• The Korean Journal of Malacology
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• v.21 no.2 s.34
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• pp.113-120
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• 2005

In this experiment of natural Atrina pectinata spat collection, the number of the pen shell spats settled on a collector were 4.2, 6.8, and 2.7 in the first, second, and third year, respectively. The highest number of pen shell spat settled on the collector was observed in August, and the shell length of juvenile pen shells grew up to 42.5 mm six months after setting. The relation between shell length (SL) and days (D) after setting could be expressed as; SL = 0.3854D + 0.8423 ($r^2$ = 0.9764). The spats developed the best in depth of 10-20 m. Spat collectors in mesh size of $1{\times}2mm$ mm were better for spats to survive than the ones in $1{\times}1mm$. The most efficient material as substrate for the settlement of pen shell spat was a polyethylene monofilament in the spat collectors.

• Journal of Aquaculture
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• v.15 no.2
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• pp.111-117
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• 2002

Effect of substrate composition, stocking density and food organisms on survival and growth of the surf clam, Spisula sachalinensis was studied. Spat collection from the substratum was the highest, when its sand size was less than 250 $\mu m4; at such substratum, survival and growth of the surf clam were also the highest. The spat (1.4 mm) grew to 4.6 mm and 8.2 mm in shell length on day 30 and 50, respectively. The relationship between shell length (SL) and shell height (SH), shell breadth (SB), total weight (TW) and shell weight (SW) of the spat are formulated by the following equations; SH : 0.7351SL+0.2272 ( $r^2$ =0.9600)i SB = 0.4037SL+0.2112 ($r^2$ = 0.9452); TW : 0.2824SL^{2.7020} ($r^2$ = 0.9820)i SW = $0.4021SL^{2.0217} ($r^2$ : 0.6169). In the substratum containing fine sand, growth and survival of the clam roared at the density of 1~2 ind./$cm^2$ were optimal. The quality of feed decreases in the following order; C. calcitrans, mixture group, I. galbana, P. lutheri, T. suecica.

• Proceedings of the Malacological Society of Korea Conference
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• 2005.07a
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• pp.41-41
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• 2005

• Korean Journal of Fisheries and Aquatic Sciences
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• v.5 no.1
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• pp.23-28
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• 1972

The following results were obtained from the experiment on the oyster spatfall, Crassostrea gigas by means of the rack method in YonghoBay, on the southern coast of Korea, from June to August in 1962 and 1963. 1. The Outside of shells as a collector showed better result than inside in numbers of attached oyster spats. 2. The horizontal type of the rack was more efficient for spatfall than the typical type of the rack. 3. The mode variance, in shell height, were shown as 21-25mm and 26-30mm, and the variance of range was 13.0-53.0mm for 77 days. 4. The optimum spat-fall season was from August 17 to 19 and 24 to 27, and spat of the oyster were attached in number of 7 per collector each day. 5. The optimum exposure time in spatfall was 4 hours. 6, The average water temperature and specific gravity, during the spawning season, was $25.98^{\circ}C$ and 0.1871, respectively.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.21 no.4
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• pp.206-216
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• 1988

In order to set up a predictive model for effective spat collection of pen shell, Atrina (Servatrina) pectinata, the survival rate and time required at each developmental stage of drifting larvae were surveyed during the period from June 8 to October 16 in 1986 at the Yongku inlet Chilchon Is., Chinhae Bay, the southern part of Korea. And also the experiments of spat collection were carried out In Yongku inlet during the period from July 6 to November 23 in 1987 and In Yoja Bay during the period from July 9 in 1987 to February 15 in 1588. The advent of D-shape larvae ca. $135\times144um $ long had three peaks in that area: August 1, 12 and 25. Umbo shape larvae ca. $300\times317um$ and full grown larvae ca. $455\times450um$ long also sowed three peaks: August 9, August 22 and September 4 for the former, and August 23, September 3 and September 16 for the latter. Nine to ten days was required for D-shape larvae to develop to umbo shape larvae. The instantaneous survival rate was 0.94 with a total survival rate if $54\%$ at this intermorphological stage. The required time of umbo to full grown larvae varied from twelve to fourteen days with a instantaneous survival rate of 0.88 and total survival rate of $19\%$. Twenty-two to twenty-three days was required for each group of the D-shape larvae to reach a fullgrown stage, and their total survival rate was $10\%$ during this developmental period. The number of the spat attached to the spat collector is 0.16 inds. per $m^2$ vertical spat collector in Yongku inlet and 0.48 inds. per $m^2$ horizontal spat collector in Yoja Bay. The average shell length of spat attached was $0.51({\pm}0.15)\;mm$ on September $27,\;38.52({\pm}6.98)\;mm$ on November 21 in 1987 and $49.00({\pm}10.77)mm$ on February 15 in 1988.

