Reproductive Biology And Fry Breeding Technology Of Trachidermus Fasciatus In Jinghai Gulf

Trachidermus fasciatus is a kind of small benthic fish and mainly distributed in thePacific Rim. It is founded in the Philippines at the first time, and have recorded inJapan and north Korea. In the last few decades, because of the economic development,the estuary was polluted seriously, with the influence of overfishing, Trachidermusfasciatus reduced sharply in our country. It was classified as the national secondaryprotect animal in1988. At present it is an endangered species and need to be savedquickly. To solve this problem, artificial reproduction will be the key. This paper wasmainly researching the reproduction control of Trachidermus fasciatus, I hope what Ihave written can provide some theoretical basis to production and be helpful to thespecies enhancement and releasing.1. This paper discovered the artificial breeding technologies of Trachidermusfasciatus. The parents fish were collected from the wild environment, we got thefertilized eggs through using oxytocic. The fertilized eggs were hatched at6-11℃, thewater salinity was33~34, keep the water containing enough oxygen and no light at thesame time. The fertilized eggs hatched30d after fertilization. The foster conditions ofthe larvae were just like the hatching time, natural water temperature, enough oxygenbut need a little light.3days after hatching, we need to feed rotifer.10days afterhatching, feeding copepods and Artemia nauplii. When the larvae got to30years old,the bait should be changed to Artemia. In the later period, the bait was meat of fish andcalm. Throughout the processes, we should change the water frequently to keep it clean,in case the disease happening.2. We have observed the embryonic development of Trachidermus fasciatus. Itwas observed by Nikon ECLIPSE E200microscope and the photos were taken byNikon coolpix4500camera. The present study described the morphologicalcharacteristics of every period which from fertilized egg to larva. As the result, thefertilized eggs of Trachidermus fasciatus are irregular round, and have different colors, like light yellow, yellow and orange. In the eggs, there are several oil droplets, one ofthem are much bigger, and no matter how do you rolling the eggs, the oil droplets arealways in the front. This makes much more difficult to observing. To describe themorphology characteristics clearly, I have drawn some pictures in the observing time.The fertilized eggs hatched30d after fertilization. The embryonic development can bedivided into5stages. The study discussed the temperature influence to the duration ofembryonic development, and the importance of the water dissolved oxygen.3. In this paper, we have observed the larvae development of Trachidermusfasciatus. This study described the morphological characteristics of the larvae ofTrachidermus fasciatus and measured the full length of the larvae in different period.The larvae development of Trachidermus fasciatus was as follow,1to3days afterhatching was the yolk-sac larvae, it takes a big yolk sac, and live with the nutrition inthe yolk sac.4to5days after hatching they began to eat.6to16days after hatching,the tail was forming.20days after hatching, they began to live in the bottom.25daysafter hatching, the pelvic fin has formed.27days after hatching, the dorsal fin hasformed.35days after hatching, we called it juvenile fish. The larvae grown slow in theearly time, and get faster and faster in the after.4. This paper describes the morphology, histology of gonad in Trachidermusfasciatus which were hatched at the same time.3months after hatching, we takesamples every month. As the result, the development of gonad can be devided into5stages. The fishes were hatched in April, and the testis developed into stageⅠin July. Inautumn, they were at stage Ⅱ. In September, got into stage Ⅲ. During October andNovember, they stayed in the stage of Ⅳ. They developed into stage Ⅴ in Decemberand kept the stage to January in the next year. During July to September, the ovarieswere at stage Ⅱ, and then developed into stage Ⅲ and Ⅳin October and Novemberseparately. In December and January, the ovaries stayed in the stage of Ⅴ. The resultsof this paper indicate that this fish spawns only once a year, and the maturation age is1year old. The production shows that the time of laying eggs of Trachidermus fasciatusin north is later than the ones in south, the reason seems like north is a little colder.