Move or die: change in European catfish (Silurus glanisL.) behaviour caused by oxygen deficiency

Abstract

Key-words:invasive species, Silurus glanis, winter, behaviour, hypoxia European catfish (Silurus glanis L.) is a large predatory fish native to an extensive area in Europe. It has been introduced to its western and southern parts, where it is considered an invasive species with a negative impact on native fishes. European catfish is a territorial species exhibiting site fidelity. Cold water in winter usually leads catfish to exhibit notably low activity. Nevertheless, our telemetric study on 19 juvenile individuals of S. glanis provides information on their unexpected high activity and displacement in winter. Our data reveal that these behavioural changes were caused by oxygen deficiency. Our data also indicate that oxygen deficits may induce migrations of this species. RÉSUMÉBouger ou mourir : changement de comportement du silure glane (Silurus glanis L.) causé par un manque d'oxygène Mots-clés : espèces envahissantes, Silurus glanis, hiver, comportement, hypoxieLe silure glane (Silurus glanis L.) est un grand poisson prédateur indigène à une vaste aire en Europe. Il a été introduit dans les parties occidentales et méridio-nales de cette aire, où il est considéré comme une espèce envahissante ayant un impact négatif sur les poissons indigènes. Le silure glane est une espèce territoriale présentant une fidélité au site. L'eau froide en hiver entraîne généralement le silure glane à présenter notamment une faible activité. Néanmoins, notre étude té-lémétrique sur 19 individus juvéniles de S. glanis fournit des informations sur leur activité élevée inattendue et leur déplacement en hiver. Nos données révèlent que ces changements de comportement ont été causés par un manque d'oxygène. Nos données indiquent également que les déficits d'oxygène peuvent provoquer des migrations de cette espèce.

Seasonal changes in diel activity of juvenile European catfish Silurus glanis (Linnaeus, 1758) in Byšická Lake, Central Bohemia

“…Dissolved oxygen concentrations within the given range also had no observable impact on catfish behaviour, either. In our previous work (Daněk et al., ), by contrast, we found a strong effect of dissolved oxygen concentrations within the range of 1.3–2.4 mg/L, which prompted catfish to start moving and relocate to oxygen refuges. The blood of European catfish contains 30%–35% haemoglobin, which helps the fish balance out different oxygen condition, including low oxygen levels (Copp et al., ).…”

“…When there is danger, however (e.g. an oxygen deficit), catfish may temporarily increase their activity in winter (Daněk et al., ).…”

“…“Copiapo”); azimuths were plotted with the plugin “Tarsius” (http://www.tarsiusproject.org/download). The term “resting place” was defined as a restricted square area of less than 2 × 2 m where fish dwell during daytime (for at least three subsequent 3‐hr intervals, of which at least two were during daytime; see Daněk et al., ). “Movement” was defined as the distance (m) each individual moved during a three‐hour interval.…”

“…Data from 14 to 28 December 2010 were excluded from the analyses because of an oxygen deficiency in this period, which seriously affected fish behaviour. This extraordinary event was analysed in a separate study (Daněk et al., ). Data samples were grouped by season: spring (21 March to 20 June), summer (21 June to 20 September), autumn (21 September to 20 December) and winter (21 December to 20 March), following Slavík et al.…”

Spatial distribution patterns of the non‐native European catfish, Silurus glanis, from multiple online sources – a case study for the River Tagus (Iberian Peninsula)

“…In fact S. glanis exhibits a low dispersal capacity, inferred from its mean distance travelled per day of <50 m day À1 Danek et al 2014). This initial putative human-mediated dispersal is the most plausible mechanism as the distance of new records is beyond the limit of the species natural dispersal.…”