The Giant Eel of the Rideau Canal

There have been reports of at least one giant eel in the Rideau Canal in Ottawa, Canada. We’ll look at those reports in more detail, but first some historic perspective.

The Rideau River in Ontario Canada feeds into the larger Ottawa River. In 1880 a giant “sea serpent” was caught in the Ottawa river not far upstream from the confluence with the Rideau. This was presumably an eel, but the Rideau River empties into the Ottawa via the Rideau Falls where the water drops 40 ft. Even if there are giant eels in the Ottawa River how could they get into the Rideau River? That’s where the Rideau Canal comes in. The Canal was built to allow boats to navigate from the Ottawa River to Kingston on Lake Ontario, and it starts with a staircase of locks to raise the boats around the Rideau Falls. A side effect of building these locks in 1830 is that any fish in the Ottawa River could now make their way upstream into the Rideau canal and the the Rideau River system.

From then our story goes cold until 2015. At that time two Environmental Studies students, Paul Boateng and Brennan Guy, studying at Carelton University, decided to make a study of the fish populations at nearby Dow’s Lake on the Rideau Canal. This is the deepest section of the 11Km Canal with depth of 10 -15 metres. The water is murky but their cameras seemed to capture the fins of a much larger fish than expected. This led to more cameras, with more lights and eventually a clear image of an oversized American eel. 

Estimates of the size of the eel (since named Elvis) range from 10 – 14 metres. (33 – 45 ft). Clearly this is some kind of abnormality or mutation. Speculation on why this happened has focused on the unique habitat of the Rideau Canal, which could provide Elvis with an abundance of fish to eat (swept downstream from the Rideau River system), and no natural predators. Further observations have shown that Elvis sleeps at the bottom of Dow’s Lake in the day, and then hunts along the length of the canal at night.

In 2018 Elvis was observed not only eating fish but attacking ducks and geese floating on the canal. Eels have been observed to attack water fowl before, but not in such a systematic way. Elvis doesn’t seem to eat his birds immediately but lodges them at the bottom of the canal. This may reflect the behavior of other large predators, notably crocodiles that store food when times are good in readiness for when things are lean. In the case of Elvis the Rideau Canal is frozen and used as a skateway for 4 months each year, stocking a larder for the winter seems a prudent habit.