• The Korean Journal of Malacology
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• v.28 no.4
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• pp.313-319
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• 2012

Mass production method on artificial seedling production of hard clam Meretrix petechialis was developed indoor culture system. Spawning of adult clam (SL $65.8{\pm}8.4mm$) was induced using the combined method of air exposure and water temperature raising. The fertilized eggs were developed to D-shaped larvae after 17.7 hours at $27^{\circ}C$ and hatching rate was 6.1%. Shell length (SL) of D-shaped larvae was measured to be $131.4{\pm}2.6{\mu}m$ and thereafter the larvae grew to the settled spats with SL $190.2{\pm}7.5{\mu}m$ in 4 days. Estimated survival rate of settled spats was 48.1%. Spat collection on 130,000 spats with SL $0.19{\pm}0.01mm$ performed conducted by sand bottom circulation filtering method. Collected spats grew up to $3.1{\pm}0.8mm$ in 46 days, $6.6{\pm}1.8mm$ in 87 days, and $10.5{\pm}0.9mm$ in 114 days. The relative growth between SL and shell height (SH) was calculated to be SH = 0.8501SL + 0.0196 ($R^2=0.9987$) during the whole spat period. During spats rearing, they were suffered from one time of mass mortality at SL 3.1 mm, but 51,000 spats were finally survived with the rate of 39.2% at 114 days of spat rearing in indoor tank system.

• Journal of Aquaculture
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• v.15 no.2
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• pp.95-101
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• 2002

During the periods from lily to October, 2000 in Hongseong and lucy to October, 2001 in Taean in the west coast of Korea, the following environmental conditions prevailed : water temperature : 22.0~26.817, salinity 27.23 ~30.80%, dissolved oxygen 4.12 ~6.26 ml/l, pH 7.89 ~8.09, phosphate 0.39 ~0.65 $\mu m$ , inorganic nitrogen 5.05~9.26 $\mu m$, suspended solid 5.4~20.8 mg/l and chemical oxygen demand 1.12~1.87 mg/l. The B-shaped veliger larvae of the Ark shell occurred in maximum number at $25^{\circ}C$ prevailing from mid-August at Hongseong and Taean. Full grown larvae reached maximum abundance from late August. To identify the effectiveness of the substratum for spat collection, raschel net were tested to Larval settlement. The most effective depth to collect the larvae in natural environment was the collectors suspended at 7~8 m depth. At these depths, about 49 to 94 spats were found on the collector (40$\times$50 cm), The growth of shell height (Y) to shell length (X), and total weight (W) to shell length (L) could be formulated as follows respectively: Hongseong: SH = 0.7168 SL -0.6466 ( $r^2$ = 0.9839), TW = $0.0001SL^{3.1705}$ ($r^2$ = 0.9882) Taean: SH = 0.736 SL -0.8824 ($r^2$ : 0.9899), TW : 0.00005 $SL^{3.3731}$ ($r^2$ : 0.9899)

• The Korean Journal of Malacology
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• v.17 no.1
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• pp.35-44
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• 2001

