The study analyses for the first time the diet composition of grey seals inhabiting the Polish Baltic Sea coast. Samples of seal scat were collected in the Mewia Łacha Nature Reserve at the mouth of the Vistula River. Using genetic and osteological methods, the remains of organisms included in the grey seals diet were analysed for their taxonomy (families and species). Based on the analysis of 49 scat samples from grey seals, 761 hard parts that could be identified by taxon were isolated. The predominant species in the samples were perch, Perca fluviatilis (almost 78% of samples); pikeperch, Sander lucioperca (67%); lamprey, Lampetra fluviatilis (almost 35% of samples); Baltic cod, Gadus morhua callarias (almost 31% of samples) and sea trout, Salmo trutta trutta (26.5%). Genetic analysis confirmed the presence of Atlantic cod DNA in 69% and sea trout in 63% of samples. The genetic material of the Atlantic herring, Clupea harengus has not been identified in the analysed scat samples. Information on grey seals feeding on river lampreys seems to be valuable in the context of lack of knowledge on the occurrence of lampreys in the Vistula River. The methodology used showed that seals fed on species that were the most abundant in the area which is directly associated with the migration cycle of fish. The results of our study allowed the conclusion that the grey seal is an opportunistic predator and its diet reflects and exploits the variations in its habitat.

该研究首次分析了居住在波兰波罗的海沿岸的灰海豹的饮食组成。海豹粪便的样本收集在维斯杜拉河口的MewiaŁacha自然保护区。使用遗传学和骨科学方法，分析了灰海豹饮食中所包括的有机体的分类（科目和物种）。在分析灰色海豹的49个粪便样本的基础上，分离出可以通过分类群识别的761个坚硬部分。样品中的主要物种是鲈鱼，Perca fluviatilis（几乎占样品的78％）；梭子鱼，Sander lucioperca（67％）; 七鳗，南美白对虾（几乎占样品的35％）；波罗的海鳕鱼，加杜斯·莫尔瓦·卡里亚里亚斯（几乎占样本的31％）和海鳟Salmo trutta trutta（占26.5％）。遗传分析证实69％的样品中存在大西洋鳕DNA，63％的样品中存在海鳟。在所分析的粪便样本中尚未鉴定出大西洋鲱的遗传物质Clupea harengus。在缺乏对维斯杜拉河中七lamp鳗的发生情况的了解的情况下，有关以河七lamp鳗为食的灰海豹的信息似乎很有价值。所使用的方法表明，海豹捕食的是该地区最丰富的物种，这与鱼类的迁移周期直接相关。我们的研究结果可以得出这样的结论，即灰海豹是一种机会掠食性动物，其饮食反映并利用了其栖息地的变化。