Invasive Fish Species Research Articles

You shall (not) pass! Steep low-head ramps as potential selective barriers for fish movements

River fragmentation by instream barriers obstructs the movements of organisms, reducing the amount of available habitat for native fishes. However, instream barriers can also block the spread of non-native invasive ones. This study aimed to assess the selectivity of a small instream barrier, a steep (120%) low-head ramp, for successful movements of a native (the Iberian barbel, Luciobarbus bocagei), a non-native translocated (the Pyrenean gudgeon Gobio lozanoi) and a non-native invasive (the bleak, Alburnus alburnus) fish species, representing a harmfulness gradient to river ecosystems. Two variables were recorded: i) the number of attempts (AT) to negotiate the ramp and ii) the number of successful negotiations (S), which were used to calculate passage efficiency PE(%). Overall, AT was significantly higher for the barbel relative to the gudgeon and the bleak. PE(%) was also far superior for the barbel than for the non-native fishes: accordingly, thirty-four ramp successful negotiations were reported for the former – resulting in an overall PE (%) of 26.6 - whereas no gudgeon or bleak individuals were able to negotiate it (PE(%) = 0). The results of this study show that selectivity at small barriers can be achieved if properly designed, being useful in river management where non-native invasive species are a concern.

Invasive Fish Species Can Easily Learn from Natives

Invasive Fish Species Can Easily Learn from Natives

The critical need for long-term biomonitoring: The case study of a major river system in Anatolia.

The long-term monitoring of freshwater ecosystems has been globally recognized for its critical role in preserving natural biodiversity and human well-being over the past century, yet monitoring efforts remain heterogeneously distributed. The Anatolia region in Turkey is known to host three out of the world's 34 biodiversity hotspots, boasting high biodiversity, but is increasingly threatened by anthropogenic effects and invasive freshwater fish species. Although the introduction of non-native fish species and pollution has detrimental effects on different river catchments in this area, long-term biomonitoring studies in Anatolia remain scarce and inconsistent. Collecting information of the Gediz River basin, a major Anatolian river catchment as a model that has been significantly impacted by human activities, published between 1971 and 2023, a total of 21 fish species from 12 families were identified. The spatial and temporal occurrences of these species fluctuated significantly due to heterogeneous sampling efforts that did not follow a clear pattern, indicating a complex ecological and conservation scenario characterized by both spatial and temporal variability in species prevalence, endemism and abundance. The presented results emphasize the need for comprehensive long-term biodiversity monitoring for anthropogenically impacted catchments like the Gediz River basin. Only with a coherent basis of high-resolution monitoring data can the multiple stressors threatening Anatolia's freshwater biodiversity be disentangled and, subsequently, be mitigated. Using the Gediz River basin as an example, this study emphasizes the urgent need for comprehensive, long-term biodiversity monitoring in understudied regions worldwide to protect regional biodiversity and ensure ecosystem health.

Public information use—are invasive demersal fish species more effective than natives?

Abstract Organisms determine environmental quality using their senses and personal experience (personal information) but can also use byproducts of other individuals’ activities (i.e. public information). The ability to use public information originating from both con- and heterospecifics gives an advantage over individuals relying only on personal information or conspecific cues. The role of public information in invasion ecology is of high concern, as any differences in this aspect between alien and native species may determine the success of the former. Here, we studied 2 pairs of sympatric invasive and native demersal fish species (racer goby Babka gymnotrachelus/European bullhead Cottus gobio; monkey goby Neogobius fluviatilis/gudgeon Gobio gobio) facing 2 types of public cues (associated with antipredatory and foraging behavior). We used them as a model to check if the invaders could use public information from more sources than the natives. Both invaders and the native gudgeon used cues from con- and heterospecifics, exhibiting antipredatory behavior, while the native bullhead failed to recognize such cues from heterospecifics. The monkey goby and both native species were attracted to foraging cues from donors less likely to exert competitive pressure on the observer (i.e. native species rather than potentially more aggressive invaders). On the other hand, the racer goby appeared unable to correctly recognize heterospecific foraging cues. Our results showed that public cues can enable invaders to read threat from a wide range of individuals and to find optimal food patches, which may contribute to their invasion success.

