Gibel Carp Carassius Gibelio Research Articles

Intermittent hypoxia differentially affects metabolic and oxidative stress responses in two species of cyprinid fish.

Oxygen fluctuations are common in freshwater habitats and aquaculture and can impact ecologically and economically important species of fish like cyprinids. To gain insight into the physiological responses to oxygen fluctuations in two common cyprinid species, we evaluated the impact of short-term intermittent hypoxia on oxidative stress and metabolic parameters (including levels of prooxidants and oxidative lesions, antioxidants, mitochondrial enzyme activities, mitochondrial swelling, markers of apoptosis, autophagy and cytotoxicity) in silver carp Hypophthalmichthys molitrix and gibel carp Carassius gibelio. During hypoxia, gibel carp showed higher baseline levels of antioxidants and less pronounced changes in oxidative and metabolic biomarkers in the tissues than silver carp. Reoxygenation led to a strong shift in metabolic and redox-related parameters and tissue damage, indicating high cost of post-hypoxic recovery in both species. Species-specific differences were more strongly associated with oxidative stress status, whereas metabolic indices and nitrosative stress parameters were more relevant to the response to hypoxia-reoxygenation. Overall, regulation of energy metabolism appears more critical than the regulation of antioxidants in the response to oxygen deprivation in the studied species. Further research is needed to establish whether prioritizing metabolic over redox regulation during hypoxia-reoxygenation stress is common in freshwater cyprinids.

High trophic similarity between non-native common carp and gibel carp in Turkish freshwaters: Implications for management

Although the detrimental ecological and economic effects of introducing freshwater fish species have been extensively documented, non-native freshwater fishes continue to be introduced in large numbers globally to enhance fisheries and aquaculture. In Turkey, stocking of common carp Cyprinus carpio is practised to provide food security for people and job security for artisanal fishers, resulting in a country-wide distribution. These stockings, however, increase the risk of accidental introductions and have led to introductions and subsequent invasions of gibel carp Carassius gibelio, a globally invasive and highly detrimental fish species. Here, we assessed the growth types, body conditions and trophic interactions via bulk carbon and nitrogen stable isotope analysis of common and gibel carp in both natural and artificial water bodies in Turkey. The results indicated that common and gibel carp express similar growth types and body conditions in all waters and have similar trophic ecologies. This leads to substantial trophic niche overlaps in waters where they co-occur, with the potential for strong interspecific competition. Considering the ongoing stocking of common carp for fishery enhancement, we recommend to specifically target these stockings in waters where gibel carp has already become invasive. Our findings, indeed, suggest that common carp releases have the potential to hamper invasive gibel carp populations by increasing the competitive interactions between the two species.

A new species of Myxobolus (Cnidaria: Myxosporea: Myxobolidae) from the gibel carp Carassius gibelio (Cypriniformes: Cyprinidae).

Myxobolus zhaltsanovae n. sp., is described from the gills of gibel carp Carassius gibelio found during a survey of myxozoans from the watershed of Lake Baikal, Russia, based on morphological and molecular characterizations. Plasmodia of M. zhaltsanovae n. sp. develop extravascularly and measure 500-1000 μm long, 25-100 μm wide. The myxospore is circular to oval, measuring 13.23 ± 0.09 (11.3-14.8) µm (mean ± SD, range) in length, 10.19 ± 0.07 (9.1-11.4) µm in width, and 6.49 ± 0.12 (5.4-7.2) µm in thickness. Polar capsules are unequal and subspherical; measurements of polar capsules are: length 5.62 ± 0.06 (4.7-6.7), width 3.44 ± 0.04 (2.4-4.4) µm and length 3.42 ± 0.05 (2.5-4.1), width 1.94 ± 0.04 (1.3-3.3) µm. Phylogenetic analysis with the 18S rDNA gene shows M. zhaltsanovae n. sp. as a sister species of the subclade formed by M. musseliusae, M. tsangwuensis, and M. basilamellaris, which infect common carp Cyprinus carpio.

