• 한국어류학회지
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• 제11권2호
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• pp.155-162
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• 1999

강원연안의 까나리 자치어(仔稚魚)의 형태발달 및 분포를 파악하기 위하여 1996년 1월부터 12월까지 강원도 연안 6마일 이내의 해역 60개 정점을 선정하여 난(卵) 치자어(稚仔魚) 네트 (RN 80 net)와 기선권형망의 일종인 소형선인망으로 채집하여 관찰하였다. 강원연안에서 까나리 자치어(仔稚魚)의 체장조성 및 출현양상은 1~3월에 평균체장이 10.0~30.0 mm의 개체가 $5.0{\sim}6.0^{\circ}C$의 수온에서 주로 출현하였으며, 4~6월에는 평균체장이 40.0~80.0 mm의 개체가 $7.2{\sim}12.0^{\circ}C$의 수온에서 분포하였다. 자치어(仔稚魚)가 출현하였던 시기는 1월에서 6월까지였고, 6월에 가장 높은 밀도를 나타냈다. 수온이 낮은 2~3월까지 동해 남부해역에서만 분포하지만, 표층수온이 $7.2^{\circ}C$ 이상으로 상승하는 4월부터 점차적으로 북상하여 중부와 북부해역에 나타났고, 분포상 특성은 수온과 밀접한 관계가 있는 것으로 나타났다.

• 생명과학회지
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• 제23권10호
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• pp.1288-1294
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• 2013

뱀장어 자어의 형태변화에 관한 연구는 자어의 인공사육을 위해 알아야 할 중요한 부분이다. 본 연구에서는 두부의 형태학적 관찰과 함께, 부화 이후 변태 직후까지의 단계별 안구의 조직학적인 변화를 관찰하였다. 이들 결과로 부화 후 100일과 변태를 기점으로 상악과 하악의 발달에 큰 차이를 관찰할 수 있었으며, 치아는 실뱀장어로 변태하면서 퇴화한다는 것을 알 수 있었다. 안구 망막에서의 조직학적인 주요 변화는 부화 100일 이후의 OPL (outer plexiform layer)과 ONL (outer nuclear layer)의 형성과 변태 이후 간상세포층의 변화이며, 안구의 각막은 부화 10일째 자어에서 관찰되지 않았지만 이후 모든 단계에서 관찰되었다. 실뱀장어의 양산을 위해 초기 자어의 발달에 관한 더 많은 정보가 필요하며, 본 결과가 자어의 인공사육시스템 안정화에 도움이 될 것으로 기대한다.

• 한국해양생명과학회지
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• 제8권2호
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• pp.128-135
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• 2023

엽상자어(Leptocephalus)는 뱀장어목(Anguiliformes)에 속하는 어류의 자어로 5~6월에 우리나라 남해안 일대의 정치망에서 멸치와 함께 어획 후 방류하지만 대부분 폐사하는 실정이다. 따라서 본 연구의 목적은 멸치어업을 하는 정치망에서 무분별하게 포획되는 엽상자어의 종을 구명하여 수산자원보호 및 이들 자치어 생태 연구를 위한 기초 생물학적 자료를 제시하고자 수행하였다. 실험에 사용된 엽상자어는 5~6월에 남해의 정치망에서 채집하였으며, 외부형태와 유전학적 특성을 붕장어(Conger myriaster), 갯장어(Muraenesox cinereus) 및 뱀장어속(Anguilla) 4종의 성어와 비교하였다. 유전학적 분석은 추출한 DNA를 12s rRNA, 16s rRNA 부분단편을 PCR로 증폭하여 염기배열을 분석한 후 분자계통수를 작성하여 장어류 유생이 붕장어, 갯장어 및 뱀장어속 4종 중 어느 쪽의 성체와 클러스터 그룹화를 이루는지 계통학적 유연관계를 확인하였다. 엽상자어의 외부형태 계수 및 계측결과 엽상자어의 전장에 대한 머리길이의 백분비와 뒷지느러미 기점거리의 백분비는 붕장어와 가장 유사한 비율을 보였고, 척추골수 역시 붕장어와 가장 유사하였다. 또한 엽상자어의 유전자 분석결과는 모두 붕장어 성체와 클러스터 그룹화를 이루는 것을 확인함으로서 남해안에서 5~6월에 어획되는 엽상자어는 모두 붕장어의 자어임을 할 수 있었다.

• 한국수산과학회지
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• 제53권4호
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• pp.551-556
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• 2020

Eel Anguilla japonica is an economically important inland culture fish species in East Asian countries, particularly in Korea, Japan, China, and Taiwan. In this study, the effects of feeding frequency on larval growth and survival rate were investigated. Eel larvae (average length, 6 mm) were fed a slurry-type diet containing shark eggs three, five, seven, or nine times per day. Survival rates differed significantly among the four experimental groups. Feeding frequencies of at least five and seven times a day were required until 15 and 30 days after hatching, respectively, to maintain an acceptable survival rate. Leptocephalus growth improved with increased feeding frequency until 15 days after hatching. The results suggest that providing an opportunity for early food intake enhances eel survival and growth in the early leptocephalus stage.

