• Fisheries and Aquatic Sciences
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• 제24권12호
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• pp.437-445
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• 2021

Roughscale sole (Clidoderma asperrimum) is only wild caught because basic reproductive research on this species is lacking and gamete production in an artificial setting has not been successful. Exogenous hormone treatment has been used to induce gonadal maturation and final spermiation in wild-caught individuals. In this study, the effects of an exogenous hormone on spermiation in roughscale sole was investigated by implanting different concentrations of a salmon gonadotrophin-releasing hormone analog (sGnRH; 0, 25, 50, and 100 ㎍/kg body weight) into male fishes. The control group did not produce sperm after 21 days post-implantation, and the duration of spermiation was shorter compared to the other groups. The spermiation period and milt amount differed among the hormone-treated groups according to the hormone concentration used. Milt volumes in the groups treated with 25 and 100 ㎍/kg sGnRH increased compared to the control group, whereas exogenous hormone treatment had no effect on the movable sperm ratio. The spermatocrit was high at the beginning of spermiation in all groups and then tended to decrease gradually over time except in the experimental group treated with 100 ㎍/kg sGnRH. Plasma levels of testosterone, 11-ketotestosterone, 17α, 20β-dihydroxy-4-pregnen-3-one were not significantly affected by the sGnRH treatments. Our results demonstrate that it is possible to prolong the spermiation period and increase milt volume by treating male roughscale soles with an exogenous hormone. In addition, the artificial hormone treatment did not affect sperm motility.

• 수산해양교육연구
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• 제24권6호
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• pp.1003-1012
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• 2012

The gonadosomatic index (GSI), sex steroid hormones and gonadal development of roughscale sole Clidoderma asperrimum cultured in indoor tank were investigated to evaluate its sexual maturation and reproductive cycle. The highest GSI values of female and male were $6.91{\pm}4.03$ (May) and $0.16{\pm}0.08$ (August), respectively. The reproductive cycle would be classified into four successive developmental stages: growing stage (December to February), maturation stage (March to April), ripe and spawning stage (May to June), recovery and resting stage (July to November). The highest plasma testosterone (T) and estradiol-$17{\beta}$ ($E_2$) levels of female were $259.4{\pm}76.8$ and $633.3{\pm}182.5$ pg/mL, respectively in May. Also $17{\alpha}$, $20{\beta}$-dihydroxy-4-pregen-3-one ($17{\alpha}$, $20{\beta}$-OHP) levels of female peaked in April before spawning season ($244.2{\pm}42.5$ pg/mL). The highest plasma testosterone (T) and 11-ketotestosterone levels of male were $231.0{\pm}46.0$ and $273.9{\pm}54.5$ pg/mL, respectively in April. But there was no significant difference in $17{\alpha}$, $20{\beta}$-OHP.

• 수산해양기술연구
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• 제50권1호
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• pp.1-11
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• 2014

To compare the catches made using gillnets, trammel nets, and gillnets with supporting lines, several experiments were conducted with commercial vessels near Uljin and Pohang in Eastern Korea between July 2010 and May 2011. Two sets of 13 different nets were used, including 5 panels of gillnets and trammel nets each with stretched mesh sizes of 7.6, 9.1, 10.6, 12.1, and 13.6 cm and 3 panels of gillnets with a mesh size of 9.1 cm with supporting lines with different line spacing. The outer (stretched) mesh size of the trammel nets measured 51.5 cm. The target fishes of the fishing nets were various types of flounders. The catch rate of flounders was 50.7% of the total catch in weight. The total catch for all nets was 443.8 kg. The predominant species was pointhead flounder (Cleisthenes pinetorum). The total catch by trammel nets was 1.4 times that of the comparable gillnets. But more pointhead flounder were caught by gillnets than by trammel nets, though there was no significant difference. Fishermen catching the pointhead flounder in Korea said that there was no need to use trammel net to catch it; this was an unexpected finding compared to the findings of other flounder fisheries. The amounts of roughscale sole, brown sole, and blackfin flounder caught by trammel nets were greater than those caught by gillnets. The mean lengths (standard deviation) of blackfin flounder, pointhead flounder, brown sole, and roughscale sole were 21.0 (4.57), 22.9 (3.40), 24.7 (4.90), and 28.3 (5.43) cm, respectively; there were significant differences in mean length (p < 0.00001). Therefore, in order to catch flounder efficiently, the fishing nets and mesh size should be chosen according to the target species. One advantage of using supporting lines is that it prevents breakage by strengthening the material especially when utilized on a rough bottom. Catch by using gillnet with supporting lines was not greater than that by using trammel net for the conservation of fisheries resources.

• 한국어류학회지
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• 제25권3호
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• pp.163-168
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• 2013

통영주변해역에서 2010년 1월부터 8월까지 낚시, 자망 그리고 새우조망을 이용하여 돌가자미 102개체와 줄가자미 101개체를 채집하고 위내용물을 분석하였다. 각각의 위내용물 분석 결과 돌가자미는 이매패류와 어류가 대부분을 차지하였고, 줄가자미는 거미불가사리류가 위내용물의 대부분을 차지하여 저서성 육식어류로 나타났다. Prey-specific abundance 분석 결과 다른 가자미과 어류들과 비교하여 깊은 수심에 서식하는 돌가자미와 줄가자미는 각각 이매패류와 거미불가사리류에 섭식이 특화된 specialist predator로 나타났다. 돌가자미와 줄가자미는 같은 지역에 출현하는 유사종 사이에서 나타날 수 있는 먹이경쟁을 피하기 위해 서로 다른 식성을 가지는 것으로 판단할 수 있다.

• 한국어류학회지
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• 제34권2호
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• pp.86-95
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• 2022

줄가자미의 난발생 및 자치어 형태발달을 관찰하여 종자생산 및 분류학적 연구의 기초자료로 이용하고자 한다. 2017~2018년까지 동해안에서 어미를 채집하여 원형수조(Ø 6 ×1 m) 수온 12.8±1.9℃에서 사육하였다. 수정란의 크기는 1.42~1.59 mm (평균±SD, 1.51±0.04 mm, n=50)였고, 난의 형태는 구형의 무색 투명한 분리부성란이었다. 난발생 과정은 수정 60분 후 난황과 난막이 분리되었고, 62시간 후 배체가 형성되었다. 수정 144시간 후 전체의 50% 이상이 부화가 완료되었다. 부화 직후의 자어는 전장 4.22~4.64 mm (4.53±0.16 mm, n=10)로 입과 항문은 열리지 않았고, 부화 후 10일째 전기자어는 전장 5.88~6.62 mm (6.31±0.33 mm, n=10)로 난황 흡수가 완료되고, 입이 열리기 시작하였다. 부화 후 55일째 중기자어는 전장 10.4~13.3 mm (12.7±1.3 mm, n=10)로 척추말단 끝부분은 휘어졌다. 부화 후 120일째는 전장 35.3~40.5 mm (39.5±2.4 mm, n=10)였고, 각 지느러미 기조 수는 등지느러미 79~94개, 뒷지느러미 63~75개로 정수에 달하면서 치어기로 이행하였다.