Length and weight distribution of the river lamprey, Lampetra fluviatilis (L.), sampled in the Nemunas River Estuary

Data on the population state, catch sizes, migration time, and intensity of the river lamprey, Lampetra fluviatilis (L.), are presented. Biological indexes of lamprey sampled in 2007-2009 in the lower reaches of the Nemunas River were analyzed. The study revealed that lamprey body length and weight characteristics have remained almost unchanged in recent years. However, it was found that reproducers had become smaller in size compared to investigation findings from the twentieth century.