• Korean Journal of Fisheries and Aquatic Sciences
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• v.31 no.5
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• pp.673-676
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• 1998

Preparative conditions of high-gel strength agar from Gelidium amansii have been studied, The effect of NaOH pretreatment on the quality and yields of agar extracted from Gelidium amansli was examined. The Bel strength of agar extracted from C. amansii pretreated with NaOH was higher than that of agar extracted from G. amansii non-pretreated with NaOH. The gel strength of agar extracted from G. amansii was influenced by concentration, temperature and time of pretreatment with NaOH. It was found that the proper concentration, temperature and time of NaOH pretreatment to produce high-gel strength agar was $6\%$ NaOH, $80^{\circ}C$ and 2$\~$3 hrs. The principal sugars of agar extracted from G. amansli were galactose and 3,6-anhydrogalactose.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.31 no.5
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• pp.707-712
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• 1998

Seasonal variation in the proximate composition, cholesterol (CHOL) and $\alpha$-tocopherol ($\alpha$-Toc) content of 12 spices of fish muscle, which caught off Tongyeong coast of the Southern Sea (Nam-Hae) from Mar. 1995 to Feb. 1996, was studied. Lipid and moisture content showed remarkable seasonal variation and there were a negative correlation between the both (r= -0,85, p<0.001), while protein and ash content unchanged almost through the sampling period. The lipid content of anchovy, hickoryshad, black sea bream, finespotted flounder sea eel, bastard, and file fish was high in Dec. Oct. Nov. Jan. Jan. Nov, respectively, and low in the season corresponding to their spawning period. However, in case of striped mullet, yellow tail, mackerel, rock fish and red sea bream, there was no correlation between their lipid content and spawning period, and thus these fishes fore considered to be affected more by water temperature and the content of their diet. CHOL content increased In :he season containing a high level of lipid, whereas $\alpha$-Toc content unchanged almost through the sampling period.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.27 no.5
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• pp.633-642
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• 1994

Distribution of ichthyoplankton in the adjacent waters to Kori were surveyed during the period from April, 1991 to January, 1992. The dominant fish eggs included the eggs of Engraulis japonica, Maurolicus muelleri, Callionymus spp. and others. The eggs of Engrualis japonica and Maurolicus muelleri were $79.52\%$ and $1.86\%$ of the total eggs abundance, respectively. A total of 15 taxa of fish larvae were found. The dominant species was Engraulis japonica accounting for $52.39\%$ of the total larvae and followed by Callionymidae fish($29.36\%$). Other major species were Stephanolepis cirrhifer($6.30\%$), Sebastes schlegeli($3.16\%$), Ammodytes personatus($1.33\%$) and Girella punctata($1.70\%$). These 6 taxa constituted $94.30\%$ of the total larvae collected. In this area, distributions of warm water had a great influence on larvae and juvenile distribution which usually is along the coast and the other places where there layer water movements since, upwelling in the open sea affects ichthyoplankton distribution.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.27 no.5
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• pp.549-559
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• 1994

Razor clam, Solen (Solen) strictus, was collected between May 1989 and July 1990 on a macrotidal flat, Inchon, Korea. The population sampled at just above mean sea level had a mean density of 126 individuals/$m^2$. Age was determined for 872 specimens by counting annuli, a series of closely-spaced concentric growth lines. According to the fatness index spawning seemed to have occurred once per year in June, and the first recruits for the 1989 year cohort population were found in July. Solen (Solen) strictus on the Chokchon tidal flat reached a shell length of 6.2 cm in four years. Mean growth in shell length can be described by the von Bertalanffy function, which yielded estimates of growth parameters equivalent to $L_{\infty}=81.865\;mm$ shell length and K=0.320 per year: $$L_{t}=81.865(1-e^{-0.320(t+0.487)})$$$$W_{t}=7.173(1-e^{-0.320(t+0.487)})^3$$

• Korean Journal of Fisheries and Aquatic Sciences
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• v.27 no.5
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• pp.560-571
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• 1994

A single station representative of the razor clam, Solen (Solen) strictus, on a macrotidal flat, Inchon, Korea was sampled at bimonthly intervals between May 1989 and July 1990 by using a can corer. Estimates of growth rate and annual production of this razor clam have been made using the techniques of cohort growth analysis. Growth rate and production were highest during the first year after spawning and recruitment. The annual production was $2.83g\;DWt/m^2/yr$, mean annual biomass $256.3\;g/w^20$, and a turnover time of 5.00 yea, giving an annual turnover rate (P/B) of $0.20\;yr^{-1}$. The total annual production in wet weight ($33.22g\;WWt/m^2/yr$) appeared to consist of water in live flesh($72.6\%$) and shell($18.9\%$), whereas the dry weight of the soft parts was $8.52\%$, the ash-free dry weight $5.4\%$, and the ash content $3.1\%$ of the total wet weight.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.27 no.1
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• pp.59-68
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• 1994

