Historic Connections Can Become Avenues For Invasives

ArrayAugust 25, 2017 at 12:20 pm

By IFW Fisheries Biologists Greg Burr and Colin Shankland         [caption id="attachment_2459" align="alignright" width="478"] This clogged culvert that separated the two Getchell Lakes caused Upper Getchell to flow into the St. Croix watershed.[/caption] A watershed is defined as “The region draining into a river, river system, or other body of water”. The divide between watersheds is usually quite distinct, generally separated by mountains and hills, but sometimes different drainage areas are so close they can be manipulated and connected by canals for the benefit of industry. Canals were created as a way to move water, materials and vessels cheaply and efficiently. Connections between watersheds can be problematic for fishery managers when invasive fish species are illegally introduced and migrate between drainages. For instance, there are fears that the Chicago canal, which connects Lake Michigan with the Mississippi River System may allow Asian carp into the Great Lakes.  A similar potential problem occurred this spring with a report of an invasive largemouth bass being caught in Third Machias Lake, and if true, is the result of an illegal introduction in the upper Machias River watershed. Third Machias Lake resides in the Machias River Watershed .  Both the St. Croix and Machias watersheds were once connected by a 700-yard channel dug in the 1900’s for the purpose of driving logs between the two river systems. An earthen barrier between Wabassus Lake an Upper Getchell Lake in the man-made channel now separates the two watersheds. Wabassus flows in the St. Croix watershed and both Getchell Lakes flow into the Machias River watershed. While investigating the potential of invasive largemouth migrating into the upper  St. Croix River system,  a debris clog was discovered in the culvert between Upper and Lower Getchell Lakes,  which caused Upper Getchell to flow into the St. Croix’s Wabassus Lake, and Lower Getchell to flow into the Machias’s Third Machias Lake. Wabassus Lake flows into West Grand Lake. Largemouth have been confirmed  in some areas of the lower St. Croix Watershed but have been kept out of West Grand and the lakes above due to the hydraulic jump in the fish-way at the West Grand Lake dam. The introduction of invasive largemouth bass migrating through Wabassus Lake would have the potential to negatively impact the ecosystem of the upper St. Croix watershed, including West Grand and many other lakes that have prized cold-water fisheries. [caption id="attachment_2458" align="alignleft" width="562"] Once water levels rose due to the clogged culvert, the existing barrier was not high enough to stop Upper Getchell Lake from flowing into Wabassus Lake and the St. Croix watershed.[/caption] Once the situation was explained to the land owner, they agreed to let us remove the blockage in the culvert. Water levels stabilized, and both Getchell Lakes are again flowing into Third Machias Lake. We have recommended a deeper and wider road crossing structure be installed between the Getchell Lakes to prevent future clogging, in conjunction with a permanent blockage to be reinstalled in the man-made channel between the watersheds. These actions will restore the drainages and should ensure that an illegal introduction of largemouth bass in the upper Machias River watershed does not negatively impact the upper St. Croix watershed. Illegal introductions negatively impact Maine’s aquatic ecosystems.  These impacts are long lasting and often irreversible.  Never transfer any fish from one water to another and if you see illegal activity do your part and report it to Operation Game Thief by calling 1-800-Alert-Us.  We are all stewards of Maine’s natural resources.