Multi-Species Marine Traps
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Fukui's Monthly News Letter
Japanese scallop cooperative model of farm efficiency
When I was in Northern Japan a few years ago, I met with the
director of a scallop growout cooperative that had 80 farm members.
During my flight I had read a report that, in 1993, Canada produced
14 metric tons (mt) of scallop meat from farm operations.
Production in the US was similar.
Through an interpreter I was told that the cooperative's 80 farmers
had produced 800 mt of meats in 1994. I questioned those numbers.
How could only 80 farmers and their staff produce so much more than
the whole nations of Canada or the US?
Their reply was also disbelief. With all the area for farms that
we have in North America, why were we not producing more?
A) Deep water cages, which are pearl nets tied in a line of up to 30 nets deep, are deployed starting at a mean depth of 50'. The pearl nets are less efficient than lantern cages. However, the experience of the farmers was that in deeper water, lantern cages, due to their greater vertical surface area, suffered from a pendulum effect caused by tidal or storm surge. That, in turn, crowded the animals to one side of the cage thus increasing mortalities.
The pendulum effect is reduced dramatically, to almost none, with pearl nets because of their design and the fact that they are independent of each other. So, even with the increased handling factors, this method is the most efficient for the Japanese farmers in deep water because the yield is maintained. They also have discovered that the weight and bulk of going with more than 30 pearl nets deep is counterproductive to labour efficiency.
B) Shallow water cages, which are lantern cages, are deployed starting at mean depths of 35' using a five-level unit, 40' using a 10-level unit, and 45' using a 15-level cage. The surges at these depths are different enough that the cages are not affected as much as in the deeper water, thus the labour efficiency of the lantern cage proves itself. The farmers have found that cages of more than 15 levels become difficult to handle with the current equipment being used.
C) Horizontal ear hanging is the next method employed by the Japanese framers in their efficient use of the water column within the site.
Using a special ear-drilling machine, a hole is drilled through one of the ears on the scallop shell. The shell is then laced onto a special loop cord and suspended horizontally in the water column between two anchor lines. This method is normally deployed at mean depths of 20' - 30'
D) The final part of the efficiency model is to bottom-seed the area between the ear hanging and minimum depth at shore with year-old scallop seed (grown in pearl nets). When fully grown, the scallops are harvested in the traditional dragger method.
Use what's proven
While only the well-organized larger farms or cooperatives are now able to take full advantage of this new technology, the caveat is that small to medium-size farms can become big producers in short order.
Contact Don Bishop at:
Fukui North America
PO Box 669
110-B Bonnechere St.W.
Eganville, Ontario K0J 1T0
**NEW**Tel: 613-559-0075 or 613-628-5266
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