Seasonal and Spatial Distribution Patterns of Non-Native Fishes in Inland Waters of Guangxi

Fish invasions can damage the ecological environment of invaded areas, causing negative effects such as monotony of ecological types in invaded waters and endangerment of native species. It is important to monitor their presence and spread in invaded areas. This study aims to update the available data on non-native fish species in the inland waters of Guangxi and to determine their seasonal and spatial distribution in this region. Taking the inland waters of Guangxi as the study area, 34 sampling sites were set up in the major river systems, and systematic sampling was conducted in four seasons in 2023. The data showed that a total of 7690 non-native fish were collected from 23 species, belonging to 7 orders, 13 families, and 20 genera. Of the non-native fish species, 19 species were introduced for aquaculture purposes, and three species were introduced for ornamental purposes. The most non-native fish species were found in summer with 21 species, which were followed by 20 species in winter, 18 species in spring, and only 15 species in autumn. However, the distribution composition was similar in each season, with Coptodon zillii being dominant in each season, which was followed by Oreochromis niloticus. The Hongshuihe River had the highest number of non-native fish species with 16 species, followed by the Xunjiang River with 14 species, the Qianjiang River with 13 species, and the Npanjiang River had the lowest number of non-native fish species with 7 species. In addition, the Xunjiang River and the Qianjiang River showed significant separation in the PCoA results, and the overall test showed significant differences in non-native fish composition among the river system. The main reasons for the differences in their spatial distribution are geographical location and temperature. O. niloticus and C. zillii were found in all river systems and have become the main invasive non-native fish species in the inland waters of Guangxi.

Non‐Native Invasive Fish Species (NIFS) in Inland Waters of India: Management Issues, Strategies and Suggestions

ABSTRACTIn India, there are 626 non‐native invasive fish species (NIFS), with 16 becoming invasive in inland waters, adversely impacting native biodiversity, and fisheries by altering the abundance of NIFS in commercial catches. Scientific findings highlight that the movement of NIFS interacts with agricultural activities and the evolving environment, facilitating their spread and establishment. The scenario of NIFS invasion disrupts biological communities, ecosystem services and fisherfolk livelihoods. Despite the implementation of existed guidelines, issues related to NIFS have persisted and escalated over time scale putting increased pressure on indigenous aquatic biological resources in inland waters. This paper suggests the need of framing a new management plans, guidelines and regulatory policies to control NIFS invasions, protecting riverine fish biodiversity and ecosystem services. Proposed management strategies include functional response (FR) and adaptive response (AR)‐based approaches, which are discussed to address NIFS management in inland waters.

Round gobies (Neogobius melanostomus) in the River Rhine: Population genetic support for invasion via two different routes

The round goby, Neogobius melanostomus, is a successful invasive fish species. Originating from the Caspian and Black Sea, it is now distributed widely within European fresh- and brackish waters. The River Rhine was colonized in 2008 only a few years after the opening of the Rhine-Main-Danube canal and only four years after N. melanostomus was first reported in the upper Danube River. Its invasion history of the River Rhine was unclear because the species was first detected close to the Rhine river delta which would suggest a route of invasion other than via the Rhine-Main-Danube canal. To investigate the colonization history of N. melanostomus in the Rhine, we combined abundance estimates with molecular analysis. Abundance estimates found N. melanostomus to be dominant in the Lower Rhine (> 90% of all catches). Molecular analysis was done on 286 individuals from four different sites. Using the mitochondrial control region (d-loop), we found three different haplotypes in both Rhine sites. None of the potential invasive source populations in the rivers Danube and Trave exhibited all three haplotypes. The molecular data therefore supported a scenario of two different colonization directions. Our results show that the invasion history of the River Rhine is complex and warrants further investigation.

Diet and feeding ecology of the pike perch (Sander lucioperca), an invasive fish species: seasonal diet shifts

Diet and feeding ecology of the pike perch (Sander lucioperca), an invasive fish species: seasonal diet shifts

Use of Electrofishing to Limit the Spread of a Non-Indigenous Fish Species in the Impoundment of Aoos Springs (Greece)

The impoundment of Aoos springs was created in 1990 to facilitate hydroelectric production, and fish fauna has been enriched through the years due to deliberate or accidental fish stockings, with certain invasive alien fish species arising (i.e., Lepomis gibbosus, Carassius gibelio), some of which are ranked among the most dangerous species for global biodiversity. A three-year monitoring survey was conducting to map the nesting areas of Pumpkinseed, L. gibbosus, to assess the effectiveness of electrofishing as an active method to reduce the spread of the corresponding species and to identify the impact of the L. gibbosus on native species. The largest percentage of nests was found in areas with silty-sand bottoms (53.4%) and low vegetation. The potential nesting area was estimated at 1.97 km2 and the area of confirmed nesting was 0.33 km2. The species appeared to nest in a small area, compared to the potential nesting area. The results also indicate that a significant percentage of the target species (71.6% of the total number of species) was removed, with an average time per sampling of 1.2 ± 1 h, whereas the impact on the other native species was minimal. These results are important for designing and implementing programs for the eradication or reduction of L. gibbosus in the impoundment of Aoos springs.

