• Korean Journal of Fisheries and Aquatic Sciences
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• v.34 no.5
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• pp.465-472
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• 2001

The effects of water level reduction in rearing tank and fish transference during fish selection process on the stress response (hematological factors, cortisol, glucose, lactic acid and osmolality) of tank-reared olive flounder Paralichthys olivaceus of large (FL), small (FS) and Japanese croaker, Nibea japonica (JC) were examined in running seawater culture system. The water level of rearing unit was lowered from 33 cm to 8 cm in the course of 2 minutes in the water level reduction experiment. The fish were removed from rearing tank (12 ton) to 450 L tank in 30 seconds after capture in the fish transference experiment, In water level reduction, the hematocrit of FL was significantly increased from $14.6\%$ at beginning to $23.5\%$ after 10 hours, However, it decreased to the value of beginning after 46 hours. Plasma cortisol concentration of FL was the highest concentration (13.7 ng/mL) after 22 hours, but it decreased to 4.0 ng/mL at the end of experiment. Cortisol concentration of FS did not show any significant difference during the experiment. The cortisol concentration of JC were significantly higher at 4 hours (282.3 ng/mL) and 22 hours (350.5 ng/mL), Glucose concentration of JC was the highest (138.0 mg/dL) at 22 hours. Lactic acid concentration was not different between experimental groups. In the fish transference experiment, red blood cell of FL was increased from $1.9\times10^6\;cell/{\mu}\;L\;to\;4.2\times10^6\;cell/{\mu}L$ in 24 hours. Blood hemoglobin of JC were significantly elevated in 24 hours. At 1 hour after transference, plasma cortisol concentrations in both fish species were increased to 95.3 ng/mL in FL and 175.5 ng/mL in JC. Glucose concentration of JC was increased to 132.5 mg/dL at 1 hour, 129.5 mg/dL at 3 hours after transference.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.5 no.3
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• pp.88-96
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• 1972

1. The present paper deals with the contents of heavy metals such as mercury, cadmium, lead and copper in 17 species of edible seaweeds collected from Jumunjin, Pohang, Pusan, Chungmu, Yeosu and Wando areas. 2. The concentration of mercury in the air-dried seaweeds ranged from 0.02 to 0.52 ppm, as shown by the following species: 0.36ppm (0.09-0.50) in Enteromorpha spp., 0.25 ppm (0.14-0.31) in Undaria sp., 0.19 ppm (0.02-0.52) in Porphyra spp., and 0.10ppm (0.02-0.24) in Laminaria spp. in that order. If these concentrations are converted to the wet bases, they will be about 1/4 to 1/5 of the present levels. In general, the samples collected from the east coast showed relatively lower levels than those from the south coast. The mercury concentrations found in the Korean seaweeds are lower than the permissible levels reported. 3. The concentration of cadmium in the air-dried seaweeds ranged from 0.02 to 1.48 ppm, and the levels in the different species showed in the following order: 0.97 ppm (0.41-1.18) in Hizikia sp., 0.33 ppm (0.03-0.63) Undaria sp., and 0.32 ppm (0.04-0.67) in Porphyra spp. The concentration of cadmium in the samples on the wet bases become 1/4 to 1/5 of the present level. The laver Porphyra spp. collected from the east coast showed relatively lower levels than those of the cultured species along the south coast. All of the concentrations are still below than the permissible levels. 4. In general, lead concentration is 0.20-1.31 ppm which is lower than the permissible level. The concentration becomes about 0.05-0.3 ppm on the wet base. 5. Copper concentration ranged from 0.90-17.0 ppn on the dry base which is about 0.2-4.0 ppm on the wet base. It is interesting to note that the samples collected from Busan region showed relatively higher levels than those sampled from other regions.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.13 no.4
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• pp.179-183
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• 1980