Risk of invasiveness of non-native fishes in the South Caucasus biodiversity and geopolitical hotspot

Aquatic invasions are one of the major threats for freshwater ecosystems. However, in developing countries, knowledge of biological invasions, essential for the implementation of appropriate legislation, is often limited if not entirely lacking. In this regard, the identification of potentially invasive non-native species by risk screening, followed by a full risk assessment of the species ranked as higher risk, enables decision-makers to be informed about the extent of the threats posed to the recipient (risk assessment) area. In this study, 32 non-native extant and horizon fish species were screened for their risk of invasiveness under current and predicted climate conditions for the South Caucasus – a biodiversity and geopolitical hotspot that includes the countries of Armenia, Azerbaijan and Georgia. Overall, the number of very high-risk species increased from four (12.5%) under current climate conditions to 12 (37.5%) under predicted climate conditions. The highest-risk species under both conditions included the already established gibel carp Carassius gibelio and topmouth gudgeon Pseudorasbora parva, the locally translocated pikeperch Sander lucioperca and the horizon North African catfish Clarias gariepinus. Under predicted climate conditions, a very high risk of invasiveness was predicted also for the translocated three-spined stickleback Gasterosteus aculeatus and Eurasian perch Perca fluviatilis, for the already established eastern mosquitofish Gambusia holbrooki, ruffe Gymnocephalus cernua, sharpbelly Hemiculter leucisculus and Nile tilapia Orechromis niloticus, and for the horizon pumpkinseed Lepomis gibbosus and largemouth bass Micropterus salmoides. Future research on the non-native species in the South Caucasus should be conducted both country- and region-wide and should account not only for the high biodiversity, but also for the critical geopolitical situation affecting the study area.

Morphological variations of an invasive cyprinid fish (Carassius gibelio) in lentic and lotic environments inferred from the body, otolith, and scale shapes

AbstractThis study investigated the morphological variation of gibel carp Carassius gibelio collected from various water bodies in Türkiye. The fish samples were obtained from three dams (Karacaören‐1, Karakaya, and Keban), two natural lakes (Beyşehir and Suğla), and a river (the Tigris River). The dimorphism in body shape was examined with geometric morphometrics, while elliptic Fourier analysis and shape indices were used to describe the variation in lapilli otoliths (hereafter “otoliths”) and scale shapes. The body of C. gibelio revealed higher variations, particularly in the body depth, snout length, caudal fin, and caudal peduncle, among different stations. Geometric morphometric analysis determined a streamlined body shape of C. gibelio in the Tigris River compared to other stations, while C. gibelio from the natural lakes had a deeper body shape. The body of C. gibelio exhibited a significant homogenous shape between the Beyşehir and Suğla lakes, providing the lowest Procrustes distance. The elliptic Fourier analysis revealed that the otolith shape varied significantly between all stations. However, the scale shape was remarkably similar among nearby areas such as Karacaören dam, Suğla, and Beyşehir lakes. These results evinced high degree of intra‐population morphological variation in C. gibelio in response to prevailing environmental conditions that probably facilitate their successful establishment in a novel environment.

Two Strains of Gibel Carp (Carassius gibelio) Exhibit Diverse Responses to Carbohydrates in a Low-Lipid Diet

An 8-week feeding trial was conducted to investigate carbohydrate use in a low-lipid diet between different strains of gibel carp (Carassius gibelio). The wild-type Dongting strain and artificially selected CASIII strain were fed three levels of carbohydrate: 15%, 30%, and 45%, in a low-lipid formulation (4%). The results showed that low-lipid supplementation with high carbohydrate seems to improve the feeding rate (FR) and specific growth rate (SGR), while it did not result in hyperglycaemia in gibel carp. Transcriptional regulation was slightly affected by carbohydrate levels; only hepatic pfk expression was more increased in the 30% and 45% carbohydrate diets than in the 15% carbohydrate diet ( p < 0.05 ). Regarding the strains, CASIII obtained higher growth performance by having higher FR and SGR than Dongting ( p < 0.05 ). Relatively higher glycaemia was found in CASIII, and it was coupled with increased plasma triglycerides and insulin ( p > 0.05 ). Enhanced gene expression of pk involved in glycolysis and decreased mRNA levels of pepck in gluconeogenesis were also observed in CASIII ( p < 0.05 ). There were strong strain ∗ diet interactions of gene expression involved in lipogenesis, and Dongting had higher mRNA levels of srebp-1, acly, and fas when fed carbohydrate at 45% ( p < 0.05 ). In conclusion, the tolerant level of carbohydrates in a low-lipid diet could be up to 45% for gibel carp by an improvement of growth and noninducement of postprandial plasma glucose. CASIII had a better ability to use dietary carbohydrates for growth with active glycolysis and restrained gluconeogenesis, and Dongting had more potential in lipid metabolism in response to carbohydrate intake.