The effects of silt and clay, water temperature and salinity on the metabolic activities: rates of respiration, filtration and nitrogen excretion in the clam, Mactra veneriformis, were investigated in ranges of $0{\sim}250ppm,\;15{\sim}25^{\circ}C\;and\;10{\sim}30\%0$ respectively. The weight specific respiration rate decreased with shell length and significantly declined at lower temperatures and lower salinity levels. Average respiration rates, filtration rates and ammonia excretion rates of the clam groups declined as water temperature was lowered. The respiration rate(R) and the filtration rate(F) decreased as the concentration of silt and clay(C) increased, the relationships between the two parameters were expressed as a regression line, R=a+b LogC and LogF=a+b LogC, respectively. On the rearing experiment treated with 50ppm of silt and clay, the relationship between the accumulative mortality(M) and the elapsed day(T) was $M=0.0186T^{2.7965}$, and the median lethal time was calculated at 16.8 days. From the rearing experiment, both rate of respiration and ammonia nitrogen excretion of experimental groups and control groups decreased with elapsed days, the rates of experimental groups, especially declined more compared with those of the control groups.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.32 no.2
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• pp.198-203
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• 1999

Gonadal development and reproductive cycle off Gomphina melanaegis collected in the coastal waters of Chumunjin, Korea were investigated monthly from April 1996 to April 1997. G. melanaegis was dioecious, The gonads were located between the digestive diverticula and muscle tissues of the foot, The ovary was composed of a number of ovarian sacs, and the testis was composed of several testicular tubules. The flesh weight rate was reached the maximum in August ($23.0\%$), and then decreased to $19.8\%$ in September. In March, the value was reached the minimum ($17.8\%$) and then increased, The size of mature oocyte was ranged $50\~60\mu$m in diameter and had a germinal vesicle with a nucleolus. Mature oocyte contained a large number of yolk granules and lipid granules in its cytoplasm. The spermatozoon was consisted of a conical nucleus with acrosome, a middle piece containing four mitochondria and proximal and distal centrioles, and a flagellum, Sex ratio (male/female) and minimum size for sexual maturation of G. melanaegis were 0.79 and about 25 mm in shell length, respectively. The reproductive cycle could be classified into five succesive stages: multiplicative (December to March), growing (April and May), mature(June), sprawning (July and August), and degenerative and resting (September to November) stages.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.30 no.3
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• pp.423-427
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• 1997

The effect of different treatments on the quality and yield of purified agar produced from Gelidium amansii has been studied, and the extraction condition ol agar produced from G. amansii has been examined. The contents of ash, sulfate in agar produced from g. amansii collected from different places were $2.63\~2.92\%\;and\;1.38\~1.78\%$, respectively. Yields and gel strength of agar produced from G. amansii collected from different places were $31.6\~46.8\%\;and\;496\~887g/cm^2$, respectively. It was effective to extract agar at $120^{\circ}C\;for\;2\~3hrs$. Agar was purified by D.W. washing, EDTA washing, chitosan treatment, CPC treatment, PEG treatment, ethanol precipitation, acetone precipitation and propanol precipitation. The mineral contents of agar produced from Gelidium amansii were Na (2934ppm), Ca (2472ppm), Mg (2259ppm), K (2527ppm), P1(81.1ppm), Fe (66.4ppm), Al (71.7ppm), Zn (29.7ppm) and Pb (ND: not detected), respectively.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.30 no.3
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• pp.428-431
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• 1997

Chemical components of red algae (Gelidium amansii, Gracilaria verrucosa, Gigartina tenella, Carpopeltis cornea, Plocamium ovicornis, Callophyllis adnata, Lomentaria hakodatensis, Gymnogongrus flabelliformis, Chondrus pinnulatus, Adinotrichia fragilis, Gloipeltis tenax and Campylaephora hypnaeoides) were examined. The contents of carbohydrate, ash, crude protein and fat in dried red algae are $40.38\~69.88\%,\;8.57\~30.23\%,\;18.11\~33.90\%\;and\;0.11\~0.90\%$ on dry base, respectively. Yields of water-soluble compound in dried red algae and contents of sulfate in water-soluble compound extracted red algae were $4.32\~55.78\%\;and\;1.65\~19.48\%$, respectively. The principal sugars of water-soluble compound extracted from red algae were galactose, 3, 6-anhydrogalactose, glucose and xylose.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.30 no.3
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• pp.432-441
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• 1997

Stomach contents of fat greenling, Hexagrammos otakii were analyzed to understand feeding ecology of the fish in the coastal waters, Shinsudo, Sarhon. Specimens were collected by angling and by gill net from February 1984 to September 1985. The fish consisted of 4 age groups from 0 to 3. The food items of the fish changed slightly by seasons and with growth of the fish. Main preys were copepods, gammarids and caprellids for the fish of age group 0, gammarids and caprellids for age group 1, and brachyurans and carideans for age group 2 and 3. The prey composition of the fish were more varied by seasons than by ages. Food items was not different between male and female of the fish. The fish positively selected for gammarids, polychaetes and brachyurans, but negatively selected for gastropods. The degree of selectivities for the other preys were changed with growth. As the fish grows it consumed larger preys in case of small preys such as gammarids and caprellids, however, it did not consumed larger preys beyond an optimal size in case of large preys such as sphaeromids, brachyurans and polychaetes.