• 수산해양기술연구
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• 제53권1호
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• pp.49-59
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• 2017

The objective of this study was to investigate the growth rate and the optimal stocking density of sea cucumbers. Grow-out was studied in situ by conducting a follow-up survey using visible implant elastomer (VIE) tags. The rearing systems were made of polypropylene pipe for the frames and netting. The experiment ran for 70 days near Yeosu, Korea in the water depth of about 7 m. A total of 576 sea cucumbers which have three groups of body sizes (small: 5.15, medium: 12.34 and large: 23.26 g) were used. The five groups of stocking densities (150, 300, 450, 600 and $850g/m^2$) in rearing system for sea cucumber were considered. Sea cucumbers were fed a mixed diet (mud, mineral, fish meal, etc.). The feed was supplied to 10% of their body wet weight once every 7 days. The survival rate (73%) of sea cucumber in $850g/m^2$ was lower than those of other density groups ($150g/m^2$: 89%, $300g/m^2$: 84%, $450g/m^2$: 78% and $600g/m^2$: 86%). The survival rate of medium size group was higher than those of small and large groups regardless of the density (P<0.05). Most of density groups have no significant difference except for $850g/m^2$ (P>0.05). The growth rate of small size group ($0.63%day^{-1}$) was higher than those of medium ($0.38%day^{-1}$) and large ($0.34%day^{-1}$) group regardless of the density (P<0.05). The threshold water temperature was $11.0^{\circ}C$ for sea cucumber growth in winter season.

• 한국양식학회지
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• 제20권1호
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• pp.31-40
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• 2007

가막만, 여자만과 사량도에서 피조개(Scapharca broughtonii) 치패의 살포시기와 양식장 환경에 따른 피조개의 성장과 생존율 감소 요인을 파악하였다. 피조개는 여자만과 가막만에서는 2004년 11월에 인공산 치패를 바닥식으로 살포하였으며, 사량도에서는 2005년 3월초에 중국산과 국내산 치패를 바닥식으로 살포하였다. 살포된 피조개의 치패는 2005년 3월부터 12월까지 매월 성장과 생존율을 측정하였으며, 양식장의 수질(수온, 염분, DO, 영양염, Chl. a)과 퇴적물(산소투과 깊이, 미세산소 분포, 강열감량과 COD) 환경을 조사하였다. 조사기간 동안 피조개의 누적 생존비는 가막만에서 가장 높았으며, 여자만에서는 대부분 폐사하였다. 피조개 개체의 성장은 여자만과 가막만에서 5월에 가장 빠른 것으로 나타났으며, 사량도에서는 국내산이 중국산보다 빠른 성장을 보였다. 여자만에서 피조개의 높은 폐사(>65%)는 하계의 수온 상승, 저염분 수괴의 유입과 퇴적물의 낮은 DO 농도가 영향을 미치는 것으로 나타났다. 계절에 따른 가막만과 사량도에서 피조개의 생존비는 영양염과 퇴적물의 COD 농도에 영향을 받는 것으로 나타났다. 피조개의 성장과 폐사는 양식장 환경과 살포시기에 따라 차이를 보였다.

• 한국어류학회지
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• 제25권1호
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• pp.1-8
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• 2013

나프탈렌이 조피볼락의 생존과 아가미의 조직학적 변화에 미치는 영향을 관찰하였다. 실험에 사용된 조피볼락은 전장 $10.36{\pm}0.49cm$, 전중 $16.28{\pm}1.86g$, 270개체이며, 실험기간은 28일이었다. 실험농도는 6개 농도구를 설정하였다(대조구, 에탄올(solvent) 대조구, 0.5, 1.0, 1.5, 2.0 mg Nap $L^{-1}$). 실험기간 동안 사망개체를 매일 파악하여 생존율로 환산하였으며, 실험 종료 후 생존개체의 아가미는 조직표본 제작 후 조직손상의 정도(degree of tissue change (DTC))를 파악하였다. 생존율은 대조구, 에탄올 대조구, 0.5 및 1.0 mg Nap $L^{-1}$에 노출된 개체들은 90% 이상을 나타냈다. 1.5 및 2.0 mg Nap $L^{-1}$에 노출된 개체들은 노출 후 약 20일부터 급격히 감소하여 각각 80%와 62.2%를 나타냈다. 아가미의 조직학적 변화는 새엽 및 새판 상피세포의 증식이 대조구를 포함해 전 노출 농도구에서 관찰되었으며, 농도 증가에 따른 DTC의 증가는 나타나지 않았다. 하지만, 새판 상피층의 탈락 및 융합, 새판 모세혈관 확장, 울혈, 동맥류 및 괴사는 농도의존적 증가를 보였다. 특히 새판의 융합, 모세혈관 확장 및 울혈은 1.0 mg Nap $L^{-1}$ 이상의 농도에서 관찰되었으며, 동맥류와 괴사는 1.5 mg Nap $L^{-1}$ 이상의 농도에서만 관찰되었다. 이와 같은 결과는 생존율의 감소와 아가미의 조직학적 변화가 밀접한 관련이 있으며, 나프탈렌의 독성영향을 결정하는데 있어 DTC의 유용성을 보여준다.

