| The coastal ecological environment was negative affected by human activities such as water pollution,land reclamation patterns activities,and tourism development,which led to the decline trend of the ecological service capacity of the natural habitat of offshore fishes,the simplification habitat type structure,and the quality of the ecological environment showed rapidly degraded trend.As a result,the habitat environment of fish spawning grounds,nursery grounds and fattening grounds in offshore areas shows significant characteristics of fragmentation,low ecological value and offshore.Affected by this,offshore fishery resources are showing a trend of younger ages and miniaturization,the sustainability of fishery resources and the stability of fish resource replenishment are undermined,and marine fishery resources fall into a vicious circle.At the same time,the sustainability and stability of fishery resources has been destroyed,and marine fishery resources have fallen into a vicious circle.At present,repairing and improving the structure and function of fish habitat has become an ecological scientific problem and ecological engineering problem that needs to be urgently to promote the healthy and sustainable development of fishery resources.Therefore,repairing and improving the structure and function of the offshore ecological environment have significance scientific and practical effects for the sustainable development of marine fisheries.Marine Ranching can establish different type of offshore fishery resources protection and restoration models suitable for different areas by placing different structure of artificial reefs in the ocean,proliferation and release activities and building a three-dimensional monitoring platform.Artificial reefs can establish suitable habitats,restore the offshore marine ecological environment,and protect fishery resources was a strategic choice for offshore ecological restoration and sustainable fishery development.However,the construction of artificial reefs in fish habitat restoration areas requires in-depth discussion of two scientific issues: 1.The integrity of the regional ecological service function and structure of fish habitat based on the construction of artificial reefs;2.The adaptability and selectivity of fish behavior in fish habitat areas based on the construction of artificial reefs.According to the classic ecological succession theory,the newly built artificial reefs area will first attract rock fishes,followed by pelagic fishes.Therefore,studying the behavioral selection and adaptation of rockfishes to reef areas is not only a requirement for the design of artificial reefs,but also an important for the site selection of Marine Ranching construction.Studying the behavioral response characteristics of typical rockfishes to artificial reef habitats was helpful to analyze the “fish collection mechanism”,thereby improving the ecological restoration function of artificial reef habitats and realizing fishery proliferation.This study selected Sebastes schlegelii as the target fish to study the juvenile stage(body length: 11±0.5cm)and adult stage(body length: 30±0.5cm).Studying the behavior response pattern of Sebastes schlegelii to changing fish reef habitats can provide a certain scientific reference for the design and construction of artificial reefs and the site selection of marine ranches.The main contents of this research include:(1)Studying the tempo-spatial pattern of target fish,shelter,and habitat of Sebastes schlegelii in different life history stages around artificial reefs with different structures.(2)To study the response characteristics and distribution of Sebastes schlegelii in different life history stages to different flow field environments in artificial reef areas.(3)To study the change of the time series of Sebastes schlegelii at the different life history periods in different artificial reefs and different flow field environments,analyze the fluctuations in diurnal changes,and obtained the juvenile and adult fish.The characteristics of time series changes of fish under different experimental conditions.The results of the study showed that:1.The Sebastes schlegelii juvenile have significant collective behavior and negative phototaxis behavior,and the swimming ability is relatively poor.Cube-shaped artificial reef(CAR)has a best trapping effect on juvenile fish,((Mean gathered rate(MGR),average MGR equals 47.21%,followed by pyramid-shaped artificial reef(PAR),average MGR equals 28.82%,and star-shaped artificial reef(SAR)again,average MGR equals 14.95%,the last is round tube-shaped artificial reef(TAR),average MGR equals 9.02%.In the static water environment(Flow field environment1,FE1),except for PAR and SAR,the average MGR of juvenile fish in the other reefs has significant differences(P<0.05);in the flowing water environment(Flow field environment 2 and 3),the average MGR of juvenile fish in the four different reefs all have significant differences(P<0.05).However,the same reef has different effects in attracting juvenile fish in different flow environments,specifically: except for CAR,the average MGR of other reefs in static and flowing water environments have significant differences(P<0.05).In different flow environment,the average MGR of juvenile fish inside and outside the reef region,and the behavior pattern showed significantly different(P<0.05)in the four reefs.2.The negative phototaxis and clustering behavior of Sebastes schlegelii adult were not significant.PAR has the best trapping effect for adult fish,average MGR equals 40.15%,followed by CAR,average MGR equals 36.34%,and SAR again,average MGR equals 12.75%,the last of TAR,average MGR equals 10.7%.In the FE1,there were significant differences in the MGR of the adult fish in the four reefs(P<0.05);In the FE2,there was no significant difference in the MGR of the adult fish around the TAR and SAR(P>0.05),the MGR between PAR and CAR was significantly different(P<0.05);In the FE3,in the MGR of PAR and CAR have no significant difference(P>0.05).Except of the PAR,the trapping degree of the other three reefs to the adult fish is greatly affected by the flow field environment,that is,the adult fish MGR has significant differences in the three different flow field environments(P<0.05).There were significant differences in the accumulation of adult fish inside and outside the reef in different flow field environments.Among them,in the FE1,with the exception of CAR,the MGR of the adult fish was significantly different in the reef area and outside of the other three reefs(P<0.05);in the FE2,except for SAR,the MGR of adult fish is significantly different in the reef area and outside of the other three reefs(P<0.05);in the FE3,the MGR of the adult fish was significantly different in the reef area and outside of the CAR and PAR(P<0.05),SAR and TAR showed opposite pattern(P>0.05).3.Wavelet analysis of the distribution numbers of juvenile and adult fish on different reefs,it was found that the number of juvenile and adult fish has different wavelet periods around different reefs.The diurnal wavelet spectrum of the number of juvenile and adult fish around CAR has the strongest continuity,that is,the quantity changes are extremely significant in a day,while TAR fluctuations are relatively small.In the same experimental flow field environment,with the increase of flow velocity,the wavelet spectral continuity of juvenile and adult Sebastes schlegelii on the four reefs gradually weakened,that is,the diurnal accumulation of Sebastes schlegelii became stable.4.The structure of the reef,the environment of the flow field and the interaction factors of the flow field environment and the structure of the fish reefs,all have extremely significant effects on the accumulation of juvenile and adult Sebastes schlegelii(P<0.01).The structure of the reef has a more significant effect on the accumulation of juvenile and adult fish.In summary,the continuous observations of Sebastes schlegelii on the long-term behavior of different reefs showed that Sebastes schlegelii has different behavior choice for different reefs in different life history stages.Under the same conditions,the flow rate was different,the impact on adult and juvenile fish presents a big difference.In the construction of artificial reefs,PAR and CAR can be considered,which can significantly restore the habitat of rocky fish. |
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