I cannot give you data because I'm not part of the actual control personnel, but I think there's no question, pesticide is by far the most effective.
I alluded to the use of traps that are being used at the present time mostly for population evaluation purposes in terms of what densities of lamprey we are dealing with, as opposed to being used for outright control because of the high variability in efficiency. Typically efficiency is quite low, especially in very large river systems like the St. Marys.
In terms of the barrier dam issue, it can be quite good, in that it really prevents animals from moving up into spawning habitat and it's a one-time cost in the sense that you have to build a barrier only one time. Of course you have to go and collect the animals. And it's effective.
There is a problem with that. During the latter part of my undergraduate studies in the late nineties I actually participated in a study that looked at the effect of those barrier dams on the migration patterns of other native fish species. Yes, we do stop sea lamprey, but we also stop a number of other fish species that actually have their spawning migration roughly around the same time. An example at hand would be the common white sucker, catostomus commersoni, which also has its spawning migration right at the same time as when sea lamprey do. So yes, we stop sea lamprey, but it has other effects. So again, it's kind of a double-edged sword.
In terms of the other methods, namely the sterile males, I'm not aware of any data in terms of how effective it is. If you were to ask somebody from Fisheries and Oceans Canada they probably could give you better data on that, but I know that due to cost issues that program was terminated lately, even though we do know that once those animals are sterilized they cannot spawn.
The pheromone program is not at the stage of actually being used for any kind of control, and the repellent is just starting up, so those would not figure at all into the overall equation.