Research Document - 2004/120
The Laurentian Channel as an Alternative Ballast Water Exchange Zone : Risks, Analysis and Recommendations
By Simard, N., M. Hardy
Abstract
The present report aims to provide an assessment of the risks that the use of the Laurentian Channel as an Alternative Ballast Water Exchange Zone (ABWEZ) may pose to fisheries and to the marine ecosystem of the St. Lawrence and Atlantic waters. These risks were evaluated by analysing: 1) the importance of foreign origin vessel traffic that used or can potentially use the Laurentian Channel for exchange; 2) the biodiversity and species richness of organisms found in ballast water and sediments of incoming foreign vessels; 3) environmental conditions of the Gulf of St. Lawrence (GSL); and 4) the dispersion patterns of organisms inoculated in this area with ballast water discharges.
Although the shipping industry does not appear to use the Laurentian Channel extensively as an ABWEZ, analyzed data indicated that a high number of vessels (1948), transporting 12.2 Mt of ballast waters, could have transited in this area in 2000 and potentially use it to perform ballast water exchanges. The majority of ballast waters from all vessels originated from FAO Region B where environmental conditions can be similar to those found in the GSL, particularly during the summer for the North and Baltic Seas. However, the vessels which have declared to have used the Laurentian Channel as ABWEZ originated principally from FAO Region A; the duration of trips from this region is generally shorter than for other FAO regions. Several studies showed that a diverse assemblage of live organisms (including non-indigenous taxa, toxic/harmful taxa and potential risk taxa) from all around the world are present in the ballast tanks of foreign vessels entering the Gulf of St. Lawrence. Simulations of the discharge of organisms in the Laurentian Channel showed that inoculated plankton is retained within the Gulf (higher retention of phytoplankton occurred in spring and late summer) and transported towards coastal areas. The model identified a few areas that are particularly at risk, depending on the season: the Magdelen Islands, southwestern Newfoundland, Northern Cape Breton Island and southern Anticosti Island.
The present risk assessment identified the ABWEZ southeast of Anticosti Island as a potentially vulnerable area for ballast water-mediated introduction of non-indigenous species into the Estuary and Gulf of St. Lawrence and Atlantic provinces. This risk is considered to be generally lower in winter because of cold conditions that prevail throughout the Gulf during that time of the year. However, although the survival rate would be low, there are always a few highly opportunistic forms which can manage to adapt to cold conditions. On the other hand, many taxa may survive during the summer months but their long-term prognosis may be limited.
Given the high potential risk of aquatic invasive species (AIS) introduced through ballast water to the Gulf of St. Lawrence, River and Estuary, where local ecological conditions have proven conducive to the establishment of many types of AIS, the use of the Laurentian Channel as an ABWEZ should be minimized as much as possible. Under extraordinary circumstances, it is recommended that ballast water exchange be allowed if the ship is transiting the Laurentian Channel between December 1 and May 1 or if the ship is carrying freshwater ballast. A decision-support system would be needed to control ballast water exchange between the months of May and December.
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