• Journal of Fisheries and Marine Sciences Education
• /
• v.27 no.2
• /
• pp.526-536
• /
• 2015

Changes of oxygen consumption in juvenile giant grouper, Epinephelus lanceolatus were investigated in order to find out the physiological responses associated with freshwater and low salinities acclimation. Salinity changes in this experiment were set as follows; 35 psu (Exp. I) as control, decrease in the manners of $35{\rightarrow}20{\rightarrow}10{\rightarrow}0$ psu (Exp. II), $35{\rightarrow}10{\rightarrow}0$ psu (Exp. III) and $35{\rightarrow}0$ psu (Exp. IV). The average oxygen consumption at $27^{\circ}C$ in Exp. I (control) was $106.9{\pm}0.7mg$ $O_2/kg/h$. In Exp. II, according to the changes of $35{\rightarrow}20{\rightarrow}10{\rightarrow}0$ psu in freshwater acclimation, fish showed the gradual decrease in oxygen consumption as $108.1{\pm}2.1$, $99.6{\pm}2.9$, $74.6{\pm}0.9$ and $62.7{\pm}1.0mg$ $O_2/kg/h$, respectively. The fish in Exp. III also revealed the same tendency as $106.5{\pm}1.3$, $77.0{\pm}1.2$ and $64.7{\pm}1.2mg$ $O_2/kg/h$, respectively. In Exp. IV, fish showed the decreased oxygen consumption from $109.0{\pm}0.9mg$ $O_2/kg/h$ of 35 psu to $71.6{\pm}2.0mg$ $O_2/kg/h$ of 0 psu. Giant grouper is thought to be a diurnal fish species, because the level of oxygen consumption during light period was higher than that during dark period.

• Proceedings of the Korean Aquaculture Society Conference
• /
• 2003.10a
• /
• pp.114-115
• /
• 2003