Analysis of nowadays fisheries and the recommendations of the regulation of the main commercial fish species stocks exploitation in the Dniestrovskiy liman

The dynamics of the catch of the main commercial fish species of the Dniesterovskiy liman are presented. The sizeage composition of the gibel carp Carassius gibelio (Bloch, 1783), common carp Cyprinus carpio (Linnaeus, 1758), common bream Abramis brama (Linnaeus, 1758), roach Rutilus heckelii (Nordmann, 1840) and common pike-perch Sander lucioperca (Linnaeus, 1758) from commercial catches in the Dniesterovskiy liman in 2012–2021 was analyzed. The obtained data were used to analyze the state of fish stocks and to obtain the recommended optimal indicators of their exploitation using modern models BSM, LBB and LB-SPR. The overexploitation of gibel carp in the Dniesterovskiy liman was observed accordingly BSM, LBB and LB-SPR results. A sharp increase in the level of exploitation of gibel carp has led to its stock decline. The level of common carp exploitation in 2018–2021 has approached the optimal value. The currently state of its population in the Dniesterovskiy liman is relatively good. Commercial exploitation of the common bream and roach remains at an excessive and at a relatively moderate level respectively. The catch and CPUE of the pike perch have been declined significantly in recent years. The stock of this species is in a very unfavorable condition. The recommendations for further use of the main commercial fish species in the Dniesterovskiy liman are given. Accordingly obtained results the value of the maximum sustainable yield (MSY) of gibel carp is 813 tons with the optimal average commercial length in the catch – 18.5–19 cm. MSY of common carp is set at 92.7 tons with the optimal length in the catch – 39.9 cm, common bream – 148 tons with an optimal length in the catch no less than 30.0 cm. MSY of roach is set at 57.7 tons. The value of pike perch biomass is significantly lower than the critical value of Bpa=0.5 BMSY – its catch should not exceed 5 tons. The strict compliance with the Rules (1998) and Regimes of commercial fishery, as well as commercial fishing regulating by limiting the use of fishing gear are the most effective methods of the abundance increasing and rational use of water biological resources of the Dniesterovskiy liman.

Effects of pharmaceutically active compounds (PhACs) on fish body and scale shape in natural waters.

BackgroundIn recent years, there are growing concerns about pharmaceutically active compounds (PhACs) in natural ecosystems. These compounds have been found in natural waters and in fish tissues worldwide. Regarding their growing distribution and abundance, it is becoming clear that traditionally used risk assessment methodologies and ecotoxicological studies have limitations in several respects. In our study a new, combined approach of environmental impact assesment of PhACs has been used.MethodsIn this study, the constant watercourses of the suburban region of the Hungarian capital (Budapest) were sampled, and the body shape and scale shape of three fish species (roach Rutilus rutilus, chub Squalius cephalus, gibel carp Carassius gibelio) found in these waters were analyzed, based on landmark-based geometric morphometric methods. Possible connections were made between the differences in body shape and scale shape, and abiotic environmental variables (local- and landscape-scale) and measured PhACs.ResultsSignificant connections were found between shape and PhACs concentrations in several cases. Despite the relatively large number of compounds (54) detected, citalopram, propranolol, codeine and trimetazidine significantly affected only fish body and scale shape, based on their concentrations. These four PhACs were shown to be high (citalopram), medium (propranolol and codeine), and low (trimetazidine) risk levels during the environmental risk assessment, which were based on Risk Quotient calculation. Furthermore, seven PhACs (diclofenac, Estrone (E1), tramadol, caffeine 17α-Ethinylestradiol (EE2), 17α-Estradiol (aE2), Estriol (E3)) were also categorized with a high risk level. However, our morphological studies indicated that only citalopram was found to affect fish phenotype amongst the PhACs posing high risk. Therefore, our results revealed that the output of (traditional) environmental/ecological risk assessment based on ecotoxicological data of different aquatic organisms not necessarily show consistency with a “real-life” situation; furthermore, the morphological investigations may also be a good sub-lethal endpoint in ecotoxicological assessments.

