European River Lamprey (<i>Lampetra fluviatilis</i>) Fishing and Lamprey Populations in some Rivers Running into Bothnian Bay, Finland

Abstract

The coastal region of Bothnian Bay is now the center of fisheries for European river lamprey Lampetra fluviatilis in Finland. This species has been studied in the Kalajoki and Pyhäjoki rivers and data are also available from the Lestijoki River. In the Kalajoki River in 1977, 30 fishermen operating 70 trap nets and 900 basket traps caught about 134 000 lampreys. Fewer traps were used by a smaller number of fishermen in 1978, but the catch remained the same. In the Pyhäjoki River in 1977, 50 fishermen operating 50 trap nets and 330 basket traps caught 184 000 lampreys. In 1978 fewer traps were used by a smaller number of fishermen and the catch was 93 000 lampreys. Tagging indicated that about 80% of the upstream migrants (estimated at 200 000 in 1977) were being captured in the Kalajoki River, but only about 65% in the Pyhajoki River (estimated at 400 000 – 500 000 in 1977). Reasons for the differences between rivers and years are discussed.Key words: Lampetra fluviatilis, Finland, fishery, rivers