• 수산해양교육연구
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• 제25권6호
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• pp.1360-1365
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• 2013

다양한 염분 농도에 따른 어린 돌기해삼의 생존과 피부계의 구조적 이상을 관찰하였다. 돌기해삼의 크기 및 수는 습중량 $1.0{\pm}0.2g$, 250 개체였다. 실험농도는 0, 5, 10, 15, 20, 25, 30, 35 및 40 psu 였으며, 96시간 노출 후 7일간 일반해수에서 회복과정을 통해 생존을 관찰하였다. 그 결과 25-35 psu에 노출된 개체들은 모두 100%의 생존율을 보였으며, LC50은 21.05 psu로 나타났다. 돌기해삼의 피부계는 20 psu 이하의 염분 농도에 노출된 개체들의 경우 상피층 두께 감소, 상피세포 핵 응축, 점액세포 감소 및 진피층 결합조직의 성긴 배열 등이 주로 관찰되었다. 하지만 이와는 반대로 40 psu의 염분 농도에 노출된 개체들은 상피세포 핵의 비대, 점액세포 증가 및 진피층 결합조직의 치밀배열 등이 나타났다. 진피층에서 관찰된 alcian blue(pH 2.5) 양성 분비세포들은 20 psu 이하에서는 노출 24시간 내에 대조구에 비해 급격한 증가 및 감소폭을 보였다. 40 psu 에서는 노출시간이 길어질수록 증가한 후 회복일수에 따른 감소경향을 보였다.

• 한국수산과학회지
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• 제53권5호
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• pp.725-732
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• 2020

The sudden drop of water temperature in winter is very threatening factor that affects the productivity of farmed fish and the management in aquafarm. In this study, we investigated the effect of low temperature on the survival, oxygen consumption and stress responses of parrotfish Oplegnathus fasciatus due to acute drop of water temperature. The survival rate of parrotfish Oplegnathus fasciatus was 5% at 6℃, 95% at 8℃ and 100% at 10℃ on the 4^th day of exposure in each experimental temperature. Low-lethal temperature for 4days of parrotfish Oplegnathus fasciatus (4 day-LT₅₀) was 6.99℃ (confidence limit, 6.55-7.42℃). Oxygen consumption rate was significantly decreased with decreasing water temperature. Temperature coefficient (Q₁₀) was found to be 4.0 between 10℃ and 8℃ and 0.39 between 8℃ and 6℃. As a result of investigating the stress response according to the drop in water temperature, the concentration of SOD (Superoxide dismutase), cortisol, glucose, total Ig, AST (Aspartate) and ALT (Alanine aminotransferase) increased with decreasing of water temperature. This study would be useful for the management of temperature about cultured fish.

• 수산해양기술연구
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• 제45권4호
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• pp.251-259
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• 2009

Swimming crabs, Portunus trituberculatus(Miers) are commercially important off the coasts of Korea, Japan and China. Harvest of swimming crabs has been fluctuated along their distribution ranges. Fluctuations in the interannual harvest of swimming crabs may be correlated with the survival rate during the larval period. The survival rates, intermolt periods, and growth of larval swimming crabs were investigated in the laboratory. Larval swimming crabs are released and undergo development from April to August off the western coast of Korea in the Yellow Sea. Sea surface temperatures off the western coast of Korea during the larval season were used for the laboratory experiments, and ranged from 22 to 26${^{\circ}C}$. Larvae were individually cultured at four different temperatures, 22${^{\circ}C}$, 24${^{\circ}C}$, 26${^{\circ}C}$, and 28${^{\circ}C}$. Zoea molted to megalopa at all temperatures and developed to the first crab stage at 24${^{\circ}C}$, 26${^{\circ}C}$, and 28${^{\circ}C}$. Survival rates from zoea I to the first crab stage increased with increasing temperatures. Intermolt period and the growth rate of the mean carapace length were inversely correlated with temperature. Our research helps understand the changes in survival rate and growth of larval swimming crabs resulting from changing oceanic temperatures. Further, our study suggests that the fluctuations in fishery harvest of swimming crabs off the coast of Korea may be related to changes in larval survival affected by changing ocean conditions.

