| The Squaliobarbus curriculus,commonly known as weed fish and red-eye fish,had strong adaptability to environment and high meat content.Its muscles contained rich nutrients.Edible curriculus had a tender taste and a delicious taste and was popular with consumers.It is one of the important freshwater fish species.In recent years,due to the influence of human factors such as shipping and fishing,the resources of red eye trout have been sharply reduced.In order to restore its fishery resources,a large number of breeding and release have been carried out in various places.It is noted that since the13 th Five-Year Plan,the red-eyed trout in the Qiantang River system of Zhejiang Province has reached about 14.95 million units.In the 14 th Five-Year Plan(2021-2025),Zhejiang Province clearly pointed out that it should carry out the rescue and protection of rare and endangered and endemic species.Restoration of indigenous fish stocks of trout,Spinibarbus denticulatus and Coilia ectenes will be carried out.Therefore,it is very necessary to evaluate the effect of breeding and releasing of the native fish in Qiantang River with the trout as the representative.This study is expected to provide a scientific basis for the sustainable development of the trout fishery resources.This material is derived from the data of breeding and releasing of red eyed trout in Qiantang River(Lanxi-Fuyang River section)conducted by Zhejiang Freshwater Fisheries Research Institute from 2021 to 2022.The content of the paper is summarized as follows:1.The applicability of different tagging for Squaliobarbus curriculus was investigated.In this study,five methods for tagging squaliobarbus curriculus were tested:hoop tagging,"T" tagging,fin clipping tagging,visible implant fluorescent colloid tagging(VIE)and passive integrated transponder tagging(PIT).The survival rate,labeled retention rate and specific growth rate(SGR)of trout were analyzed under different labeling methods.The results showed that the overall survival rate of control group and T marker(100%)>VIE marker(90%)> fin clipper marker(88.90%)> hoop marker(86.70%)>PIT marker(85%).The retention rate of observed markers at 7 days after labeling was as follows: clipped fin marker(100%),VIE marker(100%),PIT marker(100%)> "T" marker(60%)> Iron ring marker(36.66%).After half a year of mixed temporary breeding,the proportion of the number of identified marker fish to the number at the time of release was PIT marker(74.51%)>VIE marker(18.52%)>clipped fin marker(2.50%)> "T" marker(1.67%)> hoop marker(0.00%).After 208 days of mixed culture,the SGR of red eyed trout was no label(1.56%/d)> clipped fin label(1.32%/d)> fluorescent label(1.30%/d)> T label(1.28%/d)> PIT label(1.08%/d).According to comprehensive analysis,VIE has higher survival rate than other labeling methods.Although the labeling retention rate is lower than PIT,it has no obvious inhibition on the growth of red eyed trout.2.In the water temperature of 26℃-29℃,Young red trout of 20 days of age(average body length 1.51-2.41cm)were soaked in alizarin red S in different concentration groups(0mg/L,50mg/L,100mg/L,150mg/L,200mg/L,250mg/L,300mg/L)for continuous 24 h to observe the death of the fish and determine the lethal concentration and safe concentration.Under non-lethal concentration,equidifferential concentration gradient groups(0mg/L,30mg/L,60mg/L,90mg/L,120mg/L,150mg/L,180mg/L)were set to soak juvenile red eye trout for 8h,12 h,24h,respectively.Image Pro Plus was used to analyze the average optical density(AOD)of otolith of juvenile red trout to explore the staining effect of alizarin red S.The results show that:Observed under natural light of microscope,red ring marks can be seen in microotolith and starotolith of young red trout dyed by alizarin red s.The marked color tended to be significant with the increase of the concentration of dye solution and the extension of soaking time.The overall effect intensity of otolith markers was180mg/L > 150mg/L > 120mg/L > 90mg/L > 60 mg /L >30mg/L.Soak 24h>12h>8h.Under the same soaking conditions,the staining effect of microotolith was better than that of astrootolith.After 180 days of continuous cultivation,it was found that the labeling effect of microotiths and astrootiths was gradually weakened,but the retention time of microotiths was longer than that of astrootiths.3.Based on the 2021-2022 fishery resource fishing survey of Qiantang River(Lanxi-Fuyang section),combined with social survey and marker fish recovery data,the biological growth characteristics of red-eyed trout in Qiantang River(Lanxi-Fuyang section)were explored,and the Beverton-Holt model was used to analyze the resource utilization status of red-eyed trout in Qiantang River,and the results showed that the current fishery points F=0.16 and tc=2.125 fishery resources were underutilized.Finally,the large-scale release of red-eyed trout from the perspective of economic,social and ecological benefits in Qiantang River(Lanxi-Fuyang section)in 2021 was quantitatively evaluated,and the results showed that the total input-output ratio was1:2.44,the total residual weight at TC age after release was 2.87×105kg,nitrogen transfer was 8.61×103kg,phosphorus was transferred 1.38×103kg,and fishermen’s satisfaction with breeding and releasing reached 96% through questionnaire statistics.The results of this study will provide a scientific basis for the subsequent management and optimization of release measures for aquatic organisms in inland waters of Zhejiang Province. |
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