| Exopalaemon carinicauda is one of economic shrimp in China. The area of E.carinicauda aquaculture is about10000hm2, and its production accounts for one thirdof polyculture along the east coasts of our country. However, due to the industrialbreeding technology of E. carinicauda has not been developed, the shrimp seed ismeanly acquired from the ocean, then the development of E. carinicauda aquacultureis limited evently. Therefore, it is urgent to study the reproductive biology andbreeding technology of E. carinicauda. In this paper, we studied the reproductivebiology, embryonic and larval development of E. carinicauda and the effects ofenvironmental factors on the early development of E. carinicauda, and for further, theartificial breeding method was explored. The results are as following:In this study the tuber between the fifth pair of paraeiopod of the male wasreported for the first time, and by this method the male could be distinguished easily.The sexual ratio of females vs. males is1.14:1in a year cycle; the monthly sexualratio is close to1:1except April, which is significantly greater than1(P<0.05). Thereproduction pattern of female is a cycle of molting, mating, spawning, re-molting,re-mating and re-spawning. Generally, spawning is observed within several hoursafter mating.The female reproductive system consists of ovary, oviduct and oviporus.Oogenesis could be classified into five different phases, which include oogonium,previtellogenic oocytes, endogenous vitellogenic oocytes, exogenous vitellogenicoocytes and mature oocytes. The ovary development could be also divided into fivephases: proliferative phase, minor growth phase, major growth phase, mature phaseand postpartum recovery phase. In breeding season the female could spawn severaltimes. The male reproductive system is composed of testis, vas deferens and male gonopore. The testis consists of many seminiferous tubules, in which there are manysperms at different development stages. The spermatogenesis could be classified intospermatogonium, primary spermatocyte, second spermatocyte, spermatid and sperm.The vas deferens could be separated into anterior, medial, posterior and terminalsegment. The spermatophore generates in the vas deferens.The embryonic development of E. carinicauda could be divided into elevenstages, which include zygote, two cells stage, four cells stage, eight cells stage,sixteen cells stage, thirty-two cells stage, blastula stage, gastrula stage, nauplius stage,anterior zoaea stage and posterior zoaea stage. The newly hatched larva is similar tomysis of prawn, and it metamorphoses into post larva by molting five or six times. Inthis paper, the larva of E. carinicauda is classified into six mysis stages, while parts oflarva could metamorphose into post larva only by molting five times.The biological zero of embryonic development of E. carinicauda is11.05℃，andthe effective accumulative temperature from fertilized egg to hatching is181.63℃·d.The hatching time and hatching rate are significantly affected by temperature(P<0.05). Under the experimental range of temperature (19-31℃), the course ofembryonic development accelerates with the temperature increasing. The hatchingtime at19℃was536.50±18.33hours，while it is only218.68±5.51hours at31℃. Thehighest hatching rate (64.11±12.51%) and the lowest hatching rate (14.79±5.17%) aregained at25℃and at19℃respectively. Estimated from the correlation equations,the optimum temperature of embryonic development of E. carinicauda is25.33℃.Duration of larval development and survival rate of metamorphosis aresignificantly influenced by temperature (P<0.05). Within a temperature range of16to32℃, duration of larval development from first mysis stage to postlarvae stage andthe body length of postlarva both decrease with the temperature increasing, however,the daily growth of body length increases. The highest survival rate of metamorphosisis gained at28℃(91.67±7.64%). Larvae fails to metamorphose into PL1stage at36℃. Estimated from the correlation equations, the optimum temperature of larvaldevelopment of E. carinicauda is27.60℃.Salinity has an significant influence on larva development (P<0.05). When the salinity falls to5‰，the duration of larval development increases and the daily growthof body length decreases. On the contrary, the survival rate of metamorphosis and thebody length of post larva are not significantly influenced by the salinity (P>0.05).The suitable salinity scope for larva development is10‰to25‰.The breeding experiment is carried out in indoor concrete ponds. Screen with bigmesh is used to separate the larva and parent shrimp, and the larva is collected withlight induction. By the measures above, the account of larva preyed by parent shrimpsincreases obviously. This method could be promoted in artificial breeding of othershrimp, which larva has the characteristic of phototaxis. In the experiment,2751700post larva at body length of8.25±1.42mm is got in total. The average and highestlarva incubation rate is57.45％and69.9％. The suitable density of larvacultivation is one hundred and fifty thousand per cubic meter. |
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