Not a lot of information in this article but we can safely assume that the contamination came from pesticides running off from the recent heavy rains.
The Department of Fisheries and Oceans has closed two areas of P.E.I. shoreline to shellfishing as a precautionary measure after fears of contamination from heavy rainfall.
On P.E.I.’s north shore, the closure runs east from Gillis Point to a point just east of Cavendish, and takes in the important shellfishing areas of both Malpeque Bay and New London Bay.
On the south side of the Island, the closure affects an area from the church in Mont Carmel east to just east of the Desable River.
The closure restricts harvesting of oysters, mussels, clams and any other bivalve mollusc in a three-kilometre band from shore.
The DFO has brought in similar closures in the past after heavy rains.