• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.35 no.2
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• pp.156-160
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• 1999

This experiment was carried out to investigate the auditory threshold of the scorpion fish Sebastiscus marmoratus which was suitable for Marine ranching by a classical respiatory conditioning technique using a sound coupled with a delayed electric shock. The thresholds were determined by analyzing the electrocardiogram. The auditory thresholds were observed among the 12 fish with much difference from 100Hz to 300Hz. The audible range of the scorpion fish extended from 80 to 800Hz with a peak sensitivity of 90㏈(0㏈= $1\mu$Pa) at 100Hz. As the frequency became higher than 300Hz, the auditory threshold increased rapidly. The scorpion fish was least sensitive to sound of 500Hz among 6 frequency points and the value was about 12㏈.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.32 no.2
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• pp.132-147
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• 1996

The optimal design of floating type fisheries facilities in the open sea is demanded considering with the severe hydrodynamic forces on floating body, mooring tension and holding force of anchor. For conserving the facilities in most effective state, design and selection of anchor system is one of the most important fundamental subject. To enhance the design procedure of anchor system the holding forces of anchor are investigated by the hydraulic model test and are compared with the typical conventional results for various anchors. Applicability of previous estimation methods of holding force are checked and holding mechanism of anchor is discussed. Using the results a new computational concept of holding force is suggested considering mainly the effects of passive soil pressure (resistance), steady soil pressure, and surface friction etc. The new estimation method is proved as a feasible one by comparing the results of hydraulic model experiments. Applicability of various anchors to the anchor system on open sea fisheries structures is comprehensively reviewed using the present model tests and previous study results in the viewpoint of economy, construction and stability etc. Using the results, fundamental anchoring system design procedures are suggested to apply huge marine ranching complex with increase of the holding capacity of anchor under the optimum cost.

• Korean Journal of Environmental Biology
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• v.24 no.2 s.62
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• pp.126-137
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• 2006

Effect of night-lights on zooplankton attraction has been studied in Tongyeong marine ranch area during the period from 12 July to 30 August, 2004. Each sampling has been carried out to collect zooplankton from both control area in natural waters experiment area of night-lights waters at night. A total of 43 taxa of zooplankton occurred during the study. Copepods showed the prosperity in species number with 15 species. Acartia erythraed and Copepodite occurred abundantly in night-lights waters. Zooplankton abundance appeared to increase in night-lights mainly due to the gathering of copepods and larvae through the study period. Average $3\sim166$ times of zooplankton abundance was recorded in night-lights when compared with that in control area of natural waters due to the gathering of copepods and larvae. Cluster analysis, based on monthly abundance data of the 13 most frequent species, showed that the species were seperated into two different groups: the photo-positive group and the photo-negative group.

• Ocean and Polar Research
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• v.23 no.3
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• pp.245-253
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• 2001

To investigate the community structures and the their seasonal variation of phytoplankton and zooplankton, a study was conducted at 6 selected stations during the period from April 1999 to October 2000 in the marine ranching ground off Tongyeong. One hundred ninety species of phytoplankton were identified, including 146 diatoms, 38 dinoflagellates, 4 silicoflagellates and 2 euglenophytes. Phytoplankton standing crops varied extensively by months and stations, ranging from $3.0{\times}10^4\;cells/l\;to\;1.0{\times}10^6\;cells/l.$. The dominant species varied from the vertical distribution as well as seasonal changes. In April and July 1999, Skeletonema costatum and Ceratium fusus were predominant in both the surface and the bottom water columns. Leptocylindrus danicus was the dominant species in April and June 2000, and Thalassiosira spp. were also predominant in bottom waters in June 2000. Pseudonitzschia pungens and Chaetoceros spp. were the dominant species at both surface and near bottom waters in August and October 2000, respectively. Zooplankton abundance was comparatively high in April and July in 1999, and April, June, and October in 2000, but extremely low in November 1999. The density of dominant zooplankton was higher in 2000 than in 1999. Copepods were the most predominant group except for July 1999 when the bivalve larvae showed extremely high abundance. Acartia omorii and Oithona similis were the dominant or subdominant copepod species mainly in April 2000, and June/July, while O. davisae and O. plumifera had peaks in August and October 2000. Corycaeus affinis and Paracalanus sp. also showed higher peaks in April and June (or July), even though they occurred in all sampling time. Centropages abdominalis occurred abundantly only in April 1999. Oikopleura dioica, a gelatinous zooplankton, was another important zooplankton, showing high density in all samples except in July 1999.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.41 no.2
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• pp.113-118
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• 2008

Diel rhythm of oxygen consumption (OC) of the starry flounder Platichthys stellatus was measured at different water temperatures in a closed recirculating seawater system with a respiratory chamber. The fish consumed 70.5, 79.7, and 90.6 mg $O_2/kg/hr$ at 15, 20, and $25^{\circ}C$, respectively, showing a linear increase in OC with water temperature. The OC of fish showed a clear diel rhythm, with lower values during the day and higher values at night, in accordance with the light (09:00-21:00) and dark (21:00-09:00) phases of the diel cycle (12L:12D) in water at 15 and $20^{\circ}C$. However, the OC of the fish showed an unclear diel rhythm with the light and dark phases of the diel cycle at $25^{\circ}C$. The respective OC at 15, 20 and $25^{\circ}C$ was 63.8, 72.4, and 88.4 mg $O_2/kg/hr$ during the light phases and 77.2, 87.1, and 92.8 mg $O_2/kg/hr$ during the dark phase. The starry flounder is thought to be a nocturnal fish with a higher OC at night, while it rests during the day. Its OC was the most stable in the light, when it did not feed. Consequently, the night-time OC is the active OC and the day-time OC is the resting OC in the starry flounder.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.40 no.5
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• pp.315-322
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• 2007