• 수산해양교육연구
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• 제26권6호
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• pp.1209-1216
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• 2014

This feeding experiment was conducted to investigate the effects of slurry type diet on growth performance and survival rate of growing leptocephalus, eel larva. We need to find new materials of diets for rearing eel larvae. Test diets were formulated with the eggs of the shark, fish soluble concentrate, soybean peptide and fish protein hydrolysate. Fish (average length 6 mm) were fed 3 slurry type diet(A, B and C) based on shark egg for 5 times per day. During feeding experiment, survival rates were significantly different among 3 slurry type diets. Total protein, lipid, moisture, ash and free amino acids contents were analyzed for slurry type diets. Leptocephalus fed the C slurry type diet was grown up to $38.0{\pm}9mm$ at 150 days. But all leptocephalus fed B slurry type diet were died at 100 days, reaching $16.4{\pm}8mm$. This results suggest that basic information for diet development of eel leptocephalus.

• 한국발생생물학회지:발생과생식
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• 제1권1호
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• pp.91-97
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• 1997

In order to study the reproductive physiology of Sand ell(Hypoptichus dybowskii) catched at kangwon-do, Wooamjin Bay, spawning and egg development were investigated in April and May, 1996. The observed spawning period was from the middle of April to the end of May with the water temperature above $8^{\circ}$C. Body size and colouration were distinguished between male and female. The type of testicular structure is lobular, and the ovary is a pair of sac-sahaped covering with a fibromuscula capsule and comprising a mature egg of average 86. The unfertilzed egg are demersal and adhesive, and their diameter were 1.65-1.95 mm. the colour of yolk is light yellow and contained a lot of tiny oil globules. The average spawned egg was 62 in sargasso weeds. Hatching was observed in 12 days after fertilization with the water temperature of 14 ${\pm}1^{\circ}$C. The average size of larva after hatching was 6.85${\pm}$0.23mm in total length, and larva were containing yolk including globule.

• 한국어병학회지
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• 제2권1호
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• pp.1-18
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• 1989

지금까지 조사보고(調査報告)된 바 없는 한국산(韓國産) 양식(養殖) 뱀장어의 부레에 기생(寄生)한 선충에 의(依)한 피해여부(被害與否)와 예방대책(豫防對策)을 수립할 목적(目的)으로 기생(寄生)한 선충의 종(種)과 기생율(寄生率), 병해성(病害性) 그리고 생활사(生活史)를 조사(調査)하였다. 1. 성숙(成熟)한 충란의 크기는 $80{\sim}92(86.7){\times}62}\sim}71(67.4){\mu}m$였고, 자충의 크기는 $210{\sim}240(225){\times}18{\sim}23(20.6){\mu}m$였다. 2. 본충의 중간숙주(中間宿主)는 Thermocyclops hyalinus이며, 이것의 복강(腹腔)에 침입(侵入)한 유충은 4일후(日後)에 감염력(感染力)을 가졌고 이때의 유충 크기는 $360{\sim}420(390){\times}28{\sim}35(31)\;{\mu}m$였다. 3. 감염력(感染力)을 갖는 Thermocyclops hyalinus를 뱀장어가 섭취(攝取)한 뒤 50일(日) 경과(經過)되어 뱀장어 부레내에서 성충으로 발육(發育)되었다. 4. 검출(檢出)된 성충의 크기는 female$7.3{\sim}31.0(16.5){\times}0.5{\sim}2.2(1.2)mm$, male$4.9{\sim}13.3(8.3){\times}0.3{\sim}0.9(0.4)mm$로서 내외부(內外部) 형웅(形熊)를 비교(比較)한 바 Anguillicola crassa로 동정(同定)하였다. 5. 뱀장어에서의 월별기생율(月別奇生率)은 6, 9, 12월(月)에 높았고, 1~3월(月)에 비교적(比較的) 낮았다. 6. 감염(感染)되지 않은 정상어(正常魚)와 감염어(感染魚)의 비만도(肥滿度)를 월별(月別), 체장별(體長別)로 그 유의성(有意性)을 검정(檢定)한 결과(結果) 유의성(有意性)을 인정(認定)할 수 없었으며 본충 감염(感染)으로 인(因)한 뱀장어 성장(成長)에는 영향(影響)이 없는 것 같았다. 7. 본충의 기생(寄生)에 의한 뱀장어 부레조직(組織)의 이상(異狀)은 보이지 않았다. 8. 수온(水溫) $25.0{\sim}26.7^{\circ}C$ 때 masoten을 처리(處理)한 농도별(濃度別) Thermocyclops hyalonus의 사망시간(死亡時間)은 0.5ppm 14시간(時間), 0.4ppm 20시간(時間), 0.3ppm 22시간(時間), 0.2ppm 30시간(時間), 0.1ppm 42시간(時間)이었다.

