Browsing by Author "Ribeiro, F."
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- Angler’s preferences, perceptions and practices regarding non-native freshwater fishPublication . Banha, F.; Gago, João; Margalejo, D.; Feijão, J.; Casals, F.; Anastácio, P.M.; Ribeiro, F.It is globally recognized that freshwater anglers can have a decisive role in promoting fish introductions. The aim of this study was to analyze fresh water anglers’ actions and perceptions regarding fish introductions, comparing two distinct situations, one with recently arrived non-natives fishes and another with older fish introductions, using the Iberian Peninsula as a case study. To achieve this goal, a bilingual survey was implemented on-line in Portugal and Spain and in person (direct inquiries) in two Iberian regions: Lower Ebro (older fsh introductions) in Spain; and Lower Tagus (recent fish introductions) in Portugal. Results showed spatial diferences in perceptions and actions, namely about the target species, awareness of the impact of non-native fishes, fish introductions reported and proportion of anglers that wanted new fish species. In the Ebro river there is a high percentage of foreign anglers, higher awareness of fish introduction impact and lower introduction rates reported than in the Tagus river. However, popularity of non-native species like European catfish, was higher in the Ebro. In general, although risk behaviors such as use of fish as life bait was of low prevalence for both countries (approx. 5%), it corresponds to large numbers of fish being introduced. Our conservative estimates revealed 273,600 events of bait discharge per year. Regarding the intentional introductions, we estimated a total of 140,000 intentional introduction (illegal) events per year. These findings may help to improve monitoring, awareness and fisheries management programs led by governmental agencies.
- Condition and size of the non-native pikeperch Sander lucioperca (Linnaeus, 1758) in Portuguese river basinsPublication . Gago, João; Neves, A.; Gkenas, C.; Ribeiro, D.; Ribeiro, F.We studied life-history traits focusing on the growth and condition of the pikeperch Sander lucioperca to evaluate its phenotypic plasticity when introduced to new environments. Pikeperch is a non-native fish introduced to Iberian freshwater fauna in 1998 that quickly spread to other river basins through human-mediated activities, occupying now a wide variety of habitats along mainland Portugal. Condition (K and SMI), fork length at age, and length-weight relationships were studied for Portuguese populations. Pikeperch fork length for ages 1, 2, 3, and 4 was different between several populations. We applied generalized linear models (GLM) to study the influence of habitat type, latitude, altitude, time after first detection, and fish prey richness on pikeperch populations size at age 4 and condition. We observed higher condition values on populations from lower altitudes at lentic systems more recently introduced. But higher fork length at age 4 was found in populations from higher altitudes, on older populations with higher prey richness. Habitat type, time since first detection, and fish fauna composition are discussed as the main environmental factors explaining the observed phenotypic plasticity with concerns on predatory impact on native fauna.
- Diet of non-native pikeperch Sander lucioperca (Linnaeus, 1758) in Portugal: a first perspective on Tejo basin dietary patternsPublication . Ribeiro, D.R.; Gago, João; Gkenas, C.; Ferreira, M.; Gabriel, S.; Ribeiro, F.The introduction rate of new species is expanding worldwide, being a major driver of biodiversity loss and biotic homogenisation (Strayer & Dudgeon 2010). Such phenomenon is particularly serious in Mediterranean regions (Anastácio et al. 2019) with the modification of habitats (construction of dams and barriers) associated with the establishment of non-native fish (hereafter NNF) (Radinger et al. 2019). The spread of these species promotes a cascade effect disrupting the food webs and ecosystems (Baxter et al. 2004, Clavero et al. 2013). Iberia is a bio-invasion hotspot for freshwater fish introductions containing nearly 30% of NNF relative to total number of present fish species (Leprieur et al. 2008, Leunda 2010). For instance, Portuguese freshwaters contain 20 NNF of a total of 64 fish species, and nearly half of these non-natives have arrived in the last 2 decades (1 new NNF/2 years) (Anastácio et al. 2019). Some of recent NNF are top predators with potential high impact to fish communities and aquatic food webs (Ribeiro & Leunda 2012). The pikeperch (Sander lucioperca) arrived to mainland Portugal in 1997, being firstly reported in Ermal reservoir (Ave basin, NW Portugal) (Barros et al. 1998). In less than a decade, it was spread across mainland Portugal, reaching the Guadiana basin in 2005 (Ribeiro et al. 2009a, b). Only one study has addressed the pikeperch diet in Iberian freshwaters (Perez-Bote & Roso 2012), being important to evaluate its predation pressure in different habitats (lotic and lentic) within its invaded range. Here it is described the diet of pikeperch in Tejo basin and how the diet competition varies between different habitats.
- Evaluating the range expansion of recreational non-native fishes in Portuguese freshwaters using scientific and citizen science dataPublication . Martelo, J.; Costa, L. M.; Ribeiro, D.; Gago, João; Magalhães, M. F.; Gante, H. F.; Alves, M. J.; Cheoo, G.; Gkenas, C.; Banha, F.; Gama, M.; Anastácio, P. M.; Tiago, P. M.; Ribeiro, F.Updating information on the distribution of recently introduced and other poorly known non-natives is essential to prevent and control their spread and better address biological invasions. Here, we combine scientific and citizen science data to update the distribution of five recently arrived (i.e., < 25 years), non-native fish species (Alburnus alburnus, Ameiurus melas, Rutilus rutilus, Sander lucioperca and Silurus glanis) and one rare, longer established (i.e., > 50 years), non-native (Esox lucius) in Portugal. These species have been increasingly targeted by recreational fishermen, thus likely expanding their distribution. Specifically, we obtained distribution maps for each species, based on data gathered through a comprehensive search for records in 1) scientific literature, 2) unpublished reports of research projects, and 3) citizen science databases. We gathered 443 valid records, of which 64% were from citizen science data, mainly provided by recreational fishermen. Data highlighted that all species have expanded their distribution in the last 20 years, with high numbers of new records for A. alburnus, S. lucioperca and S. glanis, mostly located in the Tagus, Guadiana and Douro river basins. Changes in species distributions reflected dispersal within invaded basins and colonisation of previously unoccupied drainages. Integrating citizen science with scientific data provides an effective framework to understand non-native species introduction and spread, stressing the need for increasingly encourage and engage recreational fishermen in information sharing.
