Seasonal migration of the snailfishLiparis tanakaeand their habitat overlap with 0-year-old Japanese flounderParalichthys olivaceus

Abstract

The snailfishLiparis tanakaeis an annual fish, growing up to >300 mm in total length. This species is known as a predator of 0-year-old Japanese flounderParalichthys olivaceus. To reveal when and where the predation occurs, monthly collections of both species at various depths were conducted off Fukushima, Japan. The snailfish inhabited shallow areas ≤50 m deep until June. Thereafter, they shifted their main habitat to offshore areas ≥100 m deep from July to September. The snailfish migrated to inshore areas with depths of ≤50 m again around October–December, during which time the habitat overlap between snailfish and 0-year-old Japanese flounder was observed. In that period, >40% of 0-year-old Japanese flounder were vulnerable to the snailfish. Larger snailfish showed stronger piscivory, and some flatfish were found in their stomachs. These results suggest that by not releasing hatchery-reared Japanese flounder until September can forestall predation by the snailfish.