양식 생물에게 있어 용존산소는 호흡에 필수적이며, 양식 시설 내에서 적절한 용존 산소량을 유지하는 것은 생산량을 좌우하는 가장 중요한 요인이며, 어종, 수온, 광주기, 나이와 크기, 어류의 행동과 먹이 공급 및 환경 조건에 따라 달라진다. 이 중 같은 종 내에서 선발육종된 개체와 일반 양식 종 그리고 이들 계통간 잡종에 대한 대사 효율 즉, 용존산소 소비율의 차이에 관한 연구는 거의 없다. 따라서 본 실험에서는 한국해양연구원에서 선발육종 해 온 참돔과 일본 양식산 참돔 및 이들의 교배 자손들을 대상으로 수온과 광주기 변화에 따른 용존산소 소비율을 조사하였다. 실험어는 일본 양식산인 TPN 교배구 자손과 한국해양연구원 선발육종산인 KORDI F4 교배구 자손, JPN♀×KORDI F4♂ 그리고 KORDI F4♀×JPN♂ 교배구 자손을 대상으로 실시하였다. 체중이 각각 52.0±0.6 g(JPN 교배구; 그룹 1), 52.3±0.7 g(JPN♀×KORDI F4♂; 그룹 2), 51.7±0.4 g(KORDI F4♀ × KORDI F4♂; 그룹 3) 그리고 52.1±0.7 g(KORDI F4♀ × JPN♂; 그룹 4)인 참돔 치어를 각각 5마리씩 3반복 수용하여 실험에 이용하였다. 실험기간 동안 사육수의 pH는 8.1±0.1, 염분도는 34.0±0.5‰로 유지하였으며, 실험 장치는 김(1999)이 고안한 순환 시스템을 이용하였다. 수온은 각각 15℃, 20℃ 및 25℃로 변화시켰으며 각 수온 조건에서 광주기를 24L:0D, 12L:12D 그리고 0L:24D로 변화시켜 매 조건마다 용존 산소 소비량을 측정하였다. JPN 교배구인 그룹 1의 경우, 수온 15℃일 때 산소 소비량은 170.35∼266.29 mg O₂/kg fish/hr의 범위를 보였으며 수온 20℃와 25℃일 때 각각 236.76∼307.37 mg O₂/kg fish/hr와 346.96∼459.30 mg O₂/kg fish/hr 범위를 보여 수온 상승에 따라 산소 소비량 역시 증가하는 것으로 나타났다. 그룹 2의 경우, 수온 15℃일 때 산소 소비량은 162.01∼279.51 mg O₂/kg fish/hr의 범위를 보였으며 수온 20℃와 25℃일 때 각각 303.48∼342.72 mg O₂/kg fish/hr와 447.18∼528.45 mg O₂/kg fish/hr 범위를 보여 그룹 1과 마찬가지로 수온 상승에 따라 산소 소비량 역시 증가하는 것으로 나타났다. 그룹 3의 경우, 수온 15℃일 때 산소 소비량은 170.11∼220.98 mg O₂/kg fish/hr의 범위를 보였으며 수온 20℃와 25℃일 때 각각 262.62∼282.27 mg O₂/kg fish/hr와 302.24∼415.73 mg O₂/kg fish/hr 범위를 보여 그룹 1, 2와 유사한 경향을 보였다. 그룹 4의 경우, 수온 15℃일 때 산소 소비량은 156.03∼214.49 mg O₂/kg fish/hr의 범위를 보였으며 수온 20℃와 25℃일 때 각각 238.40∼274.28 mg O₂/kg fish/hr와 379.93∼430.97 mg O₂/kg fish/hr 범위를 보여 수온 상승에 따라 산소 소비량 역시 증가하는 것으로 나타나, 그룹 1, 2와 유사한 경향을 보였다. 모든 실험구에서 수온 상승과 함께 산소 소비량이 증가하는 것으로 나타났으며 가장 높은 산소 소비량은 그룹 2에서 관찰되었다. 실험 결과 JPN 계통의 암컷을 사용하여 생산된 그룹 1과 2의 산소 소비량이 KORDI F4 계통의 암컷을 사용한 그룹 3, 4보다 대체적으로 높은 것으로 나타났다. 연속적인 명기 조건인 24L:0D에서 수온 15℃의 경우 그룹 1, 2, 3 그리고 4의 시간당 산소 소비량은 각각 266.29 mg O₂/kg fish/hr,279.51 mg O₂/kg fish/hr, 220.98 mg O₂/kg fish/hr 그리고 214.49 mg O₂/kg fish/hr으로 나타났고, 명기와 암기가 동일한 조건인 12L:12D에서는 각각 192.20 mg O₂/kg fish/hr, 258.03 mg O₂/kg fish/hr, 192.76 mg O₂/kg fish/hr 그리고 170.40 mg O₂/kg fish/hr로 나타났다. 또한 연속적인 암기 조건인 OL:24D 조건에서는 각각 170.35 mg O₂/kg fish/hr, 162.01 mg O₂/kg fish/hr, 170.11 mg O₂/kg fish/hr 그리고 156.03 mg O₂,/kg fish/hr로 나타났다. 그리고 수온 20℃와 25℃에서도 그룹간의 변화는 이와 비슷한 경향을 보였다. 연속 명기 조건인 24L:0D에서의 산소 소비량이 명기와 암기가 동일한 조건인 12L:12D와 연속 암기 조건인 0L:24D에서의 산소 소비량 보다 대체적으로 높은 것으로 나타났으며, 그룹 2의 연속 명기 조건에서 528.45 mg O₂/kg fish/hr으로 가장 높게 나타났다. 그룹 4에서는 대사량이 점점 더 높아지는 수온 상승과 함께 연속 명기 조건과 더불어 12L:12D 조건에서의 산소 소비량이 크게 증가하는 것으로 나타났다.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
• /
• v.21 no.1
• /
• pp.36-43
• /
• 2016

Wild glass eels found in the Korean peninsula are thought to migrate along the North Equatorial Current and undergo the processes of spawning and incubation in the Mariana Trench. Juveniles of the wild glass eels are collected from the southern and western coasts of the Korean peninsula and used as seeds for aquaculture. To investigate the feeding behavior of wild glass eels, we collected glass eels from the Nakdong River estuary during March and April 2014 and analyzed the total length, wet weight, dry weight, carbon and nitrogen contents, and stable isotope ratio of eels as well as water temperature and salinity. Water temperature in the Nakdong River estuary was $13.2{\pm}1.0$ (mean ${\pm}$ 1SE; range, $10.1{\sim}15.7)^{\circ}C$ and salinity was $24.8{\pm}2.4$ (13.2~34.0), showed a lower range from 13.2 to 30.0 (a mean of 21.2) when the floodgates were opened. The total length of glass eels was $56.5{\pm}0.2$ (51.0~63.6) mm, wet weight was $70.9{\pm}1.4$ (33.6~133.2) mg, and dry weight was $16.5{\pm}0.3$ (10.1~29.1) mg. Carbon and nitrogen contents of glass eels were $51.0{\pm}0.8%$ and $13.9{\pm}0.1%$, respectively. Mean ${\delta}^{13}C$ and ${\delta}^{15}N$ values of glass eels collected from the Nakdong River estuary were -20.9±0.2‰ and 6.1±0.1‰, displaying similar values to those of leptocephalus, glass eel larvae collected from the North Equatorial Current. Therefore, this result suggest that the glass eels collected from the Nakdong River estuary do not feed on prey after metamorphosis from eel larvae to glass eels their migration.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.36 no.2
• /
• pp.117-125
• /
• 2000

