I have seen two articles about bloodsucking lampreys in UK rivers, which warn swimmers about the risks of lamprey attacks when swimming in rivers and lakes. Our river lamprey spend their adult lives in the sea and only return to the rivers to breed. Is it possible to be attacked by a lamprey when swimming in the sea?



  • 1
    if its in a tabloid news paper you can safely assume its BS.
    – ldgorman
    Oct 18, 2019 at 8:24
  • 1
    @Idgorman, The Guardian is not exactly a tabloid news paper...
    – fgysin
    Oct 21, 2019 at 9:46
  • @fgysin in the UK the Guardian is a bit hit and miss for 'trusted' sources. The Express though, they enjoy some scaremongering. I mean the title on the site itself is clickbait.
    – Aravona
    Oct 22, 2019 at 13:10

1 Answer 1


I have no certainty on this answer as there are a few species of lamprey, only one of which spends all its life in fresh water. The sea lamprey is probably the most likely to attach to a swimmer - so the answer would be yes. However, the risk is relatively small as sea lamprey are not commonly found in British waters as a general population - it seems mostly Northern areas such as Norway, North Sea and the Baltic.

The same source above has this to say about human attacks:

Lampreys do not attack humans as they are adapted to attach themselves to cold- 
blooded fish and not warm-blooded mammals. Occasionally lamprey will attempt 
to attach themselves to a swimmer but they can be fairly easily removed, and 
would probably detach themselves anyway when the realise that they are not 
feeding on a fish. Swimmers in America’s Great Lakes appear to be the most 
commonly ‘attacked’ by lampreys. The famous Canadian long distance swimmer 
Marilyn Bell successfully swam the thirty-two mile width of Lake Ontario in 
1954 when she was just sixteen years old. Along with strong winds, high waves 
and bad weather she listed attacks from lamprey which constantly attached 
themselves to her swimming suit and attempted to feed on her as one of the 
biggest challenges of the swim.

However, I can not find any record of statistics on lamprey attacks other than mention that they are very rare - so probably not a thing to be concerned about in either fresh or salt water.

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