Risk of invasiveness of non-native aquatic species in the eastern Mediterranean region under current and projected climate conditions

Human-induced biological introductions pose a major threat to global biodiversity, and this is especially frequent in the eastern Mediterranean region, which is a globally important biodiversity hotspot area of high conservation value. To predict at which level introduced species in this region might become invasive under current and projected climate conditions, 232 non-native aquatic organisms were screened using the Aquatic Species Invasiveness Screening Kit. Based on receiver operative characteristic curve analysis, thresholds were identified to distinguish between low, medium and high risk species. The “top invasive” (very high risk) species identified were: brown bullhead Ameiurus nebulosus, blue crab Callinectes sapidus, gibel carp Carassius gibelio, Philippine catfish Clarias batrachus, Chinese mitten crab Eriocheir sinensis, bluespotted cornetfish Fistularia commersonii, silver carp Hypophthalmichthys molitrix, silver-cheeked toadfish Lagocephalus sceleratus, half-smooth golden pufferfish Lagocephalus spadiceus, Suez pufferfish Lagocephalus suezensis, signal crayfish Pacifastacus leniusculus, fathead minnow Pimephales promelas, channeled applesnail Pomacea canaliculata, red swamp crayfish Procambarus clarkii, devil firefish Pterois miles and European catfish Silurus glanis. The risk of being invasive of more than half of the screened species increased after taking global warming predictions into account, and several species considered to be globally invasive (cf. high risk) were classified as posing only a medium risk for the eastern Mediterranean region. Region-specific risk screenings, as implemented in this study, are therefore essential for setting priorities in preventative management for the conservation of key biodiversity hotspots and the optimal allocation of resources in view of full risk assessment for the species identified as (very) high risk.

The current state of aquatic biological resources and fisheries in the lower Dniestr and Dniestrovskiy liman

The fish species composition and structural characteristics of the ichthyofauna of the Lower Dniester and Dniesterovskiyliman are presented. In total 79 species of fish from 16 orders, 24 families, 61 genera were observed in 2006–2018.The largest number of species in two orders: Cypriniformes and Perciformes (40.5 and 25.3%, respectively); largest number of genera and species in families: Cyprinidae – 22 genera and 29 species, Gobiidae – 7 genera and 13 species,and Percidae – 5 genera and 5 species. Ichthyofauna of Lower Dniester and Dniesterovskiy liman is represented byfour main faunal complexes. The dominant complex is the Ponto-Caspian, combining brackish and marine fish species.Ichthyofauna of the Lower Dniester is formed mainly by freshwater (55.7% of the total number of identified species)and brackish-water fish (26.6%). Most of species (77.2%) are demersal and bottom dwelling, phytophiles (34.2%)and lithophiles (22.8%), benthophages and carnivores. The remaining groups are represented by fewer species.The analysis of the current state of aquatic bioresources are presented. From 16 to 28 species of fish are recorded inthe commercial catches of the Lower Dniester and Dniestrovskiy liman. The dynamics of catches of the main commercialfish species are presented according to official statistics. Significant increase in the catch of gibel carp, an increase inthe catch of common carp? roach and common bream, and a decrease in the number of populations of predatory fishspecies was observed. The total catch of aquatic biological resources from 2013 to 2017 increased sharply from 547.9 to2344.3 tons per year. Gibel carp Carassius gibelio (Bloch, 1782) is the dominant fish species in the Lower Dniester.The catches of this species increased significantly (up to 1967.8 tons). The age and sex composition, as well as the sizemasscharacteristics of the main commercial species are presented. A decrease in the age composition of the populationsof the main commercial fish species as a result of an increase in the intensity of fishing was observed. The commercialfish mortality rates and stocks of the main commercial species are presented. The stock of gibel carp is set at 5,000–6,000 tons, bream – 630 tons, roach – about 150-200 tons, common carp about 200–250 tons, pikeperch – 20–25 tons.Forecasts of the allowable catch of the main commercial fish species of the Lower Dniester are presented.

