Comparing the impact of bottom and suspended oyster culture on bay-scale food resources (Foxley/Trout River, PEI)
Bivalves, such as mussels and oysters, are filter feeders that extract naturally occurring food, such as plankton, from the water. Their culture does not require the addition of feed, however, growth depends on the availability of food in the environment. When farming these species, special care must be taken to ensure that the number of cultured animals - does not exceed carrying capacity of the area. Exceeding carrying capacity will ultimately result in decreased growth of the cultured animals and could potentially impact other components of the ecosystem.
Oyster (Crassostrea virginica) aquaculture is gradually evolving from the traditional use of the benthic environment (bottom culture) to suspension culture, where the animals are grown in or on structures suspended in the water column where higher growth rates are often observed. The Foxley/Trout River system in Prince Edward Island (PEI) is considered to be one of the more heavily utilized oyster producing areas on the island. Some oyster culturists in this area have experimented with this new approach and are requesting to convert their bottom leases to suspended leases. However, both industry and regulators recognize the need to evaluate the ecological impact of growing oysters in the water column before lease conversions are granted. Since suspended culture holds a greater density of shellfish than bottom culturing, food availability may be an issue if all leases were to become suspended culture.
This project is designed to address the issue of carrying capacity by examining the extent to which the diet of bottom and suspended oysters overlap; comparing the filtration rates of oysters from the two culture types (bottom and suspended); and incorporating this information into a simple bay-scale model to quantify the impact of different culture scenarios on available food resources.
The outcome will provide managers and regulators with a quantitative framework for assessing the impact of converting oyster leases from bottom to off-bottom status and having both bottom and off-bottom oyster leases within the same bay area.
Carrying capacity: the maximum bivalve stocking density that can be cultured without excessively compromising individual growth rate, and without compromising other components of the ecosystem.
2012 - 2014
Atlantic: Gulf of Maine, Scotian Shelf
Research Biologist, Aquaculture and Coastal Ecosystems, DFO Gulf
343 Université, Moncton, NB, E1C 9B6
Tel.: (506) 851-2977
Fax: (506) 851-2079
Luc Comeau, DFO- Gulf Region
Claudio DiBacco, DFO-Maritimes Region BIO
Réjean Tremblay, Institut des sciences de la mer de Rimouski, Università du Québec à Rimouski
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