The waveform and spectrum analysis of Tursiops truncatus(bottlenose dolphin) sonar signals were carried out on the basis of data collected during the dolphin show at the aquarium of Cheju Pacificland from October 1998 to February 1999. When greeting to audience, the pulse width, peak frequency and spectrum level from the five dolphins'sonar signals were 3.0ms, 4.54kHz and 125.6dB, respectively. At the time of warm-up just before the show, their figures were 5.0㎳, 5.24kHz and 127.0dB, respectively. During the performance of dolphins, with singing, peak frequency ranged 3.28∼5.78kHz and spectrum level ranged 137.0∼142.0dB. With playing ring, pulse width, peak frequency and spectrum level were 7.0㎳, 2.54kHz and 135.9dB, and when playing the ball, the values were 9.0㎳, 2.78kHz and 135.2dB, respectively. The values determined from the five dolphins during jump-up out of water were : pulse width 2.0㎳, peak frequency 4.50kHz and spectrum level 126.8dB. When they responded to trainer's instructions, the values were 2.25㎳, 248kHz and 148.7dB, respectively, and greeting to audience, the peak frequency and spectrum level were 5.84kHz and 122.5dB. During swimming under water, peak frequency and spectrum level were determined to be 10.10kHz and 126.8dB. It was found that there exited close consistencies in pulse width, frequency distribution and spectrum level between whistle sounds and dolphin's sonar signals. Accordingly, the dolphins can be easily trained by using whistle sound based on the results obtained from the waveform and spectrum of the dolphin's sonar signals.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.38 no.2
• /
• pp.156-163
• /
• 2002

In order to development the construction and dimension of fishing gear for gizzard shad coastal purse seine, first of all investigated to the sinking speed and underwater geometry of net, behaviour of fish school to the net during the fishing operation In the field. The results obtained are summarized as follows; 1. Average sinking speed of net was 13cm/sec in bunt, 9.0cm/sec and 9.5cm/sec in 170m and 280m of center, 4.9cm/sec in end wing side, therefore was fastest in start of shooting and decreased gradually during the shooting process. 2. The most of leadline was reached in bottom from the shooting immediately to hauling time and the mean depth of timber bar used equipment for the escaping prevention of fish school was within the 2.7m. 3. The fish school of gizzard shad was appearanced higher density and remained to the most time in bottom than the surface and repeated to vortical movement, and its tendency to distinct in rapid time of tide current. 4. Behaviour of fish school in the net was showed to the vortical movement by sinking and rising immediately with the shooting of net and then divide with the two shape to follow round the wall of net and no patterns straightly movement in the net, and tendency easily catched in fish school of the wall of net. 5. Escaping of fish school in the gap of wing side was to busy after that seting the timber bar, therefore its function for escaping prevention of fish school was very lowed. 6. Escaping behaviour of fish school was differenced with the depth of fishing ground, the above 20m escaped to busy through the below in ledline because the sinking speed of fish school is fast than the net.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.38 no.3
• /
• pp.217-225
• /
• 2002

