| Abstract [eng] |
The rapid expansion of Great Cormorant populations during the second part of the 20th century has caused many conflicts, mostly with fisheries. Cormorants are often considered as important reason for depleted fish stocks, although evidences are often insufficient. This study of the Great Cormorant diet took place in the largest Lithuanian colony near Juodkrantė. Important for the impact evaluation cormorant nutrition aspects, including diet composition, its temporal variation and feeding selectivity, were determined. The reliability of pellet analysis for quantitative dietary assessments was evaluated for the first time using a stable isotope mixing model. Great Cormorant impact on spatial fish distribution was also assessed for the first time. Long-term fish community monitoring data were used for Cormorant impact assessment in the Curonian Lagoon. The results of our study are important for providing improved assessments of the long-term effects of Cormorants on fish communities in large, complex, highly productive aquatic systems. The practical significance of this study is its evaluation of competition between cormorants and commercial fishermen, which enables to substantiate the need to regulate cormorant population. Assessments of Cormorant impact on invasive Round Goby populations is also important. |