This research was conducted to develop seedling production techniques in flat oyster, Ostrea dense lamellosa. The cultivation of larvae, artificial spat and spats collection in natural conditions rate were examined. In the mass culture tank (3 tons), average growth rates of the D Shape larvae of initial shell length (153.4 ㎛) and shell height (153.4 ㎛) were 202.6% and 212.9% at 16 days and 227.1%, 241.8% at 20 days, respectively. Instantaneous death and survival rate of the larvae were 0.160 and 54.8% at 16 days and 0.057 and 43.2% at 20 days, respectively. Collection rate of flat oyster from bottom using various collectors with oyster shell, scallop shell, ark shell and PVC plates were 32.9%, 24.1%, 16.8% and 10.0%, respectively. and the greatest collecting rate was 131.9 individuals/shell (32.9%) in laid collectors on the bottom. The collecting rate of the oyster larvae were better in laid collectors on the bottom 83.8 individuals/collection than in the suspended string 54.2 individuals/collection. in all collecting substrates. Early spats settled on collectors were grew to 2.38 $\pm$ 0.97 ㎜ in shell length and 2.16 $\pm$ 0.86 ㎜ In shell height at 26 days. The spats were grew to 28.58 $\pm$ 2.39 ㎜ in shell length and 31.65 $\pm$ 2.03 ㎜ in shell height during the 4 month mid-term cultivation. In the period of cultivation, the mean number of spats attached to collectors were 10.3 individuals at oyster shells, 5.8 scallop shells, 4.0 ark shells and 1.5 PVC plates, respectively.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.7 no.2
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• pp.79-86
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• 1974

The results from the experiment of natural collection and growth of arkshell(Anadara broughtoni, SCHRENCK) spat, which was collected at Seok-gok Bay located at Chang-weon-gun, Korea, and grown in the 1ittoral zone of Sa-gok-ri, Geo-je-gun, Korea, beginning from August 1,1973 to April 8,1974 are as follows; The larvae of arkshell came out from the very first day of the study August 1, which continued till the end of September, whose amount was not so much varied, but relatively continuous. The drifting larvae were also rather small amount, from which some 200 to 400 larvae were attached through the respective collecting equipment made from straw with the dimension of length 1.5m and breadth 12cm. It is regarded relatively large amount collected and recognised worth while enough to use as the industrial collecting method. The average shell length of spat attached was 0.54mm on 17th September, 4.11mm on 21st October, 10.47mm on 25th November in 1973 and 11.08mm on 8th April in 1974 whose progress was recognized relatively faster, comparing with the other up-to date report, The relationship between the shell length(L) and the longest radial rib(R) was as follows: Below 2.5mm of the shell length: R=0.7393 L -0.0080 Above 2.5mm of the shell length: R=0.8253 L-0.2595 And the relationship between the shell length (L) and the shell breadth (B) was as follows: Below 2.5mm of the shell length: B=0.3505 L +0.0527 Above 2.5mm of the shell length: B=0.4631 L -0.3602 The exponential curve equation between shell length (L) and the total weight (W)was as follows : Below 16mm of the shell length: W=0.19957 $L^{2.5726}$ Above 16mm of the shell length: W=0.20602 $L^{2.8400}$ In view of the above the relative growth among the shell length, the longest radial rib and the shell breadth was changed in the vicinity of 2.5mm of the shell length. And relationship between the shell length and the total weight was changed in the vicinity of 16mm of the shell length.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.32 no.1
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• pp.62-67
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• 1999

Infection rates of oyster ovarian parasite, Marteiliodes chungmuensis and productivity of the oyster shellstock infected with the parasite were investigated at the main seed collection areas in the southern coast of Korea where the extreme bad seed collection of oyster occurred in 1992 and 1993 to evaluate the cause of the bad seed collection. Additionally, the bacterial flora of the sea water and oyster lana were examined to identify the shellfish larva pathogenic bacteria like Vibrio sp. and Pseueomonas sp. In August 1992 to September 1993, infection rate of oyster ovarian parasite, M. chungmuensis at Tongyong, Kyongsangnam province, and Yosu, Chollanam province where the bad seed collection occurred, were $11.8\~100\%$ and $14.3\~100\%$, respectively. But the parasite was not detected in the shellstock collected at Daechon, Chungchongnam province. While a virus-like particle was identified in the cytoplasm of the egg infected by the parasite. The parasite infected egg was not able to fertilize completely. Uninfected egg in the gonad contaminated by the parasite could be able to fertilize but showed an abnormal development till D-shaped larva and then, died of necrosis after D-shaped lana. And some lana developed from low lipid content egg could not develop to the spat and died after the early umbo stage. The predominant bacteria in the oyster lana collected at bad seed collection areas were Pseudomonas sp. and Pseudomonas like bacteria and the occupancy rates were $53.3\~87.1\%$.