- First record of Silurus glanis Linnaeus, 1758 in Portugal (Iberian Peninsula)Publication . Gkenas, C.; Gago, João; Mesquita, N.; Alves, M. J.; Ribeiro, F.
- Local environment and fragmentation by drought and damming shape different components of native and non-native fish beta diversity across pool refugesPublication . Martelo, J.; Gkenas, C.; Ribeiro, D.; Alves, M.J.; Ribeiro, F.; Cucherousset, J.; Gago, João; Magalhães, M.F.Pool refuges are critical for maintaining stream fish diversity in increasingly intermittent streams. Yet, the patterns and drivers of beta diversity of native and non-native fish in pool refuges remain poorly known. Focusing on Mediterranean streams, we decomposed beta diversity of native and non-native fish into richness difference (RichDiff) and species replacement (Repl), and local (LCBD, LCBDRichDiff and LCBDRepl) and species (SCBD) contributions. We assessed the influence of environmental and spatial factors associated with drought and damming fragmentations on beta diversity components and LCBDs, and of local species richness and occupancy on LCBDs and SCBD, respectively. Overall, non-native species showed a more limited occupancy of pool refuges than native fish. RichDiff dominated beta diversity, though it was influenced by drought and damming fragmentations for native fish and local environment for non-native fish. Repl for native fish was slightly influenced by local environment, but for non-native fish was largely driven by drought and damming, albeit with a contribution of local environment as well. LCBD and LCBDRichDiff increased in pools in low order streams for native fish and at low elevations for non-native fish, and with high or low species richness. SCBD was higher for native species with intermediated pool occupancy, but for non-native species with low occupancy. Our results suggest that stream fragmentation may drive native species loss and non-native species replacement in pool refuges, and that environmental filtering may shape non-native species loss. Pools in lower order streams har bouring unique species-rich or species-poor assemblages should be prioritize for conservation and restoration, respectively, and pools at low elevation with unique non-native assemblages should deserve control efforts. We encourage the partitioning of beta diversity and individual analysis of native and non-native fish in intermittent streams, which may be key in stressing the importance of pool refuges in safeguarding native fish diversity.
- Raça Sorraia: primeiro nascimento mundial por transferência embrionáriaPublication . Azevedo, Paula; Vicente, António; Marques, Nuno; Ribeiro, F.; Bliebernicht, M.
- Reproductive traits of the European catfish, Silurus glanis, during the early stages of invasionPublication . Gkenas, C.; Sequeira, V.; Ribeiro, D.; Gago, João; Dias, D.; Verma, C.R.; Kumkar, P.; Ribeiro, F.In recent decades, the European catfish Silurus glanis has spread across Europe and elsewhere, significantly impacting the native fauna of the recipient ecosystems. Studies on its reproductive traits from its non-native range are limited, although this is a critical step in developing effective management plans. Here, we explore the reproductive characteristics of invasive European catfish populations in the Lower River Tagus in Portugal, focusing on its sex ratio, size at maturity, spawning period, fecundity and oocyte diameter. European catfish were collected monthly by electrofishing, gill nets, baited hooks, and professional fishermen from January 2022 to November 2023. A total of 217 females, 156 males and 301 immature fish were analysed. The female-to-male sex ratio was 1.4 : 1, with females and males reaching size at first maturity (TL50) at 72.9 and 68.8 cm total length, respectively. The spawning season was protracted, from February to June, showing asynchronous oocyte development patterns. The absolute fecundity was positively correlated with total length and total weight and ranged from 8,364 to 319,000 oocytes. Relative fecundity varied from 4.39 to 23.53 oocytes, with the mean diameter of the matured oocytes ranging from 1.50 to 3.21 mm. The results obtained in this study enhance our understanding of the reproductive biology of invasive species and can contribute to the development of effective management strategies, such as population control and density- dependent fecundity strategies.
- Spatial distribution patterns of the non-native European catfish, Silurus glanis, from multiple onlinesources : a case study for the River Tagus (IberianPeninsula)Publication . Gago, João; Anastácio, P.; Gkenas, C.; Banha, F.; Ribeiro, F.Effective management of invasive fishes depends on the availability of updated information about their distribution and spatial dispersion. Forensic analysis was performed using online and published data on the European catfish, Silurus glanis L., a recent invader in the Tagus catchment (Iberian Peninsula). Eighty records were obtained mainly from anglers’ fora and blogs, and more recently from www.youtube.com. Since the first record in 1998, S. glanis expanded its geographic range by ≈700 km of river network, occurring mainly in reservoirs and in high-order reaches. Human-mediated and natural dispersal events were identified, with the former occurring during the first years of invasion and involving movements of >50 km. Downstream dispersal directionality was predominant. The analysis of online data from anglers was found to provide useful information on the distribution and dispersal patterns of this non-native fish, and is potentially applicable as a preliminary, exploratory assessment tool for other non-native fishes.
- Variation in diet patterns of the invasive top predator Sander lucioperca (Linnaeus, 1758) across portuguese basinsPublication . Ribeiro, D.; Gkenas, C.; Gago, João; Ribeiro, F.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.