A strange fish

With a bite like a vampire, the lamprey is a sinister-looking fish with a shady past, says Aeneas Dennison

- Aeneas Dennison

CLOUDS hung low over the Owenduff River in Ireland’s Co Mayo when, after a lengthy wait, fisherwoman Miriam Moore landed her first salmon of the season. On its flanks were several large, circular wounds. She recognised the sign at once: the double-fanged mark of the lamprey.

With good reason, the lamprey is known as the vampire of fish. It seeks out other fish and latches onto them with its circular, jawless mouth, ringed with rows of vicious teeth, then gorges on their blood. Attached to its victim, it is incredibly difficult to remove. It will remain clamped to a fish such as a salmon throughout its journey from the sea upriver, until it finds a suitable breeding area, at which point it releases its victim and settles down in a quiet corner of the river to reproduce. In theory, the lamprey tries not to suck so much blood from the host fish that it kills it, although it often does. Instead, it uses its host as a means of transport and a mobile food source—making the lamprey quite possibly the worst choice of travelling companion.