GENETIC DIVERSITY OF EUROPEAN EEL ANGUILLA ANGUILLA (L.) IN LATVIAN LAKES

The number of European eel populations have decreased rapidly by over 95% since 1980 throughout its range, due to environmental changes, parasites, bacteria, pollution, ecological changes associated with global warming, loss of habitat, migration barriers, as well as anthropogenic factors – uncontrolled and unsustainable fishing. As a consequence, the European eel has been listed as critically endangered on the IUCN red list. The EU Commission proposed stopping eel fishing for six months in 2023. European eels play an important role in ecosystem dynamics. Eels have the ability to adapt to changing oxygen concentration, and tolerance of different ranges of water salinity. European eels have been used as a bioindicator species worldwide. In addition to a bioindicators species, European eels are a commercially important fish species. The European eel is the only eel species which inhabit in Latvia. Glass eels are mainly used for stocking in lakes and rivers in Latvia. Only four water bodies in Latvia are freely accessible to natural migration of eels. Little is known about the genetic diversity of European eels in Latvian lakes. Research about the genetic diversity of eel populations from waterbodies in Latvia started to develop during the last years and this genetic knowledge is necessary for eel resource management. The present study may provide additional data for further investigation of European eel population in Latvia. In this study eight microsatellite loci were used to investigate the genetic structure within and between samples in five Latvian lakes, namely Liepajas, Usmas, Kisezers, Aluksnes and Sivers. Allelic variation was different in all investigated eel samples; the observed and expected heterozygosity level was quite high. Bayesian-based STRUCTURE analysis suggested that there are three main genetic groups within our study area. The high values of genetic differentiation revealed in the present study are possibly the result of gene pool mixing after multiple restoking events and eel natural migration, where it still is possible.