Biometric Data and Bone Identification of Topmouth Gudgeon Pseudorasbora Parva and Sunbleak Leucaspius Delineatus

Identification and analysis of the size and composition of prey taken by piscivorous predators assists in the further understanding of ecology of piscivorous fauna (Mann & Beaumont 1980, Hansel et al. 1988, Copp & Roche 2003). Comprehensive evaluation of the digested prey is central to the assessment of predation impacts and is equally important for sustainable fisheries management. Two non-native fish species in England that may be potential prey for native species are sunbleak Leucaspius delineatus (Heckel) and topmouth gudgeon Pseudorasbora parva (Temminck et Schlegel). These species were introduced to English waters in the mid 1980’s (Farr - Cox 1996, Gozlan et al. 2002) where they have since developed extensive populations (Gozlan et al. 2003, Hickley & Chare 2004). Recent studies associate sunbleak and topmouth gudgeon with novel non-native parasites (Beyer et al. 2005, Gozlan et al. 2005). Results such as these have emphasized the need to be able to identify these two species as part of the native predators’ diet. The aim of the study was to provide a tool for species identification and to elaborate the biometric relationships between bone dimensions and body size of sunbleak and topmouth gudgeon. Head bones of fish are particularly useful for identifying the size and composition of prey species from the food remains of predators, as they withstand digestion and are taxonomically valuable (Copp & Kováč 2003)

Non-native fish dispersal as a contaminant of aquatic plant consignments – A case study from England

© 2017 The Author(s) and 2017 REABIC. The introduction of non-native species as contaminants of aquatic plant consignments is poorly documented. This paper reports on the introduction of pumpkinseed Lepomis gibbosus, a North American sunfish, into an angling lake as a contaminant of native aquatic plants during their stocking to enhance the fishery. Growth and life-history data for the L. gibbosus specimens captured in the water body provided biological evidence (relatively rapid juvenile growth and early maturation) that supports the assumption that L. gibbosus was accidentally introduced as a contaminant of the aquatic plant consignment. This study highlights the importance of adhering to current guidelines on the movement of aquatic plants (e.g. Great Britain’s “Be Plant Wise” educational initiative), which aims to prevent unwanted transfer of aquatic organisms

Do non-native pumpkinseed Lepomis gibbosus affect the growth, diet and trophic niche breadth of native brown trout Salmo trutta?

Brown trout Salmo trutta Linnaeus, 1758, is a priority species for conservation and management efforts in many European countries. In its native range, interactions with non-native fishes often adversely affect somatic growth rates and population abundances. Consequences of introduced North American pumpkinseed Lepomis gibbosus (Linnaeus, 1758) for native S. trutta were examined in stream stretches with and without L. gibbosus. Data for somatic growth rates and trophic niche breadth (using stable isotope analyses) provided little evidence of L. gibbosus presence being detrimental for S. trutta. Shifts in S. trutta diet at all sites were associated with increased piscivory with increasing body length, with no evidence to suggest that interspecific resource competition with L. gibbosus structured the food web or affected trophic positions. Three years later, and following L. gibbosus removal, data revealed slight shifts in the food web at each site, but these related to shifts in resources at the bottom of the food chain rather than a response to L. gibbosus removal. Consequently, the ecological consequences of L. gibbosus for S. trutta in the study stream were minimal, with S. trutta populations responding more to natural mechanisms regulating their populations than to the presence of this non-native fish species

Risk assessment of non-native fishes in the Balkans Region using FISK, the invasiveness screening tool for non-native freshwater fishes

A high level of freshwater fish endemism in the Balkans Region emphasizes the need for non-native species risk assessments to inform management and control measures, with pre-screening tools, such as the Fish Invasiveness Screening Kit (FISK) providing a useful first step. Applied to 43 non-native and translocated freshwater fishes in four Balkan countries, FISK reliably discriminated between invasive and non-invasive species, with a calibration threshold value of 9.5 distinguishing between species of medium and high risk sensu lato of becoming invasive. Twelve of the 43 species were assessed by scientists from two or more Balkan countries, and the remaining 31 species by a single assessor. Using the 9.5 threshold, three species were classed as low risk, 10 as medium risk, and 30 as high risk, with the latter category comprised of 26 moderately high risk, three high risk, and one very high risk species. Confidence levels in the assessments were relatively constant for all species, indicating concordance amongst assessors

Is it absent or is it present? Detection of a non-native fish to inform management decisions using a new highly-sensitive eDNA protocol

© 2019, The Author(s). Environmental managers require a sensitive and reliable means to prove, with the highest level of confidence possible, where non-native fish species exist and where they do not. Therefore, a nested PCR (nPCR) protocol was developed to detect the environmental DNA (eDNA) of a case-study species, topmouth gudgeon Pseudorasbora parva, which was recently the subject of a national eradication campaign in the UK. The nPCR protocol was tested in the laboratory and in the field in a series of coordinated surveys (eDNA and conventional sampling with traps) at a commercial angling venue in southern England where an initial eDNA survey, based on conventional PCR (cPCR), found P. parva to be present in one of the seven ponds. In the laboratory, the nPCR protocol was on average 100× more sensitive than cPCR, providing a 100% detection rate at DNA concentrations of 3 × 10 −8  ng/µL (8 DNA copies per µL). In the field, nPCR and conventional trapping both detected P. parva in only one of the seven angling ponds, the same infested pond as in the previous cPCR-based study. Following eradication work on the infested pond, no eDNA of P. parva was detected using nPCR in either the formerly-infested pond or the adjacent pond, which had been used to quarantine large commercially-valuable fishes. In management applications where the veracity of negative results may be of equal importance as confirmation of positive detections, nPCR protocols provide a useful addition to the analytical toolkit available to inform decision makers responsible for non-native species management

The UK risk assessment scheme for all non-native species

1. A pest risk assessment scheme, adapted from the EPPO (European and Mediterranean Plant Protection Organisation) scheme, was developed to assess the risks posed to UK species, habitats and ecosystems by non-native taxa. 2. The scheme provides a structured framework for evaluating the potential for non-native organisms, whether intentional or unintentional introductions, to enter, establish, spread and cause significant impacts in all or part of the UK. Specialist modules permit the relative importance of entry pathways, the vulnerability of receptors and the consequences of policies to be assessed and appropriate risk management options to be selected. Spreadsheets for summarising the level of risk and uncertainty, invasive attributes and economic impact were created. In addition, new methods for quantifying economic impact and summarising risk and uncertainty were explored. 3. Although designed for the UK, the scheme can readily be applied elsewhere