• Journal of Aquaculture
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• v.10 no.2
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• pp.123-131
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• 1997

Growth of triploid abalone, Haliotis discus hannai induced by cody (3$^{\circ}C$) shock and its feed efficiency were investigated from larva to adult for 51 months. After 51 months from triploidy induction, the triploid abalones have outgrown to diploid abalones in shell length and total weight. Triploid abalones with inhibition of extrusion of first polar body (3n-1pb) were outgrown to diploid abalones, however, triploid abalones with inhibition of extrusion of second polar body (3n-2pb) were not significantly different from diploid controls in shell length and total weight through the whole rearing period (P<0.05), because of their heterozygosity differences. Daily feeding rates and feed conversion rates decreased with the growth of abalones and both rates had no differnce between two experimental groups. After 51 months from inducing triploid, conditin index of triploid abalone (64.1%) was higher than that of diploid control (59.4%) (P<0.05). Survival rate was 63.0% in triploid group (3n-1pb 62.0%, 3n-2pb 64.0%) and 62.0% in diploid group during the experimental period.

• Journal of Aquaculture
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• v.10 no.2
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• pp.105-112
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• 1997

For improvement of fishermen's income by oyster cultivation in eastern coast of Korea, the spats of oyster (Crassostrea gigas) collected from Hadong in southern coast of Korea were transplanted to Chumunjin and cultured by hanging long line method from August 1994 to July 1995 for examination of their growth and ground environmental conditions. The environmental conditions show the annual range of water temperature as 8.33~$25.62^{\circ}C$, salinity as 32.84~$34.28\textperthousand$, PO4-P as 0.09~0.40$\mu$g-at/1, dissolived inorganic nitrogen (DIN) as 0.32~3.21$\mu$g-at/1. The growth of oyster in hanging culture was as follows : 88.7mm (shell hight) in upper layer (7m), 84.9mm in middle layer (10m) and 78.0mm in lower layer (13m) after one-year cultivation. Thus, the oysters in upper layer had grown relatively faster than those in lower layer. The relationships between shell hight (SH) and shell length (SL) in each culturing depth as follows : SL=0.5403 SH+8.5486 (r=0.9959) in upper layer, SL=0.5813 SH+3.7775 (r=0.9869) in middle layer, and SL=0.5159 SH+6.8736 (r=0.9961) in lower layer. The meat weight of oyster was the highest value as 13.24g in upper layer, and 12.68g in middle layer, and lowest as 10.96g in lower layer. The relationships between total wight (TW) and meat weight (MW) with culturing water layer were as follows : MW=0.1933 TW+0.1051 (r=0.0073) in upper layer, MW=0.1915 TW+0.1894 (r=0.9984) in middle layer, and MW=0.1650 TW+0.0558 (r=0.9983) in lower layer.

• The Korean Journal of Malacology
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• v.28 no.2
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• pp.125-129
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• 2012

The study describes growth and survival on different kinds of sediment improvements of early spats of the hard clam, Meretrix petechialis. Specimens of the mature hard clam were collected in the intertidal zone of Yeonggwang, Korea, July 2011. After transportation, early spats(shell length $196{\pm}14{\mu}m$) collected in mature hard clam were used. Experiment period were July 7 to August 6 in 2011 (30 days). Sediment improvements used iodine(10 ppm), hydrogen peroxide($H_2O_2$, 5 ppm), sodium hypochlorite (NaClO, 100 ppm), chlorine dioxide($ClO_2$, 100 ppm) and potassium permanganate ($KMnO_4$, 5 ppm). After cultured during 30 days, shell length growth of hard clam were observed $1.04{\pm}0.26mm$ in sodium hypochlorite 100 ppm, $1.03{\pm}0.25mm$ in chlorine dioxide 100 ppm and $1.01{\pm}0.28mm$ in iodine 10 ppm. Survival rate were 31.4% in chlorine dioxide 100 ppm, 12.1% in sodium hypochlorite 100 ppm, 11.6% in iodine 10 ppm, 1.5% in hydrogen peroxide 5 ppm and 0% in potassium permanganate 5 ppm.

• The Korean Journal of Malacology
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• v.27 no.1
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• pp.1-7
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• 2011

Age and growth of the short-necked, Ruditapes philippinarum were collected from Goheung coast in Korea. Relative growth equations among SL, SH, SW and TW of Ruditapes philippinarum were ranged from 0.8059 to 0.8859. The ring radius were estimated from a von Bertalanffy method with the values of $SL_{1.58}=12.51{\pm}2.55\;mm$, $SL_{2.58}=20.27{\pm}3.08\;mm$, $SL_{3.58}=26.90{\pm}2.49\;mm$, $SL_{4.58}=31.35{\pm}3.62\;mm$, $SL_{5.58}=35.45{\pm}3.54\;mm$, $SL_{6.58}=38.78{\pm}4.04\;mm$. Back calculated total weight at the formation of annual ring on the shell of Ruditapes philippinarum with the values $TW_{1.58}$=0.35 g, $TW_{2.58}$ = 4.62 g, $TW_{3.58}$ = 5.84 g, $TW_{4.58}$ = 6.71 g, $TW_{5.58}$ = 7.50 g, $TW_{6.58}$ = 8.14 g. Growth curves for shell height and total weight fitted to the von Bertalanffy equation were expressed as: $SL_t= 51.01(1-e^{-0.1738(t+1.07)})$ $TW_t = 11.65(1-e^{-0.1738(t+1.07)})^{2.9519}$.

