Um, yes.
Freshwater Dolphins:
Some dolphins also live in areas that were saltwater that are becoming freshwater.
As Seen Here
The Ganges and Indus River Dolphins are found in respective freshwater rivers. Similar species are found in India, Bangladesh, Nepal, and Pakistan.
en.wikipedia.org...
Dolphins are also found in the Amazon.
en.wikipedia.org...
Freshwater Seals:
The Baikal Seal lives in a freshwater lake in Siberia.
en.wikipedia.org...
The Ladoga Seals are also found in freshwater in Russia.
en.wikipedia.org...
Some other seals live in the Freshwater Iliamna Lake in Alaska.
scottdickerson.com...
The Saimaa Ringed Seal is found in a lake in Finland, and are entirely a freshwater species.
en.wikipedia.org...
Any freshwater pinnipeds or cetaceans in British Columbia are cryptids at this point in time. That Angelfire site seems to be one of the only sources
for them. Of course this would only be a cryptid if the seal or dolphin is located in a freshwater lake. I think, because of the reports of the
dolphins in lakes that were saltwater and became freshwater, it is possible that the changing geography landlocked the normal populations of the BC
coast, or populations that relocated through rivers. That would be my guess.
[edit on 8/29/2009 by ravenshadow13]