High genetic diversity in an invasive freshwater fish species, Carassius gibelio, suggests establishment success at the frontier between native and invasive ranges

Non-native freshwater fish introductions can have direct and indirect negative effects on native flora and fauna, ecosystems, and national economies. Although invasions are paradoxical from an evolutionary standpoint, population genetics could be useful to understand invasion scenarios of non-native species. One of the most common introduced fish in Europe and Turkey is the gibel carp Carassius gibelio, which was first introduced from East Asia in the 17th century. To find out the origin and distribution pattern and characterise the genetic variation of gibel carp in Turkey, the aim of this study was to identify haplotype the species’ diversity and distribution in the country. Three mitochondrial (COI, Cyt-b and D-loop) and one nuclear (ITS1) DNA markers were used in 20 populations sampled from 18 different geographic locations, resulting in eight newly-identified haplotypes. The present results: (i) suggest high genetic diversity across regions at both the mitochondrial (29 haplotypes, h = 0.9058, π = 0.0152) and nuclear (3 haplotypes, h = 0.6365, π = 0.0094) level; (ii) confirm previous findings that this species may have entered Turkey directly either from its native or through its invasive range; (iii) suggest that, given the distribution of the identified haplotypes by geographic location, the majority of individuals not only originated from the northern (European) part of Turkey but also from the southern (Mediterranean) part of the country. Understanding the genetic characterisation of gibel carp can contribute to more efficient management actions for this species, including prevention of (multiple) introductions and eradication/control of those populations with relatively low genetic diversity.

Myxobolus himalayaensis sp. nov. (Cnidaria: Myxozoa) parasiting Schizothorax richardsonii (Cyprinidae: Schizothoracinae) from River Poonch in North West Himalaya, India

This study provides morphological and molecular data of a new myxozoan species belonging to genus Myxobolus from the gill filaments of an endemic cyprinid fish from River Poonch in North West Himalaya, India. Parasitological observations under stereozoom binocular microscope revealed single large type of plasmodia 2–10 mm in diameter residing on the gill filament, while clinical signs revealed mucous laden gills. Infection was found in the 21 of 80 examined Schizothorax richardsonii with a prevelance of (26.25%). Mature spores appeared oval to spherical in frontal view, and broadly rounded posterior end measuring 8.56–10.02 (9.64) x 6.07–8.10 (7.06) μm. Two equal polar capsules were pyriform measuring 4.89 x 2.70 μm, and polar filaments coiled 5–6 turns. Phylogenetic analysis indicated that the obtained 18S rDNA sequence of M. himalayaensis sp. nov. (MK087655) did not match any available myxozoan sequence and was sister species to Henneguya doneci infecting gills of gibel carp Carassius gibelio from China and showing less than 95% sequence similarity with Myxobolus linzhiensis using BLAST search. Histological observations of infected gills revealed plasmodia of type FV2 intrafilamental vascular type causing hypertrophy, hyperplasia, uplifting of epithelial cells and necrosis.

The Effects of Fermentation Process with Acid and Lactic Acid Bacteria Strains on the Biogenic Amine Formation of Wet and Spray-Dried Fish Silages of Discards

ABSTRACTThe impacts of fermentation process with acid and lactic acid bacteria strains (Lactobacillus plantarum, Lactobacillus brevis, Pediococcus acidilactici, Enterococcus gallinarum, and Streptococcus spp.) on the biogenic amine formation of wet and spray-dried fish silage obtained from whole gibel carp (Carassius gibelio, freshwater discard), whole ponyfish (Equulites klunzingeri, seawater discard), and processing by-products of seabass (Dicentrarchus labrax) were investigated. The results showed that among biogenic amines, cadaverine, putrescine, spermidine, spermine, serotonin, dopamine, and agmatine were predominant in all groups. Significant differences (p < 0.05) in biogenic amine concentrations of wet and spray-dried fish silage were observed. Raw fish and wet silages contained histamine level lower than the allowable limit of 50mg/kg, indicating the use of raw fish material with low microbial counts. In addition, no histamine was detected in spray-dried fish silage, except for seabass by-products with a trace quantity of histamine (<0.04mg/100g). The starter culture used for silage preparation did not effectively retard formation of biogenic amines compared to acid silage. It can be concluded that there is potential use of fermented fish silage as a protein source and possibly as a probiotic ingredient for animal feed in both wet and dry form.

