OPPORTUNITIES FOR MULTI-TROPHIC AQUACULTURE IN HAWAII AND THE PACIFIC

Integrated multi-trophic aquaculture (IMTA) systems have been  explored and  demonstrated on land and at sea. The basic concept mimics that of the food chain where a waste product from a higher trophic species such as fish,  is bioextracted and  assimilated by lower trophic species including bivalves and marine plants .  

The University of New Hampshire (UNH) has been evaluating a marine IMTA raft that has brought steelhead trout, kelp, and mussels to the marketplace (Fig. 1) . A nitrogen (N) mass balance model was utilized for the project.  Nitrogen input via fish food was calculated and compared to N retained in the fish tissue at harvest and N extracted by mussels and kelp cultured around the fish net .   The results suggested a 1:3 ratio of higher trophic to lower trophic species for a N neutral balance when the organisms are harvested and removed from the environment .

More recently, UNH was funded by Sea Grant to build a second generation, commercial scale IMTA platform called the AquaFort (AF). The two-year program will recruit fishermen and farmers from ME, NH  and MA to participate in workshops and daily operations of the AF farm with production capacity of 20,000 kg. The goal is to increase safe and responsible seafood production in the US.

This concept will be explored for Hawaiian waters with local finfish, bivalve and macroalgae species. Permitting, site selection, culture structure, farm operations and ecotourism will be discussed as a potential business model for Pacific Islands.