19 replies to this topic

[Still Waters]

Quote

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.

http://www.alaskadis...e-sleeper-shark

[Mattshark]

It is an interesting hypothesis, but the problem is that these lakes are fresh water and Greenland sharks are not able to alter their osmoregulation.

[orangepeaceful79]

I always wondered why freshwater fish and saltwater fish couldn't just switch environments.  Do fresh water and salt water have different capacities for holding oxygen?  

[Blackwater]

Temperature determines how much dissolved oxygen is contained in water. Colder water holds more oxygen.  As Matt stated osmoregulation is a huge factor, also salinity and food sources.  A marine animals cells have adapted to having the high presence of salinity around them constantly.  A freshwater animal would dehydrate in saltwater.. a marine animal would take in too much water.  Not to say there aren't species who can tolerate a bit of both.  

Also brackish water is another beast altogether..

Edited by Blackwater, 04 May 2012 - 05:51 PM.

[Farmer77]

Interesting hypothesis however the peoples of that area are extremely experienced outdoorsmen. The wild and the animals contained within are their livelihood and their recreation. I find it hard to believe that these witnesses, some of whom I have known personally, wouldn't have recognized the creature as a  shark.

[Old Man Waffles]

interesting theory...  (っ◕‿◕)っ ♥

[TheLostProphet14]

(^///^) I like Sharks

[Nightpath]

Bullsharks, eels, trout, salmon, etc

Yep, no fish can cross the fresh to salt water boundary...

[Mattshark]

Nightpath, on 05 May 2012 - 04:59 PM, said:

Bullsharks, eels, trout, salmon, etc

Yep, no fish can cross the fresh to salt water boundary...

Some fish can, most cannot and greenland shark are one of the ones that cannot.

bigtroutak, on 04 May 2012 - 05:42 PM, said:

Interesting hypothesis however the peoples of that area are extremely experienced outdoorsmen. The wild and the animals contained within are their livelihood and their recreation. I find it hard to believe that these witnesses, some of whom I have known personally, wouldn't have recognized the creature as a  shark.

But witnesses are extremely unreliable, and when people see something they don't understand or cannot recognise most people's brains will produce an explanation by itself, usually not a rational one.

Edited by Mattshark, 05 May 2012 - 08:54 PM.

[Nightpath]

There really hasnt been enough studies on the Greenland shark, among others, to see if they could live in fresh water for any amount of time. These sharks are hard to get to and not as common as other types, and it's already been stated by researchers that this could be a possibility (key word here).

My best bet is still on a sturgeon.

[Mattshark]

Most likely option is people actually seeing seals in Loch Ness.

Edited by Mattshark, 06 May 2012 - 09:01 AM.

[Rafterman]

I seem to recall seeing some images of the river that runs out of Loch Ness to the sea having some rapids that would be difficult for a canoe to get through - much less a Greenland Shark.

I know that there are bull sharks  that have been observed jumping rapids salmon style in South America, but that is somewhat rare.

[95-Nasty]

Is it possible that if it is sleeper sharks, couldnt they have evolved over the years to survive in fresh ans cold water?

[Mattshark]

95-Nasty, on 06 May 2012 - 01:28 PM, said:

Is it possible that if it is sleeper sharks, couldnt they have evolved over the years to survive in fresh ans cold water?

It is beyond reasonable doubt that they haven't though, not least for the fact that people would notice such a shark going through a city such as Inverness which it would have to do and add to that the fact that there are lock gates on the water way. Additionally there is no driving force on the greenland shark to push its evolution in that direction

Edited by Mattshark, 06 May 2012 - 01:33 PM.

[Still Waters]

Rafterman, on 06 May 2012 - 01:15 PM, said:

I seem to recall seeing some images of the river that runs out of Loch Ness to the sea having some rapids that would be difficult for a canoe to get through - much less a Greenland Shark.

That sounds like the weir, and there's also a series of locks to get through.