• 한국수산과학회지
• /
• 제22권1호
• /
• pp.36-40
• /
• 1989

The eels, Anguilla japonica, were reared in a tank with daily feeding for up to 97 days, and otoliths were regularly collected for the observation of their microstructures. Microscopic observation of the thin-sectioned otolith under dark field provided significant information on daily growth increments as well as the difference in visual contrast shown by the increments. Clearly defined elver mark formed during the metamorphosis from leptocephalus to the elver can be considered as the origin of the age for the sedentary yellow eel in continental water. The close correspondence between the number of increments outside elver mark and chronological age in days from the beginning of feeding indicates that increment deposition on a daily basis was initiated with the start of feeding for the sedentary yellow eel. Either 7 or 14 daily growth increments were grouped together into 2 alternative units, each distinguished by prominent checks or by visual contrast. The absence of any apparent environmental variations with 7 or 14 day period in the reared tank implies that the phase of the moon could be a zeitgeber for the endogenous rhythm.

• 한국수산과학회지
• /
• 제44권4호
• /
• pp.359-365
• /
• 2011

This study was conducted to investigate the production, elver stocking, rearing facilities and rearing method of eel culture to determine aquaculture management conditions for optimal rearing of eel Anguilla japonica. The production of eel culture was evaluated by the proportion of eels from the main inland fin fish species production in Korea. Elver stocking was assessed by the elver stocking densities of pond and recirculation culture. Rearing facilities were investigated according to the rearing tank size proportion of the pond and recirculation culture. We selected sample farms by region and by size. We visited sample farms and recorded the number of elvers stock for pond area, size of tanks, feed and feed quantity, and the size and number of harvest eels. The production capacity of Jeollanam-do and Jeollabuk-do were 71.9% and 21.3% respectively. This production quantity represented 93.2% of the total Korean eel production quantity. In Jeollanam-do, there are 236 eel farms, 202 pond farms, and 34 recirculation aquaculture facilities. The elvers' first density data by each aquaculture method revealed that elvers' first density varied more in recirculation system farms, as compared to pond aquaculture. In intensive pond farms, the elvers' first density decreased as the size of farm increased. There was a correlation between the size of tank(x) and the facility of a water wheel for dissolved oxygen in pond culture systems(y=0.022x-0.494; $R^2$=0.860). Another strong correlation was found between the weight of eel(x) and eel density(y) in pond culture systems(y=283.5x-0.27; $R^2$=0.992). Finally, there was a strong correlation between the length of eel(x) and the weight of eel(y) in intensive pond culture(y=0.0005x-3.2783; $R^2$=0.9775). The final survival rate did not differ significantly among pond sizes and culture types.

• 한국어류학회지
• /
• 제12권4호
• /
• pp.244-249
• /
• 2000

국내에 이식된 유럽산 및 북미산 실뱀장어와 극동산실뱀장어의 구분을 위해 계수 계측 형질을 비교한 바 다음과 같은 결과를 얻었다 A rostrata는 등지느러미 기점거리가 걸고 척추골수가 현저히 적어 A. anguilla와 A. japonica로부터 구분되었다. 한편 A. japonica는 뒷지느러미 기점거리가 다른 두 종에 비해 짧아 통계적으로 구분되었다. 성장에 따른 형태적 변화를 조사한 결과 A. rostrata는 두장, 등지느러미기점거리의 비율이 두 종과 다른 변화 경향을 보여 계통학적으로 주목되었다. 이러한 결과를 토대로 A. japonica, A. anguilla 및 A. rostrata는 등지느러미 기점거리, 뒷지느러미 기점거리, 척추골수의 특징을 조합하여 종간 구분이 가능한 것으로 나타났다.

• Animal cells and systems
• /
• 제13권2호
• /
• pp.179-186
• /
• 2009

Discriminating between eel species of the genus Anguilla using morphological characteristics can be problematic, particularly in the glass eel and elver stages. In this study, sequence-characterized amplified region (SCAR) and polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP) markers were developed for the identification of Anguilla japoniea, Anguilla btcoior bicaor. Anguilla rostrata, and Anguilla anguilla. Random amplified polymorphic DNA (RAPD) fragments from A. japoniea (362 bp), A. bicolor bicctor (375 bp), A. rostrata (375 bp), and A. anguilla (375 bp) were isolated, sequenced, and converted to SCAR markers. The principal difference between the SCARs of A. japoniea and the three other species is the absence of a 13 bp deletion in the A. japoniea SCAR. Specific PCR primers amplified a 290 bp fragment for A. japoniea and 303 bp fragments for A. bicolor bicoior. A. rostrata, and A. anguilla. Restriction enzyme digestion with Taql, Mael, and Tru9l yielded PCR-RFLP patterns with differences that, when analyzed together, are sufficient for distinguishing each of the four eel species. In addition, RAPD fragments for A. japoniea (577 bp), A. bicoior bicoor (540 bp), A. rostrata (540 bp), and A. anguilla (509 bp) were also isolated and sequenced. The A. japoniea, A. bicoior blcoior. A. rostrata, and A. anguilla PCR products contain ten, nine, nine, and eight tandem repeats, respectively, of a 37 bp sequence. These results suggest that SCAR and PCR-RFLP markers and repeat numbers for specific loci will be useful for the identification of these four Anguilla eel species.

• 한국수산과학회지
• /
• 제7권4호
• /
• pp.179-186
• /
• 1974

1973년 4월부터 1974년 6월 말까지 뱀장어의 효과적인 초기사육을 위하여 일연의 실험을 한 결과는 다음과 같다. 1. 뱀장어의 초기사육의 최적성장수온은 $20\~34^{\circ}C$의 범위내에서 실험한 결과 $30^{\circ}C$로 나타났다. 2. $20\~30^{\circ}C$ 사이에서 10일간의 성장배수는 R=0.0056296$T^{1.80740}$이라는 곡선식으로 나타났다. 3. 오랫동안 축양하여 두었던 실뱀장어도 채포후 바로 사육하는 것에 비해 성장이 나쁘지 않았다. 4. 사육중 크지 않고 성장이 나빴던 것도 이번 시험사육결과 정상적인 성장을 하였다. 5. ammonia는 5ppm 이하에서는 섭이에 영향을 주지 않으나 6ppm에서는 섭이량이 현저히 줄었다. 6. 뱀장어의 고밀도 사육시 배설물의 제거는 좋은 수질을 유지하는 데 매우 중요하다.