| Ultrasonic telemetry is an important method in the study of ethology and physiology in marine animals,application in the study of fishes,cephalopods,crustaceans,and some mammals and reptiles,and used in aquaculture and natural resources protection.In this paper,the ultrasonic biotelemetry method is used to carry out fish tracking,and two stages are studied in different sea areas:First step,to understand the behaviors of the restocking and releasing fishes,two kinds of restocking and releasing fishes-Lutjanus argentimaculatus(grey snapper)and Acanthopagrus schlegelii(black snapper)were tracked by using ultrasonic tags at Seven-star Bay in Shenzhen from July 16 to July 31,2016.The signal of the tags was received by buoy wireless data transmission receivers,and the behaviors of fishes were analyzed preliminarily.2 of 4 sample fishes(a grey snapper and a black snapper)have a completed data but other 2 sample fishes(grey snapper)were lost after tracked for 4days.Both of the grey snapper and the black snapper in this study have obvious circadian rhythm and hiding behavior,activity in a small area(about 100m)near the released place,the amount of data obtained during the daytime(7:00-20:00)was significantly less than that at night(20:00-7:00),the black snapper activity in 9-10m layer at daytime and 8-9m layer at night,the grey snapper activity in 2-3m layer at daytime and 1-2m layer at night.This paper aims to promote the application of tracking by tags in fish behavior research and evaluation of effect of restocking and releasing and sea ranching construction.Next step,to understand the attractive effect of artificial reef and the activity trait of fishes,between 7th,July and 8th,September,2017,5 species of 9 common rock fishes(22.0±3.5cm;314±186g)in the Beibu Gulf were tagged and tracked within artificial reef area,using Vemco position system(VPS),11 of receivers(VR2Tx,Vemco,69kHz)launched in artificial reef area of Fangchenggang inshore,the transmitters(V9P-2x,Vemco,69kHz)tied on the back of fishes.Not each fish have a good position results,only 3fishes are able to analyze the home range,95%Minimum convex polygons(MCPs)ranged between 12,687.6 and 17,123.2 m~2,the MCPs show that the fishes activity in a small range;Other 6 fishes have poor position results(between 0and 14 results),although the signal cannot be receive with 3 or more receivers,the data can be detected indicate that the fishes are still moving near the reef area because the range of signal receive is only about 200m in the artificial reef area.3 fishes with poor position results leave the area during this study between 28 to 51 days and then come back,this appearance indicate that the fishes are fond of the environment of artificial reef area.During the study,the activity of fishes showed certain depth change rule,the fishes activity in the shallower layer between 15:00—22:00,the fishes activity above the reefs during the time,perhaps it could be the optimum time frame to search the quantity of resource of this species fishes in this area.To ensure the accuracy of the results,we eliminate the effect of tide before calculate the result of depth.However,the method of ultrasonic biotelemetry have an intuitive feeling for fish activity,but the method is be in experimental stage in China,the high cost is one reason why it cannot be widely promoted,meanwhile,the current experiment is difficult to achieve the desired effect.We hope to analyze the effectiveness for fish attraction and daily activities of fishes to provide a reference for the rational planning of fish resource investigation in the reef area based on this study,and accumulated experience for the subsequent application of this method. |
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