A Study on the Gonadal Maturation and Egg-Stripping by Hormone Treatments of Tiger Puffer, Takifugu rubripes

자주복, Takifugu rubripes의 성성숙과 호르몬 처리에 의한 인공채란에 관한 연구

Formerly, adult-tiger puffer, Takifugu rubripes with ova caught in the sea, were used for seedling production. But it was difficult to secure naturally-ripened adults. For the purpose of adult tiger puffer in captivity, this study was carried out. To determine the growth 220 tiger puffers hatched in 1990 (3-year-old) and 1991 (2-year-old) were used. For spawning and egg incubation leading to fry development, eggs were stripped from tiger puffers hatched in 1988 (5-year-old) and 1990 (3-year-old) through human chorionic gonadotropin (BCG) treatments. In May, 1993, mean body length and mean body weight of 2-year-old tiger puffer were $30.72\pm1.35cm\;and\;1,048\pm228 g,$ and that of 3-year-old tiger puffers were $36.02\pm1.17cm$ and $1,402\pm66g$ respectively. The relationship between body length (L) and body weight (W) of 2-year-old the tiger puffers during the experiment period was represented as $W\;=\;1.7892L^{31524}\times10^5$ (r= 0.9436) and that of 3-year-old, $W=\;3.2840L^{36099}\times10^6$ (r= 0.9070) respectively. The GSI in female 2-year-old-fish changed from $0.23\times0.l2\;to\;0.74\pm0.08$, during the experiment period, and in male it didn't change remarkably until November, but thereafter it increased and showed a peak of $8.69\pm5.09$. The GSI of 3-year-old-fish showed a peak of $8.05\pm5.58$ in April in female and $12.65\pm4.60$ in May in male. The change of HSI in 3-year-old-fish was correlative to the change of GSI, but in 2-year-old-fish it was little correlative. In female gonad of 2-year-old tiger puffer, the mature oocytes reached $350{\mu}m$ in April, but thereafter they didn't spawn and became atrophied. But in male gonad, a great number of spermatozoa were crowded in the testicular lobuli in April. Female gonad of 3-year-old tiger puffer had the mature oocytes of 650 pm in March and the ripe oocytes, $900{\mu}m$ in April. Male testis development was similar to that of 2-year-old-fish. Egg-stripping after hormone treatments was possible past 139 hours and 142 hours from each of two 5-year-old-fish (500IU/kg, BW), and after 114 hour from a 3-year-old-fish (1,000 IU/kg, BW) under water temperature $16.3\~17.8^{\circ}C$. Eggs stripped amounted was 650 g and 400 g from two 5-year-old-fish and 610 g from the 3-year-old-fish, and fertilization rates were $98.0\%,\;97.4\%\;and\;96.5\%$ respectively. All the hatched larvae devloped into normal fry.

자주복, Takifugu rubripes 수정란 확보를 목적으로 실내 수조에서 사육한 1990년산(3년어), 1991년산(2년어)를 인공 사육 조건하에서 성장에 따른 월별 생식소숙도지수 (GSI)와 간숙도지수(HSI)를 조사하고, 1988년산(5년어)과 1990년산(3년어)을 대상으로 태반성 성선 자극 호르몬(HCG)을 처리하여 배란을 유도한 후 채란시험을 실시한 결과는 다음과 같다 1993년 5월까지 성장은 2년어는 체장과 체중이 각각 $30.72\pm1.35cm,\;1,048\pm228g$였고, 3년어는 자각 $36.02\pm1.17cm,\;1,402\pm66g$이었다. 그리고 시험 기간중 양식 자주복의 체장(L)과 체중(W)과의 상관 관계는 2년어는 W=\;1.7892L^{3.1524}\times10^{-5}$ (r=0.9436)였고, 3년어는 $W=3.2849L^{3.6099}\times10{-6}$ (r=0.9070)였다. GSI의 변화는 2년어 암컷은 시험기간 중에 $0.23\pm0.12$에서 $0.74\pm0.08$의 범위였지만, 수컷에서는 11월까지는 변화폭이 적었지만 그 후 증가하여 4월에 최고 값인 $8.69\pm5.09$을 나타났다. 3년어 암컷은 4월에 8.05\pm5.58$, 수컷에서는 5월에 $12.65\pm4.60$로 최고 값을 나타냈다. HSI의 변화에 있어서 3년어는 GSI와 정상관적인 변화를 보이나 2년어는 거의 상관관계 없이 나타난다. 수컷 2, 3년어는 기능적 성성숙에 도달하나, 암컷에 있어서 2년어가 $230{\mu}m$ 전후의 초기 성숙 단계까지 발달하여 그 후 퇴행 변성되고, 3년어는 난경 $900{\mu}m$까지 발달하여 완숙란에 도달하고 있다. HCG 처리후 채란까지 소요시간은 수온 $16.3\~17.8^{\circ}C$에서 5년어(500 IU/kg, BW)는 각각 139시간, 142시간, 3년어(1,000IU/kg, BW)는 114시간이었다. 1마리당 채란량은 5년어가 각각 650g, 400g이었고, 3년어에서는 610g이었으며, 수정율은 각각 $98.0\%,\;97.4\%$와 $96.5\%$였다. 호르몬 처리에 의한 채란은 성공적이었고, 수정이후 정상적인 부화자어로 이행이 확실하였다.