First report of the non-native Manila clam Ruditapes philippinarum on the Swedish Skagerrak coast

The Manila clam Ruditapes philippinarum (Adams and Reeve, 1850) was introduced to Europe in the 1970's to support aquaculture industries. Since then, it has been relocated and dispersed naturally and now occurs in most coastal areas of Europe. In recent decades R. philippinarum has progressively spread further into the North Sea. Here we present observations of a recently discovered and geographically isolated population on the west coast of Sweden. The potential timing and origin of this invasion are discussed, as well as the ability of this new species to naturalize and spread further into surrounding waters. • The Manila clam was observed for the first time in Sweden in early 2025. • Species identification was verified using genetic analysis. • Presence of multiple cohorts suggest a self-sustaining population. • Further spread in to surrounding waters is likely. • The exact origin of this new population is still unknown.