• Korean Journal of Food Science and Technology
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• v.14 no.1
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• pp.11-15
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• 1982

The growth rate and heat resistance of two types of Bacillus cereus isolated from cooked rice were observed. The FB-1 strain showed positive to haemolysis and negative to starch hydrolysis, but FB-2 strain positive to both reaction. The cell number of B. cereus FB-1 reached to more than $10^7\;cells/ml$ within 6 to 12 hours at $25{\sim}35^{\circ}C$ when cultured on the medium of cooked rice homogenate (cooked rice 30g-phosphate buffer solution 80 ml), but the numbers at its maximum growth were only $10^4{\sim}10^6\;cells/ml$ at $45{\sim}55^{\circ}C$. The specific growth rate of FB-1 strain were $0.82hr^{-1}\;at\;20^{\circ}C$, $1.76hr^{-1}\;at\;30^{\circ}C$, $2.21hr^{-1}\;at\;35^{\circ}C$ and $1.84hr^{-1}\;at\;40^{\circ}C$, respectively. D-values of FB-1 and FB-2 spores at $70{\sim}100^{\circ}C$ were in the range from 18 to 3.1 min and 23.5 to 3.7 min, respectively.

• Journal of Aquaculture
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• v.11 no.4
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• pp.449-455
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• 1998

The small size food organism(under the size 150${\mu}m$) is needed as food for early stage of marine fish larvae of small mouse (e.g the group of grouper). This study was investigated to develop a method for copepod Apocyclops sp. culture in combination with the rotifer B. rachionus for stable culture of copepod species and harvest of various size food organisms. The culture conditions as temperature, salinity, culture volume, photo period, culture preiod and observation interval were 25${\circ}C$, 22ppt, 40ml, all dark except to observation time, 16 days and every two day during the experimental period, respectively. The Tetraselmis suecica was used as the food for the two testing orgtanisms. After every two day counting, theses two organisms were transferred to fresh culture tanks with Tetraselmis suecica of $7{\times}10^5$cells/ml. In the mixed culture of B. rotundiformis and A. sp., growth of rotifer was suppressed by mixed culture with A. sp. whereas the growth of copepod Apocyclops was promoted in the mixed culture with rotifer B. rotundiformis (the maximum density was 22 individuals/ml through the 16 culture days). Moreover, the number of copepod nauplius were promoted about 2 times in the mixed culture compared to the numbers in single species culture. With this combination culture, the havested two food organisms of variable sizes. This size variation of food organisms was useful tools for larval rearing of small mouse marine fish larvae and next step food organism size of post hatched larvae.

• Journal of Aquaculture
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• v.10 no.2
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• pp.133-141
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• 1997

Gonadal maturation and annual reproductive cycle of the cultured scallop, Patinopecten yessoensis from eastern waters near of Kangwon-do province, Korea were studied on the basis of monthly variation of gonadosomatic indices (GSI) and histological observations of gonadal tissue. During the experimental period, water temperature at the depth of 20m and sunshine duration per day were ranged from $5.3^{\circ}C\;to\;18.0^{\circ}C$ and 9.4 to 14.6 hours, respectively. GSI values of femal were in a wide range from $2.8\pm0.37(August)\;to\;22.66\pm4.38(April)$. GSI values began to increase in March and reached the maxium in April, then decreased repidly. GSI values of male were in a range from $2.04\pm0.80(August)\;to\;20.46\pm1.49(April)$ and were same tendency with female's. Digestive diverticula indices (DDI) of both sex reached the maximum values in December, then deceased gradually until September. Contrary to GSI, adductor muscle indices (AMI) of both sex were the minium values in April, but began to increase rapidly until July and reached $47.71\pm3.17(female)\;and\;48.70\pm3.55(male)$. In the scallp collected hermaphroditic gonads were found. Monthly changes of oocyte diameter were in a range from 11.3 um(October) to 73.3um (April) and nuclear diameters were in a range from 8.3um (September) to 35.3um (April), similar tendency with each other. The changes in number of ovarian tubules were reciprocal tendency with those of oocyte diameter and monthly number of ovarian tubules per $\textrm{mm}^2$ in the tissue perpatation was in a range from 51 (April) to 175 (August). As the results, the annual reproductive cycle of the cultured scallolp from eastern waters of Korea could be classified into five successive stages : multiplicative (October), growing (November to February), mature (March and April), spawning (April to June) and recovery (July to September) in female ; multiplicative (October and November), growing (December and January), mature (February to April), spawning (April to June) and recovery (July to September) in male.