The authors examined the response of electrocardiogram(ECG) of Nile tilapia, Oreochromis niloticus [Linnaeus] to light stimuli. The experiments were performed in such a way that three levels of light stimuli(10, 100 and 400 lu$\chi$) were given to fishes with an electrode inserted into their bodies and then their ECGs were recorded continuously for 60 minutes in 16~18$^{\circ}C$. The results which are divided into by day and by night and then analyzed by fishes' conditions are as follows; 1. Nile tilapias reached a stable condition 3 minutes after anesthesia. In stable condition, the heart rate average was 47.6beat/min by day and 45.1beat/min by night. And the action potential average was 1.0.4$mutextrm{V}$ by day and 1.24$mutextrm{V}$ by night. 2. The heart rate average by three levels of light stimuli was, \circled1 In stimulus condition, in case of 10 lu$\chi$ 39.7beat/min by day and 38.2beat/min by night, in case of 100 lu $\chi$8.7beat/min by day and 36.9beat/min by night, and in case of 40.0. lux 36.8 beat/min by day and 35.8beat/min by night. \circled2 In recovery condition, in case of 10 lu$\chi$ 47.1beat/min by day and 46.0beat/min by night, in case of 100 lu$\chi$ 47.2beat/min by day and 45.6 beat/min by night, and in case of 400 lu$\chi$ 48.1beat/min by day and 46.6beat/min by night. 3. The action potential average by three levels of light stimuli was, \circled1 In stimulus condition, in case of 10 lu$\chi$ 1.22$mutextrm{V}$ by day and 0.71$mutextrm{V}$ by night, in case of 100 lu$\chi$ 0..63$mutextrm{V}$ by day and 0.90$mutextrm{V}$ by night, and in case of 400 lu$\chi$ 1.39$mutextrm{V}$ by day and 1.63$mutextrm{V}$ by night \circled2 In recovery condition, in case of 10 lu$\chi$ 1.26$mutextrm{V}$ by day and 1.59$mutextrm{V}$ by night, in case of 100 lu$\chi$ 2.63$mutextrm{V}$ by day and 3.65$mutextrm{V}$ by night, and in case of 400. lu$\chi$ 2.52$mutextrm{V}$ by day and 3.67$mutextrm{V}$ by night.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.27 no.1
• /
• pp.13-20
• /
• 1991

This paper describes the fish-density dependence of the mean backscattering strength with aggregations of encaged, free-swimming fish of known density in relation to the experimental verification of echo-integration technique for estimating the density of fish shoals. In this experiment, various numbers of gold crussian, Carassius burgeri burgeri, with a mean length of 18.5cm and a mean weight of 205.9g, were introduced into a net cage of approximately 0.76m super(3). During the backscattering measurements. the cage was suspended on the sound axis of the 50kHz transducer having a beam width of 33 degrees at -3dB downpoints. The volume backscattering strengths from fish aggregations were measured as a function of fish density. Data acquisition, processing and analysis were performed by means of the microcomputer-based sonar-echo processor including a FFT analyzer. The calibration of echo-sounder system was carried out at field with a steel ball bearing of 38mm in diameter having the target strength of -40.8dB. The dorsal-aspect target strengths on anesthetized specimens of gold crussian used in the cage experiment were measured and compared with the target strength predicted by the fish density-echo energy relationship for aggregations of free-swimming gold crussian in the cage. The results obtained can be summarized as follows: 1. The target strengths in the dorsal aspect on anesthetized specimens of gold crussian, with the mean length of 19.1cm and the mean weight of 210.5g, varied from -40.9dB to -44.8dB with a mean of -42.6dB. This mean target strength did not differ significantly from that predicted by the regression of echo energy on fish density of free-swimming gold crussian in the cage. It suggests that the target-strength measurements on anesthetized fish was valid and can be representative for live, free-swimming fish. 2. The relationship between mean backscattering strength(, dB) and distribution density of gold $crussian(\rho, $ fish/m super(3)) was expressed by the following equation; =-41.9+11 $Log(\rho)$ with a correlation coefficient of 0.97. This result support the existence of a linear relationship between fish density and echo energy, but suggest that this line has steeper slope than the regression by the theory of estimating the density of fish schools.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.16 no.3
• /
• pp.241-248
• /
• 2010

