Biological Characteristics And Spatial Patterns Of Typical Sciaenidae Fishes In Rocky Island Waters

Fishery is one of the most valuable resource to human.With the pressure of fishing and human disturbance,fishery shows a tendency of drop decline.There are many islands lying around China,with a large amount of Sciaenidae fishes which is important due to its high value in economy and ecology.With the rapid development of aquatic culture,fishery proliferation and sea ranching,it is necessary to conduct deeper research on the habitat of Sciaenidae fishes in order to ensure the sustainable utilization and protection of the Sciaenidae fishes.It is helpful to enrich the knowledge of Sciaenidae fishes ecology by analyzing the temporal and spatial patterns of Sciaenidae fishes and its response to environmental factors in different scales,so as the fishery proliferation and sea ranching.This paper studies on the typical Sciaenidae fishes in regional and local scales based on the individuals collected off Ma’an Archipelago and Dachen Islands(Taizhou city)in2016～2017,2020～2021 respectively.The resource density and biological characteristic of typical Sciaenidae fishes and its response to environmental factors were analyzed,which contributing to the exploration of the temporal and spatial patterns of typical Sciaenidae fishes in rocky island waters.The results are showed as listed:1.In regional muddy habitat off Ma’an Archipelago,there was a significant distribution pattern of Larimichthys polyactis in seasons and regions for that resource density was the highest in summer and higher in areas adjacent to islands than that in areas off islands.1-year-old individuals was the most in all seasons except for summer(0-year-old individuals up to 75.5%).The abundance of food items of Larimichthys polyactis in areas adjacent to islands was higher than that in areas off islands in summer,which contrary in other seasons.2.In local muddy habitat off Dachen Islands,the typical Sciaenidae fishes in muddy habitat of Dachen Islands had a special temporal and spatial patterns.The resource density of typical Sciaenidae fishes off Dachen Islands in summer>in autumn>in winter,in areas adjacent to reef >in areas off reef and the algae may be the driver.The body length and weight of typical Sciaenidae fishes in summer< in autumn,and in areas adjacent to reef >in areas off reef.Female ratio was high in summer,autumn and winter.There was a positive correlation between the resource density and temperature,salinity and chlorophyll,and a negativity between the sex maturity and depth and chlorophyll.There was a negative correlation between the body length,weight and temperature and salinity.In the muddy habitat off Dachen Islands of local scale,the dominant food items of Sciaenidae fishes was Acetes chinensis,Harpadon nehereus and Metapenaeus joyneri in summer,autumn and winter,respectively.The seasonal distribution of the food items may cause the difference in seasons and species.3.In local rocky habitat off Dachen Islands,the resource density of typical Sciaenidae fishes in rocky habitat of Dachen Islands in summer>in autumn>in winter,and it was different in the natural rocky habitat and aquatic culture area.The migration of the Sciaenidae fishes and the manmade food items may be the driver.The body length and weight of typical Sciaenidae fishes in summer and winter< in autumn,and the number of species of Sciaenidae fishes in summer>autumn>winter due to the migration.The female ratio was different in seasons among different species,and the sex maturity in autumn and winter> in summer.The Sciaenidae fishes were at different life stage in different seasons among species,so the female ratio was different in seasons among species.The feeding grade of Sciaenidae fishes in different seasons may be related to the life stage.In this research,the resource density and biological characteristics did not show a significant relationship with the environmental factors.In conclusion,1)Ma’an Archipelago provided a suitable habitat for Larimichthys polyactis to feeding,sheltering and breeding with natural and artificial habitats created by islands and human structures.The Larimichthys polyactis(especially juvenile fishes)prefered to the adjacent-to-island habitat with specific environment;2)the migration of Sciaenidae fishes,the existence of macroalgae and the artificial habitats had effects on the temporal and spatial distribution of Sciaenidae fishes;3)the rocky island itself,with the community(e.g.macroalgae)around and the expanding artificial habitats with the rapid development of aquatic culture attracted the Sciaenidae fishes feeding and breeding together to some extent.