Diversifying Hawai'i Aquaculture with Clam and Oyster Culture

Final Report for FW09-311

Project Type: Farmer/Rancher
Funds awarded in 2009: $50,000.00
Projected End Date: 12/31/2012
Region: Western
State: Hawaii
Principal Investigator:
Dr. Maria Haws
Pacific Aquaculture and Coastal Resources Center
Maria Haws
Pacific Aquaculture & Coastal Resources Center
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Project Information


This project was designed to resolve issues related to the dependence of new bivalve farmers on purchasing large oyster seed rather than buying less expensive, locally available eyed oyster larvae and setting these at their farms. The ability to purchase less expensive larvae and set them, then use a floating upweller system (FLUPSY) will greatly enhance the ability of new farmers to reduce costs and control their own production. An improved understanding of the basics of oyster biology and culture methods is also essential to new oyster farmers. A functional and useful FLUPSY was designed and tested at two traditional Hawaiian pond sites that are among the first to culture oysters in Hawaii. The ability to use a solar powered FLUPSY will enhance farm efficiency and profitability, as electrical costs are high in Hawaii.


Hawaii has long been the only U.S. state where bivalve shellfish cannot be farmed due to the Department of Health’s (DOH) partial implementation of the State Shellfish Sanitation Plan. DOH has traditionally only implemented the portions of the Plan that relate to importation of shellfish, not the components related to classification of growing areas. In June 2012, DOH began full implementation of the Plan and began the water quality sampling required to classify shellfish growing areas. Hence this Western SARE-funded project came at a most fortuitous time and will contribute to the development of a Hawaiian shellfish industry.

Shellfish farmers have two options for obtaining stock for their farms. Stock or “seed” is one of the highest costs for shellfish farmers. They can buy “spat” (juvenile animals), which is a high cost-option. For example, 4 mm oyster spat cost around $10 per thousand ($10,000 per million) and most farms require several millions to stock their farms as some mortality occurs in the nursery process. The lowest cost option is to buy eyed-larvae and set it themselves. Eyed-larvae currently cost $150/million (2013). Even with some morality during the setting process, purchasing eyed-larvae and setting these on the farm is clearly the lowest cost option for farmers.

Hatcheries produce eye-larvae, which are advanced-stage larvae on the verge of being ready to go through metamorphosis and set on a substrate. These larvae can be shipped without water at a low cost to farmers to set in their remote areas. This process is called “remote setting.” Remote setting requires the farmer to have one of several possible setting systems to be feasible. Generally setting is done either in tanks or in downwelling systems. After setting, the small spat are then transferred to a Floating Upwelling System (FLUPSY) which constitutes a nursery system. The FLUPSY is one of the most efficient methods of raising small bivalve seed. Electrical power is required for this system as a pump is used to supply the spat with water and algae that is found naturally in the water.

A complicating factor is that most of the prospective oyster farmers in Hawaii do not have electrical power in their farming areas. The configurations of the ponds and surrounding sites, particularly the large extents of shallow water, inhibit use of conventional setting systems. Moreover, electrical costs are among the highest in the nation. Hence, if a FLUPSY is to be used in Hawaii, an alternative source of power is needed. The goal of this project was to design and test a solar-powered FLUPSY that would effective in the unique settings of the Hawaiian fish ponds.

Project Objectives:

Objective 1: Pre-implementation meetings and planning for producers and aquaculture extension specialists, with training in basic shellfish culture also to be presented (Month 1).

Objective 2 : Procurement and shipping of materials to the two demonstration sites. Development of draft training materials to be used in training. Experienced oyster farmer to provide assistance in training and advise on design of systems (Month 2-3).

Objective 3: Field days on Moloka`i and O`ahu to build and install remote setting systems and floating upwelling systems (FLUPSY) with accompanying training. Experienced oyster farmer to provide assistance in training. (Month 4).

Objective 4: Larvae to be sent to Moloka`i and O`ahu for setting in remote setting system with training from aquaculture extension specialists (Month 5).

Objective 5: Spat previously set in remote setting systems on Moloka`i and O`ahu to be transferred to FLUPSY for nursery state with accompanying training (Month 6-7).

Objective 6: Grow-out in FLUPSY (Month 8-9) with monitoring of growth and survival.

Objective 7: Transfer of spat to grow-out system in ponds. Training in shellfish grow-out methods. (Month 10).

Objective 8: Grow-out in ponds with monitoring of growth and survival (Months 10-22). Revision and final printing of extension materials based on results.


