• Journal of the Korean association of regional geographers
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• v.12 no.3
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• pp.339-351
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• 2006

The purpose of this study is to investigate and analyze the relationships between tidal cycles, surface landforms, and sediments of tidal flats and their resident life. The study areas are Uengdo Ri in the Garolim Bay with wide the mud flat, Doou Ri in the Youngwang tidal flat which is developed sand flat and salt field, and Gomso Bay which is developed aquaculture industry. For resident around tidal flats, sea working takes precedence over farming, and main earnings gets from tidal flats. Resident life around the tidal flats is deeply related to tidal cycles, and low water level of spring tide becomes, they are most active and get more earnings than usual day, so it seems to be periodic markets. It is usually developed shellfish aquafarms in the mud flat, the stow net fishery in the sand flat, and salt fields in the mixed flat near the coast. Also a tidal flat has specialization of economic activity, and is divided into salt field and fish-farming in the supratidal zone, shellfish aquafarm in the intertidal zone, and oyster and porphyra culture in the subtidal zone.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.10 no.4
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• pp.181-195
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• 2005

To study the effects of aquaculture activity of marine cage fish farms on marine environment, field researches including hydrography, sediment, benthos and trap experiment at the marine cage fish farms(Site A) around estuaries of Tongyeong city were carried out during June $26\~27$, 2003. A simulation using numerical model-DEPOMOD was conducted to predict the solid deposition from fish cage and to assess the probable solid deposition, and the efficiency of environmental management of marine cage fish farms was studied. The marine cage fish farms cultured mainly common sea bass (Lateolabrax japonicus), red seabream (Pagrus major), striped breakperch (Oplegnathus fasciatus) and black rockfish(Sebastes schlegeli), and total amount of cultured fish of the Site A were 23.1MT. The amount of husbandry fish by unit area(and volume) of the fish cage was $43.0kg\;m^{-2}(6.1kg\;m^{-3})$. The daily mean amounts of food fed by unit biomass and cage area were $30.8g\;kg^{-1}day^{-1},\;1.32kg\;m^{-2}day^{-1},$ respectively, at the Site A. The concentration of ORP of the sediment below the center at the Site A was -334.6 mV and the concentrations of AVS, COD, Carbon and Nitrogen were $0.43mg\;g^{-1}dry,\;17.75mg\;g^{-1}dry,\;10.19mg\;g^{-1}dry\;and\;3.49mg\;g^{-1}dry$, respectively. Capitella capitata was dominant benthic species which occupied $57.8\%$ of total species, and the Infaunal Trophical Index(ITI) was marked below 20 within 20 m distance from the edge of the Site A. The result of trap experiment, the solid deposition from the Site A was $34,485g\;m^{-2}yr^{-1}$ at 0 m from the center of the cage and $18,915g\;m^{-2}yr^{-1}$ at 42 m. From a model simulation, it was estimated that using a model simulation, the proportion of unfed food was $40\%$ at the Site A and the annual total amount of solid deposition was 63,401 accounting for $24.4\%$ of the annual total food fed at the Site A. The area solid deposition settled was estimated to be $8,450m^2$, which was about 16 times of the total area of fish cage at the Site A. And concerning ITI and abundance of benthos, the model predicted that sustainable solid flux at the Site A was below $10,000gm^{-2}yr^{-1}$. The percentage of food wasted was main element of solid deposition at the marine cage fish farms, and for minimizing solid deposition it is necessary to increase the efficiency of the food uptake. Based on the result of the model simulation, if the percentage of food wasted decreases to $10\%$ from the current $40\%$, then the solid deposition could decrease to a half. In addition, it was predicted that if farmers use EP pellets as food fed instead of MP and fish trash, solid deposition could decrease by $57\%$. Also this study proposes that the cage facility ratio of the licensed area be decreased to less than $5\%$ to minimize the sediment pollution.

• Journal of the Korean Society of Marine Environment & Safety
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• v.21 no.4
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• pp.339-346
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• 2015

We examined the effect of warm temperature on the survival of larvae of walleye pollock and on their swimming behavior during the four days of post-hatch. Observations were conducted on larvae in Petri dishes and in 85 cm tall, cylindrical tanks that had a warmer upper layer and cooler lower layer separated by a small thermocline. Mortality was carried out in four temperature ranges from $3.1^{\circ}C$ to $9.7^{\circ}C$. The number of days to 50 % mortality ($D_{50}$) was longest (18.7 days) at $3.1^{\circ}C$ and decreased with increasing temperature to 10.3 days at $9.7^{\circ}C$. And $D_{50}$ were similar level to that at temperature 3.1 and $5.1^{\circ}C$(17.9 days). Larval responses to warmer temperatures varied depending on developmental stages. 2dph larvae changed the distribution to the thermocline of the water column. And, 3dph larvae had a ability for escaping from the unfavourable warmer temperature. These results suggest that the warmer water negatively affects the larval survival.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.32 no.3
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• pp.359-367
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• 1999

