♦ Japanese scallop, Patinopecten. Yessoensis
Japanese scallop, Patinopecten. yessoensis, is a cold-tolerant species inhabiting coastal areas of the subfrigid zones such as the north Pacific Oceans, the East Sea (also known as Sea of Japan), and along the coasts of the Kurile Islands, Sakhalin, Hokkaido, North Honshu, Sikhota Alin, and South and North Korea (Shumway, 1991). In Korea the northeastern parts of the peninsula, mostly belonging to Kangwon province, are a key place for the production of P. yessoensis.The place is remote from human activities and, thus, provides an agreeable environment for scallop aquaculture. |
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The scallop aquaculture in this place commenced in the late 1980s with a pilot scale effact and was successful,
annually producing up to around 2,000 metric tons, until the late 1990s when unexplained mass moralities were first observed.The mass mortalities are now a key issue among the scallop aquaculture managers. A factor that is believed to influence scallop survival in the farm is
daily fluctuation of water temperature that is probably due to conversion of different
water masses in the coastal waters.Recent temperature data from a real time monitoring system have shown a local daily temperature fluctuation of up to 15℃. The fluctuation is serious enough to stress to the scallop causing death.
To cope with the mass mortality, production of temperature-resistant seeds, together with real time temperature
monitoring of the farming grounds, is strongly suggested.
♦ Seed Production
scallop spawners for hatchery-based seed production.
The scallop spawners are normally 2-3 years old
Seeds of the scallop are wild and hatchery-based with an increasing reliance on the hatchery-based ones.This is related to developed seed production technology in quality and quantity.In the hatchery-based seed production, maturation condition of the healthy spawners in captivity is important because Korean population of the scallop comes to maturation two to three months later than Chinese population in nature.Earlier production of the seed is always beneficial in the later management of the species in the farming ground.Water temperature is the environmental factor influencing scallop reproduction.Exposure to extremely low water temperature is a crucial factor initiating gonad development of the scallop.Therefore, one of our research items on the species is maturation condition by temperature and food manipulations.
The annual change in water temperature at the culture depth of 15m is in the range of 4∼22℃, and salinities range between 32.5 and 34.5 ppt.Scallops are commercially important and prominent animals which are considered to be a valued food in many countries. Suspended culture is executed in 534.7 ha which is the total area of nurseries including net culture, ear-hanging culture and suspended bottom culture depending on culture location.The table shows location and number of scallop nursery in Kangwon province.Scallop nurseries from Kosung to Samchuck belongs to Kangwon province while nursery from Uljin to Pohang belongs to Kyungbuk province. most scallop nurseries are concentrated in the Kangwon province. There are approximately 404 ha for bottom culture with regard to benthic fauna, water movement, and environmental condition.
Area and number of nurseries for suspended culture and bottom culture in Kangwon province
(Unit: ha)
|
Method |
Sum
|
Kosung |
Sokcho |
Yangyang
|
Kangnung |
Samchuck |
Uljin |
Youngduck |
Pohang |
Suspended culture |
534.7
(86) |
77
(9) |
48.5
(7) |
101.6
(13) |
139.9
(22) |
66.5
(15) |
36
(10) |
59.5
(7) |
5.7
(3) |
Bottom culture |
404
(17) |
124
(15) |
50
(2) |
120
(6) |
-
(-) |
110
(4) |
-
(-) |
-
(-) |
-
(-) |
* A parenthesis means the number of scallop nurseries.
- Wild-based seed production
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| Substrates for wild seed collection of the scallop |
Locating the seed collectors on the seedling ground in the Kangwon province |
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Net lanterns for the scallop culture |
Plastic lanterns. Ten to twelve units are put together vertically. |
-Hatchery-based seed production
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Scallop(weight 250g) |
Female scallop |
Spawning stimulation |
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Algae culture |
Larval rearing |
D-shaped larvae (2 days) |
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Umbo-stage larvae(15 days) |
Full-grown larvae(28 days) |
Attached larvae(50 days) |
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Young spat(150 days) |
iSpat(shell length 1 cm) |
Stock |
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KOREA-US AQUACULTURE -> Main Species->Shellfish->Scallops
