Sustainable Integrated Finfish/Nori Aquaculture for Bioremediation and Production of Food and Biochemicals

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Sustainable Aquaculture


George Nardi GreatBay Aquaculture, LLC Co-Principal Investigator
Christopher Neefus UNH - Department of Biological Sciences Principal Investigator

Students Involved:

Jennifer Day UNH - Department of Biological Sciences

On a global scale, marine aquaculture is a rapidly expanding multi-billion dollar industry, while capture marine fisheries have been level or declining. Virtually all recent increase in demand for marine finfish and shellfish has been met through increased aquaculture production. The United States is a major consumer of marine aquaculture products, yet we grow only a tiny fraction of global production.

Since 1980, through a number of federal programs, the U.S. government has actively encouraged the expansion of U.S. aquaculture and the development of new industry sectors. A recent program is the National Marine Aquaculture Initiative (NMAI), which has provided research funding for solutions to obstacles impeding the growth of U.S. aquaculture. The NOAA Sea Grant Program has continually supported applied research for the development of marine aquaculture.

One obstacle to the growth of aquaculture has been concerns over environmental impacts, including nutrient loading of coastal waters from effluent generated by coastal and shore-based aquaculture operations. Inorganic nutrients (nitrogen and phosphorus) leach from uneaten fish food and are excreted as metabolic waste products from fish. Elevated dissolved inorganic nutrient levels in coastal water can trigger harmful algal blooms, which in turn have serious negative effects on coastal ecosystems.

One of the goals of the NH Sea Grant Strategic Plan is to ensure that aquaculture is environmentally sustainable. One of the listed "Actions and Opportunities" for achieving this goal is the development of improved methods of waste management for land-based and coastal/offshore aquaculture. An ideal solution for removal of dissolved inorganic nutrients from the effluent stream of land-based aquaculture operations is through integrated aquaculture that combines fish production with production of a commercially valuable seaweed species such as the red seaweed Porphyra (nori). Nori is grown extensively via aquaculture in Asia with annual production in excess of U.S. $1.8 billion; it is used for food and as a source of valuable biochemicals.

Seaweeds require nitrogen and phosphorus for growth and production of proteins and photosynthetic pigments and they uptake these nutrients from the water. When the seaweed is harvested from an integrated aquaculture system, the nutrients are removed from the system and eliminated from the effluent stream. Nori is especially well suited for integrated aquaculture as it has very high growth and nutrient uptake rates, plus high commercial value.

The goal of our proposed Sea Grant project is to implement and refine a demonstration scale Modular Integrated Recirculating Aquaculture System (MIRAS) combining the culture of finfish (cod and black sea bass) with the production of several species of Porphyra (nori) that are native to New England. The system has already been constructed as part of previous Sea Grant and NMAI research projects, but its operation and experiments utilizing the system have been postponed due to loss of funding for the final year of the NMAI project (resulting from elimination of the entire NMAI budget by the U.S. Congress).

Objectives of our proposed Sea Grant project are to demonstrate the operation of the system for the production of fish and seaweed and to demonstrate that effluent from the system has greatly reduced levels of dissolved organic nutrient compared to conventional flow-through and recirculating systems. In our system, nori will initially be grown as a source of r-phycoerythrin, a valuable red pigment used in a number of biotechnology assays. A series of experiments will determine fish-to-nori biomass ratios and other operating conditions that optimize the production of fish biomass and nori pigments, the maintenance of water quality, and the removal of nutrients. Production figures and operating costs will be used to develop a business model for implementation and operation of the system. This


1) Demonstrate the performance of a continuously operating, integrated aquaculture system from which finfish and nori are harvested

2) Demonstrate that acceptable water quality can be maintained in the system and that overall nutrient discharge can be significantly reduced

3) Determine nutrient removal, biomass production and pigment production rates of five native species of Porphyra (nori) in a demonstration scale system

4) Determine nutrient excretion rates of two fish species (cod and black sea bass) in relation to feeding rate, stocking density and size in a demonstration scale system

5) Determine optimum fish to seaweed biomass ratios

6) Provide educational opportunities in the technical and scientific aspects of integrated aquaculture

7) Develop a business model for the system to facilitate acquisition of capital by startups and existing aquaculture businesses interested in implementing integrated aquaculture systems


The Modular Integrated Recirculation Aquaculture System (MIRAS) constructed at the Great Bay Aquafarms facility during a previous NOAA OAR NMAI project will be put into operation. It will be used for a series of experiments to determine optimum operating conditions for fish and seaweed (nori) production, maintenance of water quality, and reduction of nutrient load in effluent. Production figures and operating costs will be used to develop a business model for implementation of the system.


A goal of the NH Sea Grant Strategic Plan is to ensure that aquaculture is environmentally sustainable. A listed "Actions and Opportunities" for achieving this goal is to develop improved methods of waste management for aquaculture. An attractive approach for decreasing nutrients in effluent from land-based operations is via polyculture systems that integrate the culture of finfish with the production of economically important seaweed (e.g., nori). Seaweeds accumulate and utilize nutrients in the production of proteins and biomass; when the seaweed is harvested, the nutrients are effectively removed from the system.