Hypoxic(oxygen-deficient) water masses are a key threat to the ecosystem of shallow marine coastal areas worldwide. The phenomena of hypoxia occurred at Gamak Bay, on the southeast coast of Korea, in late June 2007. In this paper, the physicochemical characteristics of seawater were surveyed for a period of hypoxic water mass disappearance. The hypoxic water mass was located between Sunso and the northwestern area of the inner bay. The dissolved oxygen(DO) concentrations of surface and bottom water were $1.3mgL^{-1}$ and less than $2mgL^{-1}$, respectively, in the hypoxic water masses, and $4.5{\sim}6.8mgL^{-1}$ and $3.8{\sim}6.0mgL^{-1}$ at the other oxygen-rich sample sites, respectively. Chlorophyll a concentrations were $4.9{\sim}25.3{\mu}gL^{-1}$ at the surface, $2.3{\sim}23.1{\mu}gL^{-1}$ in the middle, and $1.9{\sim}9.0{\mu}gL^{-1}$ at the bottom of the hypoxic water masses. When the hypoxic water mass appeared in Gamak Bay, it formed three different vertical types. The first type occurred throughout the water depth around Sunso. The second type developed from the bottom. The third type of hypoxic water mass was formed in the middle water layer when the inversion of water temperature occurred. The third type of phenomena appeared at only St. 9, St. 14 and St. 21 sites near the Hodo coast. Aquatic surface respiration of bottom-dwelling fishes such as the oriental goby(Acanthogobius flavimanus) was observed and many crustaceans were seen along the adjacent shore of the hypoxic water mass area. About 3,000 oriental gobies as well as many crustaceans died due to this event in Gamak Bay. The results of this study could provide fundamental data for the mechanism of hypoxic water masses in Gamak Bay.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.40 no.1
• /
• pp.86-94
• /
• 2004

This study was conducted to mesh selectivity of Beam trawl for shrimps fishing experiment in the coastal waters around Geomundo, South sea of Korea, during from Oct. to Nov. 2002. The selectivity parameters of big head shrimp (Solenocera melantho) have been studied on the covered con-end method. with mesh of 8, 38, 51 and 61 mm. Selection curves and selection parameters were calculated by using a logistic function S=1/(1+exp-(aCL+b)). The mesh selection master curves were estimated by S=1/(1+exp$^{({\alpha}(CL/M)+{\beta}}$), and the optimum mesh size were calculated with (L/M)50 of master curve. Optimum mesh size and selectivity master curves for the southern rough shrimp (Yrachysalambria curvirostris) and smoothshell shrimp (Parapenaeopsis tenella) optimum mesh size and selectivity master curves were estimated by big head shrimp master curves. The results obtained are summarized as follows : Selection parameters '${\alpha}$' and '${\beta}$' of the master curve for big head shrimp were 8.84 and -5.89, and The selection factor of the master curve (L/M)$_{50}$ was 0.67. The optimum mesh size of minimum length for sexual maturity for big head shrimp was 30.7 mm. Estimated (L/M)$_{50}$ for southern rough shrimp and smoothshell shrimp by using the master curve of big head shrimp was 0.73 and the optimum mesh sizes were 25.5 mm for southern rough shrimp and 16.9 mm for smoothshell shrimp, respectively.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.37 no.2
• /
• pp.124-132
• /
• 2001

The authors examined the response of electrocardiogram (ECG) of Mirror carp, Cyprinus carpio [Linnaeus] to light stimuli. The experiments were performed in such a way that three levels of light stimuli (10, 100, and 400 lux) were given to fishes with an electrode inserted into their bodies and then their ECGs were recorded continuously for 60 minutes. The results which are divided into by day and by night and then analyzed by fishes conditions are as follows : 1. Mirror carps reached a stable condition 5 minutes after anesthesia. In this condition, the average heart rate was 64.9 beat/min by day and 65.3 beat/min by night. And the average action potential was 36.9 nV by day and 32.9 nV by night. 2. The average heart rate by three levels of light stimuli was, 1) In a stimulus condition, in case of 10 lux 68.7 beat/min by day and 46.0 beat/min by night, in case of 100 lux 53.4 beat/min by day and 44.1 beat/min by night, and in case of 400 lux 53.2 beat/min by day and 40.1 beat/min by night. 2) In a recovery condition, in case of 10 lux 67.9 beat/min by day and 57.2 beat/min by night, in case of 100 lux 68.8 beat/min by day and 61.0 beat/min by night, and in case of 400 lux 69.6 beat/min by day and 63.6 beat/min by night. 3. The average action potential by three levels of light stimuli was, 1) In a stimulus condition, in case of 10 lux 59.1 nV by day and 24.0 nV by night, in case of 100 lux 26.8 nV by day and 45.6 nV by night, and in case of 400 lux 71.7 nV by day and 14.4 nV by night. 2) In a recovery condition, in case of 10 lux 38.8 nV by day and 27.3 nV by night, in case of 100 lux 29.0 nV by day and 39.3 nV by night, and in case of 400 lux 66.4 nV by day and 21.4 nV by night.