Click linked name(s) to expand
  • John Austin
  • Robert Howerton
  • Hi'ilei Kawelo
  • David Nisbet
  • Walter Ritte


Materials and methods:

Although this work began promptly and showed early signs of success, significant setbacks were experienced due to several factors. First, Hawaii suffered from two tsunamis (2010 and 2011), one of which damaged the Molokai farm sites in early 2011. Fortunately no human lives were lost and property damage around the state was less than expected, but Keawanui fishpond site did suffer significant damage, with approximately 80% of the wall destroyed. Work at this site could not proceed until the Hawaiian Learning Center personnel were able to repair the pond wall. Traditional Hawaiian fish pond of the kuapa type were constructed by building massive stone walls in the intertidal area (Figure 1). Repairing the walls takes considerable time and labor. The wall was repaired by summer 2012, so work was resumed.

Another setback was that the building used by Pae Pae `O He`eia on Oahu was demolished by the owners (Kamehameha schools) in 2011 so that a new educational center could be built. During the time between the demolition and new construction, the pond site was largely closed down and it was difficult to work at the site. During this time, the PACRC personnel focused on developing two prototypes at the PACRC in preparation for resuming work at the farm pond sites. (Figure 2).

The major difficulty in designing the system was determining the number of solar panels and battery size required to run the FLUPSY without interruption during extended cloudy periods and at night. The eastern half of Hawaii Island is on the leeward side of the island and cloudy conditions can persist for weeks. The leeward sides of the Hawaiian Islands are usually windy as well, and it took some effort to develop a stable, floating base and a “roof” structure that could hold the solar panels yet present a small enough profile that it would not tip over in high winds. The major design constraint was the goal of keeping the total materials cost to under $1,000 since beginning oyster farmers have few financial resource.

The design of the second prototype was successfully tested producing several cohorts of 2-4 mm spat. This prototype used a wood frame. Spat growth in the PACRC FLUPSY was about 30% faster than using the previous hatchery-based nursery system. This was a beneficial experience for the PACRC as it motivated us to move the bulk of spat production outside the hatchery to the renovated waste water treatment tanks to increase spat production. Additionally, it also spurred us to experiment with fertilization methods to create a greenwater culture in the tank to feed the spat. Although we are not using the prototype solar powered FLUPSY any more, it led to a larger, more efficient design (Figure 3) in which an air blower is used to create lift to move the water. The first three FLUPSYs of this latter type were used to produce 8 million spat during spring and summer 2012. These spat were cared for by the students employed in the Aquaculture Workforce Training Program at the PACRC. Forty thousand dollars were generated by selling the spat to an industry cooperator, who then supplied this spat to 15 oyster farms in the Pacific Northwest. The year 2012 was a year in which there was a scarcity of spat on the market due to problems associated with ocean acidification, so this assisted the farmers in the Northwest to obtain stock for their farms. The revenues from this experiment will cover the wages of the twelve student employees for about nine months.

The third FLUPSY was then built on the farm site of the Hawaiian Learning Center on Molokai(Keawanui pond) beginning in March 2012. Fifteen students participating in a continuing education class helped build this FLUPSY. The FLUPSY was used to test spat growth in late 2012 and good results were obtained (Figure 4). The major difficulty encountered were the high winds which buffet this site nearly every day starting in the afternoon. Although the FLUPSY was stabilized through a mooring system, we felt the design was not fully adequate to the conditions, although it does function. The cost for this model was $650. Currently we are building an improved system for use during the production season of 2013 using other funds.

We then redesigned the FLUPSY to make it more more stable under high wind and wave conditions. This fourth FLUPSY was built at the He`eia pond on Oahu that is managed by Pae Pae `O He`eia in September 2012. Several improvements were made. The base and frame were made from PVC. While more expensive than wood, the sealed PVC frame is equally buoyant all around and eliminates the need for the larger, expensive buoys that were used for the Molokai model. The base also has a larger footprint which makes it more stable. The increased space around the central sump make it easier to access the spat to work with them. The “roof” which supports the solar panels is also made from PVC and allows wind to move around the structure, making it less likely to catch the wind and thus tip the entire structure. This design cost $940. While more expensive, it still met our initial goal of designing a FLUPSY for less than $1000.

The final model of the solar powered FLUPSY consists of the following:
• A base made from 6” PVC pipe, elbows and T’s
• Vertical frame made from 2” PVC pipe
• Eight 6” to 2” PVC reducers and couplers

• One to two solar panels totaling 290 watts
• Solar panel battery charge controller, 12V
• A marine 12 V battery with a plastic box with lid to protect it from the water
• Electrical wire
• 2 spare 5 amp marine fuses
• A small marine bilge pump (360 gph)-this is somewhat oversized for the application but is one of the smaller pumps that is available on the market
• Miscellaneous PVC pipe, 1” and 2”
• Four fiberglass cylinders with mesh bottoms-these were custom made and were modeled on standard hatchery downweller systems commonly used on the West Coast. The mesh bottoms are made using fiberglass window screen. For the Molokai model, these canisters were not available. Sections of 55 gallon plastic barrels were used. One barrel yields three sections to which the window mesh can be attached after sanding the cut ends of the barrel sections. These are the blue barrels commonly used to collect rainwater.
• One 32 gallon plastic garbage can (the Rubbermade Roughneck brand was found to be the sturdiest)-this serves as the central sump through which water is pumped from the source to each of the upwelling canisters
• PVC primer and glue
• One-half sheet of 8’x4’ ¼” plywood
• Bolts to attach the solar panels to the plywood
• Electrical tape.

