The pros and cons of the invasive freshwater apex predator, European catfish Silurus glanis, and powerful angling technique for its population control

Abstract

Catfish have spread across Europe and several countries out of this region within the last decades. Basic knowledge of this apex predator has revealed concerns of invasive behaviour and questions regarding its utilization as a biomanipulation species. However, a method enabling its regulation to a required level has not yet been developed. We simulated the impact of angling on the catfish population by method of hook-lines in two post-mining lakes with a monitored population consisting of tagged individuals and in two reservoirs as reference sites. Further, the efficiency of hook-lines as a reducing device was examined and the economic aspects were determined. Catfish population in localities where the species is unwanted or invasive may be efficiently reduced to a harmless level by hook-lines and angling (depending on the approach of anglers). The most efficient time of the year seems to be spring to early summer with catch efficiency of 5.4 individuals per 10 baits in one day. The catch efficiency markedly decreased during the second part of the year and did not exceed 2.8 individuals per 10 baits in one day. Mean size of catfish had negative impact whereas catfish biomass had positive impact on the catch efficiency. Trophic status and number of catfish in the locality had no impact on the catch efficiency. According to model, 11-18 bait-days per 1 ha per season is efficient to decrease catfish population to 10% of the original size. Both angling and hook-lines are very simple, they are financially and time bearable mechanisms of catfish regulation in any condition. However, catfish play an important role as a biomanipulative species in many localities. In this case where catfish is beneficial, angling presents a real threat of population collapse and loss of the biomanipulative effect.

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

“…These results led to the conclusion that both lifestages of I. punctatus show a potential to compete with juvenile S. glanis but not with each other, likely due to diet-and behavioralbased intra-specific avoidance mechanisms. However, it should be noted that including mature individuals of S. glanis, as shown in Syväranta et al (2010) and Vejrík et al (2019), might have an effect of this species' niche occupation and the observed niche partitioning (Haubrock et al, 2019b). With the use of mixing models, different preferred prey items were identified for both species, while the use of priors, when applicable, indicated a considerable feeding activity by S. glanis on I. punctatus.…”

“…Moreover, several of the species present in the Arno river (e.g., P. clarkii, S. glanis, D. villosus, G. chinensis, P. antipodarum, P. parva, G. holbrooki; Gherardi et al, 2008;Nocita and Lenuzza, 2016) are listed among the worst invasive species and other comparable lists of high-profile invasive species (Vilà et al, 2009;Nentwig et al, 2018). It can be considered as a unique melting pot for alien species from Asia and North America, mainly voluntarily introduced for sport fishing and commercial fishing purposes (Nocita, 2002;Vejrík et al, 2019). Consequently, manifold interactions that can only be observed in such an invaded range are of great importance from both a theoretic and management point of view.…”

Behavioural and fitness effects of translocation to a novel environment: Whole‐lake experiments in two aquatic top predators

“…This in turn could explain why the activity‐space size of the translocated catfish was consistently elevated relative to wild conspecifics—a pattern only seen conclusively (when judged based on statistical significance) in one foreign pike population. Previous catfish stocking experiments in Czech reservoirs have shown that catfish respond to conditions surpassing ecological carrying capacity with extended movements, declines in growth and high catchability to angling gear, indicating intensive foraging in their new environment (Vejřík et al, 2017, 2019). Also, in previous work catfish have been found to be stressed by social competition (Carol et al, 2007; Slavík & Horký, 2009; Slavík et al, 2014), and are also challenged by finding shelter among unfamiliar individuals (Slavík, Horký, Maciak, & Wackermannová, 2016).…”

Influence of internal seiche dynamics on vertical movement of fish

“…Fish were captured between 5 and 10 May 2015 by electrofishing, longlining and angling (Vejřík et al, 2019). After capture, fish were anaesthetized with 2-phenoxy-ethanol (SIGMA Chemical Co., USA; see supporting information Supp1), measured, weighed and tagged.…”