The efficiency of energy transfer by a population of the farmed pacific oyster, Crassostrea gigas was studied during culture period of 10 months July 1979-April 1980, in Geoje-Hansan Bay near Chungmu City. Energy use by the farmed oyster population was calculated from estimates of half-a-month unit age specific natural mortality rate and data on growth, gonad output, shell organic matter production and respiration. Total mortality during the culture period was estimated approximate $36\%$ from data on survivor individual number per cluster. Growth may be dual consisted of a curved line during the first half culture period (July-November) and a linear line in the later half period (December-April). The first half growth was approximated by the von Bertalanffy growth model; shell height, $SH=6.33\;(1-e^{0.2421(t+0.54)})$, where t is age in half-a-month unit. In the later half growth period shell height was related to t by SH=4.44+0.14t. Dry meat weight (DW) was related to shell height by log $DW=-2.2907+2.589{\cdot}log\;SH,\;(2, and/or log $DW=-5.8153+7.208{\cdot}log\;SH,\;(5. Size specific gonad output (G) as calculated by condition index of before and after the spawning season, was related to shell height by $G=0.0145+(3.95\times10^{-3}{\times}SH^{2.9861})$. Shell organic matter production (SO) was related to shell height by log $SO=-3.1884+2.527{\cdot}1og\;SH$. Size and temperature specific respiration rate (R) as determined in biotron system with controlled temperature, was related to dry meat weight and temperature (T) by log $R=(0.386T-0.5381)+(0.6409-0.0083T){\cdot}log\;DW$. The energy used in metabolism was calculated from size, temperature specific respiration and data on body composition. The calorie contents of oyster meat were estimated by bomb calorimetry based on nitrogen correction. The assimilation efficiency of the oyster estimated directly by a insoluble crude silicate method gave $55.5\%$. From the information presently available by other workers, the assimilation efficiency ranges between $40\%\;and\;70\%$. Twenty seven point four percent of the filtered food material expressed by energy value for oyster population was estimated to have been rejected as pseudofaeces : $17.2\%$ was passed as faeces; $35.04\%$ was respired and lost as heat; $0.38\%$ was bounded up in shell organics; $2.74\%$ was released as gonad output, $2.06\%$ was fell as meat reducing by mortality. The remaining $15.28\%$ was used as meat production. The net efficiency of energy transfer from assimilation to meat production (yield/assimilation) of a farm population of the oyster was estimated to be $28\%$ during culture period July 1979-April 1980. The gross efficiency of energy transfer from ingestion to meat production (yield/food filtered) is probably between $11\%\;and\;20\%$.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.31 no.2
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• pp.186-194
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• 1998

Species composition and biomass of intertidal benthic algae were studied at the coast of Yonggwang Nuclear Power Plant area and its adjacent stations over 4 seasons (October 1995-August 1996), Of 68 species identified, 7 were Cyanophyta, 12 were Chlorophyta, 14 were Phaeophyta and 35 were Rhodophyta. The largest number of algal species (44) was found at Sangnok, the northernmost station of the study area, whereas the smallest number of species (15) was found from Tongho, ca. 13 km north of the power plant site. Number of species showed highest during the spring (44) and minimum was recorded in autumn (28). Biomass per unit area showed maximum in spring ($189.5\;g\;dry\;wt{\cdot}m^{-2}$ in average) and minimum in winter ($107.9\;g\;dry\;wt{\cdot}m^{-2}$ in average). Biomass values exhibited a wide range of variation among the stations, ranging from a low of $22.0\;g\;dry\;wt{\cdot}m^{-2}$ in annual average at Tongho to a high of $295.7g\;dry\;wt{\cdot}m^{-2}$ in average at Sangnok. Dominant species in biomass were Corallina pilulifera, Sargassum thunbergii, Gymnogongrus flabelliformis and Enteromorpha compressa. There have been little variation in the dominant algal species around the power plant site during the past 10 years and also these algae appeared throughout the west coast of Korea with higher frequency.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.34 no.4
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• pp.299-308
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• 2001

