-The construction of the Daugava hydro power station (HPS) cascade has significantly transformed Latvia's largest river the Daugava, reducing its importance in the natural reproduction of anadromous fish species. Currently in Latvia, as well as in other Baltic Sea countries, the river lamprey catch is decreasing, whereas the landings in the river Daugava have tended to increase. The dynamics of the river lamprey landings show the possible redistribution of lamprey stocks between the rivers Gauja and the Daugava. Possibly, this is a result of anthropogenic influence and changes in the river lamprey resource management may be necessary in the future.

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.

No abstract

Plastic particles impact on freshwater ecosystem -a mesocosms case study 12.00-12.

No abstract