• The Korean Journal of Malacology
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• v.28 no.2
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• pp.101-108
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• 2012

Bivalves collected by a dredge in Yeongil Bay of Gyeongsangbuk-Do Province, Korea in May, 2010 and August, 2010 were 2 species including Dostinorbis japonicus and Scapharca broughtonii. The total abundance of bivalves were 1,703 inds. and 140.9 kg. Among them, the abundance of D. japonicus were 1,198 inds. and 76.1 kg. And the abundance of S. broughtonii were 505 inds. and 64.8 kg. The shell length by bivalves species were 25.76-67.88 mm (mean, 58.08 mm) in D. japonicus and 46.82-113.74 mm (mean, 76.86 mm) in S. broughtonii consisting mainly of recruitment group. By regional abundance comparison, the bivalves abundance collected in the outside harbor was 1,332 inds. and 105.4 kg, which was much more than that of the inside harbor indicating 371 inds. and 35.5 kg. In terms of size, the bivalves collected in the outside harbor were 49.49-67.88 mm (mean, 58.47 mm) in D. japonicus and 48.21-113.74 mm (mean, 77.48 mm) in S. broughtonii, which were larger than those of the inside harbor. The yearly biomass of the main commercial target species, S. broughtonii by swept area method (SAM) was estimated up to 242.1 tons. However, considering the regional differences of bivalves between the inside harbor and the outside harbor by abundance and size comparison, it might have been overfished to bivalves in the inside harbor.

• The Korean Journal of Malacology
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• v.28 no.2
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• pp.131-136
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• 2012

Growth, oxygen consumption, ammonia excretion, feeding and assimilation rate were examined from May 2010 to February 2011 in order to assess the physiological changes of Haliotis discus hannai in accordance with changes in season. The water temperature was in the range of $8-23.2^{\circ}C$ and the salinity in the range of 31.9-34.1psu during the examination period. The length of shell of Haliotis discus hannai grew from 36.3 mm to 66.1 mm in the 1 year old entities and from 60.6 mm to 66.1 mm for the 2 year old entities, while the weight of the meat increased from 3.16 g to 12.04 g and from 15.8 g to 21.5 g, respectively. The oxygen consumption and ammonia excretion rate displayed trend of increase in accordance with the increase in water temperature, while the feeding rate was high during the period from July to October. The assimilation rate was in the range of 68%-71% without significant difference between the age of the entities and seasons. SFG displayed +value throughout the year for the 1 year old entities of Haliotis discus hannai as well as for the 2 year old entities with the exception of the period of July, thereby showing that they are growing throughout the year. Therefore, there was no environmental effect including water temperature and salinity during the examination period.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.31 no.5
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• pp.677-684
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• 1998

The distribution and elimination of oxolinic acid (OA) following oral (80mg/kg body weight) and bath (20 mg/$\ell$) treatment were examined in the organs and plasma of Nile tilapia (Oreochromis niloticus) on different temperatures and physiological conditions using a bioassay method. On the analysis of temperature effect, both absorption and elimination of OA after oral administration were delayed in the group at $15^{\circ}C$. but significant difference of the peak concentrations in the tissues of the groups at $15^{\circ}C$ and $25^{\circ}C$ was not revealed. However, the changes of maximam concentration, absorption and elimination rates in the tissues of fish following bath treatment depending on different temperatures were more significantly different from the results of the studies with oral administration. The pharmacokinetics of OA in the tissues of diseased fish, the main target of drug treatment, also appeared to be distinguishable from those of healthy fish.

• 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.16 no.2
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• pp.154-159
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• 1983

A Gymnophallid cercaria was found in the gonadal tissue of Tapes philippinarum, and was described as a new species, Cercaria tapes n. sp. The host clams were collected from the intertidal zone of Seo-myon, Seo-chon gun, Korea from September 1980 to August 1981. The size of sporocysts was $380-650{\times}130-160{\mu}m$. The anterior part of the cercaria bears a subterminal opening and pharynx. The sporocyst bears ca. 30 cercariae and germ balls. The cercaria is elliptical in shape. The dimension of body is $160-187{\times}62-77{\mu}m$. the tail stem is $47-52{\times}17{\mu}m$, and the tail furcae is $67-72{\times}12-15{\mu}m$. Excretory bladder is Y-shaped, and the flame cell formula is 2(1)+(1)=4. The infection rate of the cercaria to the host clam was $2.01\%$ (42 infected/2,086 short-necked clams observed). The highest infection rate ($5.74\%$) was found in March, and the lowest one ($0.4\%$) observed in January. No infection was detected in May and June. The infection rates varied with the size of the short-necked clam. It was the clams of host of 2.1-3.0 cm, 3.1-4.0 cm and 4.1-5.0 cm in shell length are $0.38\%,\;15.3\%$ and $0.09\%$ respectively. The cercaria was not observed in the specimens smaller than 2.0 cm in shell length.