Damien and locals collecting samples
Native Hawaiian Fishponds:
Environmental and Economic Relevance

By: Damien Cie

Over the past century, the collapse of marine fisheries has become a far too common occurrence.  With the global human population continuing to increase at an exponential rate and the demand for fish at an all time high, it is presently believed that 30% of world marine resources are exploited beyond sustainability (Duarte 2007). In part, to circumvent harvesting diminishing wild populations, commercial aquaculture has been developed at unprecedented levels, providing in excess of 40 million tons of products annually (FAO 2007). However, the majority of aquaculture is focused on freshwater organisms, with only an estimated 10% from marine species. Moreover, within the past decade, techniques for establishing and maintaining aquaculture have been consistently criticized for their environmental impacts, including erosion, coastal degradation, and increased occurrence of harmful algal blooms (Maso & Garces 2006, Jayappa et al. 2006, Pergent-Martini et al. 2006). These environmental conditions have caused numerous ecological (i.e. fish die-offs, marine mammal strandings) as well as human health concerns, namely the consumption of infected fish and crustaceans and the ingestion of contaminated water (Sapkota et al. 2007, Vasas et al. 2007, Lopez-Rodas et al. 2006, Maso & Garces 2006).

The goals of this project, will be to improve upon current techniques and management practices for marine aquaculture, through a detailed study of historical techniques that were used successfully throughout the Hawaiian Islands for hundreds to thousands of years (Costa-Pierce 1987, Kikuchi 1976).The Hawaiian systems of farming or “ahupua’a” combined numerous farming techniques by integrating agriculture with freshwater and marine aquaculture into a complete system. Originally, these systems were built to be self-sufficient, with nutrients and food passing through the systems from high watersheds ultimately to extensive marine fishponds. During their existence, these ponds were used to cultivate a variety of fish, invertebrates, and algae. Although recent advances in modern aquaculture techniques have met some success and led to many breakthroughs, we believe that much can be learned from techniques that have been in existence and have proven effective in the past. In fact, current studies in Canada and the United States have begun to focus on the integration of multiple species into complex aquaculture systems (Chopin 2006, Troell et al. 2003). Known as Integrated Multi-Trophic Aquaculture (IMTA), the central concept shares the ideology used successfully over 2000 years ago by Native Hawaiians. Since Hawaiian fishponds produced a variety of species, they are a perfect historical example of a true multi-trophic integrated system.

Previous research pertaining to Native Hawaiian fish ponds primarily focused on economic, permitting procedures, and restoration issues. This study will address the scientific aspect of traditional aquaculture with emphasis on the concerns related to the environment and food safety, particularly those associated with the rearing and harvesting of marine species for consumption. The project aims to educate the public and scientific community by addressing issues related to the establishment of more environmentally conscious aquaculture that could ultimately provide healthier seafood. Objectives will include the site-specific assessment of the environmental impacts of present and past marine aquaculture, the ecological and economic feasibility of developing marine aquaculture systems based on historical techniques, and application of geographic information system (GIS) environmental models to aid in site selection for new facilities. In addition, performing a contingent valuation survey would help support the push for such facilities, by providing relevant market information.

Methods:

(Water samples)
To assess nutrient levels, algal concentrations, bacterial abundance, and salinity within and around active and non-active fishponds two 150ml water samples were collected from both the center and exterior (approximately 100m away from the pond walls) of each of the 11 ponds surveyed. Salinity was then determined using a refractometer (Fisher #1394625).  For preliminary bacteria comparisons, 5ml from each sample were placed in a petri dish prepared with marine agar and allowed to cultivate for 48 hours. Additionally, 15ml from each sample were transferred over to falcon tubes containing 0.2% formalin fixative for subsequent bacterial comparisons. Lastly, the remaining 130ml were then filtered through GFF filters and placed on ice.  Filters were then wrapped in aluminum foil and placed in a moisture-free container. After field collection and preparations, all samples and filters were transferred over to a -20oC freezer for storage.  