The effect of C/N ratio on bacterial community and water quality in a mussel-fish integrated system

A 30-day experiment was conducted to evaluate the effect of C/N ratio on water quality and bacterial community in an integrated system comprising one molluscan species (pearl mussel Hyriopsis cumingii) and two fish species (gibel carp Carassius gibelio and silver carp Hypophthalmichthys molitrix) at five C/N ratios (6, 8, 10, 12 and 14). The mussel and fishes were reared in the experimental tanks (400 L), but gibel carp received formulated feed. Water quality in the experimental tanks was analysed on day 0, 10, 20 and 30, and bacterial community in the water column and sediment was analysed on day 30. Total nitrogen, total phosphorus and total organic carbon accumulated in the tanks over time. Ammonia and nitrite decreased with the increase in C/N ratio. Bacterial community in the water column and sediment changed at the phylum and genus levels with the increase in C/N ratio, and the critical C/N ratio causing a functional shift of bacterial community occurred at 10 in water column and 12 in sediment. The increase in C/N ratio benefited the growth of both potential probiotics and pathogenic bacteria. The high C/N ratio enhanced the bacterial functions of chemoheterotrophy and hydrocarbon degradation, but depressed the functions of nitrification and denitrification in the water column and sediment respectively. This study reveals that the C/N ratio can be used as a tool to manipulate the bacterial community and water quality in the mussel-fish integrated system.

Comparison of Taxon‐Specific and Taxon‐Generic Risk Screening Tools to Identify Potentially Invasive Non‐native Fishes in the River Neretva Catchment (Bosnia and Herzegovina and Croatia)

AbstractThe Freshwater Fish Invasiveness Screening Kit (FISK) v2 and Aquatic Species Invasiveness Screening Kit (AS‐ISK) risk identification screening tools were used to assess the invasiveness potential of 24 non‐native (NNS) freshwater fish species in the River Neretva catchment (Bosnia and Herzegovina and Croatia), a risk assessment (RA) area that is an important Mediterranean hotspot for fish endemism. The two assessors assigned similar scores for the invasiveness potential of the NN fishes, and both screening tools successfully distinguished invasive from non‐invasive species. Mean calibrated threshold scores were 10.25 for FISK and 10.00 for AS‐ISK, with the latter increasing to 12.62 when questions that assess the likely impact of predicted future climate conditions on the RA were taken into consideration. These relatively low threshold values are characteristic of areas with an elevated number of translocated species and suggest that NN fishes pose a considerable threat to native species and ecosystems. FISK ranked 50.0–62.6% of the species as being of ‘high risk’ compared with 58.4–59.3% using AS‐ISK. The highest scores (‘very high risk’) were attributed to gibel carp Carassius gibelio (Bloch, 1782) and pikeperch Sander lucioperca (Linnaeus, 1758). The generic screening tool for aquatic species (AS‐ISK) provided similar risk rankings to its predecessor, FISK, as regards invasiveness potential. For this reason, it is likely to be an effective tool for evaluating the potential invasion risk of NNS freshwater fishes for other RA areas in the Balkans. Copyright © 2017 John Wiley &amp; Sons, Ltd.

Can Application of Commercial Microbial Products Improve Fish Growth and Water Quality in Freshwater Polyculture?

AbstractA 31‐d experiment was conducted to examine the effects of three commercial microbial products (Novozymes pond plus, Zhongshui BIO‐AQUA, and Effective Microorganisms) on production performance and water quality in freshwater tanks stocked with Grass Carp Ctenopharyngodon idellus, Gibel Carp Carassius gibelio and Silver Carp Hypophthalmichthys molitrix. Four treatments were used: blank control (BL), adding Novozymes pond plus (NO), adding BIO‐AQUA (PB), or adding Effective Microorganisms (EM). The fish were fed daily with a formulated feed, and each of the microbial products was added to the tanks every 10 d. No significant differences were found in survival, weight gain, and feed conversion ratio of the fishes, Secchi depth, chemical water quality, and phytoplankton between the blank control and any other treatments (NO, PB and EM). This study indicates that the addition of these three microbial products every 10 d has limited function to improve production performance and water quality in freshwater polyculture of Grass Carp, Gibel Carp, and Silver Carp within the first 31 d of application.

