| Chinese large-water fishery has gone through four stages:natural fishing,extensive aquaculture,intensive aquaculture,and coordinated development of fishery and the environment,and is now in a transitional period.Most of the ecological fisheries use multi-trophic ecological proliferation and release technology,but there is no unified standard for this technology.An important reason is that the supporting theoretical research of this technology is insufficient.In this paper,the Ecopath model of Weishui Reservoir is constructed mainly based on the survey data of basic bait organisms and fish resources survey data from 2020 to 2021.The ecological system structure,energy flow and material circulation characteristics of Weishui Reservoir were analyzed,and the suitable release types and release quantities in the multi-trophic proliferation and release scheme of Weishui Reservoir were discussed.In order to provide technical support for the multi-trophic ecological proliferation and release technology.The main results were shown as follows:The annual survey results of bait organisms in Weishui Reservoir show that 8 phyla,72 genera and 131 species of phytoplankton have been found in Weishui Reservoir,of which Chlorophyta has the largest number of species,with a total of 24 genera and 47species,accounting for 35.9%of the phytoplankton species.;Bacillariophyta are 19 genera and 40 species,accounting for 30.5%of the phytoplankton species;Cyanophyta are 13genera and 23 species,accounting for 17.6%of the phytoplankton species.The main dominant species were Melosira granulate and Phormidium tenue,and the annual average abundance and biomass of phytoplankton were 5.97×10~7ind./L and 9.01 mg/L,respectively.A total of 31 genera and 51 species of zooplankton were found in the Weishui Reservoir,of which rotifers were found in 12 genera and 23 species,accounting for 45.01%of the total zooplankton species,followed by protozoa,with a total of 6 genera and 12species,accounting for 23.52%of the total zooplankton species.The main dominant species were nauplii and copepods.The annual average abundance and biomass of zooplankton were 5182.29 ind./L and 3.50 mg/L,respectively.A total of 12 species of benthic animals were found in the Weishui Reservoir,including4 species of oligochaetes,accounting for 33.3%of the total species of benthic animals;5species of aquatic insects,accounting for 41.7%of the total species of benthic animals;the main dominant species are oligochaetes The annual average abundance and biomass of hairs,chironomids larvae and benthic animals were 2307.67 ind./m~2 and 0.92 g/m~2,respectively.The temporal distribution characteristics of biological abundance and biomass of basic food are that the high temperature season is more noteworthy than the low temperature season(different for benthic animals,the low temperature season is more prominent than the high temperature season),and the spatial distribution characteristics are that the upper reaches of the reservoir are larger than the lower reaches of the reservoir.The survey results of fish resources in Weishui Reservoir show that a total of 3 orders,3 families,17 genera and 20 species of fish have been found in Weishui Reservoir,including15 genera and 17 species of Cyprinidae,1 genus and 1 species of Kuehidae,1 genus and 2species of Acetidae;the main dominant species is bighead carp,the relative importance index is 1402.72.The Ecopath model of Weishui Reservoir is composed of 17 functional groups,the effective trophic level of each functional group ranges from 1.000 to 3.341,The key species is Culters,the niche overlap map shows that the niche overlap between Hemiculter leucisculus and the main economic species,Hypophthalmichthys molitrix and Aristichthys nobilis,is relatively high.The circulation index(FCI),system connectivity index(CI),and system omnivorous index(SOI)of the Weishui reservoir are 11.35,0.30,and 0.11,respectively,indicating that the Weishui reservoir has a high proportion of material recycling,and its functional groups have relatively high ratios of material recycling.close and complex connections.The total flow rate(TST)of the ecosystem in Weishui Reservoir was 32193.34 t/(km~2·a),and the ratio of total primary production to total respiration(TPP/TR)was 4.63,indicating that the overall scale of the system was suitable and mature.Using the Ecopath model of Weishui Reservoir,4 sets of Ecopath models corresponding to the multi-trophic proliferation and release scheme of Weishui Reservoir were constructed.The key parameters of the proliferation and release technology construction,such as the ecological capacity,maximum sustainable yield,and stocking quantity,of the released fish under the 4 sets of plans were calculated,providing technical support for the multi-trophic ecological proliferation and release technology.The ecosystem health benefits,nitrogen and phosphorus removal benefits,and economic benefits of each scheme were discussed to provide reference for the relevant fishery management departments to designate fishery measures.The results show that if economic benefits and nitrogen and phosphorus removal benefits are considered as the main factors,the suitable breeding scheme for the Weishui Reservoir is scheme 1,the release species are Hypophthalmichthys molitrix and Aristichthys nobilis,and the amount of Hypophthalmichthys molitrix and Aristichthys nobilis released is 135158 indeed and 490769 indeed.The maximum sustainable output is 486.57 t and1766.77 t respectively.The total output value,total profit value and output value per square kilometer in the economic benefit indicators are 80.40 million yuan,70.04 million yuan and 3.50 million yuan/km~2 respectively.The removal amounts were 2.95 t～23.13 t and0.85 t～6.53 t,respectively,and the ecosystem health benefit indicators total primary production force/total respiration(TPP/TR)value,connection index(CI)value,system omnivorous index(SOI)value,Shannon’s diversity index values were 4.030,0.304,0.114,and 1.557,respectively.If the ecological benefits and economic benefits are considered comprehensively,the multi-trophic proliferation and release plan of the Weishui Reservoir is Plan 3,and the fish composition is mandarin fish,yellow catfish,common carp,crucian carp,Hypophthalmichthys molitrix and Aristichthys nobilis,and the quantity of Hypophthalmichthys molitrix,Aristichthys nobilis,and the rest of the fish.45229 indeed,164227 indeed and 27880 indeed respectively,and the maximum sustainable yields are 1.15t,3.75 t,18.77 t,5.60 t,162.82 t,and 591.22 t,respectively.The output value per square kilometer is 30.42 million yuan,25.62 million yuan,and 1.28 million yuan/km~2,respectively.The annual net removal of total nitrogen and total phosphorus is 1.06 t～8.17t and 0.29 t～2.21 t respectively.The total primary ecosystem health benefit index includ of generative force/total respiration(TPP/TR),connectivity index(CI),system omnivorous index(SOI),and Shannon diversity index were 4.616,0.302,0.117,and 1.597,respectively. |