• Parasites, Hosts and Diseases
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• 제50권2호
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• pp.113-118
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• 2012

From July 2008 to June 2009, livers of the swamp eels (Monopterus alba) were investigated for advanced third-stage larvae (AL3) of Gnathostoma spinigerum. Results revealed that 10.2% (106/1,037) and 20.4% (78/383) of farmed eels from Aranyaprathet District, Sa Kaeo Province and those of wild-caught eels obtained from a market in Min Buri District of Bangkok, Thailand were infected, respectively. The prevalence was high during the rainy and winter seasons. The infection rate abruptly decreased in the beginning of summer. The highest infection rate (13.7%) was observed in September and absence of infection (0%) in March-April in the farmed eels. Whereas, in the wild-caught eels, the highest rate (30.7%) was observed in November, and the rate decreased to the lowest at 6.3% in March. The average no. (mean${\pm}$SE) of AL3 per investigated liver in farmed eels ($1.1{\pm}0.2$) was significantly lower (P=0.040) than those in the caught eels ($0.2{\pm}0.03$). In addition, the intensity of AL3 recovered from each infected liver varied from 1 to 18 ($2.3{\pm}0.3$) in the farmed eels and from 1 to 47 ($6.3{\pm}1.2$) in the caught eels, respectively. The AL3 intensity showed significant difference (P=0.011) between these 2 different sources of eels. This is the first observation that farmed eels showed positive findings of G. spinigerum infective larvae. This may affect the standard farming of the culture farm and also present a risk of consuming undercooked eels from the wild-caught and farmed eels.

• Parasites, Hosts and Diseases
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• 제57권2호
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• pp.207-211
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• 2019

Anisakiasis is a zoonotic disease induced by anisakid nematodes, and endoscopic inspection is used for a diagnosis or remedy for it. Anisakis simplex, Anisakis physeteris, and Pseudoterranova decipiens had been reported to be the major species causing human infections, particularly, in Japan. However, in Korea, recent studies strongly suggested that Anisakis pegreffii is the major species of human infections. To support this suggestion, we collected anisakid larvae (n=20) from 20 human patients who were undergone gastrointestinal endoscopy at a health check-up center in Korea, and molecular identification was performed on the larvae using PCR-RFLP analysis and gene sequencing of rDNA ITS regions and mtDNA cox2. In addition, anisakid larvae (n=53) collected from the sea eel (Astroconger myriaster) were also examined for comparison with those extracted from humans. The results showed that all human samples (100%) were identified as A. pegreffii, whereas 90.7% of the samples from the sea eel were A. pegreffii with the remaining 9.3% being Hysterothylacium aduncum. Our study confirmed that A. pegreffii is the predominant species causing human anisakiasis in Korea, and this seems to be due to the predominance of this larval type in the fish (sea eels) popularly consumed by the Korean people. The possibility of human infection with H. aduncum in Korea is also suggested.

• Parasites, Hosts and Diseases
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• 제53권5호
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• pp.619-625
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• 2015

The present study was performed to determine the infection status of swamp eels with Gnathostoma sp. larvae in Myanmar. We purchased total 37 Asian swamp eels, Monopterus albus, from a local market in Yangon in June and December 2013 and 2014. All collected eels were transferred with ice to our laboratory and each of them was examined by the artificial digestion technique. A total of 401 larval gnathostomes (1-96 larvae/eel) were detected in 33 (89.2%) swamp eels. Most of the larvae (n=383; 95.5%) were found in the muscle. The remaining 18 larvae were detected in the viscera. The advanced third-stage larvae ($AdL_3$) were 2.3-4.4 mm long and 0.25-0.425 mm wide. The characteristic head bulb ($0.093{\times}0.221mm$ in average size) with 4 rows of hooklets, muscular long esophagus (1.025 mm), and 2 pairs of cervical sacs (0.574 mm) were observed by light microscopy. The average number of hooklets in the 1st, 2nd, 3rd, and 4th rows was 41, 45, 48, and 51, respectively. As scanning electron microscopic findings, the characteristic 4-5 rows of hooklets on the head bulb, a cervical papilla, tegumental spines regularly arranged in the transverse striations, and an anus were well observed. Based on these morphological characters, they were identified as the AdL3 of Gnathostoma spinigerum. By the present study, it has been confirmed for the first time that Asian swamp eels, M. albus, from Yangon, Myanmar are heavily infected with G. spinigerum larvae.