Risk assessment of non-native fishes in the catchment of the largest Central-European shallow lake (Lake Balaton, Hungary)

The Fish Invasiveness Screening Kit (FISK) has proved to be a useful tool for assessing and screening the risk posed by potentially invasive fish species in larger risk assessment (RA) areas (i.e. country or multi-country level). In the present study, non-native freshwater fishes were screened for a smaller RA area, the closed and vulnerable but economically important drainage basin of Lake Balaton (Hungary). Receiver operator characteristic analysis of FISK scores for 26 fish species screened by four assessors identified 21 species with scores of ≥11.4 to pose a ‘high risk’ of being invasive, with five species ranked as ‘medium risk’ and none as ‘low risk’. The highest scoring species were gibel carp Carassius gibelio and black bullhead Ameiurus melas, with three Ponto-Caspian Gobiidae identified as amongst the species posing the potentially greatest threat to the catchment. The results of the present study indicate that FISK can be applied to risk assessment areas of smaller geographical scale.

Dynamics of Catches and Actual State of Stock of Gibel Carp Carassius gibelio and Bream Abramis brama in the Dniester Liman in 2004-2014

Paper deals with dynamics of catches, age structure and size-mass characteristics of the main commercial fish species of the Dniester liman - gibel carp Carassius gibelio (Bloch, 1782) and bream Abramis brama (Linnaeus, 1758). Age structure of gibel carp and bream populations turned to domination of younger groups owing to intensive commercial catches. Estimated parameters of the Bertalanffy equation, coefficients of total, natural and fishery mortality are presented. Stocks of gibel carp and bream were assessed. The stock of gibel carp in the Dniester liman is about 1150 tons, of bream – about 630 tons.

Bioaccumulation of heavy metals in tissues of the gibel carp Carassius gibelio: Example of Marmara Lake, Turkey

Within the scope of this study, heavy metals presence (Al, Cr, Ni, Cu, As, Cd, Hg, Pb) in water samples and liver, gills and muscle tissue of gibel carp Carassius gibelio caught in Marmara Lake was analyzed seasonally. It was determined that there was not any difference seasonally with regard to heavy metals studied in lake waters (p > 0.05). Mineralization of fish tissues was made by microwave-wet decomposition. To evaluate heavy metal concentrations in water and tissue samples, method of inductively coupled plasma—mass spectroscopy (ICP-MS) was applied. TORT 2 lobster hepatopancreas was used as certified reference matter in this study. According to obtained results, bioaccumulation rates for gills were found as Cu > Cd > Ni > Pb > Cr > Al > As > Hg, for liver and muscle tissues they were found as Cu > Cd > Ni > Cr > Pb > Al > As > Hg. It was proved that the most bioaccumulated heavy metal was Cu and the least bioaccumulated was Hg for all of the studied tissues.

Risk screening of non-native freshwater fishes at the frontier between Asia and Europe: first application in Turkey of the fish invasiveness screening kit

The aim of the present study was to assess the invasive potential of introduced non-native and translocated fishes in Turkey (Anatolia and Thrace) by applying the Fish Invasiveness Screening Kit (FISK), a risk identification tool for freshwater fishes. From independent evaluations by two assessors of 35 species, calibration of FISK for Turkey identified a threshold score of 23, which reliably distinguished between potentially invasive (high risk) and potentially non-invasive (medium to low risk) fishes for Anatolia (Asia) and Thrace (Europe). No species was categorized as ‘low risk’, 18 species were categorized as ‘medium risk’ and 17 as ‘high risk’ (two being ‘moderately high risk’, nine ‘high risk’, and six ‘very high risk’). The highest scoring species was gibel carp Carassius gibelio, whereas the lowest scoring species was Caucasian dwarf goby Knipowitschia caucasica, a translocated species. Assessor certainty in their responses averaged overall between ‘mostly uncertain’ and ‘mostly certain’, with red piranha Pygocentrus nattereri and topmouth gudgeon Pseudorasbora parva achieving the lowest and highest certainty values, respectively, and with overall significant differences in certainty between assessors. The results of the present study indicate that FISK is a useful and viable tool for identifying potentially invasive non-native fishes in Turkey, a country characterized by natural biogeographical frontiers.