Origin of the diversity of sticklebacks in Lake Constance deciphered

Most recreational fishermen do not take notice of the little threespine stickleback fish - it is too small and spiny to make a good meal. In Lake Constance however, the professional fishermen involuntarily became acquainted with it a few years ago. That's because the stickleback population has exploded in the lake, resulting in half of the fish biomass belonging to this species and them often clogging the fishermen's gill nets. The acquaintance is a rather new one because stickleback have been historically absent from the Lake Constance catchment, but were introduced in the 19th century by humans, at times when the colorful stickleback males, not yet competing with colorful tropical fish for aquarist's likings, were popular pet fish. Maintaining phenotypic differences. Stickleback have not only reached high numbers in the lake, but they also grow up to 11 cm in length and are heavily armored with thick lateral bony plates on their flanks and long spines on the back and belly. More than a decade ago, Ole Seehausen started investigating these stickleback with Biology students from the University of Bern in annual practical courses.