THE OPAE'ULA CHALLENGE!
Part I: Restoring the Anchialine Ponds
A coral sinkhole where opae'ula have been found on Oahu. At low tide,
there is little or no water. At high tide the opae'ula come out of the
cracks and crevices to feed. Reproduction takes place in the hypogeal
Many thousands of years ago, sealevel was much higher than it is today and reefs surrounded much of Oahu. Today sealevel is lower and fossil coral reefs cover much of the Ewa plain. Some of the offshore islands are remnants of coral reefs.
In sharp contrast, the anchialine ponds of the Big Island are in low
spots in the lava. This is a man-made pond built by a developer to
replace the natural ponds that were filled in during construction of a
Within a short time of completion, opae'ula naturally colonized it. Most ponds are small and shallow but there is a full range. Some are collapsed lava tubes. Another is geothermally heated with 95° F water.
Opae'ula was once abundant enough to be used by native Hawaiians to regularly feed the offshore opelu koas. The photo shows a pristine pond. Opae'ula average 1/2" or less and 1 square foot may have over 500.
With most staying in the hypogeal section, there may be over 1 million opae'ula in a 500 square foot pond! It was initially estimated that 10% can be sustainably collected each month without depleting the population. Recent captive breeding trials show this is a very conservative estimate as the trials produced in excess of 100% increase per year!
OPAE'ULA DISAPPEAR SOON AFTER ALIEN FISH ARE INTRODUCED!
The ponds were once in pristine condition with an abundance of opae'ula.
However, access to the ponds, human activity, and development resulted
in the decimation of the opae'ula population. Since the opening of the
Queen Kaahumanu Highway that connected the port of Kawaihae with
Kailua-Kona in the 1970's, over 95% of the formerly pristine anchialine
ponds now have alien predators. While it is illegal to
fill in the ponds without a special permit, it is possible to make them part of beautiful landscaped gardens and fill
them with colorful attractive carp.
The vector control section of the Hawaii State Department of Health also introduce mosquito fish into the ponds in their efforts to reduce the impact if the West Nile Virus should ever appear in Hawaii. Fishermen threw unused live bait into the ponds. Aquarium hobbyists have also introduced fish into ponds.
The ancient Hawaiians were highly skilled aquaculturists who utilized
the larger anchialine ponds to raise fish. Each year, young mullet
fingerlings were caught along the shoreline and released into the ponds
where they were fed daily at the same time and the same place. The
mullet in the photo are about 16" long and weigh about 2.5 pounds
each. When the chiefs requested
fish, the largest and fattest was easily netted. Wrapped in seaweed and
dipped occasionally in the ocean, runners were able to deliver live fish
many miles away!
There are valid alternate uses for anchialine ponds besides being opae'ula habitats but there are also ill-conceived practices that should be stopped and there is a need for public education.
Tilapia have been introduced into some ponds to serve as another food
fish and the photo shows the round nesting holes they typically create.
Tilapia are especially a problem as they are mouth brooders. A sea bird
may catch one and occasionally drop it into a new pond. This is believed to be how
tilapia was introduced into aquaculture prawn ponds on Kauai and into
the Waikoloa Anchialine Pond Preservation Area. Initially
they were not noticed, but during the record high tides of the spring of
2004, the pond complex merged into a single large pond and the tilapia
spread throughout the makai ponds.
Some introductions were well intentioned. Hawaii's aku (tuna) fishing industry depends on having silvery nehu to use as chum to keep the aku in a feeding frenzy while they are being hooked. With nehu becoming scarce, Mexican mollies were introduced into the ponds to increase. Unfortunately, mollies dive and take the aku away from the boats. Now the mollies are invading more ponds.
is a pond that was invaded by molies and the fish disrupt the ecological
balance. The fish prey upon
the opae'ula and
in having to retreat into the hypogeal habitat, are not able to keep the
algae under control. As
shown in the photo, this results in excessive blooms of filamentous
algae which continues to grow enough to float to the surface
encouraging other predator insect species (e.g. dragon flies, water
boatmen, etc.) to inhabit the pond.
The surface layers of algae exposed to the hot sun die and at night these floating mats sink to the bottom adding to the organic debris and eutrophication of the pond. Mats of these algae that do not rise to the surface are smothered and anaerobic conditions are created with the release of toxic hydrogen sulfide. If left uncorrected, the pond basically becomes a stinking mess and a health hazard to the public. Over time, the rotted debris and organic detritus will eventually seal off the pond from any tidal inflow and prevent any future recruitment of opae'ula.
fish reproduce and their larger volume of waste products increase
the nutrient levels in these pools and further
promotes the buildup of organic matter, silt and exotic plants. Anchialine ponds
have a relatively short geological lifespan. Over time, they fill up
with silt and organic matter and become grasslands or forests. The
introduction of alien predator fish greatly decreased the lifespan of an
When there are no predators, opae'ula can increase dramatically and ponds can contain huge populations with the bottom of the ponds appearing red! Populations are naturally controlled as ponds with limited food still have small populations even without alien predators. The native Hawaiians were once able to sustainably harvest large quantities of opae'ula for food and to use as bait. Once predators are removed it will be possible to establish prudent sustainable harvesting procedures.
There are numerous reasons why opae'ula are declining and it's easy to lament and try to establish blame. But the challenge is to find viable workable solutions beginning with: "How can we preserve and restore anchialine ponds?"