For investigating the activities of algicidal bacteria, the variations of algicidal bacterial population and chlorophyll-a were checked weekly in Chindong Bay, Korea from May to July, 1998. For identifying their killing characteristics, three strains were selected from the isolated algicidal bacteria. The density of algicidal bacteria kept changing in the range of $6.0\times10^1$ to $6.4\times10^5$ cell $\ell^{-1}$. The density flux of algicidal bacteria coincided with that of chlorophyll-a by a week of lag time. Three algicidal bacteria isolated from field strains, H519S5-4, H605S5-15 and H605S5-22, were investigated in nine microalgal species, Heterosigma akashiwo, Chattonella sp. (Raphidlphyceae), Gymnodinium catenatum, Gyrodinium impudicum, Cochlodinium polyklikoides (Dinophyceae), Chaetoceros sp., Coscinodiscus granii, Ditylum brightwellii, Thalassiosira rotula (Bacillariophyceae). Strain H605S5-22 showed a wide algicidal activities over nine microlgae, strain H605S5-15 over H. akashiwo, G. catenatum, T. rotula, Chattonella sp. and strain H519S5-4 over H. akashiwo, Chattonella sp., Chaetoceros sp., G. catenatum. The activities of the three strains were detected by the secretion of algicidal substances. Therefore, it is suggested that the activities of algicidal bacteria have a significant influence over the population dynamics of phytoplankton and get involved with the sharp decrease in red tides in the coastal area.

• Journal of Aquaculture
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• v.13 no.4
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• pp.295-301
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• 2000

Mature foliose thalli of P. suborbiculata f. Iatifalia were collected at Chindo, Chonnam Prefecture on 24 February 1996. Growth and reproduction were observed at selected temperatures (5~30tt photon flux densities (10-80 ${\mu}$mol m$^{-2}$s$^{-1}$) and photoperiods (14L:I00, 10L:140). The thalli grew fastest at 15 t under both photoperiods and produced archeospores at 10-$25^{\circ}C$ under both photoperiods, but zygotospores at 10-15$^{\circ}C$ under 10L:140 and at only 15$^{\circ}C$: under 14L:I00. Size and shape of the thalli at 1$0^{\circ}C$: under short photoperiod were similar to the field materials. The optimum temperature and photoperiod for growth of the conchocelis colony were 20-$25^{\circ}C$: under both photoperiods. The foliose thalli and the conchocelis filaments could not survive at 30 t. Conchosporangial branches were produced at 15-$25^{\circ}C$ under 14L:100 and 10L:140.

• Journal of Life Science
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• v.18 no.6
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• pp.832-838
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• 2008

Mackerel water-soluble protein fraction produced by washing the mackerel meat were concentrated by isoelectric point shifting precipitation process, and the concentrates were utilized as the alternative feed of fish meal. In the 1st aquaculture diet experiment for Israel common carp, the feed conversion ratio decreased in proportion to the rise in the percentage of the recovered protein containing a residual lipid, which was added to the fish meal. It was supposed that the low feed efficiency was because of lipid oxidation in the recovered protein fraction. In addition, 2nd aquaculture diet experiment for Israel common carp was conducted after removing the oxidized lipid in the recovered protein fish meal. When a portion of the fish meal was substituted by the recovered protein devoid of the residual lipid, the feed conversion ratio increased in proportion to the amount of the substitute being added to the fish meal. Therefore, the recovered protein fraction of the mackerel washing wastewater from mackerel processing factory could be used as the alternative feed of fish meal.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.48 no.4
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• pp.322-336
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• 2012

To study the catching efficiency of biodegradable trammel net for swimming crab (Portunus trituberculatus), three types (biodegradable, monofilament and multifilament) of trammel nets were used in the field test, and the tests were carried out 16 times with two different mesh sizes (105mm and 160mm) in the Yeonpyeong fishing ground of Korea, 2009~2011. The catching efficiency of three type nets was analyzed by catch in number, catch in weight and average weight per individual of small and large size swimming crab by net types and mesh sizes. Statistical T-test was also carried out to verify the efficiency between the three types of nets. The results are as follows. The catch in number of swimming crab was 24,667 and formed about 81.0% of total catch. Of all swimming crab catch, small swimming crabs with less than 64mm in carapace length which is a prohibited landing size by law formed 48.1%, larger swimming crabs with more than 64mm in carapace length which is a landing size formed 51.9%. In 105mm mesh size trammel net test, the catch share in number of small size swimming crab by biodegradable trammel net was 47.5% in comparison with multifilament trammel net and 74.2% in comparison with monofilament trammel net, so biodegradable trammel net has more protective effects on small size swimming crab than other types of trammel nets. The protective effects for small size swimming crab by biodegradable trammel net was 25.8~52.5% in comparison with other types of trammel nets. The catch share in weight of large size swimming crab by biodegradable trammel net was 98.3% in comparison with multifilament trammel net and 92.3% in comparison with monofilament trammel net, so biodegradable trammel net has a similar catch efficiency to multifilament trammel net. The results of 160mm mesh size trammel net test have shown similar results of 105mm mesh size trammel net test. This study shows that biodegradable trammel net is a more useful fishing gear than multifilament and monofilament trammel net because biodegradable trammel net has lower catch rate than other types of nets in small size swimming crab and similar catch rate than multifilament trammel net which is a well used net by fishermen.

