A little info that might could use a little digging. 20 times the biomass??</font id=“blue”>
Artificial Reefs
History
In 1957 the Territory of Hawai`i began looking into the possibility of installing artificial shelters in areas of sparse natural habitat. The purpose of these shelters was to increase and enhance opportunities for fishermen.
The State’s first artificial reef was created in 1961 at Maunalua Bay, off Kahala, Oahu (74 acres). In 1963, two more artificial reefs were created off Keawakapu, Maui (54 acres) and Waianae, Oahu (141 acres).
A fourth artificial reef was created in 1972 off Kualoa, O`ahu (1727 acres). The Ewa Deepwater artificial reef (31 acres) was built in 1986. Unlike the other four reefs, which were deployed at depths of 50-100 feet, the Ewa reef was sunk in 50-70 fathoms (300-420 feet) of water for “new” bottomfish habitat.
Benefits
?Enhance the reef habitat
?Increase fish biomass (up to 20 times that of the previous barren area)
?Increase species diversity (up to 5 times that of the previous barren area)
Materials Used
For the first three years (1961-1963) car bodies were the primary material used to construct artificial reefs. Then, from 1964-1985, concrete pipes were the mainly used to build these reefs. Also during that time frame, several barges and a minesweeper were sunk. From 1985-1991 the program used concrete and tire modules as the main artificial reef components. Other items used included derelict concrete material, barges, and even large truck tires.
From 1991 to the present, materials deployed have mainly been concrete “z-modules”. Other components include barges, derelict concrete material, and several small vessels.
About “z-modules”
?Measure four feet by eight feet, with twelve inch high “legs” on end of opposing sides.
?Each module weighs approximately 2800 pounds.
?Modules contain 90 linear feet of 1/2-inch rebar for support.
?The current cost per module is $130.
?An average deployment is approximately 1,30