In the waters of the Izu Islands, reefs and boulders are formed everywhere as habitats
for fish, crustaceans and shellfish. In recent years, the reduction of catches has become
a serious problem due to reef-burning and changes in sea conditions. At IFAI, we are
continuously trying to recover the seaweed beds using iron fulvic acid, and using
artificial stones and natural stones to check the state of seaweed growth.
Oshima is an island located about 25km southeast of the Izu Peninsula, with good transportation
from Tokyo and can be accessed by ferry or airplane. Locally, the experiments are welcomed
as it also helps the offshore wind power development plan. Moreover, the Tokyo Metropolitan
Government is also considering the effective use of fishing ports in order to support the
“fishery that grows”. By utilizing this mechanism, there is a possibility of the development of an
abalone farm after the experiment.
Located in the southern part of the island, the currently inactive Sashikiji fishing port has
been selected as a place for demonstration experiments. This place, which has been approved
for three years, has already gained the support of government and fishery cooperatives.
A local environmental guidance is perceived through a nearby fishery test Centre.
The block used for seaweed development (seaweed settlement base) uses a steel slag
hydrated solidified body. As an alternative to natural materials,
this material is an environmentally friendly material that contributes to energy and
resource conservation, and is certified as a specified procurement item
under the Green Purchasing Law.
Steel slag contains essential biological elements such as iron and silicon,
so it has excellent bioadhesiveness and can be expected
to improve the biological properties of the sea area.
ARTIFICIAL REEF BLOCK
Because artificial stone has a higher density than natural stone,
it has excellent stability against tidal currents and waves,
and is used as a base for garden creatures and macroalgae.
ABOUT FULVIC ACID UNIT
STRUCTURE AND CONSTITUENT MATERIALS
OF THE FULVIC ACID IRON ELUTION UNIT
The fulvic acid iron elution unit consists of an elution material
containing iron fulvic acid and an artificial stone.
While maintaining stability against sea surface fluctuations,
it plays a role as a basis for biofouling.
The fulvic acid iron eluent is mainly composed
of the following five materials:
High-concentration divalent iron / Dam fixed sediment /
Bamboo sheath / Shochu residue / Fish residue
THE LOCAL PROBLEM
In the local fishery industry, the decrease in the catch of shellfish
has become a problem in recent years.
One reason for this is the drastic decrease in seaweed called “Aitokume”.
"Aitokume" is a seaweed that grows from spring to autumn in the shallow area around
Oshima, and is used as a food for shellfish such as abalone.
“THE CREATION OF THE SEAWEED BEDS SOLVES LOCAL PROBLEMS”
Propagating Aitokume is considered the greatest contribution to local fisheries,
and aims to improve breeding reefs and develop floating reefs.