Kjellmaniella crassifalia Miyabe is one of the valuable seaweed crops cultured in the Korean coastal waters of the East Sea. Unfortunately recent environmental changes have adversely influenced its growth, prompting the need to develop techniques for species restoration. To obtatin biological information, the growth of the species was monitored for one year. The maximum blade length, $110{\pm}45cm$, was attained in July, and zoospores were released in November. The optimum culture conditions allowing juvenile sporophytes to grow to young blades consisted of $20{\mu}mol/m^2s\;at\;10^{\circ}C$ under which the blade length grew to $1,732.5{\pm}143.3{\mu}m$ in 42 days. Sporangial sori started to form in September, reaching 85% maturity in November and 89% maturity in December. Examining the growth of the species according to depth, the individuals growing at 5 meters grew the most, reaching a blade length of $75.9{\pm}18.9cm$ in August.

• Journal of the Korean Society for Marine Environment & Energy
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• v.11 no.2
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• pp.105-112
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• 2008

The surface and bottom water were sampling in ten stations of the coastal area of Chagwi-Do, Jeju Island, which was repeated 6 times in several different months(September, November, 2004 and March, May, August, and November 2005) in order to examine the physico-chemical characteristics of water. The temperature varied by approximately $16^{\circ}C$, ranging somewhere between 1$12.2^{\circ}C$ and $28.9^{\circ}C$. Specifically, the temperature of bottom water was $13^{\circ}C$, implying the emergence of low temperature water. The salinity ranged from 30.2 to 34.9%o, and the lowest salinity in August may be attributable to the effect of land-based water. N/P ratio, the growth factor of phytoplankton, ranged from 5 to 76, which varied depending on the season and station. The ratio, however, was over 22 on the average, suggesting that phosphate phosphorus is an factor that restricts the growth of phytoplankton. TOC in the concentration of organic carbon ranged between $92.5{\mu}M$ and $438.3{\mu}M$, and the mean was $217{\mu}M$. DOC ranged from $82.5{\mu}M$ to $299.2{\mu}M$, and the mean was $130{\mu}M$. The ratio of DOC/POC was 60% with abundant dissolved organic carbon.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.32 no.4
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• pp.331-339
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• 1996

It is most important to understand the behaviour of fish in case of the betterment of the current fishing gear and methods or the development of the conditioning by acoustic sound in marine ranching. This investigation has been attempted to provide for the prediction of the response action of fish to acoustic sound. The experimental fish was conditioned with sound and bait. As the acoustic sound for stimulus, the pure tone of sine waveform at the frequency of 200Hz was used. This pure tone was determined from previous investigation about hearing ability of walleye pollock Theragra chalcogramma. The fork length of walleye pollock used in this experiment was 385~450mm. The conditioning proceeding was recorded in the video tape recorder. Frequency of appearance in the feeding area was analyzed with computer and video tape recorder. The position of fish was tracked using the mouse cursor and picture mixed on the superimpose board. The response of conditioned fish to sound stimulus was appeared in the 8th day firstly. The conditioned fish remembered the stimulus sound for 4 days. Average frequency of appearance in the feeding area during the 30 seconds sound projection or 1 minute after the sound stimulus was 51%, and was higher than before it.

• Journal of Aquaculture
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• v.20 no.4
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• pp.212-218
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• 2007

Reproductive biology (sexual maturity and reproductive cycle) of starry flounder Platichthys stellatus were examined by histological methods. From March 2004 to February 2005, 144 females and males were sampled. Gonadosomatic index (GSI) of female and male were peaked in May and February, respectively. Monthly changes of hepatosomotic index (HSI) showed a negative correlationwith those of the GSI. Changes of condition factor (CF) in female were correlated with gonad maturation, while that of male were no difference all the year round. Based on monthly GSI and gonadal development the reproductive cycle of starry flounder could be divided into four stages: growing stage (September to November), maturation stage (September to February), ripe and spent stage (March to May), and recovery and resting stage (June to August). Biological minimum size of female was 1,074 g. The relationship between fecundity (F) and body weight (BW) of the fish was expressed as $F\;=\;455.86BW^{1.2006}$.

• Journal of Practical Agriculture & Fisheries Research
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• v.19 no.1
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• pp.15-23
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• 2017

Effects of artificial releases of sea cucumber around the marine ranching area in Jeollanam-do were showed very efficient by the released good seeds(total weight, 3.2g) in 'Wolhang', compared with those in 'Hwatae'. The survival rates were the higher in 'Wolhang' by 66.0% than in 'Hwatae' by 27.0%. The results indicates that the releasing effect of sea cucumber depended on the releas size. To analyze the productivity we investigated the growth and survival rates of sea cucumber according to the releasing area. Our result showed that the growth rate and survival rate was higher in 'Hwatae' than other areas. In 'Hwatae', the growth rate and survival rate were 6.2g and 32.1% respective. The results indicates that if the food supply is continued, although proceeding contamination the productivity of sea cucumber increased. Therefore, in order to enhancement and conservation of resource, bottom of fish cage should consider to the utilization.