Interview with UVM's own Ellen Marsden

Ellen received her doctorate in Fisheries in 1988 from Cornell University, before coming to UVM in 1996 as an Assistant Professor in the School of Natural Resources.  Her interests include restoration of native species, specifically lake trout, and impending effects of introduced exotic species.  She has done extensive work on the movements of sea lamprey in response to pheromones is Lake Champlain, as well as the effect of zebra mussels on soft sediment fauna and benthic predators.  Some selected publications that may be of interest to our readers include:

Marsden, J. E., and M. Hauser. 2009. Exotic species in Lake Champlain. J. Great Lakes Res. 35:250-265.

Madenjian, C. P., B. D. Chipman, and J. E. Marsden. 2008. Estimate of lethality of sea lamprey attacks in Lake Champlain: implications for fisheries management. Can. J. Fish. Aquat. Sci. 65:535-542.

Q:  What do you believe to be the top three invasive species present in Lake Champlain
A:  Zebra mussels are clearly the first, followed closely by alewife.  As for the third, it is a toss-up between the aquatic plants milfoil and chestnut.

Q:  There has been recent debate on whether or not sea lamprey are a native species.  What is your view?
A:  First off there is genetic data that says they are native, but I believe this is not compelling, and it is easier to say that they are not native, than they are.  There is no record of sea lamprey in the records of Jesuit priests, who were incredible naturalists and took very detailed notes.  We know that there are, and were, silver lamprey in Lake Champlain, but there are no records of people seeing these organisms either.  One would think that if someone were to notice these grotesque creatures, that they would take note.  The reason sea lamprey have become such a nuisance is that we have created the perfect habitat for them; an incredibly silty environment, and the removal of their larval predator, the eel.

Q:  Do you believe there are any invasives that are helpful to Lake Champlain
A:  No matter what you do exotics will eat something, usually native, causing a some sort of negative effect.  But if this food source were plentiful, for example a brook silverside, than we can look past this.  We used to think that round gobies had no effect, but we now know that they displace the native sculpin and eat lake trout eggs.  When evaluating what is "good" or "bad", we must consider through what lens we are viewing.  Anything that humans like will be deemed good, for example white perch.  These fish do compete with natives, but there is no noticeable decline in such populations.  They also may shift fishing pressure away from the natives, and people love to catch these fish.

Q:  Could there be a time when Lake Champlain is completely invaded?
A:  Even though a system may seem wrecked or out of whack, there is still no such thing as completely invaded.  Whether the outcome is good or bad for us, the system will make adjustments to the changes.  This could take 2-3 years to occur.  Natives could indeed play a smaller role in the future, but still contribute to the system.

Q:  Do you know of any control methods for the infestation of zebra mussels?
A:  When it comes down to it, there is nothing really.  Some organisms may be realizing they are edible, such as crayfish, drum and carp.  Their population growth seems to be leveling off, as the are over their carrying capacity and beginning to compete with themselves.  The only real control we can do is in fixed situations such as intake pipes.  We have employed toxic surfaces and robots to scour the insides of the pipe, put this is very hard to get at.  Chlorine may be used, but it is detrimental to other species.  The biggest thing to do is prevention.  There are bans in the importation of baits and aquatic plants curb any new introductions into Lake Champlain.  Management has ceased the stocking of any new exotics, only the continuation or currently stocked brown and rainbow trout. Boat hauling has become closely monitored especially because the Champlain Canal is the main source of invasives.  Our only salvation to this problem would be to eliminate all boat traffic.  And of course there is always education!