The primary objective of this project was to demonstrate successful operation of the Modular Integrated Recirculation finfish/seaweed Aquaculture System (MIRAS), which we have done, and to begin initial series of experiments aimed at optimizing the production of fish, nori and nori pigments, the maintenance of water quality, and the removal of nutrients from the system effluent.
We completed a series of feeding trials at Great Bay Aquaculture, a recognized expert in the field of finfish aquaculture, for small juvenile black sea bass using three different feed rates. In addition to fish growth rate (SGR) and food conversion rates (FCR), we examined the nutrient excretion in response to feeding rates for two fish sizes and two different diets. The results have been used in conjunction with nutrient uptake data to predict safe seaweed:biomass ratios for the integrated system.
We demonstrated the successful operation of a demonstration scale Modular Integrated Recirculating Aquaculture System.
Initial integrated operation of the MIRAS systems at Great Bay Aquaculture (GBA) during this project has been very successful. We have conducted feeding, growth rate and nutrient excretion studies on two fish species: Black Sea Bass (Centripristis striata) and Atlantic Cod (Gadua morhua). We have run nutrient uptake, growth rate and pigment production studies on three native Porphyra species (P. umbilicalis and P. linearis). Finally, we have run the system in integrated mode combing Black Sea Bass with P. umbilicalis and P. amplissima, and Atlantic Cod with P. umbilicalis and P. linearis.
During the studies, fish grew at rates that equaled or exceeded those in GBA’s conventional system. The cod were produced in the GBA hatchery and introduced to the integrated system as small juveniles (50g). The system has been running for nearly a year, alternating between flow-thru mode and integrated recirculating mode and the cod have reached 650 g.
All three species of Porphyra grew well (up to 30% per day) in the integrated system and water quality remained excellent even with fish:seaweed biomass ratios as high as 2:1. Ammonium levels in the system stayed well below stress levels for the fish, and were often lower than the water coming into the GBA facility from Great Bay. Each of the integrated system runs lasted for 4 to 8 weeks. Porphyra was stocked in the tanks as small sporelings (~2 cm) and matured to harvest size (15 to 20 cm) within 3 to 4 weeks.
During integrated operation, we were able to examine nutrient production rates of the fish and nutrient uptake rates of the seaweed by interrupting the recirculation for several hours at different times of day and monitoring changes in nutrient levels in the seaweed and fish tanks. Using these results plus nutrient uptake curves generated in supplemental studies, we were able to generated predictive models of the nutrient levels that should be maintained in the system for different fish:seaweed biomass ratios for a limited set of conditions. We were able to test our predictions by adjusting the biomass of nori in the system and monitoring nutrient levels. Overall, the predictions worked well. The one factor that prevented continuous operation of the system and completion of our planned experiments was the need for a steady supply of Porphyra sporelings. The system requirements exceeded the sporeling production capacity of the research culture facilities at the University of Connecticut. Addressing this issue is a critical objective for future work.


Available from the National Sea Grant Library (use NHU number to search) or NH Sea Grant

Journal Article

  • West, A., A. Mathieson, A. Klein, C. Neefus and T. Bray (2005). Molecular ecological studies of New England species of "Porphyra" (Rhodophyta, Bangiales). Nova Hedwigia 80(1-2):1-24.
  • Kraemer, G., R. Carmona, T. Chopin, C. Neefus, X. Tang and C. Yarish (2005). Evaluation of the bioremediatory potential of several species of the red alga "Porphyra" using short-term measurements of nitrogen uptake as a rapid bioassay. Journal of Applied Phycology 16(6):489-497.
  • Kraemer, G., R. Carmona, C. Neefus, T. Chopin, S. Miller, X. Tang and C. Yarish (2004). Preliminary examination of the bioremediation and mariculture potential of a Northeast U.S.A. and an Asian species of "Porphyra." Bulletin Fish. Res. Agen. Supplement No. 1:77-82.
  • Bray, T., C. Neefus and A. Mathieson (2006). Morphological and molecular variability of "Porphyra purpurea" (Roth) C. Agardh (Rhodophyta, Bangiales) from the Northwest Atlantic. Nova Hedwigia 82(1-2):1-22, February 2006.
  • Walker, A., H. Fournier, C. Neefus, G. Nardi and D. Berlinsky (2009). Partial replacement of fish meal with Laver "Porphyra" spp. in diets for Atlantic cod. North American Journal of Aquaculture 71(1):39-45, January 2009.
  • Sampath-Wiley, P. and C. Neefus (2007). An improved method for estimating R-phycoerythrin and R-phycocyanin contents from crude aqueous extracts of "Porphyra" (Bangiales, Rhodophyta). Journal of Applied Phycology 19(2):123-129, April 2007.
  • Kim, J., G. Kraemer, C. Neefus, I. Chung and C. Yarish (2007). Effects of temperature and ammonium on growth, pigment production and nitrogen uptake by four species of Porphyra (Bangiales, Rhodophyta) native to the New England coast. Journal of Applied Phycology 19(5):431-440, October 2007.


  • Day, J. (2008). The development of a modular integrated recirculating aquaculture system using "Porphyra" (nori) for the bioremediation of marine finfish effluent. Doctoral Dissertation, University of New Hampshire.