Chlorophyll and Phaeophyta concentrations were prepared in methanol and analyzed using a Turner fluorometer. Data was then inputted into an excel spreadsheet with corresponding calibration formulas and is currently being reviewed for trends within and among the interior and exterior of the fishponds. Nutrient levels are currently being analyzed by the Marine Science Institute at the University of California Santa Barbara for phosphate, nitrate, nitrite, and ammonium using the flow injection analysis method. Bacterial abundances were addressed in two ways: 1) by visual comparisons between cultured Petri dishes prepared in the field and 2) quantitative counts of bacteria present from formalin fixed samples previously collected in the field and viewed under UV microscopy.

(Sediment cores)
To address environmental concerns from fishpond construction and use, we attempted to collect sediment cores within the fishponds to determine historical usage, sedimentation, and nutrification.  Unfortunately, 7 out of the 11 ponds surveyed consisted of a course rubble/sand mixture below the surface layer of fine sediment which damaged the coring tubes and made collecting samples difficult.  Due to time constraints, we were unable to make core modifications in the field and had to stop the procedure.  In the near future –after coring modifications and shipping issues have been addressed- we plan on re-sampling the fishponds.

(Rock cores)
Initially the historical timing of fishpond construction was to be determined by using Uranium-Thorium dating of cores of calcareous algae and/or crustose corallines growing on the basaltic rocks of the pond walls.  Unfortunately, due to the increasing concerns regarding coralline species in Hawaii, all scientific permits requesting the collection of corallines and/or live rock were denied. However, since we already have the sediment cores in our hands, we can use them instead of the rock cores to assess historical timing using carbon dating.  This, we hope, to perform during our next field season.  We will have a better picture of whether or not this is feasible after cores are inspected for dating material. 

(GPS)
During our sampling procedures, geographical data was also collected using a Garmin GPSMAP 76csx. In order to determine pond parameters, data points were collected by walking completely around each pond –a few of which were up to 2 km in circumference- and marking the end points of the pond wall and locations for all active and inactive makahas/sluice gates.  In addition, if fresh water sources (i.e. streams) were found flowing into or adjacent to the pond walls, they were also mapped and analyzed for salinity using a refractometer.

(Valuation survey)
Throughout the field study we were unable to obtain survey information due to an unexpected delay in the permitting process from the International Review Board at UCSD. Although I could not perform an in-depth contingent valuation survey to address the social and market support for fishponds, I was able to casually film and interview persons living near and working on the ponds.  While the interviews were insightful, each conversation was independent and, therefore, did not provide any standardization.  However, we are attempting to review the films/audio in order to establish a point scale system and determine value metrics, which can help provide insight in determining the levels of social and market support.

Results:
Hawaiian fishponds are estimated to have existed for over 2000yrs, supporting historical populations in excess of 1 million inhabitants.  Whether or not these ponds have the potential to provide current environmental and economic benefits has yet to be determined and has been addressed in this preliminary research. During our field study we collected water, sediment, and global positioning information from 11fishponds (Maui-2, Molokai-5, Oahu-4). Visual comparisons showed a significant difference between the interior and exterior of fishponds depending on wall conditions and use. Ponds that were still physically intact but inactive had high concentrations of algal growth and bacteria; whereas, ponds that were currently being used for fish and algal cultivation showed reduced levels of bacteria growth and algal presence. Ponds that were inactive due to missing sections of the kuapa or walls showed the least amount of bacteria and algal growth. In fact, these latter ponds showed recruitment of coral species with accompanying fish and invertebrates. In all three cases it appears that use and wall condition determine pond suitability.  Ponds that are inactive and have intact walls may become stagnant creating oligotrophic conditions.  In areas with high run-off or nearby urbanization ponds may accumulate nutrients causing localized algal abundance possibly leading to algal blooms. Although our evidence supports these inferences, they are instantaneous and do not address spatial or temporal scales. Therefore, additional sampling will be performed over the next two years to help address these issues.

Salinity levels varied depending on the frequency of rain, topography, and whether or not a freshwater source was present. Ponds that were constructed near or with freshwater input had lower levels of salinity then samples taken from the exterior of the ponds. Ponds that were either built in areas with very little rainfall, high evaporation, or without a freshwater source had elevated levels. Collected sediment cores are currently being stored and have not been analyzed.  To examine the physical and environmental parameters concerning pond construction, GPS data points were plotted onto a topographic map using ESRI ArcView. Future field work will attempt to collect additional topographic and ocean current information to help in elucidating these parameters. Video and audio information has yet to be analyzed and a more thorough contingent valuation survey will be performed in the future.