• Journal of Aquaculture
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• v.20 no.1
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• pp.51-55
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• 2007

This study was conducted to evaluate the muscle quality of the olive flounder fed on extruded pellet (EP) diets compared with a raw fish moist pellet (MP) diet for olive flounder, Paralichthys olivaceus in a commercial scale for a year. The sensory and physical qualities and palatable compounds were compared for evaluation of muscle quality in fish. Four diets were formulated for this experiment: two experimental EP diets (EP 1 and 2), one commercial EP diet (CEP) and MP diet. Crude lipid of fish fed EP1 and EP2 was significantly higher (P<0.05) than that of fish fed CEP, but not significantly different from that of fish fed MP (P>0.05). In the palatable compounds, the free amino acids composition were much alike in that of all the diets. Proline, glycine and alanine from fish fed diet EPs were the most abundant compound among amino acid compositions. There was little difference in the free amino acid compositions of all flounder from localities and the growing conditions between wild and cultured fishes. Taurine of fish fed EP1 was dominantly high over that of fish fed EP2, CEP and MP. In all nucleotides and their related compounds, ATP and IMP from fish fed EP diets were higher (P<0.05) than those of fish fed MP. In the sensory score, overall-acceptability of fish fed EP2 were significantly higher (P<0.05) than that of fish fed EP1, CEP and MP. Hardness of physical properties from fish fed EP2 was significantly higher (P<0.05) than those of fish fed CEP (P<0.01). These results strongly suggest that diets EP could be developed to replace MP diet for the grow-out stage of olive flounder without adverse effect on growth performance.

• Journal of the Korean Chemical Society
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• v.8 no.4
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• pp.192-199
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• 1964

Seasonal variations of the contents of some chemical constituents of the estuary water at two definite stations of the laver bed in Nack Dong River have been determined over one tidal cycle in spring tide from Nov. 1962 to Oct. 1963. The ranges of annual variations of the contents at station 1 and station 2 are as follows: water temp. $2.2-30.8^{\circ}C$, $3.3-28.0^{\circ}C$; pH 7.8-8.5, 7.9-8.4; chlorosity 0.025-19.66 g/l, 4.31-19.56 g/l; magnesium 0.00355-1.565 g/l, -1.524 g/l; calcium 0.00557-0.482 g/l, - -0.590 g/l; saturation % of dissolved oxygen 71.8-123.2%, 88.2-113.8%; silicate-Si 8.00-125.5 ${\mu}$g-at./l, 6.70-100.5 ${\mu}$g-at./l; phosphate-P 0.12-1.47 ${\mu}$g-at./l, 0.11-1.09 ${\mu}$g-at./l; ammonia-N 4.88-25.45 ${\mu}$g-at./l, 4.12-17.58 ${\mu}$g-at./l; nitrite-N 0.07-0.75 ${\mu}$g-at./l, 0.08-0.58 ${\mu}$g-at./l; nitrate-N 2.11-6.89 ${\mu}$g-at./l, 1.85-7.43 ${\mu}$g-at./l each. The annual tidal variations of the constituents at station 1 are more remarkable than of station 2. The chlorosity, magnesium and calcium contents are decreased nearing the slack after ebb, and increased abruptly then one hour after the slack. The contents of the other constituents are varied according to the chlorosity variety. The values of pH, chlorosity, magnesium and calcium contents are lower in summer than winter, while the difference of seasonal variations of the % saturation of dissolved oxygen is not remarkable. The phosphate-P and total nitrogen contents have a tendency of increasing within a definite range, while the silicate-Si increase proportionally, to the increasing of mixing percentage of fresh water. The average values of Si/P and N/P are several times greater than of the normal in sea water. The chemical composition considered from the value of Mg/Cl or Ca/Cl of estuarine water varies according to the variety of chlorosity, even at the high chlorosity of 19 g/l.

• Journal of Aquaculture
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• v.6 no.4
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• pp.255-271
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• 1993

