Genetic Population Trends of Trouts from Plitvice Lakes: Is There Hope for the Endangered Species?

Genetic diversity is vital for biodiversity conservation, enabling species adaptation and survival. Its reduction is often associated with harmful mutations, inbreeding depression, and reduced adaptability. Such problems have been noticed in the Plitvice Lakes area, involving the endangered native Danube trout, Salmo labrax Pallas, 1814, and the introduced Atlantic trout, Salmo trutta Linnaeus, 1758. To tackle these concerns, we conducted a comprehensive genetic structure analysis of these two closely related trout species, with the aim to provide valuable insights into their population dynamics and genetic diversity trends over time. Our results revealed the continued presence of two trout species in the Plitvice Lakes watershed, with S. labrax exhibiting higher haplotype diversity but also a decline in several populations, indicating increased extinction risk. On the other hand, S. trutta maintained stable diversity, highlighting its invasive potential. Moreover, a high level of genetic pollution was revealed by this investigation, presenting an additional threat to the survival of the native species and maintenance of its genetic integrity. These findings underscore the need for ongoing monitoring, targeted removal of the invasive S. trutta, and augmentation of genetically depauperate and vulnerable S. labrax populations to preserve its native genetic diversity and evolutionary potential.