Co-culture of invertebrates with sablefish (Anoplopoma fimbria) in IMTA in British Columbia: use of laboratory feeding trials to assess the organic extractive potential of various candidate species




Orr, Lindsay Catherine

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One advantage of Integrated Multi-Trophic Aquaculture (IMTA) is the potential for bioremediation by organic-extractive organisms. In British Columbia, a number of marine invertebrate species are being considered for use in open-water IMTA with sablefish (Anoplopoma fimbria). These include both filter-feeding bivalves (e.g. cockles, mussels, oysters, scallops) which would consume the finer suspended particulates from the finfish culture component and deposit/detrital feeders (e.g. sea cucumbers, sea urchins, prawns) which would feed on the heavier-settleable solids. The following candidate species were tested for their ability to consume sablefish faeces and uneaten sablefish feed in laboratory feeding trials: green sea urchin (Strongylocentrotus droebachiensis), basket cockle (Clinocardium nuttallii), blue mussel (Mytilus edulis), spot prawn (Pandalus platyceros), and California sea cucumber (Parastichopus californicus). Whether they can remove organic material from aquaculture wastes was tested by measuring ingestion rate or clearance rate and absorption efficiency when they were fed a diet of sablefish waste, relative to those fed a natural control diet. Egestion rates in the candidate species were quantified to estimate the potential amount of waste that may be lost from the organic-extractive component. Biophysical properties including shape, size, and settling velocity were measured in faecal pellets egested by the candidate species to provide input data for models to assess dispersal of faeces from IMTA sites. Results from the laboratory feeding trials demonstrate that all candidate species are capable of consuming wastes from sablefish aquaculture and absorbing the organic material. The relative merits and drawbacks of each candidate species are discussed with respect to the results and within the broader context of IMTA. The general conclusion is that, in order to achieve efficient removal of organic material and successful bioremediation, deposit feeders should be included in the organic-extractive component, whether alone or in conjunction with suspension feeders.



Integrated Multi-Trophic Aquaculture, organic, waste, bioremediation