RESTORING THE ANCHIALINE PONDS
Each pond restoration must address the current condition and the state of geological evolution that has already taken place. If trees and grasses have already begun to encroach and grow in the ponds, these must be removed along with excess algae that may have developed. Over time, ponds fill with silt that seals off the hypogeal environment and this must also be removed. In the construction of Mauna Lani Resort there was a major commendable effort and it took over one year to dredge out accumulated silt to restore the natural ponds.
There is a proven method to remove alien predators which includes fishes and the introduced Tahitian Prawns that have been able to penetrate the anchialine ponds and which can complete their life cycle within the anchialine ponds. Tahitian Prawn is not a hypogeal specie and would be vulnerable to rotenone.
NOTE: For the latest information regarding the use of rotenone to remove alien predators from anchialine ponds, please go to THE OPAE'ULA CHALLENGE; Part Ia: Rotenone Status Update Report.
The information that follows provides some background information but may now be either not applicable or irrelevant. It remains posted to provide a better understanding of the frustrations we endured in efforts to restore anchialine ponds!
ELIMINATING THE ROADBLOCK
There has been no action because the Hawaii Department of Health has very effectively established an intimidating roadblock that prevents the application of rotenone in anchialine ponds by certified applicators by making permits impossible to obtain. They have done this by:
* Making it impossible to obtain National Pollution Discharge Elimination System (NPDES) Permits. The Hawaii Department of Health is the designated administrator for the federal Clear Water Act which requires a NPDES permit to apply pesticides in waterways. HDOH has established bureaucratic justification with their administrative rules to justify refusal to issue a NPDES permit. They were almost successful in preventing the removal and treatment of Salvinia molesta at Lake Wilson by refusing to issue the NPDES permit. They are very successful in preventing the application of rotenone to remove alien predator fish from anchialine ponds. If that was the objective of Hawaii Department of Health, they've done an extraordinary job and must be publicly acknowledged for their achievements. But whoever had that objective should also be publicly identified and made to justify why they should have the authority to establish such objectives or to be paid for doing so.
It is necessary to eliminate this roadblock to remove alien predators from the anchialine ponds. This is a complex issue that overlaps and includes elements of the Clean Water Act, administered in Hawaii by the Hawaii Department of Health (HDOH), and the Federal Fungicide and Rodenticide Act (FIFRA), administered in Hawaii by the Hawaii Department of Agriculture (HDOA). There is federal oversight by the Environmental Protection Agency (EPA). All actions must be based upon case law that is not yet fully settled and being made by the Ninth Circuit Court of Appeals whose decisions have the force of law in Hawaii.
At this point, the issue is: "Will the Hawaii Department of Health issue a NPDES permit to allow certified pesticide applicators to apply rotenone to remove alien predator fish in anchialine ponds?"
There is a compelling need for such action and the confusion has delayed implementing an action plan. Part of the reason that there has been no resolution is that there has not been enough public support to encourage governmental agencies to resolve the problem.
RECOMMENDATION FOR AN INTERDEPARTMENTAL CONFERENCE
As the first step, there should be an interdepartmental conference of those in the Hawaii Department of Health's Clean Water Division and the Hawaii Department of Agriculture Aquaculture and Pesticide Branches to first meet to resolve this problem. Names of authoritive individuals will be forwarded to provide any needed information. The objectives of such a conference should include:
DEVELOPING LONG-RANGE ACTION PLANS
Getting rotenone cleared for immediate use by certified applicators to remove alien predators from anchialine ponds is the first priority for all who are concerned about anchialine ponds and opae'ula. This must be done on an emergency basis, as once fully established, it will be more difficult to remove the invasive species. Once the immediate objective is accomplished, all unnecessary regulatory obstacles must be removed while retaining sufficient controls.
There are many other steps that must be taken to meet "The Opae'ula Challenges!" It is necessary to have a statewide survey of all anchialine pond resources to determine their present status and whether additional regulatory protections must be enacted. There must be removal of obstacles that prevent private developers, foundations, and community groups from preserving, restoring, and conserving anchialine ponds. Captive breeding must be encouraged and supported and a way must be found for those interested in captive breeding to obtain broodstock.
These are areas that the Division of Aquatic Resources of the Hawaii State Department of Land and Natural Resources have capabilities to make major contributions. DLNR has both educational and enforcement capabilities and this would be a preferred role for them. The Department of Education and the University system should also be involved as well as private owners of lands that include anchialine ponds and private companies like Fuku-Bonsai. With the participation of all sectors of the community who have interests, we can address the first challenge of restoring the anchialine ponds.
TIME IS OF THE ESSENCE!
This information is formatted to present as clear a picture as I can. There may be errors; and if so I would appreciate being corrected. But, if the information is correct, I hope a solution can be developed during a meeting of HDOH Clean Water Branch and HDOA Aquaculture / Pesticide. Please call me if more information is needed or if I can be of assistance to facilitate such a resolution.
This essay is Part I of a series titled: "THE OPAE'ULA CHALLENGE" in the Micro-Lobster website within Fuku-Bonsai's larger website and is posted at www.fukubonsai.com/M-L2b1a.html and is subject to being updated.
© Copyright 2005, Fuku-Bonsai Inc. Permission given to reproduce for private non-publishing purposes if printed in its entirety and provided the date of the essay and this notice is included. "True Indoor Bonsai" and "The Amazing Hawaiian Micro-Lobsters!" are trademarks of Fuku-Bonsai Inc.