Conclusion:
During my field study I had the pleasure of working with Chairperson Mei-Ling Akuna from the Alliance for the Heritage of East Maui (AHEM) –a local service group that focuses on environmental issues affecting the development of East Maui. Not only does she deal with local issues but also participates in the Maui County council which has jurisdiction over the island of Molokai, where a majority of my sites were located.  This made access to the sites and collection of material much easier allowing me to increase my sampling efforts from 8 to 11 fishponds.

For centuries, fishponds have not only been a staple of the Hawaiian culture, but also a symbol of Hawaiian innovation that paved way for current marine aquaculture.  Restoring and or redeveloping fishponds seem like an obvious priority; however, what are the economic and environmental downsides?  These are the concerns that need to be addressed, most or all of which I hope to accomplish in this study.  Our preliminary data, thus far, supports the need to address the ponds appropriately by choosing to restore them for cultural preservation or redevelop them for cultivation. Since, inactive ponds pose negative environmental and economic concerns either choice would address these issues. However, each pond has its own set of social and environmental concerns that must be considered when choosing an appropriate course of action. In extreme cases it may be in the best interest to remove ponds entirely. Ponds that are unable to be restored or redeveloped have the potential to affect local water conditions, species abundance, and coastal aesthetics for rural and urban areas.  Considering the decline in many local marine species and the high dollar value of coastal property in Hawaii, this course of action would make environmental and economic sense. Since many of the ponds are state or federally owned, there may be limitations on what can actually be performed due to their protection under the National Historic Preservation Act of 1966.

While the research itself is important, sharing of the findings is equally valuable.  Therefore, I will be presenting my work and participating as a panelist in this year’s Society for the Advancement of Chicanos and Native Americans in the Sciences (SACNAS) conference at CSU San Marcos.  This opportunity will also allow me to fulfill another life’s goal: to reach out to minority students and give them perspective on graduate studies and a possible career in the sciences. I look forward to completing more of my analyses and returning to the field in the coming summer.  Much of the progress of my research has been aided by the Sussman Foundation, whose support I am grateful for.

This material is based upon work supported by the National Science Foundation under Grant No. 0333444.

Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.

References:
Chopin, T. 2006. Integrated multi-trophic aquaculture. What it is, and why you should care...and don't confuse it with polyculture. Northern Aquaculture 12.

Costa-Pierce, B. A. 1987. Aquaculture in Ancient Hawaii. Bioscience 37:320-31.

Duarte, C. M. 2007. Rapid domestication of marine species. Science 316:382-83.

FAO 2007. The state of world fisheries and aquaculture. 162.

Jayappa, K. S., Mitra, D. & Mishra, A. K. 2006. Coastal geomorphological and land-use and land-cover study of Sagar Island, Bay of Bengal (India) using remotely sensed data. International Journal of Remote Sensing 27:3671-82.

Kikuchi, W. K. 1976. Prehistoric hawaiian fishponds. Science 193:295-99.

Lopez-Rodas, V., Maneiro, E., Martinez, J., Navarro, M. & Costas, E. 2006. Harmful algal blooms, red tides and human health: Diarrhetic shellfish poisoning and colorectal cancer. Anales de la Real Academia Nacional de Farmacia 72:391-408.

Maso, M. & Garces, E. 2006. Harmful microalgae blooms (HAB); problematic and conditions that induce them. Mar. Pollut. Bull. 53:620-30.

Pergent-Martini, C., Boudouresque, C.-F., Pasqualini, V. & Pergent, G. 2006. Impact of fish farming facilities on Posidonia oceanica meadows: a review. Marine Ecology 27:310-19.

Sapkota, A. R., Lefferts, L. Y., McKenzie, S. & Walker, P. 2007. What do we feed to food-production animals? A review of animal feed ingredients and their potential impacts on human health. Environmental Health Perspectives 115:663-70.

Troell, M., Halling, C., Neori, A., Chopin, T., Buschmann, A., Kautsky, N. & Yarish, C. 2003. Integrated mariculture: asking the right questions. Aquaculture 226:69-90.

Vasas, V., Lancelot, C., Rousseau, V. & Jordan, F. 2007. Eutrophication and overfishing in temperate nearshore pelagic food webs: a network perspective. Marine Ecology Progress Series 336:1-14.