Abstract
So far, perch egg strands have been considered unpalatable biological material. However, we repeatedly found egg strands of European perch (Perca fluviatilis) in the diet of European catfish (Silurus glanis) caught by longlines in Milada and Most Lakes, Czech Republic. The finding proves that perch egg strands compose a standard food source for this large freshwater predatory fish. It extends the present knowledge on catfish foraging plasticity, showing it as an even more opportunistic feeder. Utilization of perch egg strands broadens the catfish diet niche width and represents an advantage against other fish predators. Comparison of datasets from extensive gillnet and SCUBA diver sampling campaigns gave the evidence that at least in localities where food sources are limited, multilevel predation by catfish may have an important impact on the perch population.
Highlights
A study published 31 years ago by Newsome and Tompkins [1] described perch (Perca spp.) egg strands as repellent matter for predators
We prove that perch (Perca fluviatilis) egg strands are a part of the European catfish diet
No perch egg strands were found in pike (41 individuals, LT 690–1190 mm, weight 3.6–14.2 kg).Perch egg strands were not detected in stomachs of catfish in Milada Lake, in 2014, but in 2015
Summary
A study published 31 years ago by Newsome and Tompkins [1] described perch (Perca spp.) egg strands as repellent matter for predators. Diamond and Wakefield [2] published a topical study referring to the utilization of perch egg strands by three species of caddisfly larvae (Trichoptera) and two species of flatworms (Tricladida). The paradigm of perch egg strands as unpalatable biological matter has since been widely accepted by researchers all over the world [3,4,5,6,7,8,9]. European catfish (Silurus glanis), one of the world biggest freshwater fish, is a typical opportunist with a wide diet niche. It has successfully spread worldwide accompanied by human
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