In Mutsu Bay, winter vertical mixing began
to progress from the first half of September to the latter half of September
and November, when the inflow of Tsugaru Warm Current water weakened and the
residence time of seawater in the bay increased. In order to increase
biological productivity in the bay through seabed tilling, it is necessary for
the tilling seawater to stay in the bay for a long period of time and to be
supplied to the light layer where phytoplankton can utilize that seawater.
Therefore, fall and winter seasons, when seawater is transported vertically and
the residence time of seawater in the bay is long, are considered to be the
most suitable seasons for tilling.
Seabed cultivation is a simple method that
is relatively inexpensive and can be performed simply and quickly by fishermen.
It is necessary to examine whether there
will be significant adverse effects on the marine ecosystem at the site in the
future.
Future studies are needed to examine the
effects of sediment redox environment before and after tilling, and the effects
of seabed tilling by bottom trawling on benthic organisms. By clarifying these
issues, it is expected that seabed tilling will be established as a more
effective tool for protecting the richness of the sea and conducting
aquaculture projects under appropriate management.
