River lamprey, Lampetra fluviatilis L., fishery in Latvia - Insight into the origin of catch statistics data

Abstract

Most research to date on the status of the river lamprey, Lampetra fluviatilis L. in Latvia has been done based on catch statistics data. The aim of this study was to explore the present status of the river lamprey fishery in Latvia to improve the understanding of catch statistics data. Currently, river lamprey fishing in Latvia is carried out at 24 fishing grounds located on 17 rivers. The most popular fishing gear is the lamprey fyke net, but lamprey weirs and lamprey trammel nets are also used. The type and design of the fishing gear depends on the parameters of the fishing ground. The catch size is highly variable and is greatly affected by the number of non-resources related circumstances, such as fishing regulations and meteorological factors determining the intensity of lamprey migration during the fishing season and opportunities for fishing during periods of the most intense migration. The fishing effort and the type of fishing gear have also largely changed since the 1960s and 1970s. Therefore, the fluctuation in both the long- and short-term catch data may not correspond to changes in the actual status of the lamprey population.