| Since the mid-1970s,due to environmental pollution and overfishing,the marine ecological environment has deteriorated,biological habitats have been destroyed,and marine fishery resources,especially offshore traditional fishery resources,have declined seriously.Ecosystem-based fishery resource management has become a research hotspot in marine fishery management.Dalian Wangjiadao waters are located in the northern part of China's Yellow Sea.Fish,shellfish,crustaceans and other marine biological resources are rich,but in recent years,due to disorderly fishing,the increase in the scale of aquaculture and the increase in tourists on the island,fish individuals have been miniaturized in some sea areas,and some shellfish individuals have grown slowly some phenomenons.How to develop and manage marine biological resources from the perspective of ecosystem has become a hot topic concerned by relevant fishery enterprises and fishery authorities.Based on the field survey data of Wangjiadao waters,this paper analyzes the structure and function of the Wangjiadao waters ecosystem,evaluates the ecological capacity,growth characteristics and resources of the main economic species,and proposes development and utilization strategies.It is hoped that it will be beneficial to the rational development and utilization of fishery resources in Wangjiadao waters.The main contents and results of this paper are as follows:1.According to the allocation principle of functional groups of Ecopath model and combined with the actual characteristics of Wangjiadao sea area,a total of 22 functional groups are established to analyze their ecosystem structure and energy flow characteristics.The results are as follows:(1)The characteristics of the Wangjiadao sea area ecosystem are that the total flow is 410 409.31 t·km2·a-1;The total production is 163 706.09 t·km2·a-1;The total consumption is 190 618.91 t·km2·a-1;The total output is 45 460.69 t·km2·a-11;Total respiration volume is 70 267.95 t·km2·a-1;Energy flowing to debris is 104 061.7 t·km2·a-1;TPP/TR coefficient is 1.65;TPP/TB is 49.10;The system connectivity index is 0.24;The Omnivorous index is 0.18;The energy flow cycle index is 13.89,and the average path length is3.55.The ecosystem of Wangjiadao sea area is in the development stage with low maturity and poor stability.(2)The trophic level of each energy group in the ecosystem of Wangjiadao sea area was 1?3.91,the trophic level of macroalgae,phytoplankton and debris was the lowest,which was 1,and the trophic level of Scomber japonicus was the highest;The energy flow mode of ecosystem is mainly grazing food chain,and the total flow of each trophic level decreases significantly with the increase of trophic level,which basically follows the energy pyramid law of marine ecology.2.According to the preconditions for the balance and stability of the ecosystem in Wangjiadao sea area,the biomass of relevant economic organisms in the ecoapth model of the system is increased.After proliferation,the total output energy and flow debris energy of the marine ecosystem are decreased,while the total flow and total production of the system are increased,indicating that the energy loss of the marine ecosystem is reduced and the energy utilization efficiency is relatively improved;Compared with the original ecological capacity of the sea area,Mizuhopecten yessoensis has the highest proliferation potential,with its biomass increased by 177.9 t/km2,followed by Stichopus japonicus,with biomass increased by 130.8t/km2,Portunus trituberculatus biomass increased by 1.72 t/km2,Chlamys farreri biomass increased by 5.4 t/km2 and Ruditapes philippinarum biomass increased by 1.00 t/km2.3.According to the actual production situation in Wangjiadao sea area,the growth characteristics and resource assessment of economic species such as Ruditapes philippinarum,Chlamys farreri,Platycephalus indicus and Pholis fangi beetle were analyzed to determine the catchable size and total allowable catches.According to field biological survey data in Wangjiadao sea area,the body length(shell length)and body weight of the assessment object are preliminarily analyzed according to the field survey data,the power function relationship between the body length(shell length)and body weight of the assessment object is fitted,the individual growth equation is calculated,and the inflection point age of individual weight growth,the critical age of resource group and the total death coefficient are solved,Assess the resources of the main assessment objects in the sea area.The results showed that:(1)the shell length and body weight growth equation of Ruditapes philippinarum was divided into Lt=58×(1-e-0.51×(t+0.44))and Wt=23.45×(1-e-0.51×(t+0.44))2.7309,the age of inflection point of body weight growth is 1.51 years old,the critical age of population is 1.56 years old,the resource biomass is 32 000 t,the recommended open shell length is 36.55?37.10 mm,the open fishing weight is 6.73?7.02 g,and the annual allowable fishing volume is 13 822 t;(2)The shell length and body weight growth equation of Chlamys farreri is divided into Lt=126×(1-e-0.46×(t+0.39))and Wt=823.73×(1-e-0.46×(t+0.39))2.501,the inflection point age of body weight growth is 1.59 years old,the critical age of population is 2.32 years old,the resource biomass is 18 000 t,the recommended open shell length is 75.62?89.86 mm,the open weight is 229.74?353.69 g,and the annual allowable catch is 4 995 t;(3)The body length and weight growth equation of Platycephalus indicus was divided into Lt=450×(1-e-0.66×(t+0.19))and Wt=731.27×(1-e-0.66×(t+0.19))3.047,the age of inflection point of body weight growth is 1.49 years,the critical age of population is 1.79 years,the resource biomass is 29 886.8 t,the recommended open body length is 302.34?329.16 mm,the open body weight is 217.63?281.98 g,and the annual allowable catch is 10 861.46 t;(4)The body length and weight growth equation of Pholis fangi is divided into Lt=375×(1-e-0.28×(t+0.5))and Wt=193.03×(1-e-0.28×(t+0.5))2.898,the inflection point age of body weight growth is 3.30 years,the critical age of population is 4.30years,and the resource biomass is 1 859.10 t,the open body length is 245.61?277.29 mm,the open body weight is 56.62?80.48 g,and the annual allowable catch is 275.15 t.In the future,the investigation of biological resources and environment in Wangjiadao sea area will be strengthened,and a variety of ecosystem models will be used to comprehensively analyze the structure and energy flow characteristics of marine ecosystems,and evaluate the ecological capacity of various economic species and the proliferation capacity of proliferating species.And to provide theoretical support for the releasing and efficient use of this water.To strengthen the biological investigation of main fishery species,comprehensively analyze the biological characteristics of main fishery species(such as age and growth,mortality,food composition and reproductive habits,etc.),evaluate the resources,and provide theoretical reference for the implementation of TAC management in Wangjiadao sea area. |
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