Estimating fall-off of mussels cultured on self-operating collectors

In Carleton (Chaleur Bay, Quebec), some mussel farmers are using the self-operating collector method, which consists of culturing mussels on collectors without adjusting the density. This results in a decrease in population density due to a self-thinning process. Differences in the number and size of mussels that fall to the bottom depend on whether socks or self-operating collectors are used.

Mussel fall-off with self-operating collectors can be calculated based on the principle of self-thinning. The necessary data are currently available in a publication in preparation by Lachance-Bernard et al.. However, there are at present two possible approaches to calculation.

The goal of this project was to determine the best approach and to provide a preliminary estimate of the fall-off process. The requisite samples were obtained by divers in order to minimize mussel fall-off during sampling. This work was a preparatory stage for comparison of the ecosystem effects of conventional suspension culture and mussel culture using self-operating collectors.

As a result of this project, we have found no evidence of non-linerarity in the relationship between biomass and population density. This indicates that individual growth is not dependent on population density. This piece of information will be useful for choosing the appropriate method for calculating mussel fall-off.

For further information, please contact: project leader, Marcel Fréchette, at Marcel.Frechette@dfo-mpo.gc.ca.