Tools needed to construct to construct the FLUPSY include: hack saw, wood saw, sand paper, scissors, pocket knife (or similar), screw drivers, hammer, PVC cutters, rubber gloves.

Most of the system was built on land and then floated out to the mooring site. The central sump (i.e. plastic garbage can) was installed while the system was floating as the bottom protrudes beyond the bottom of the PVC frame. This system was assembled in six hours with three people working on it.

Ten training sessions were successfully held on Hawaii, Oahu and Molokai Islands between 2010 and 2012, plus at least six working sessions to construct the systems between 2010 for new and prospective oyster farmers.

The final FLUPSY design is shown in Figures 5 and 6.

Research results and discussion:

1. A solar-powered FLUPSY has been designed and utilized that is appropriate for local growing conditions. It meets the cost criteria (less than $1000) established at the start of the project.

2. Three groups (PACRC, Hawaiian Learning Center, Pae Pae `O He`eia) have functional FLUPSYs to support their oyster farming efforts.

3. Oyster farming is now underway at the Oahu and Molokai sites. The availability of a FLUPSY is expected to make a significant positive impact on the cost of seed for these farms in the future.

4. Training in oyster culture methods was conducted at three sites (Hawaii, Oahu and Molokai Islands). A core group of pond managers (12), who will lead oyster farming efforts, were trained in the principal topics of this program (oyster biology, spat rearing and oyster farming). Figure 7 shows some of the oysters raised at the Keawanui pond with participation from high school students.

5. Over 100 students and interns benefit from training and education related to this effort.

6. A total of 20 student workers had their wages partially supported by revenues produced by using the PACRC FLUPSYs to produce spat valued at $40,000.

7. Eight million spat were distributed to two farms in Hawaii and up to 15 farmers in the Northwest (Washington, Oregon, California). These spat were the principal source of purchased spat for the industry cooperator farm (Goosepoint Oyster) in the year 2012. Supplying this spat helped partially relieve the spat shortage in 2012 that was caused the the adverse effects of ocean acidification on NW oyster hatcheries.

8. An unintended impact was increased awareness of the potential to utilize solar power for aquaculture purposes at the Hawaiian pond sites. Currently a trial oyster depuration system utilizing solar power is being tested.

We do not have sufficient information at this stage of the oyster industry development to produce an enterprise budget that would allow us to quantify the economic difference in purchasing spat as opposed to purchasing eyed-larvae, but the Virginia Institute of Marine Biology (2012) has a model enterprise budget for oyster farming that can be used to obtain some estimates. Using their model (with some adjustments for labor and materials), purchasing eyed-larvae has a significant impact on the first and second year pre-tax returns. For the first year, purchasing eyed-larvae produces a -$146,939 return as opposed to -$166,439 for purchasing spat. For the second year’s budget, purchasing eyed-larvae produced $60,831 in pre-tax returns while purchasing spat produce $41, 331. Particularly for small, beginning farmers, this difference in returns could affect long-term viability of the farm.

Participation Summary

Educational & Outreach Activities

Participation Summary

Education/outreach description:

Although the final FLUPSY produced as part of this project is adequate for nursing spat, we feel that it is still possible to improve upon the design to make the system more resistant to wind and wave action, even though the Western SARE project is completed. We are utilizing PACRC program development funds to make and test another FLUPSY. Hence we are postponing producing an instructional brochure for producers until we have finished testing the next model.

Project Outcomes

Project outcomes:

Aside from the benefits described above, this work also helped strengthen partnerships between the major partners. Collaboration is continuing on a number of other initiatives. It has also been a key step in technology transfer during the process of building a shellfish industry for Hawaii, providing both a new form of farming equipment as well as farming skills.


Potential Contributions

Several agriculture professionals benefitted from this work. Two Aquaculture Extension Agents were able to build their capacity for designing and building aquaculture systems utilizing solar power. As mentioned above, this expertise is now being applied to designing a prototype of a solar powered depuration system for oysters for use at the same ponds. The fish pond managers also benefited from the training in all stages of oyster farming. These managers are also responsible for training over 500 students and interns every year, and part of the training involves becoming familiar with oyster farming.

Future Recommendations

This work has been very helpful in demonstrating the possibilities of utilizing solar power for aquaculture systems. This can be greatly expanded upon in the future and could be highly advantageous to many Hawaii and Pacific Island farms given their often remote locations. Wind power should also be further explored.

Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.