Variation in Diet Patterns of the Invasive Top Predator Sander lucioperca (Linnaeus, 1758) across Portuguese Basins

Abstract

The introduction of non-native species is recognized as a major threat to biodiversity, particularly in freshwater ecosystems. Pikeperch Sander lucioperca, is a recent invader to Portugal, primarily providing commercial and angling interest. The aim of this work was to study the diet of this top predator across Portuguese basins and to evaluate its potential impact on recipient ecosystems. In total, 256 pikeperch stomachs from seven basins were examined, of which 88 (n = 34%) were empty. Pikeperch diet was dominated by R. rutilus, M. salmoides and Diptera in northern populations, while A. alburnus, P. clarkii and Atyidae were important prey in more humid highlands. Variation in diet was most strongly linked to latitude and ontogeny, with both size classes showing signs of cannibalism. The population niche breadth remained low and was accompanied by higher individual diet specialization, particularly in northern populations. Pikeperch dietary patterns denoted an opportunistic ability to use locally abundant prey in each ecosystem, and was size dependent, with larger individuals becoming more piscivores, causing a higher impact in the lotic systems. This first perspective about the pikeperch diet presents a very broad view of the feeding traits of this non-native predator across Portugal, being very important to deepen our knowledge about the impact of these introduced piscivores.

Cannibalism facilitates and sustains the invasion of top‐predator fish (Cichlidae: Cichla) in human‐modified ecosystems

“…In the case of peacock bass, this effect seems to manifest particularly through the conversion of lentic and lotic areas caused by the construction of dams (the main impact mapped in our database), which supports greater abundances of this invader when compared to natural systems (Espínola et al, 2010;Franco et al, 2018), and by the disruption of trophic webs and depletion of resources during the establishment process discussed previously. Greater prevalence of cannibalism in artificial reservoirs versus rivers was also observed for the invasion of the top predator Sander lucioperca in Portugal (Ribeiro et al, 2021). Therefore, the greater frequency of cannibalism in human-modified ecosystems and in non-native populations may be associated with intensified intraspecific competition in invasive populations where predator densities are high and resources are limited, favouring the development of plasticity invasiveness strategies to reduce competition, such as cannibalism.…”

A review and meta-analysis of the environmental biology of bleak Alburnus alburnus in its native and introduced ranges, with reflections on its invasiveness

“…With specific reference to A. alburnus in Iberia, no evidence was found of otter predation on A. alburnus at a large reservoir in the River Guadiana from spraint samples collected before 2001 and in 2003 as well as in 2018, despite the high A. alburnus abundance in this last period (Bedmar et al 2022). Similarly, the efficient nonnative piscivorous Sander lucioperca was not found to reduce high abundance of A. alburnus in a study of 14 different populations across Portuguese drainage basins (Ribeiro et al 2021).…”

“…Gagliardi et al 2007;Čech et al 2008;Čech and Vejřík 2011;Russell et al 2022). Use of A. alburnus as a prey (forage) species for piscivorous fishes has been the vector for introductions in the Mediterranean region (Vinyoles et al 2007), such as Spain (Ruiz-Olmo and Jiménez 2009;Vilches et al 2012;Ribeiro et al 2021) and Italy (Prigioni et al 2006;Gagliardi et al 2007), where A. alburnus has been used by recreational anglers as bait.…”

Reproductive traits of the European catfish (Silurus glanis) during the early stages of invasion in the Lower Tagus River

“…This is particularly important, as observed in the lower Po River (Castaldelli et al, 2013) where a long term monitoring program described the extirpation of two native fishes several decades after catfish invasion. Furthermore, considering Tagus endemisms like the Iberochondrostoma olisiponense (Veríssimo et al, 2018), these extinctions could have global implications, especially in endemic-rich drainages that are highly invaded by predatory fishes, such as the Lower Tagus River (Ribeiro et al, 2021; Magalhães et al, 2023).…”