We examined the growth variation with water depth, interval between suspended lines and locality of seedling production of sea squirt. Halocpthia roretzi, measuring approximately $10.1\~15.3$ mm in tunic height, was cultured at the farm near Guryongpo, Pohang city from 7 January to 6 December 1998 (333 days). Growth condition depending on culture depth was most favourable at the depth of $10\~12$m, It was concluded that nutritional conditions were better at the depth since there was a greater mount of phytoplankton than at any other depth in the water column. Growth condition depending on distance between suspended lines was most favourable at the interval of 2 m and 2.5 m than at the interval of t m and 1.5 m, There was no significance difference in growth variation with locality of seedling. The seasonal variations in growth of tunic height, meat and total weight were correlated with temperature and chlorophyll a, In the depth of $10\~12m$ the rate of increase in tunic height was generally greatest in the growth period II ($244{\mu}m/day$) and IV ($338{\mu}m/day$), lower in the period I ($108{\mu}m/day$), and slightly increased during the period III ($185{\mu}m/day$). The water column have showed a typical seasonal pattern with temperature ranged between $12.07{\sim}24.14^{\circ}C$ and over $20^{\circ}C$ between July and September.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.34 no.4
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• pp.340-347
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• 2001

Seasonal variation of the elemental and biochemical composition of the suspended particulate matter (SPM) was investigated in terms of quantity and quality of diets for suspension feeders from July 1999 to August 2000 in two coastal bay systems of Gosung and Kangjin Bays in Korea. No clear patterns in the seasonal variations of SPM concentration were found in these two bay systems. The results indicated that the seasonal variation of SPM could not be considered the variation of food available to suspension-feeders. The simultaneous peaks in chlorophyll a and biochemical components in summer indicated that the quantity of the particulate organic matter primarily depended on phytoplankton productivity. However, no correlation between chlorophyll a and biochemical components [particulate protein (PPr), carbohydrate (PCHO) and lipid] were found, indicating that other processes might also contribute to the particulate organic matter in the period when the phytoplankton biomass was low. High C: Chl a and C:N, and carbohydrate peaks during the autumn to spring period suggested that resuspension of surface sediments was a probable process to supply the particulate organic matter. The food material, represented by summing up the total quantity of three biochemical components, was highest in spring with minor peaks during the period from autumn to the next spring, The food index, calculated as the ratio of food material to total SPM, did not generally exceed $6\%$ with short peaks during the year. Therefore, nutritional quality of SPM in the bays are relatively poor than in other more productive coastal waters in the world. Our results confirm that the measurement of a single chemical variable cannot describe fully the nutritive value of the seston available to suspension-feeders as previously proposed, and the biochemical composition of SPM can provide effective information on its origin and nutritive Quality.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.26 no.3
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• pp.221-229
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• 1993

In this study fermentation of fresh ascidian was attempted to widen the utility of ascidian. Fresh deshelled and sliced ascidians were fermented for 90days at $25^{\circ}C$ with different salt contents of 5, 10, 15 and $20\%$ (w/w) and at $5^{\circ}C$ with 5 and $10\%$ salt. Changes of such components during fermentation as free amino acids, nucleotides and the related compounds, volatile basic nitrogen(VBN), trimethyl amine(TMA), amino nitrogen and total creatinine were determined. VBN increased rapidly after 30days of fermentation at $25^{\circ}C$ while slowly in cases of fermentation at $5^{\circ}C$ and with high salt concentration. Amino nitrogen and the total creatinine also increased gradually until 45 days and 30days of fermentation, respectively, hereafter tended to decrease. ATP and ADP seemed to degrade rapidly in fresh ascidian post harvest and AMP, IMP and inosine also degraded down to hypoxanthine during fermentation. After 45days of fermentation, in the free amino acid composition of fermented ascidian were taurine, proline, glutamic acid, histidine, lysine, alanine and valine in order. The amino acids known as sweetner like prolline, lysine, alanine and glycine were in increased in fermented ascidian. The result of sensory evaluation of fermented ascidian pretreated with acid or sulfite solution showed that the peculiar taste and flavor of ascidian remained without browning for 45days fermentation at $5^{\circ}C$.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.7 no.3
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• pp.169-178
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• 1974

