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Alekoko Fishpond

Proposal and Plan to Restore Fishpond

by William K. Kikuchi

           

Introduction

            Alekoko Fishpond is a cultural historic landmarkand a nationally registered site. This inland fishpond is unique in that it is a kuapa type pond set within and about a mile from the mouth of the Huleia River.  Usually kuapa type ponds are built along a sheltered coastline and not within a river system.

            Alekoko also has a legendary association and a historical record of use.

Since the 1970s, and afterseveral devastating natural disasters such as the tsunami of 1946, and storm surges from Hurricane Iwa and Iniki  the kuapa walls are deteriorating. Several sections of its walls are now open to Huleia riverflow. Uncontrolled mangrove trees are now growing on and besides the walls. Left in this condition the significant archaeological, cultural and historic site will be destroyed.

           

 Potential Uses

Alekoko is still a viable fishpond. The large site is capable of fish  and crustacean culture and has a significant economic potential for its owner.  The site can also serve as an eco-tourist and edu-tourist  destination.

Already its lookout  point serves the tourist as well as the local population with a fine scenic destination.

 

 Restoration Efforts

There are several areas that needs work at the fishpond:

     1. The  kuapa wall must be repaired.

     2. The mangrove along side the wall must be removed.

     3. The mangrove within the fishpond must be partially removed and the remaining maintained.

     4. The fishpond must be dredged to a depth of 3-5 feet.

     5. Structures for holding equipment and supplies must be constructed.

     6. All makaha should be checked and repaired if necessary.

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 Repairing the Kuapa

The kuapa or major seawall of Alekoko is constructed on a natural berm of an old levee formed by the meandering Huleia river. This meandering caused an oxbow "lake" to form. The levee was slightly above the rivers water table so that the native Hawaiians  built a stone  wall on it.  Since stone was not very abundant, the builders used  mud and silt from the river to built the wall. Stones were often set as edging to prevent erosion by the river.  Later during its use, the Hawaiians simply used dredged mud from within the pond and piled it on the existing kuapa wall. In some places the walls of dirt is over 6 to 7 feet high and over 10-15 feet wide.

 

To repair large breeches of this wall, I suggest producing mangrove logs ; pounding sections into the  levee to establish two lines of parallel vertical posts . These two vertical posts will be used to hold horizontal mangrove  trunks forming a wall of horizontally placed timbers. Two rows parallel with each other and about 5-6 feet apart will be the core of the newly repaired wall section. Once the  two wall of timbers are stacked, dredging from the pond can begin and silt can be poured  between the two walls. Once this is done, the silt-mud core  will form a solid path that closes the breech of a wall section. Stones can then be placed alongside of the

wall adding to the strength of the wall.  The work continues until all the breeches are closed.

 

This process uses mangrove timber and mud-silt which already exists at the site. Only stone need be gathered to fortify the wall sides.

 

 Mangrove Removal and Maintenance

Mangrove once growing is a most difficult plant to remove. Its octopus-like root system anchor and intertwine itself solidly into the ground.

 

Two forms of removal are suggested. The first is the simplest. This involves

simply pulling out the young mangrove seedlings as they begin to anchor themselves into the silt. This is a continuous job but a necessary one. The second is the cutting of the tree using chain-saws. The sawed tree can be hauled to a large cleared flat area where all the branches and limbs are removed. These can be put into a shredder to produce mulch . The remaining wood can be sawed to length and dried and eventually used to make the wall for  the breeched-wall repair.  Large mangrove timber, air-dried is a very hard wood which can be used for fence-posts.  The stripped bark yields a shellac like brown varnish.

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Where the trees are young, they could be easily chained and pulled by a tractor. I would recommend this method within the pond only and conducted only when the tide is at its ebb. The disturbed silt will drain out of the fishpond producing a miniature dredging process. However, this method can only be used when only two or three trees are pulled per day. Wholesale pulling will discharge large amounts of silt into Huleia.

 

I would not recommend the removal of all the mangrove within the fishpond as a few of the trees form an ideal protective environment for aquatic life. Mangrove swamps are known to increase the aquatic productivity of an area but then strict control of their growth and spread must be maintained.  Mangrove  on the fishpond walls and alongside must be removed by cutting. Because of the value of mangrove perhaps a canal cleared of mangrove can be maintained between the kuapa wall and the Huleia River. This canal will isolate the kuapa wall and even protect the walls from the threat of flooding by the river. The mangrove here will serve as a buffer for the wall but will not be allowed to grow on or near the wall.

 

 Dredging

The most efficient depth of a fishpond is dependent on the water clarity of the river. Since Huleia carries a large silt load and the river tends to be murky, the average depth of the fishpond should be around 3 to 5 feet deep. This depth allows sunlight to penetrate and permit the  bottom algae growth. Presently the pond is silting at an alarming rate. This is because the wall is breached in several places. At low tide nearly a third of the pond is only a few inches below water.  Shallow depth of water from silting will warm the water and providing  a poor environment for aquatic life to thrive.

 

Dredging was a continuous process in ancient times. Today, suction pumps on a raft can easily accomplish the task. Because of the large size of the pond, the dredging job will be time-consuming and tedious. The problem will be to pump the silt to a location via hoses and then to filter the sediments, dry and store it. Once stored the material can be trucked away as landfill.

           

Dredging will improve the water quality within the pond, improve circulation and increase the aquatic life within.

 

 Structures

Structures are needed to store boats, pumps, hoses, cutting equipment, shredders, tractors, etc. Since these equipment are expensive, maintenance is mandatory for an efficient job at the site.

 

 Makaha

Makaha is the channel openings that allow water to pass from the river into  and out-of the fishpond . The canals also serve to attract fish when the tide begins to flow  into the pond.  These are the times when harvesting is a simple task. These canals and gates must be properly maintained. If the  gates are broken,  fish will leave the pond as well allowing predator fish to flow into the pond.

 

Aquacultural Potential

Alekoko Fishpond can be reused to grow mullet, moi, awa, shrimp and Samoan crabs.  Frogs can be grown in the existing side ponds.  One of the big problems for the fishpond is to eradicate the common tilapia which feed on the fry of the valued fishes.  Continuous netting and clearing will be necessary.

 

The fishpond has a good solid dirt-wall which effectively stops any fish fry from entering. The problem areas will be the makaha-gate-grates which allow predator fry and tilapia to enter.  A rewiring of the gates and grates will be necessary to reduce the size of the wire mesh as well as to establish a series of gate-grates to further reduce introduction of unwanted fish fry.

 

The fishpond could also be sectioned by rings or row-walls of fine mesh wire to isolate portions of the pond for certain types of fish and crustacean growth. Again mangrove stakes and wire-mesh strung between  them will form sections which can be removed and replaced over time.  The soft sandy-silt-mud allows mangrove stakes to be easily pounded into it. The mangrove stakes will not grow into trees.

 

The fishpond could yield a good supply of fish for the Kauai and Oahu market .  Besides the obvious aquatic  economic potential, the site can be used for Ed-utourism-Eco-tourism as well as a valued aquacultural research station

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