Pacifastacus leniusculus


Nature Park “Salacas ieleja”
57.750671, 24.401186

In Latvia the Signal crayfish (Pacifastacus leniusculus) was first released into the wild in Lake Primma in the Salaca river basin from which it was further transported into local ponds from which it expanded naturally to the river network and is now very widely distributed. This species poses a threat to Latvia’s nature by competing for a habitat with native crayfish species, as well as it spreads crayfish plaque.

Be careful, because Latvia is also home to a native species – European crayfish (Astacus astacus) that does not threaten Latvia's biodiversity which looks similar to this invasive species.

Medium-sized, bluish or reddish-brown crayfish (7-13 cm long) with massive and blunt claws. A smooth body without spines. A very characteristic feature is a light spot at the joint of the claw opening.

Manner of introduction
First introduced in the fishing company "Brasla" and from there released into Lake Primma in the Salaca river basin. Later local residents distributed the species unsanctioned. Further distribution mainly occurs two ways – unsanctioned transport/intentionally introduction and the species expansion via the river canal network.

Characteristics of preferred habitat
Fast-flowing rivers and slow-moving sections, including lakes.

Familiarize yourself with invasive species and submit your observataions to: “Invazīvo sugu pārvaldnieks”!

Source:  “Invazīvo sugu pārvaldnieks”, Nature Conservation Agency

© Biedrība "Dabas koncertzāle" 2021