• 한국수산과학회지
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• 제47권6호
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• pp.796-800
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• 2014

A feeding trial was conducted to investigate the growth and body composition of juvenile sea cucumber Apostichopus japonicus in integrated culture with abalone Haliotis discus hannai or rockfish Sebastes schlegeli. Triplicate groups of sea cucumber averaging $1.2{\pm}0.05g$ were cultured alone or with abalone or rockfish for 12 weeks. Survival of sea cucumber was not affected by co-culturing (P>0.05). Weight gain of sea cucumber cultured with rockfish was significantly higher than that of sea cucumber cultured alone (P<0.05), and did not differ from that of those cultured with abalone (P>0.05). These findings indicate that co-culturing sea cucumber with rockfish effectively improves the growth of sea cucumber.

• 한국발생생물학회지:발생과생식
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• 제20권2호
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• pp.81-90
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• 2016

The effect of sudden changes of water temperature (WT) on the survival rate and physiological responses of the red spotted grouper (Epinephelus akaara) were examined by manipulating WT control system for 9 days. Experimental condition was divided in two different regimes at low (from $10^{\circ}C$ to $4^{\circ}C$, decreased $1^{\circ}C/d$) and high (from $28^{\circ}C$ to $34^{\circ}C$, increased $1^{\circ}C/d$) WT. Survival rate of experimental fishes were observed, and determined the changes of hematological characteristics by analyzing plasma levels of cortisol, glucose, total protein, and electrolytes ($Na^+$, $Cl^-$, $K^+$). No mortality was observed until low WT $6^{\circ}C$ (144 h) and high WT $32^{\circ}C$ (96 h), and 100% mortality was observed at low WT $4^{\circ}C$ (216 h) and high WT $35^{\circ}C$ (171 h). Plasma levels of cortisol and glucose increased rapidly as decreasing WT, and the loss of swimming ability and respiration response was observed at low WT $7^{\circ}C$ and high WT $34^{\circ}C$ conditions.

• 한국수산과학회지
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• 제53권4호
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• pp.530-537
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• 2020

This study compared the survival rates, growth, and fatty acid content of larval Pacific cod Gadus macrocephalus fed with rotifers raised on different enrichment diets. We used four commercial rotifer enrichment products (one domestic, ER1, and three imported, ER2, ER3 and ER4). Twelve 200-L tanks were used, with three replicates per treatment. Larvae were fed rotifers 3 times daily at a rate of 5 rotifers/ml/feeding from 7 to 21 days post-hatch. At the end of the feeding trial, the survival rate and total length of larvae fed ER3 were greater than those of larvae fed ER1, ER2, or ER4. ER3 had the highest proportions of eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and polyunsaturated acid (PUFA). Partially reflecting this composition, larvae fed ER3 had the highest proportions of DHA and PUFA. These results show a positive effect of rotifer DHA and PUFA proportions on the survival and growth rates of Pacific cod larvae.

• 한국수산과학회지
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• 제54권4호
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• pp.426-433
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• 2021

This study aimed to determine the appropriate salinity condition for optimal cultivation of the juvenile hybrid grouper Epinephleus akaara♀×E. lanceolatus♂ in conditions of decreasing salinity. The survival, growth, metabolic rate, stress, and histological response were investigated in juvenile hybrid grouper exposed to different salinities for 30 days. At 0 psu, the survival rate of the juvenile hybrid grouper was 60% on the 2nd day of exposure and all individuals died on the 3rd day of exposure. At salinities above 3 psu, all animals survived throughout the exposure period. Growth rate for body weight of the juvenile hybrid grouper was the highest in the control and the lowest at 10 psu. Plasma osmolality of the juvenile hybrid grouper exposed to different salinities was 313-355 mg Osmol/kg at salinities above 10 psu, and then decreased to 225-264 mg Osmol/kg at salinities below 5 psu. The oxygen consumption rate tended to decrease as the salinity decreased. Stress responses of the juvenile hybrid grouper were analyzed with decreasing salinity. Therefore, it is considered that a salinity of more than 20 psu is suitable for the culture of the juvenile hybrid grouper.