For years, legendary tales from Scotland and Western Alaska described large animals or monsters thought to live in Loch Ness and Lake Iliamna. But evidence has been mounting that the Loch Ness and Lake Iliamna monsters may, in fact, be sleeper sharks.
Two exceptionally large Arctic sharks ply northern waters -- Greenland sharks and the Pacific sleeper sharks. During the last few years, scientists have documented Greenland sharks using the St. Lawrence Seaway, lending further credence to the hypothesis that some sharks can survive in freshwater. Bull sharks are also known to swim in fresh water, but this species needs warmer waters.
The idea of sharks possibly using Loch Ness is not new; that's long been one of the hypotheses explaining the Loch Ness Monster. But until now, nobody has suggested sleeper sharks, perhaps because they're secretive and so rarely seen.
20-foot sharks
Sleeper sharks can exceed 20 feet and weigh upwards of 4 tons. Sleeper sharks probably use rivers and lakes to find food, and there is an abundance of salmon and other fish in Loch Ness and Lake Iliamna.
Sightings are often consistent with descriptions of sleeper sharks in that the monsters' shape and colors usually match that of sleeper sharks. Salmon and lots of other prey species have been found in sleeper sharks' stomachs.
As much as we know about sleeper sharks, there are still plenty of unknowns:
- How long can sleeper sharks cope with freshwater? Can they spend months in rivers and lakes?
- Do they ever over-winter in freshwater?
- What is the timing of their movements in and out of freshwater?
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Were are they getting 4 tons from? A big Greenland or sleeper shark will weigh about a ton. It would need to be made of iron to weight four tons!
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