Sustainable Mussel Farming - A Carrying Capacity Model

Summary:
The goal of this project was to develop an accurate carrying capacity model, utilizing existing data of both meat yields and hydrographic data collected to date on all leases. The model created utilized actual performance data for the past 8 years in total dry biomass mussel meat weights. In addition temperature recorders over several years in many locations in the harbour provided hydrographic data to the model. The model used existing chlorophyll levels available to the mussels and groundtruthed with actual chlorophyll data collected in 2010 at many locations in the harbour. It made a couple of clear predictions which were derived with an identical conclusion from actual mussel performance on the various leases comparatively. Dr. Annamarie Hatcher did a statistical analysis of growth data taken over the year between leases and came up with the identical conclusion as the model indicated which leases were the best performers based on food supply. This is a valuable tool for the farm to place mussels that are expected to achieve market size first on the outer leases to get a jump on to the market earlier.

 Another important factor that was identified by the model and confirmed with actual chlorophyll data that the nutrient impact of North River to trigger primary productivity was limited to a narrow window in the spring from snow melt. During the summer the main food source of phytoplankton is derived from outside the harbour and levels vary with precipitation levels. The model calculated that the actual volume of nutrients from the North River is minimal to have a significant impact on the entire harbour phytoplankton production. From a farm perspective, all these factors mean that the inner harbour must be managed carefully in order to ensure significant phytoplankton levels for growth performance. In addition, good husbandry techniques including keeping all backlines, buoys, and scope lines clean of bio-fouling filter feeders is vital to preventing overload of other filter feeders to the ecosystem.   
 
The goals were met by the study by demonstrating the level of production that must not be exceeded in specific areas of the harbour. The study indicates that in future it is vital that dry meat biomass estimates are required annually as done under the environmental

Project Lead: 5M Aqua Farms Ltd.

Total Project Cost: $170,461
           
DFO-AIMAP Contribution: $15,000

Other Financial Support:

• Recipient: 5M Aqua Farms Ltd.
• Provincial Government: Nova Scotia Department of Fisheries and Aquaculture (NSDFA)
• Enterprise Cape Breton Corporation (ECBC

For more information please contact the regional coordinator.

Maritimes Region: Cindy.Webster@dfo-mpo.gc.ca