Concentrations of mercury, cadmium, lead and copper are determined in the surrounding seawater and in seaweeds, Undarta pinnatifida and Sargassun fulvellum, from Suyeong Bay in Busan in the spring tide and neap tide from January to April 1974. The range and mean of the heavy metal concentrations in the surrounding seawater are as follows : mercury 0.00-0.39 ppb, 0. 16ppb; cadmium 0.00-0.46 ppb, 0.18 ppb, lead 0.00-0.94 ppb, 0.26 ppb : copper 0.00-0.86 ppb, 0.25 ppb respectively, and the concentrations varied slightly according to the tide. The mean values of concentration rate of Hg, Cd, Pb and Cu in air dry base were $0.42\times10^3(0.13\times10^3\~1.0\times10^3)$, $2.1\times10^3(0.8\times10^3\~4.9\times10^3)$, $8.9\times10^3(3.1\times10^3\~19\times10^3)$ and $15\times10^3(6.0\times10^3\~28\times10^3)$ in the Undaria pinnatifida, and $0.25\times10^3($0.06\times10^3\~0.56\times10^3)$, $1.0\times10^3(0.61\times10^3\~1.7\times10^3)$, $5.4\times10^3(3.1\times10^3\~8.5\times10^3)$ and $22.8\times10^3(14.4\times10^3\~52.4\times10^3)$ in the Sargassun fulvellum. The concentration rate of Hg, Cd and Pb of the Undaria pinnatifida was almost twice as much as that of the Sargassun fulvellum but the concentration rate of copper of the former was slightly smaller than of the latter.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.35 no.2
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• pp.136-146
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• 1999

The telemetry system for the oxygen, pH, turbidity and the distribution ecology of fishes was constructed by the authors in order to product and manage effectively in shallow sea culture and setnets fisheries, and then the experiments for the telemetry system carried out at the culturing fishing ground in coast of Sanyang-Myon, Kyoungsangnam-Do and the set net fishing ground located Nungpo bay in Kojedo province respectively from October, 1997 to June 1998.As those results, the techniques suggested in the telemetry system for which find out the relationship between the physical and chemical environment in the sea and the distribution ecology of fishes gave full display its function, and its system could be operated as real time system. This research can also provide base-line data to develope a hybrid system unifying the marine environment information and the fisheries resources information in order to manage effectively coastal fishing ground.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.34 no.6
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• pp.691-696
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• 2001

The first bloom of Cochlodinium polykrikoides was observed in the estuary of Nak-dong river near Pusan in Korea in 1982. Since then, there have been irregular blooms, sometimes spread over the adjoining .to Jinhae Bay even though it was confined to the bay and its vicinites until 1988. It had been outbroken frequently in the adjacent to Tongyeong, Geoje, Namhae and Yeosu coast since 1989. It became widespread along the coast of the South Sea to the East Sea of Korea in 1995. And in October in 1998 and 1999, the bloom had been taken place in Kunsan coast of Yellow Sea. According to the observations in situ, the frequency of occurrence has been increased year by year. The prevailing bloom season was from July to October with peak in September. The duration of the bloom became longer with the year, and sometimes lasted more than one month. The density of the bloom did not exceed 5,000 cells $mL^{-1}$until 1991, but it increased year by year to the highest of 43,000 cells $mL^{-1}$ in 1999. With respect to the assembleges of species in dinoflagellate blooms, C. polykrikoides was one of the important species with diatoms and the other dinoflagellates in 1980s. But since then, C. polykrikoides made an almost monospecific bloom. Based on two decadal observations of C. polykrikoides blooms, it became widespread throughout whole coast of the Korea, persistent for about one or two month long in some year, and monospecisc high density blooms. It was reported that significant fish mortalities were caused by this harmful dinoflagellate blooms especially in the fishfarms accomodating intensive fish cages such as Tongyeong, Namhae-do, Geoje, Yeosu and Geomun-do fishfarming yards. This widespread and persistent harmful algal blooms impede the development of marine aquaculture industries.