Size-dependent diet composition and feeding of Eurasian perch (Perca fluviatilis) and northern pike (Esox lucius) in the Baltic Sea

• Main Authors: Jacobson, Philip, Bergström, Ulf, Eklöf, Johan
• Format: Article in Journal/Newspaper
• Language: Swedish; English
• Published: 2019
• Subjects: Fish and Aquacultural Science; Boreal Environment Research
• Online Access: https://pub.epsilon.slu.se/16400/; https://pub.epsilon.slu.se/16400/1/Jacobson_et_al_191125.pdf

To understand food web dynamics, knowledge about factors influencing trophic interactions is fundamental. Using stomach content analysis, we investigated size-dependent predator-prey relations of two coastal predatory fish in the Baltic Sea: perch (Perca fluviatilis) and northern pike (Esox lucius). Perch undergo two ontogenetic diet shifts, from zooplankton to macroinvertebrates at ca. 50 mm; and then to fish at ca. 250 mm. For pike, all sizes (103–810 mm) fed almost exclusively on fish. The fish prey of perch and pike was predominantly three-spined stickleback in spring, and gobiids in late summer. The mean and maximum prey:predator size ratio was larger, while the minimum was smaller for pike compared with perch. Perch and pike fed on smaller-sized gobiids, three-spined and nine-spined stickleback compared within the environment. Our results on size-dependent diets of perch and pike is useful for quantitative analyses of food-web interactions and for ecosystem-based management.