For the development of seedling production techniques of the freshwater crab Eriocheir japonicus, the effects of salinity and temperature on the growth of larvae of the crab were studied. Embryos hatched out as zoea larvae were measured 0.421 mm in average carapace length. Five zoea stages needed 16-26 days for metamorphosis from zoea to megalopa at $22^{\circ}C$ and $24.5\%o$. The average carapace length of the 5th zoea was 1.16 mm and that of the megalopa larvae was 1.89 mm. Each zoea stage could be identified based on both the number of plumosed seatae on the exopodite of maxilliped, and the number of spines on the posteroinner margin of tel son and also based on the rudimentary pleopods appearence. Zoea larvae fed rotifers and Artemia nauplii were healthy and metamorphosing rate from zoea to megalopa was $80\~90\%\;at\;22\~26^{\circ}C\;and\;17.5\~31.5\%o$. The relationship between larval period (Y in days) and water temperature $(X\;in\;^{\circ}C)$ is expressed as Log Y = 3.8604-1.91735 LogX. Water temperature and salinity ranges for better survival and metamorphosis of the larvae were $ 22^{\circ}C\~26^{\circ}C\;(optimum\;at\; 26^{\circ}C)\;and\;17.5\%o\~31.5\%o\;(optimum\;at\;24.5\%)$, respectively. The duration of larval stages tend to longer as salinity levels deviated from optimum particulaly at lower end. All zoea larvae did not survive in freshwater.

• Journal of Aquaculture
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• v.6 no.4
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• pp.235-253
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• 1993

The freshwater crab, Eriocheir japonicus inhabits from sub-tropical to temperate zone in Asia. This species belongs to a large size group among freshwater crabs. Common size of this crab is 5-6cm in carapace length and occasionally 7cm in carapace length. This species of crab used to inhabit in estuaries, rivers and inland waters in Korea. However, natural population recently has been rapidly decreased because of pollution and lost their habitats by suburban development. Therefore, development of proper methods of seedling production to increase natural stock became necessity. As parts of achieving this goal, duration from mating to spawning, egg incubation period, and egg development of this species were studied. The influence of temperatures and salinities on the egg incubation and hatching was also investigated. It took 2-8 hours from mating to egg spawning and the spawning lasted 3-9 hours from the first spawning. Egg numbers per female (6cm in carapace length) were 380,000­410,000. Optimum temperature for egg incubation was $17\~23^{\circ}C$ and optimum salinity, $14.0\~31.5\%o$. Incubation period of the eggs at $14^{\circ}C,\;17^{\circ}C,\;20^{\circ}C,\;26^{\circ}C,\;and\;28^{\circ}C$ was 42, 28, 21, 15, and 14 days. respectively. Relation between temperature (X) and incubation days (Y) was LogY = Log 2764.267 - 1.608 LogX. A female can spawn 4-6 times per year by manipulation of environmental conditions. Under the conditions of $18^{\circ}C\;and\;24.5\%o$, it took 6 days up to embryo formation, 18 days up to compound eye formation, 22 days up to abdominal movement, and 25 days up to hatch out as zoea larvae.

• Journal of Aquaculture
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• v.19 no.3
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• pp.210-215
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• 2006

An experiment was conducted to investigate the effects of four water temperatures (10, 15, 20, and $25^{\circ}C$) in combination with three photoperiods (24L:0D, 12L: 12D, and OL:24D) on the oxygen consumption rate of juvenile dark-banded rockfish, Sebastes inermis (mean body weight $20.5{\pm}0.7g$). The oxygen consumption rates of S. inermis were measured in triplicate for 24 hours using a continuous flow-through respirometer. Different combinations of water temperatures and photoperiods resulted in significant differences in the mean oxygen consumption rate of S. inermis (P<0.001). The oxygen consumption increased with increasing water temperatures for all photoperiod treatments (P<0.01). Mean oxygen consumption rates at 10, 15,20 and $25^{\circ}C$ ranged $178.3\sim283.5,\;386.7\sim530.7,\;529.2\sim754.3$ and $590.0\sim785.5mg\;O_2kg^{-1}h^{-1}$, respectively. $Q_{10}$ values ranged $3.17\sim5.51$ between 10 and $15^{\circ}C,\;1.87\sim2.10$ between 15 and $20^{\circ}C$ and $1.08\siml.24$ between 20 and $25^{\circ}C$, respectively. Fish held in continuous darkness (OL:24D) used consistently less okygen than fish exposed to continuous light (P<0.05). The mean oxygen consumption offish in a 12L:12D photoperiod was higher than that offish in 24L:0D and 0L:24D photoperiods under all temperature treatments except $10^{\circ}C$. The oxygen consumption of fish exposed to the 12L:12D photoperiod was significantly higher during the light phase than during the dark phase under all temperature treatments except $10^{\circ}C\;(P<0.05)$. This study provides empirical data for estimating oxygen consumption of S. inermis under given condition. This result has application for culture management and bioenergetic model for growth of this species.

