Interactions between oyster farming and the productivity of wild oyster beds

PARR-2017-G-10

Description

In Prince Edward Island, eastern oyster (Crassostrea virginica) farming relies almost entirely on natural spat produced by wild oyster beds. In the oyster life cycle, free-floating larvae settle on and attach to a hard surface, a stage known as spat, before developing into juvenile oysters. At the time of this study, there were 226 spat collection (fishing) licences and the demand for additional licences was progressively growing with the development and expansion of the oyster aquaculture industry. The demand for oyster spat may be impacting natural settlement and recruitment processes on wild oyster beds. This study investigated the preferences of oyster larvae to man-made and natural seabed substrates for settlement. Oyster larvae from both wild and cultured oysters was exposed to three man-made and three natural substrates with and without substrate choices to determine the oyster recruitment to different substrates. Results provide a preliminary understanding of the dynamics between wild and farmed oysters and will inform management decisions regarding the use of artificial spat collectors.

Findings

Oyster larvae preferred natural substrate (i.e., oyster shells) at the tank bottom over all other available substrates (i.e., suspended shells, corrugated PVC pipe, Chinese hat and Zapco collector). Oysters did not settle passively but sought out optimal substrate. In this case, oysters were typically found on the underside of the bottom shells. There is an increased demand for oyster larvae by aquaculture and further work on the extent of the capture of wild oyster larvae diverted to culture should be explored.

Publications

Poirier, L.A., Clements, J.C., Davidson, J.D.P., Miron, G., Davidson, J., Comeau, L.A. 2019. Sink before you settle: settlement behaviour of American oyster (Crassostrea virginica) larvae on artificial spat collectors and natural substrate. Aquaculture Reports 13:100181 https://doi.org/10.1016/j.aqrep.2019.100181.

Program Name

Program for Aquaculture Regulatory Research (PARR)

Years

2017-2018

Principal investigator

Luc Comeau
Research scientist, Gulf Fisheries Centre, Moncton, NB
Email: Luc.Comeau@dfo-mpo.gc.ca

Collaborative Partners

Lennox Island First Nation
University of Prince Edward Island (Atlantic Veterinary College)
Université de Moncton