We did two things.
First, we looked at the amount of ballast water that we think is being sourced from different freshwater ports on the St. Lawrence River and is destined for the Great Lakes. The overall amount of water being carried by lakers into the Great Lakes is equal to the amount of water that's coming in from the foreign vessels from overseas. It's a substantial amount of water.
The thing about the port of Quebec is that the environmental conditions in that port are very similar to the ports where that ballast water is being discharged. If we have a huge environmental mismatch between the source port and the destination port, then we're not so worried about whether or not invaders are going to survive. If we have a saltwater source port, I'm not worried about those species surviving in the Great Lakes. But in this case, we have similar conditions in the port of Quebec City to some of the ports in the Great Lakes, and therefore we think they may pose a threat.