Flooding and dam operations facilitate rapid upstream migrations of native and invasive fish species on a regulated large river

Dams commonly restrict fish movements in large rivers but can also help curtail the spread of invasive species, such as invasive bigheaded carps (Hypophthalmichthys spp). To determine how dams in the upper Mississippi River (UMR) affect large-scale invasive and native fish migrations, we tracked American paddlefish (Polyodon spathula) and bigheaded carp across > 600 river km (rkm) and 16 navigation locks and dams (LD) of the UMR during 2 years with contrasting water levels. In 2022, a low-water year, both native paddlefish and invasive bigheaded carp had low passage rates (4% and 0.6% respectively) through LD15, a movement bottleneck being studied for invasive carp control. In contrast, flooding in 2023 led to open-river conditions across multiple dams simultaneously, allowing 53% of paddlefish and 46% of bigheaded carp detected in Pool 16 to move upstream through LD15. Bigheaded carp passed upstream through LD15 rapidly (μ = 32 rkm per day) a maximum of 381 rkm, whereas paddlefish moved an average of 9 upstream rkm per day (maximum of 337 rkm). Our results can inform managers examining trade-offs between actions that enhance native fish passage or deter movements of invasive species. This understanding is critical because current climate change models project increases in flooding events like that observed during 2023.

Some Aspects of the Biology of Invasive Fish Species from a Langat River Tributary, Selangor, Malaysia

Some Aspects of the Biology of Invasive Fish Species from a Langat River Tributary, Selangor, Malaysia

Effect of an invasive fish species on nutrient cycling and on the community structure: an experimental approach

Effect of an invasive fish species on nutrient cycling and on the community structure: an experimental approach

Large-scale serial replacement of invasive tench (Tinca tinca) by invasive carp (Cyprinus carpio) in the presence of redfin perch (Perca fluviatilis) in the Murray-Darling River system, Australia

Ecosystems worldwide are increasingly being invaded by multiple species, and the rate of biological invasion is accelerating, leading to more interactions among invasive species. One such interaction that has received little attention is the phenomenon of ‘serial replacement’ or ‘over-invasion’, where an established invasive species is supplanted by a second invasive species. Understanding this interaction is important as controlling the second species could inadvertently lead to an increase in the abundance of the first species. We used a hierarchical state-space model to analyse changes in annual abundances (commercial catch-per-unit-effort) of three invasive fish species, tench (Tinca tinca), common carp (Cyprinus carpio) and redfin perch (Perca fluviatilis), in the Murray-Darling River system (MDRS), Australia between 1954–2002. Tench were present at low abundances until the mid-1970 s, before declining to the point of no commercial catch post-1989. This rapid decline coincided with a significant increase in carp abundance, suggesting that carp may have driven the tench decline through habitat modification (particularly the destruction of aquatic plants), consistent with findings from European studies that show the disappearance of tench from ponds with intensive carp farming. Redfin perch populations, were inferred to be much less impacted by the invading carp population. While carp were present in the MDRS for the duration of the study, the rapid increase in carp abundance in the early 1970 s coincided with the introduction of a specific genetic lineage—the “Boolarra strain”. Our analysis provides compelling evidence of serial replacement of long-established tench by invading common carp triggered by the introduction of a novel carp strain.

Extraction and characterization of collagen from the skin of Pterygoplichthys spp. (armored catfish) from Chiapas

Because of its biocompatibility and safety, collagen is a valuable biomaterial that is used in various industries. While traditionally sourced from terrestrial mammals, collagen extracted from fish waste is a promising alternative due to its chemical properties and low cost. In Mexico, Pterygoplichthys spp. is considered an invasive species, inedible, and of limited commercial importance due to the low muscle content and skin covered with rigid bony plates. This study aimed to extract and characterize collagen from the skin of Pterygoplichthys spp. obtained from two communities in Chiapas, Mexico. Our results show that the extracted collagen is type 1, with a yield of 43.0% (dry weight). Sodium dodecyl sulfate polyacrylamide gel electrophoresis analysis revealed the presence of two alpha chains (α1, α2) and a beta and gamma component, consistent with type 1 collagen. Liquid chromatography coupled to mass spectrophotometry analysis identified peptide sequences homologous to those reported in other species. This study highlights the potential of Pterygoplichthys spp. skin collagen as a viable alternative to mammalian collagen. The efficiency of the extraction process and the identification of peptides resembling those of the other species underscore the feasibility of utilizing collagen from the skin of Pterygoplichthys spp. in industrial applications, offering a sustainable solution to environmental and economic challenges. Practical Application: Collagen extracted from the skin of Pterygoplichthys spp., an invasive fish species, can serve as a sustainable alternative to mammalian collagen, offering a cost-effective biomaterial with properties suitable for various industrial applications.

