| In 2020,China proposed the double carbon goal to the world.In order to realize the commitment of carbon peak by 2030 and carbon neutral by 2060,emission reduction and increase carbon sink has become a research hot spot of related disciplines.As the largest carbon pool on earth,the carbon sink of ocean is of great significance to achieve the goal of carbon neutrality.The fishery carbon sink is an important part of the marine carbon sink.Through the process and mechanism of the fishery carbon sink,the carbon sink function of fishery organisms can be better played.The construction of marine ranching is of great significance to the increase of fishery carbon sink.Resource conservation effects promote the increase of biodiversity and accelerate the transformation and transport of carbon between trophic levels of the food web.Reef fish are the target population of marine ranching conservation and breeding,but their carbon sink effect is less studied.Therefore,measuring the carbon content of reef fish,estimating the carbon storage of reef fish,predicting the carbon sink potential of reef fish,and calculating the economic value of reef fish carbon sink are conducive to scientifically evaluating the carbon sink capacity of reef fish,promoting the development of marine ranching carbon sink,fishery carbon sink and marine carbon sink system,so as to better serve the double carbon strategy of national.This study selected some typical reef fish included Sebastes schlegelii,Hexagrammos otakii,Sebasticus marmoratus,Sebastes hubbsi and Sebastes pachycephalus in Shique Beach marine ranching.This reef fish were harvested from Spring 2017.This study based on harvested data from 2017 to 2022 in the reef and contrast area and carbon content of typical reef fish,used carbon content method,Trophic level method 1(TLM1),Trophic level method 2(TLM2),GM(1,1)model,Residual correction grey model(RCGM(1,1)),Discrete grey model(DGM(1,1)),Grey Markov model and shadow price method to estimate and predict the carbon storage of reef fish and calculate its economic value.The main research results of the study showed that:(1)The mean carbon content of dry sample of Sebastes schlegelii,Hexagrammos otakii,Sebasticus marmoratus,Sebastes hubbsi and Sebastes pachycephalus were 45.73±1.37%,50.19±2.93%,45.34±3.87%,42.95±4.18%,46.37±1.27%,respectively.The mean carbon content of fresh sample were 11.76±0.42%,13.25±0.34%,12.78±0.89%.11.05±0.81%,12.67±0.36%,respectively.There were significant differences in the carbon content of dry sample between Hexagrammos otakii and Sebastes hubbsi(P<0.05),and there were significant differences in the carbon content of fresh sample(P<0.05).There were no significant difference in the carbon content of dry sample between Sebastes schlegelii and Hexagrammos otakii(P>0.05),but significant difference in fresh sample(P<0.05).There were no significant difference in carbon content between dry and fresh sample of Sebasticus marmoratus and Sebastes pachycephalus(P>0.05).(2)There were obvious seasonal changes and regional differences in carbon storage of reef fish estimated by carbon content method.TLM1 and TLM2 in six survey voyages.The estimation of carbon storage of reef fish by the three methods showed a fluctuating trend in the reef area,and an increasing trend and then a decreasing trend in the contrast area.The estimation of carbon storage of reef fish in the reef area were the highest in spring 2017,the estimated values were 293.46t,6517.12t and 44522.86t,respectively.The lowest in winter 2020,the estimated values were 63.99 t,1090.67 t,7374.97 t.It was estimated that the carbon storage in the contrast area were the highest in winter 2018,the estimated values were 59.07 t,1305.48 t.8935.72 t,and the carbon storage of reef fish captured by cage nets in the contrast area were 0 in winter 2020,spring 2021 and winter 2022.In six survey voyages,the carbon storage of reef fish estimated by the three methods in the reef area were significantly higher than those in the contrast area of the same voyage,and the total carbon storage of reef fish in the reef area were 7.78.8.04 and 7.73 times of those in the contrast area,respectively.(3)Different evaluation methods differ greatly in estimating the carbon storage of the same object.Although TLM1 and TLM2 are both established according to the principle of trophic level,the calculated carbon storage differ greatly.In six survey voyages,the carbon content method was used to estimate the carbon storage of reef fish in reef area,which were respectively equivalent to 4.50%,4.33%,4.47%,4.44%,4.39%and 4.32%of TLM1 and respectively equivalent to 0.66%,0.62%,0.66%,0.66%,0.64%and 0.64%of TLM2.The estimated value of TLM1 was 14.64%,14.26%,14.75%,14.79%,14.53%and 14.46%of TLM2,respectively.(4)Four prediction models were constructed for the carbon storage of reef fish in the reef area.Among them,the fitting accuracy of GM(1,1)model and RCGM(1,1)model were not much different,and the average relative errors were 25%and 29%,respectively.Compared with GM(1,1)model and RCGM(1,1),the fitting accuracy of DGM(1,1)model is slightly improved,and the average relative error is 22%,and the model test is also unqualified.Compared with the previous three models,the fitting accuracy of the Grey Markov model is greatly improved,and the average relative error is 7.28%.The model has passed the test and can realize the accurate prediction of reef fish carbon storage in the short term.It is predicted that the carbon storage of reef fish in spring 2023 and winter 2024 are 87.00 t and 79.03 t,respectively,showing a decreasing trend.(5)The overall marine fishery carbon sink price in Shandong Province showed an upward trend from 1990 to 2017,with the lowest in 1990 and the highest in 2017,and the average price was 337.05.According to the calculation of carbon content method of six survey voyages,the aggregate economic value of carbon storage of reef fish in the reef area is about 25×104,and the average economic value of carbon sink of about 40,000 can be created by reef fish in each survey voyage. |
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