A mysterious object has been spotted in waters near Liverpool in England's northwest, sparking speculation it could be a shark.

The object, seen at the Albert dock in Merseyside, has raised questions about the effect England's freezing waters are having on marine biology.

Some experts have said it could be a basking shark while others have said it could simply be a jetski.

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Marine biologist Tom Cornell said basking sharks were known to cruise around the coast and that they weren't a threat to humans.

"Although it is unusual for tropical island sharks to be found in this area, it