• Journal of Aquaculture
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• v.11 no.4
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• pp.547-556
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• 1998

This study was performed to obtain the basic data on the serum constituents of several marine fish spesies commonly cultured in Korea. Blood samples taken from six species of fish were analyzed for various components of serum, total protein (TP), albumin (ALB), triglyceride (TRIG), cholesterol (CHOL), glucose (GLC), lipase (LIPA), amylase (AMYL), aspartate transaminoferase (AST), sodium (Na), potassium (K), chloride (CI) and phosphorus (PHOS). The fish used were coho salmon (Oncorhynchus kisutch), rock fish (Sebastes schlegeli), sea bass (Lateolabrax japonicus), olive flounder (Paralichthys olivaceus), rock fish (Sebastes schlegeli), sea bass (Lateolabrax japonicus), olive flounder (Paralichthys olivaceus), parrot fish (Oplegnathus fasciatus) and jack mackerel (Trachurus jaonicus) reared at the Chungmu Experimental Fish Culture Station of KORDI when the water tempetature was ca. 16.5$^{\circ}C$. There were significant differences in TRIG, CHOL, LIPA and AMYZ among the species analyzed. TRIG concentratin were ranged 178~180mg/dl in jack mackeerel and rock fish, 126~159 mg/dl in olive flounder and sea bass, and 102~114 mg/dl in coho salmon and parrot fish, respectively. Jack mackerel showed the highest levels in CHOL (255mg/dl) and GLC(138mg/dl) among species. LIPA levels were recorded 256 U/dl in coho salmon, 41~42 U/dl in parrot fish and rock fisk, and 5~11 U/dl jack mackerel and sea bass, respectively. AMYL activity of coho salmon was measured as 2, 665 U/dl, and that of jack mackerel was 1,210 U/dl while sea bass showed 60 U/dl and parrot fish, olive flounder and rock fish had at most 5 U/dl. On the other hand, there was no significant difference in the concentration of Na and CI. Na and K were proved that they were negatively correlated in all the species. Generally, among blood components, PHOS and CHOL levels were different depending on environmental temperature of each fish species, especially in olive flounder. Rock fish and parrot fish showed high blood concentration of those components during low temperature period while olive flounder and jack mackerel reached high level during their optimal environmental temperature period. The electrolyte concentration and LIPA activity were high during low water temperature period, in general, but TP and ALB concentrations were high during optimal temperature period. The concentrations of TRIG, CHOL and GLC, those which were used as energy sourses, were different among species by season.

• Journal of Aquaculture
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• v.14 no.3
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• pp.197-203
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• 2001

To replace fish meal (FM) in the diet of Nile tilapia, Oreochromis nloticus, different levels of Iysine cell mass (LCM) were added to diet on protein equivalent base. fish averaging 3.0 g fed one of nine diets containing isonitrogenous and isocaloric basis of 35% crude protein and 15.3kJ available energy/g diet: $LCM_0, 100% FM: LCM_{10}, 90% FM+10% LCM, LCM_{20}, 80% FM+20% LCM; LCM_{30}, 70% FM+30% LCM; LCM_{40}, 60% FM+40% LCM; LCM_{30}l, 70% FM+30% LCM+lysine; LCM_{30}ln, 70% FM +30% LCM + lysine +NaOH; LCM_{40}lan, 60% FM+40% LCM+lysine+arginine; LCM_{40}/lan, 60% FM+40% LCM+lysine+arginine+NaOH.$. After 8 weeks of feeding trial, there were no significant differences in weight gain (WG) and specific growth rate (SGR) among fish fed LCM$_{0}$ (control diet), LCM_{10}, LCM_{30}, LCM_{40}, LCM_{30}l, LCM_{30}ln, LCA_{40}la and LCM_{40}lan diets (P>0.05)$, while fishes fed $LCM_{20} diet were significantly higher than those fed LCM_{0}, LCM_{30}, LCM_{40}, LCM_{40}la and LCM_{40$}lan diets (P<0.05). There were no significant differences in feed efficiency (FE) and protein efficiency ratio (PER) among fish fed control diet, $LCM_{10}, LCM_{20}, LCM_{30}ln, LCM_{ 40}la and LCM_{40}$lan diets (P>0.05), while fishes fed control diet were significantly higher than those fed $LCM_{30}, LCM_{40} and LCM_{40}l diets (P<0.05)$. Positive effects were not shown in WG and SGR with supplementation of amino acids (lysine & arginine) and neutralizatio, while FE and PER from fish fed $LCM_{40}la and LCM_{40}lan diets were significantly higher than those fed LCM_{30}, LCM_{40} and LCM_{30}$l diets (P<0.05). Hence, LCM can replace FM up to 40%, and dietary suppl-ementacon and neutralization of amino acids showed positive effects, when FE and PER were considered in juvenile tilapia diet.