The Canada C3 Science Perspective – June 3

By: Ailsa Barry, Canada C3 Researcher

I think everyone who visited the Glenora Fisheries Station became an eel convert. Yes, they are slippery and slimy but their energy, inquisitiveness and determination in completing their life journey makes you root for their survival. Aside from their charm, the eel population also gives us valuable data on the health of Lake Ontario’s ecosystem.

The Glenora Fisheries Station is located east of Picton on the Bay of Quinte and was originally constructed in 1872 as a foundry powered by water turbines. In 1922, it became a fish hatchery for trout and whitefish. When that was no longer economically viable, it was converted to a research station.  The long-term studies at the research station have enabled the station to collect unparalleled freshwater fish data.

Effective eel management is key in supporting the survival of the eels. The elvers, or baby eels, migrate from the Sargasso Sea, an area full of nutrient rich algae and seaweed in the mid-Atlantic, to the inland waterways of North America. They travel up the Atlantic and through the St Lawrence until they reach the Great Lakes. They navigate the dams via specially designed eel ladders. Once they have reached maturity, up to 25 years for the females, they retrace their steps to the Sargasso Sea to spawn the next generation.

The return journey is where the trouble begins. As they travel back through the Great Lakes and the St. Lawrence River to the Atlantic Ocean, the eels are led by the current into hydro dams and turbines. The Glenora Fisheries Station is participating in a program to track the eels’ movements so that they can intervene and help the fish bypass the dams as they migrate downstream.

To track the eels, the biologists insert small radio transmitters into their body cavity.  This is a delicate operation that involves anesthetising the eels and making a small incision where they insert the transmitter. Although anesthetised, the eels are still quite wriggly and have to be held tightly while the operation is performed as quickly as possible to reduce stress. After the eel is sutured back together it is ready for release back into the lake in a day or so. The transmitters will continue to emit a signal for over a year.

The fisheries team and the Canada C3 team releasing the eels.

The research station places a series of transponders in locations throughout the lake, which pick up the signals from the eels when retrieved and enables the station to determine the eels’ location.

Tom Pratt – placing a transponder to record the eels in Lake Ontario.

This information enables the station to begin to understand the eels overall migration behaviour; for example are they travelling to the north or south side of the dam. From gathering all this data the Eel Passage Research Center can develop a program to help save the eels. In some cases this means physically catching the eels just before they head over the dam and transporting them around the structure.

The program is in its sixth year but already there has been significant success in gathering data and helping these extraordinary fish continue to successfully complete their life cycle.