Developing an Additional Biofilter for Organic Wastes Originating from Atlantic Salmon Farms Using Polychaete Worms at Integrated Multitrophic Aquaculture Sites
The aquaculture industry in Canada is currently undergoing another transition phase as it strives to become more sustainable and environmentally benign. One of the methods currently being considered in this evolution is a practice known as integrated multi-trophic aquaculture (IMTA). The underlying principle behind the IMTA concept is one of re-cycling of nutrients for more profitability and sustainability. In essence, the IMTA practice combines, in the right proportions, the cultivation of fed aquaculture species (e.g. finfish) with organic extractive aquaculture species (e.g. filter feeders, deposit feeders) and inorganic extractive aquaculture species (e.g. seaweed) for a balanced ecosystem management approach that takes into consideration site performance specificity, operational limits, and food safety guidelines and regulations.
However, while the IMTA research shows that mussels are effectively filtering the fine organic particulates coming from the salmon site, the majority of the organic loads settling to the bottom are too large for mussels to physically handle. As the salmon industry is moving towards performance-based standards based on benthic sulphide concentrations to regulate their farming operations, avoiding organic enrichment of the bottom will be crucial for successful and sustainable operations.
The waste energy coming from the salmon faeces needs to be recycled through detritivores or decomposers before it reaches the sea bottom; preferably one that also has a commercial value. One group of organisms that would fit the detritivore criteria for finfish aquaculture is the polychaetes (see for example Tsutsumi et al. 2005). They are highly efficient detritivores and are also commercially valuable (up to $50/kg).
This study will begin development of a polychaete biofilter for the IMTA concept in conjunction with the salmon industry by evaluating the use of polychaete juveniles (Nereis virens) grown in cages on salmon aquaculture sites with first and second year fish.
2007 - 2009
Atlantic: Gulf of Maine, Scotian Shelf
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