spawning field of G.przewalskii were artificially determined by using UAV(unmanned aerial vehicle)technology,and artificial intelligence was applied to the identification of the spawning site,and the habitat characteristics and distribution of the field spawning of G.przewalskii in Quanji river were mastered,in order to provide a theoretical basis for the protection,establishment and evaluation of the field spawning of G.przewalskii,and provide a scientific reference for the protection of natural population resources of the G.przewalskii.In 2019-2021,this study studied the habitat characteristics of G.przewalskii in Quanji River,and assessed its scale distribution,and the results were as follows:1.The breeding time of G.przewalskii is from May to September every year,during which the flow range of the non-flow mutation period of Quanji River is 1-4m~3/s,and the flow of Quanji River is within this flow range most of the time,and the G.przewalskii basically spawns and breeds under this flow range.From the perspective of natural reproduction monitoring effect and broodstock distribution,the G.przewalskii mainly carries out natural spawning and reproduction in the downstream spawning field section,and the reproductive effect is the best.The river morphology of Quanji River is mainly divided into straight,curved and fencing types,spawning grounds are mainly distributed in fendling river channels and curved river channels,river habitats are complex,there are beaches with interlaced beaches,river bends or crossovers of beaches are prone to deep pools,deep pools in the shallow area of the shallow area,the flow rate is slower,the water depth is shallow,and the natural breeding environment required for the G.przewalskii is easy to form;the average length of the spawning farm section is 135.13m(S.D.=61.13),and the average width is 30.01m(S.D.=17.51),The average tortuous rate is1.09(S.D.=0.07),the average flow rate is 0.24m/s(S.D.=0.20),the average water depth is0.19m(S.D.=0.10),the riverbed is small and medium-sized pebbles(particle size 16-256mm),the optimal flow rate of the natural breeding spawning area of the G.przewalskii in Quanji River is 0.07-0.36m/s,and the most suitable water depth is 0.11-0.25m,of which the largest spawning field is located downstream,with an area of 16380m~2.The average area of spawning grounds is 4586.60m~2(S.D.=4201.61);non-spawning grounds are mainly distributed in straight-type rivers,the habitat is relatively simple,generally there is no edge beach,the flow rate is high,the water depth is deep,and the natural breeding environment required for the G.przewalskii cannot be formed;the average width of the non-spawning field section is 16.97m(S.D.=6.46),the average tortuous rate is1.02(S.D.=0.02),and the average flow rate is 0.52m/s(S.D.=.0.27),the average water depth is 0.34m(S.D.=0.14),and the riverbed is medium and large pebbles(particle size>64 mm).From upstream to downstream,the river morphology of the Quanji River gradually evolved from the curved and straight type to the main fencing type,and the width value of the spawning field section gradually became larger.2.The spawning grounds of G.przewalskii can be identified by UAV telemetry images,and based on the following four habitat characteristics,spawning grounds can be artificially determined:(1)river morphology:curved river channel and fencing type river channel,most of the spawning grounds of G.przewalskii exist in these two river morphologies;(2)river floodplain:there is a river section with river floodplain,the spawning grounds of G.przewalskii have edge beaches,and most of the breeding activities occur on the shoals;(3)Visible water depth range:shallow water depth(At<0.4m),from the UAV telemetry imagery,it can be seen that at the bottom of the riverbed,when the breeding activity of the G.przewalskii occurs,the water depth is mostly at(0.34±0.14)m;(4)tortuous rate:the tortuous rate is greater than>Curved section of 1.09.The judging results showed that in the flat water period,Quanji River could screen out a total of 307 the spawning grounds of G.przewalskii,with a total area of 399,320.32m~2and an average area of(1231.12±548.81)m~2,and 5 of these spawning fields were randomly selected for verification,and the actual measurement proved that they were all the spawning grounds of G.przewalskii.Using artificial intelligence to model and identify the spawning field of G.przewalskii,the spawning field of G.przewalskii identified by artificial intelligence is more fragmented,and in the flat water period,Quanji River screened out a total of 246(area greater than 50m~2)the spawning grounds of G.przewalskii,with a total area of 190,621.03m~2 and an average area of(614.13±832.82)m~2.3.This study systematically explored the habitat characteristics of the natural spawning field of G.przewalskii in Quanji River,and conducted quantitative analysis,on the basis of which an artificial and AI identification method based on UAV image identification of the spawning field of G.przewalskii was established,and its scale was evaluated,which provided a solid foundation for the protection and restoration of the spawning field of G.przewalskii in the future. |
PDF Full Text Request