Land-based culture system
The dominant marine cultured species of Korea is Olive
flounder ( Paralichthys olivaceus) and it is reared in
land based raceway culture system.
Farms are usually located the south and west coast,
especially This Je-je do which is the most southern part of
Korea. Each farm usually produces about 110 ton (110,000kg) in
a year. This is the average amount of products since some
years with mean stock density 20kg/m. This product is
purchased to Seoul and Japan by wholesaler.
Water resource, quantity and quality
Raceway system is that water should be supplied constantly. If
it is stopped it would be serious problem to the farm. The
quantity of water required is dependent on the type of
aquaculture system, species cultured, management practices,
culture densities, skill of culturist, and so on. Therefore,
it is difficult and foolhardy to generalize about water needs.
There are four functions that a water supply must satisfy:
evaporative losses, seepage losses, oxygen depletion, and
waste disposal. In addition, water may be required for other
uses of property such as fire protection, livestock watering,
facility cleaning, irrigating crops, and residential use. The
water budget should also be sufficient to take into account
future plans for expansion.
In these aspects, this farm has quite good condition of water
resource. The seawater is pumped from the open sea directly
into head tank and then it is supplied into the fish tanks.
There are usually six pumps. Four pumps are 100Hps and they
usually are used to pulling seawater. Four pipes are contacted
and it is buried, that away 150m from coastline. And pipe's
diameter is 500mm. Two pumps are back up pumps. Normally, just
two 100 Hps pumps are used. But emergency situation for
instance when one is broken down, other back up pumps would be
And also there are two other pumps for pulling underground
water powered 75Hps and 40Hps, respectively.
The min/max/mean water temperature,
dissolved oxygen, dissolved hydrogen density and salinity of
Jeju area in 2002 are shown in below table.
There is an alarm system which acts water level is changed.
The water alarm prepared
for warning low level, power failure and an instant power
failure. This system was set
up by special line of business. Check everyday and once a
month the professional
comes and check.
Nutrition and feed
Feed efficient diets and well nutrition is decide that its
healthy and price of products. So
to grow more healthy environmental conditions, diets, and
nutrition is very important
part. At these factors, if just careless of one factor it
causes disease. The most failures
will be at this situation.
After larval stage, the diet or nutrition is very important part of production
cost for marketable flatfish. The most efficient and economic diets have to
be chosen. Moisture pellets are still in current use for flounder in Korea.
Mix the fishes like mackerel, gizzard shad which has well nutritive and fresh
condition. Then press them which fishes can eat easily. This farm also makes
own feeds in the farm, just make that quantity of a day's supplement, with small
fish and commercial powder diets.
Almost of fish farms have chance to meet some natural hazards. The products
are always threatened by several hazards just like water pollution, flood, predators,
algae, shipping, etc. As usual there are several harmful factors for aquaculture
in the nature in Je-ju. The most frequent factor is Typhoon. About 7 typhoons
faced every year but only 1-2 typhoon landed in the Korean peninsula. Of which
the grade of power was not A usually B or C. Therefore landed typhoon, we can
ignore for aquaculture industry. Second factor is Red tide. Red tide is quite
often happen in the South sea Even if the red tide is very harmful for cage
culture. But the land based flounder culture system is quite safe due to use
underground seawater well. Other factor is diseases. There are virus, bacterial
and parasitic diseases around culture system. But usually only 10-15 % of mortality
has been reported from infected areas. From the daily based of fish rearing
record, the mortality of this farm due to diseases and unknown dead fish is
A typical view of land-based culture tanks. Most are round and rectangular in
Pipe lines connected to the reservoirs or to the culture tanks directly
from which the cultured waters go to the culture tanks by gravity