Invasive fish species in Romanian freshwater. A review of over 100 years of occurrence reports

Effective management of invasive alien species requires location-specific strategies involving the regular update of distribution maps to identify spatial patterns, trends, and pathways of entry and the spread and hotspots of those invasions. However, a comprehensive overview of invasive alien fish species in Romania is lacking. To fill this gap, we compiled a database with occurrences of alien fish species in Romania from diverse sources, including published literature, our own field data, online databases, social media, and online questionnaires. Occurrence data covers the 1910–2022 period. From a total of 52 alien fish species reported as present in Romania’s waterways, we assigned an invasive status to 11 species, of which Pseudorasbora parva, Lepomis gibbosus, Carassius gibelio, and Ameiurus spp. are widespread. Based on the currently available occurrence records, we evaluated the presence and distribution of invasive alien fish species at the watershed level, concluding that invasive alien fish species are present in all Romanian watersheds. We identified several hotspots consistent with the main points of entry and spread of invasive alien fish species, principally located in western, central, and eastern Romania, i.e., Mures, Crisuri, and Siret watersheds.

First record of stone moroko (Pseudorasbora parva), an invasive alien fish species, in water bodies of urban green areas in Poland

Abstract Invasive alien species are currently a major ecological problem. One such species is stone moroko, Pseudorasbora parva (Gobionidae), which has only been found to date in natural or agricultural water bodies (lakes, rivers and streams, carp ponds). Therefore, the current study is the first description of stone moroko in urban green areas (Warsaw, Poland). The fish were caught with a hydrobiological net. Four catches were conducted in ponds located in Morskie Oko Park (pond 1) and the Saxon Garden (pond 2) – two in fall and two in the spring, while two spring catches were conducted in Dolinka Służewska Park (stream). The population in pond 2 apparently survived the winter, and the fish caught in June displayed visible signs of sexual dimorphism and were significantly larger (average body mass: 1648 ± 1123 mg; range: 460–6090 mg) than those caught in the pond in the two fall samplings (404 ± 122 mg; 154–729 mg). After recording substantial numbers of specimens in the fall, no fish were caught in pond 1 during either of the spring catches, while only a few moroko were caught in the stream in April (1212 ± 869 mg; 454–2901 mg) and none were caught in June. Throughout the study, 59 specimens were caught in pond 1, 74 in pond 2, and 7 in the stream.

Effect of selected environmental factors on the growth and survivability of the larvae of the Chinese sleeper Perccottus glenii Dybowski 1877

The aim of this study was to determine the influence of the temperature (range 15 to 25°C), pH (6 to 9) and salinity of water (between 0 to 10‰) on the growth, condition and survival of larvae of the Chinese sleeper. During the 28‐day experimental rearing, the highest average body weight of 81.3 ± 16.3 mg was reached in fish from the group maintained at a water temperature 25°C, and was almost five times higher than the weight at the temperature of 15°C (15.6 ± 2.2 mg). A significantly higher body weight of Chinese sleeper larvae was also recorded in the group reared in alkaline water (pH 9), compared to those kept in acidic and neutral water. Statistically significant differences between the groups (p≤0.05) were recorded for the condition index (K) values and relative body weight (SGR) only in the experiment with different water temperatures of fish rearing. The highest number (16% of the initial stock) of abnormal larvae, associated with a lower jaw and vertebral structure deformities, was recorded in the group reared at 5‰ salinity (Z5). Simultaneously, 100% mortality of the stock was noted by the 10th day of rearing in the 10‰ salinity. The cumulative mortality of the Chinese sleeper larvae related to cannibalism Types I and II in all the experimental rearing was low, oscillating between 0.5% and 11.5% in the groups bred in water with a pH 9 and 0‰ salinity, respectively. The study results may help determine the critical values of water parameters that promote or limit development in the early stages of the Chinese sleeper and could be used in activities related to eradicating or significantly reducing the increasing abundance of this alien invasive fish species in freshwater ecosystems.

