Thirty-Year-Old Paradigm about Unpalatable Perch Egg Strands Disclaimed by the Freshwater Top-Predator, the European Catfish (Silurus glanis)

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.

Shared Histories of Co-evolution May Affect Trophic Interactions in a Freshwater Community Dominated by Alien Species

“…However, more studies are therefore needed in this direction to confirm these findings and to increase information on these alien species' impacts. These future sampling campaigns should also consider summer and autumn because behaviors and thus, interactions may differ (Vejrík et al, 2017a), potentially further enhancing our comprehension of mechanisms underlying biological invasions and species interactions.…”

Changes in recreational catfish Silurus glanis harvest rates between years 1986–2017 in Central Europe

“…Previous studies showed that increased fish catch can be positively correlated with increased fish abundance in the ecosystem (Mosindy & Duffy, ; Skov et al, ). Since catfish predation can potentially have a significantly negative effect on freshwater fish populations (Vejřík, Vejříková, Blabolil, et al, ; Vejřík, Vejříková, Kočvara, et al, ), it is possible that catfish will become a new source of conflict between fisheries and environmental protection in Central Europe (similarly to Eurasian otter Lutra lutra and great cormorant Phalacrocorax carbo ) (e.g., Kortan & Adámek, ; Lyach, Blabolil, & Čech, ; Lyach & Čech, , ). Higher population densities of catfish could potentially lead to population decrease in prey fish species (mostly cyprinids) and therefore to decreased harvest of cyprinids.…”

“…data). Majority of rivers in the study area have naturally reproducing populations of catfish (Vejřík, Vejříková, Blabolil, et al, ; Vejřík, Vejříková, Kočvara, et al, ). Eurasian catfish is a native fish species in the study area.…”

“…Vejřík et al () claims that the expanding catfish populations can be effectively controlled by angling activities but such activities can also represent a threat to catfish populations. In other study Vejřík, Vejříková, Blabolil, et al () and Vejřík, Vejříková, Kočvara, et al () discovered that catfish can have a significantly negative effect on resident fish populations due to its prey adaptability.…”

“…The goal of this catfish stocking is to provide large‐bodied and trophy‐sized fish (up to 50–100 kg) for angling purposes (Copp et al, ; Cucherousset et al, ). Previous studies stated that catfish predation can negatively affect native fish populations (Vejřík, Vejříková, Kočvara, et al, ), especially when the predatory pressure of catfish is combined with human‐induced effects like fishing pressure, river damming, straightening of river flows, and pollution (Britton et al, ; Copp et al, ; Cucherousset et al, ). Popularity of catfish angling has been increasing, the numbers of anglers‐specialists have also been increasing, and catfish is becoming one of the main targets of recreational anglers on larger rivers in Europe (Britton et al, ; Copp et al, ; Cucherousset et al, ).…”