Study On Fish Distribution In Artificial Reef Region Based On DIDSON

In recent years,with the intensification of marine pollution problems,the marine ecological environment is facing severe pressure.In order to address the damage caused by pollution to the marine environment,more and more countries are beginning to put artificial reefs in the ocean with a view to improving the ecological environment of the marine waters through artificial reefs and providing more habitat for fish,so as to achieve the effect of ecological restoration.After the artificial reefs are placed,the artificial reefs are generally followed by a follow-up survey to test the effect of artificial reefs.However,most scholars will assess the effect of artificial reefs from changes in zooplankton and some physical elements in the reef area.These methods are more or less limited.For example,in the re-assessment of reef fish distribution,the artificial reef area at the bottom of the network is difficult to reach,etc.,which will result in sampling heterogeneity,resulting in the evaluation results of the deviation.At present,there is an urgent need for a method to study the distribution of fish in the reef area and the law of fish changes in the reef area in order to provide scientific theoretical basis for the construction of subsequent artificial reefs.The fishery acoustics survey method is a new kind of fish detection technology in recent years.It compensates the shortcomings of the traditional fishery survey method and gets rid of the shackles of the net in the reef survey.It can quickly and efficiently detect the fish of Distribution in the artificial reef area.DIDSON(Dual Frequency IDentification SONar,1.1MHz / 1.8MHz)is a commonly used fishery acoustic survey instrument in recent years.It can display high-quality fish images in complex water environment.In monitoring fish behavior,the application is more extensive.In this paper,the changes of fishery resources in reef area were analyzed by continuous DIDSON observation in the area of artificial mountain reef area.Through the observation site inside and outside the reef area,the observation site was surveyed and the distribution of fish in the artificial reef area was studied by means of flight observation.The main contents and achievements of this paper are as follows:(1)The DIDSON data were processed by Echoview software,and the fish data of each observation point were extracted after a series of steps such as noise and background removal,target tracking and target conversion.Echoview counts the results of the fish when dealing with DIDSON image data.The result of the verification of the automatic counting of the software is verified.The results show that the counting result is generally larger than that of the manual counting.The results show that the body length of the fish in the image is close to the actual body length of the fish,and the fish length output by Echoview is closer to the fish than the artificial measurement.Actual body length.(2)The data of the previous survey of each site were analyzed.It is found that the number of fish in the reef area increases gradually with the increase of the number of fish from the site,and the number of fish in the reef area is obviously higher than that of the other two sites.Route observations of the reef area showed that the fish density in the reef area was similar.(3)In the reef area,the fish length observed in the reef area and the reef area was not significantly different from that of the fish in the reef area,but there were significant differences at the individual time points.Route observations indicate that the average body length of the fish surveyed in 2016 is significantly greater than the average body length of the fish observed in 2013.Indicating that the average body length of fish in the reef area has increased in recent years.(4)The behavior characteristics of fish in reef area were analyzed.The spatial location of the fish in the image was studied.The results showed that the distribution of fish in the water layer changed with the seasons.In the spring,the fish are more distributed in the upper and middle layers.In summer,the spatial distribution of fish is more uniform.There are a certain number of fish in the water layer.In the winter,there are more fish in the surface and middle and upper layers.less.The results showed that the number of fish in the reef area varied greatly day and night,and the swimming rate at different time points was also significantly different.