Market development for an invasive fish species: Blue catfish in the Chesapeake Bay, US

This research investigated market development for invasive blue catfish from the Chesapeake Bay, US. A small number of interviews with seafood processors and a large online survey of seafood consumers in the US Mid-Atlantic and Southeast (n = 1010) were used to understand factors influencing demand. The survey included a choice experiment to elicit consumer preferences for blue catfish in comparison to substitute seafood products and tested the effects of providing various types of information. Processors noted broad industry concerns related to labor availability and input costs and felt that expansion of the blue catfish market depended upon increasing consumer awareness and product familiarity. Consumer surveys revealed only one-third of respondents had consumed wild-caught blue catfish, though another third indicated they would be willing to try it. In the choice experiment, providing information on production method and product origin were found to increase consumer demand across seafood products. For blue catfish, providing additional information increasing consumer product familiarity or detailing the harmful ecological effects also increased demand. Mean consumer willingness-to-pay for blue catfish was estimated to be $9.70/lb, but increased to $22/lb in an information-rich scenario. These findings suggest a large potential market for invasive blue catfish in the US Mid-Atlantic and Southeast, with demand dependent on consumer product familiarity.

Trematode Diplostomum pseudospathaceum inducing differential immune gene expression in sexual and gynogenetic gibel carp (Carassius gibelio): parasites facilitating the coexistence of two reproductive forms of the invasive species.

Parasite-mediated selection is considered one of the potential mechanisms contributing to the coexistence of asexual-sexual complexes. Gibel carp (Carassius gibelio), an invasive fish species in Europe, often forms populations composed of gynogenetic and sexual specimens. The experimental infection was induced in gynogenetic and sexual gibel carp using eye-fluke Diplostomum pseudospathaceum (Trematoda), and the transcriptome profile of the spleen as a major immune organ in fish was analyzed to reveal the differentially expressed immunity-associated genes related to D. pseudospathaceum infection differing between gynogenetic and sexual gibel carp. High parasite infection was found in gynogenetic fish when compared to genetically diverse sexuals. Although metacercariae of D. pseudospathaceum are situated in an immune-privileged organ, our results show that eye trematodes may induce a host immune response. We found differential gene expression induced by eye-fluke infection, with various impacts on gynogenetic and sexual hosts, documenting for the majority of DEGs upregulation in sexuals, and downregulation in asexuals. Differences in gene regulation between gynogenetic and sexual gibel carp were evidenced in many immunity-associated genes. GO analyses revealed the importance of genes assigned to the GO terms: immune function, the Notch signaling pathway, MAP kinase tyrosine/threonine/phosphatase activity, and chemokine receptor activity. KEGG analyses revealed the importance of the genes involved in 12 immunity-associated pathways - specifically, FoxO signaling, adipocytokine signaling, TGF-beta signaling, apoptosis, Notch signaling, C-type lectin receptor signaling, efferocytosis, intestinal immune network for IgA production, insulin signaling, virion - human immunodeficiency virus, Toll-like receptor signaling, and phosphatidylinositol signaling system. Our study indicates the limited potential of asexual fish to cope with higher parasite infection (likely a loss of capacity to induce an effective immune response) and highlights the important role of molecular mechanisms associated with immunity for the coexistence of gynogenetic and sexual gibel carp, potentially contributing to its invasiveness.

Simple on-site extraction and GC-MS analysis of rotenone and degradation products for monitoring invasive fish eradication treatments in fresh and brackish waters

The introduction of invasive fish species to aquatic ecosystems has been demonstrated to cause disastrous ecological effects. Current conservation strategies regard rotenone-containing piscicide formulations, such as commercial product CFT Legumine, as a potentially viable alternative to the cumbersome traditional approaches to fish eradication. This consideration relies on the fast degradation of rotenone and its relatively rapid dissipation from the environment. Piscicide treatments in fragile aquatic ecosystems should thus monitor not only rotenone concentrations following application, but also other byproducts and degradation products. We present a methodology for the analysis of rotenoids in fresh and brackish waters that addresses two main challenges: the accurate determination of applied concentrations in different salinity concentrations by performing a simplified on-site solid-phase extraction, overcoming the fast degradation of rotenone in sample storage conditions, and the selective analysis of rotenoid byproducts and degradation products by gas chromatography coupled to mass spectrometry. Limits of quantification were below the ecological no-effect concentration of rotenone (2 µg/L) and average recoveries exceeded 80%. Accuracy (compared to expected values) and precision (deviation of replicates) ranged from 78 to 103% and 3 to 14%, respectively, across various rotenoid concentrations. These metrics are more than satisfactory for the intended application of this simplified procedure. The method was applied to piscicide-treated samples, revealing significant and fast degradation of parent rotenoids in storage conditions, as well as a non-negligible accumulation of rotenone in the particulate fraction of water that could impact the effectivity of eradication efforts.