• Journal of Life Science
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• v.30 no.1
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• pp.26-31
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• 2020

Heterosigma akashiwo is a globally distributed raphidophyte that forms blooms and causes significant losses to the aquaculture industry in many coastal countries. The development of a fast and sensitive detection method is therefore required to facilitate the appropriate warning of harmful algal blooms. In this study, a nuclease protection integrated with sandwich hybridization (NPA-SH) assay was developed to both qualitatively and quantitatively detect H. akashiwo. The NPA, capture and signal probes were designed by nucleotide sequencing of H. akashiwo. The applicability of NPA-SH was evaluated using cultured H. akashiwo cells and field samples collected at Goseong Bay, Korea. The results show that this method has good applicability and effectiveness in analyzing cultured cells and field samples. A linear regression equation for the quantitative analysis of H. akashiwo was obtained, and the lower detection limit of the assay was 1×10⁴ cells/ml. There was no statistically significant difference in the results of H. akashiwo quantitation using NPA-SH compared to those obtained using a microscope. These results indicate that NPA-SH can be a good alternative to the traditional microscopic method used to monitor H. akashiwo.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.34 no.2
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• pp.131-136
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• 2001

Relative growth and composition of larval development stages in brood pouch of the melania snail, Semisulcospira libertina libertina were investigated based on monthly field samples for a year. Total number of specimens examined was 1,200. Size values (mean$\pm$S. D.) of shell height (SH), shell diameter (SD), total weight (TW), meat weight (MW) and shell weight (SW) were $15.96\pm3.41\;mm$, $7.82\pm1.38\;mm$, $0.55\pm0.31\;g$, $0.24\pm0.15\;g$ and $0.39\pm0.23\;g$, respectively, Water temperature (WT) of the sampling site varied from $1.3^{\circ}C\;to\;22.5^{\circ}C$. Relative growth equations among SH, SD, TW, MW and SW of S. libertina libertina specimens pooled were as follows: SD=0,3583SH+2.1648 $(R^2=0.8391)$, $TW=0.0005SH^{2.4853}\;(R^2=0.8391)$,$MW:\;0.0005SH^{2.849}\;(R^2= 0.8391)$ and $SW=0.0004SH^{2.3798}\;(R^2=0.7057)$. Female S. libertina libertina had larvae in its brood pouch throughout the year, Average number of larvae in the brood pouch varied from $91\pm33(July)$ to $396\pm174\;(November)$, decreasing in spring and increasing in autumn. In the monthly composition of larval stage in the brood pouch, trochophore, pre-veliger, veliger and juvenile showed maximum as $66.7\%$ in May, $70.7\%$ in November, $60.9\%$ in February and $13.9\%$ in January, respectively. Percent composition of the juveniles decreased in spring and autumn. In conclusion, S. libertina libertina is likely to have two main parturition periods, March to May and September and October.

• Journal of Environmental Impact Assessment
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• v.20 no.6
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• pp.845-856
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• 2011

In order to establish fundamental data for stream restoration and environmental flow, we investigated inhabitation and species diversity of fish to substrate size in the typical streams of Geum River Basin. Field monitoring including fish sampling was conducted from October 2007 to October 2009. Substrate size was determined according to six different : silt (Si), sand (Sa), fine gravel (Fg), coarse gravel (Cg), cobbles (Co) and boulders (Bo). A total number of fish caught in the 18 sites was 7,649 representing 10 families 50 species, and Si, Sa, Fg, Cg, Co and Bo stations occupied 30, 29, 38, 30, 27 and 17 species, respectively. The most frequently found species in number was pale chum (Zacco platypus, 29.7%, n=2,275) followed by Z. koreanus (22.5%, n=1,720) in total stations. Biological diversity with increase of substrate size from the dominance of part species showed higher values as dominance index, lower and diversity, richness and evenness index. Index of biological integrity (IBI) and qualitative habitat evaluation index (QHEI) scores decreased with increase of substrate size. Therefore, it is necessary to make an effort on stream rehabilitation with evaluation of physical habitat condition by indicator species in order to maintain biodiversity and perform ecological restoration.