• Journal of Aquaculture
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• v.11 no.1
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• pp.105-111
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• 1998

For ecological studies on the habitat of geoduck clam, Panope japonica caught at the coastal water of Kangwon province located in the East of Korea. The annual water temperature of the geoduck's fishing grounds was ranged from 5.6 to $17.5^{\circ}C.$. The salinity was not so fluctuated showing from 32.27 to 34.22${\textperthousand}$, and dissolved oxygen was ranged 5.51 to 7.27 ml/l. Sediments where geoduck was distributed chiefly was consisted of very fine sands of 3.0 to 4.0 phi (49.2%) and find sand of 2.0 to 3.0 phi scale (31.87%). The shell length of geoduck was measured 70 to 135 mm (mean : 107.70mm) and the weight was 50 to 550g (mean : 299.63g). The total weight (TW) against the shell length (SL) could expressed as the regression equation as TW=$1.4446{\times}10^{-3}SL^{2.6067}$.

• Journal of Aquaculture
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• v.10 no.2
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• pp.213-218
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• 1997

Experiments on the feeding activity and environmental tolerance of geoduck clam, Panope japonica caught at the coastal water of Kangwon province located in the East Sea of Korea were performed from January to December, 1994. Twenty genera and 33 species of plankton were found in the digestive tract, and most of them are phytoplankton. In spring, 21 species of planktonic foods were indentified, but in sumer, only 11 species were identified. Nitzschia longissima and Rizosolenia alata were present evey month. Weight of the digestive tract was fluctuate seasonally : higher winter and spring, and lower summer. Adult geoduck clams could be tolerated within the range of 5 to $20^{\circ}C$ water temperature, and they could tolerated considerably well temperature than higher temperature within the range.

• Journal of Aquaculture
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• v.10 no.1
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• pp.25-32
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• 1997

Develoment precess and characteristics of eggs of the geoduck clam, Panope japonica are reporting in this study. Eggs and sperm were excised from gonad, artificially fertilized in an aquarium, reared under various temperature regimes, and record and record the larval period and the time need to reach a certain larval stage from ferilization. Unfertilized eggs of P. japonica appeared to be oval with a mean diameter of $70\mu$m and they became spherical after fertilization. The eggs of P. japonica can be classified as demersal. At a constant water temperature of $ 11^{citc}C$, it took 4 hours form fertilization to become four-cell stage, two days to become trochophore larvae, three days to become D-shape larvae, twenty-three days to become umbo stage, and thirty-six days to become fully grown veliger ready form settlement. A negative correlation was observed between the water temperature and the larval period of P. japonica. From fertilization to D-shape larvae, it took five days at 8$^{\circ}C$, while it was only two days to become D-shape larvae at $ 17^{citc}C$. Time required to D-shape larvae from fertilization was proportional to temperature, and the relationships were expressed as follows : To 8-cell stage, 1/t=0.0209 w-0.1167 (r=0.9967) To blastula stage, 1/t=0, 0055 w-0.0192 (r=0.9825) To trochophore stage, 1/t=0.0034 w-0.0155 (r=0.9907) To D-shape larvae stage, 1/t=0.0014 w-0.0023 (r=0.9843) (t, time in hours ; w, water temperature) Bioligical minimum temperature for egg development was calculated as 3.82$^{\circ}C$ in average.

• Journal of Aquaculture
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• v.10 no.2
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• pp.113-121
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• 1997

In order to developed the techniques for artificial seedling production of geoduck clam, Panope japonica, various stimulution for spawning induction and hatching condition were studied. Spawning induction by the air day or UV-irradiation stimulus were not effective. Water temperature stimulus was responsed 15.0~25.0% in May and 10.0% in June. But spawning induction by the gonad incision was highest with 15.0~45.0%. Ammonium hydroxide (NH4OH) stimulus adding in seawater were responsed 15.0% at 8/1000N~10/1000N, and ammonium hyhroxide solution injected in the gonads were responsed 5.0~10.0% at 5/100N~7/100N. The highest fertilization and hatching rate at various water temperature were ranged 74.5~89.2% in 11~$17^{\circ}C, \;84.3~89.5%\;in\;8~14^{\circ}C$, respectively. the highest fertilization rate and hatching rate in various salinity were ranged 72.5~88.5% in 25~$35tetperthousand$, 82.7~86.9% in 30~$35tetperthousand$, respectively. The optimum water temperature and salinity for fertilization and hatching to the 11~14$^{\circ}C$ and 30~$35tetperthousand$, respectively.