White Bream Research Articles

Occurrence of priority and emerging organic compounds in fishes from the Rhone River (France)

The main objective of this study was to collect new data on the occurrence, levels of priority and emerging organic compounds in freshwater fish sampled in the Rhone River. The 34 studied contaminants included alkylphenols, bisphenol A, polybromodiphenylethers (PBDE), perfluorinated compounds, hexabromocyclododecanes (HBCD), hexachlorobenzene and hexachlorobutadiene (HCBD). About 50 fish samples (individual specimens or pooled fish) were collected from three sites located upstream and downstream of the Lyon metropolitan area in the Rhone River (France). Four species were caught at each site, namely: the barbel (Barbus barbus), the common bream (Abramis brama), the white bream (Blicca bjoerkna) and the chub (Squalius cephalus). Some contaminants were quantified in all the 32 fish samples analysed: 4-nonylphenol, α-HBCD, the six PBDE congeners (28, 47, 99, 100, 153, 154), perfluorooctanesulfonate (PFOS) and perfluorodecanoic acid. Twenty three of the 32 samples had a concentration of PFOS above the Environmental Quality Standards (EQS) (up to six times higher than the EQS), and all the 32 samples had concentrations of PBDE above the EQS (up to 4,000 times higher, with the sum of six PBDE varying from 4.5 to 182 ng/g dry weight). Clearly, the interest to consider PFOS and HBCD as new priority substances is confirmed. In contrast, the pertinence of a priority status for HCBD, which was never quantified in our study, might have to be reconsidered in the future.

Bioaccumulation of six PCB indicator congeners in a heavily polluted water reservoir in Eastern Slovakia: tissue-specific distribution in fish and their parasites

Concentrations of six indicator PCB congeners (IUPAC nos. 28, 52, 101, 138, 153, and 180) were measured in several organs and adipose tissue of a freshwater predatory fishes (European perch, northern pike, pike perch, wels catfish) as well as in nonpredators (common carp, freshwater bream, goldfish, white bream) and in acanthocephalan Acanthocephalus lucii from the water reservoir Zemplínska šírava (Eastern Slovakia), which is considered to be one of the most PCB-contaminated places in Europe. Concentration of PCBs was determined by capillary gas chromatography in samples from May to September 2009. The two-way main-effect ANOVA confirmed that feeding habits of fish (P < 0.00001) and peculiarity of individual fish organs (P < 0.01) affect PCB bioaccumulation. The total amount of PCBs was significantly higher (P < 0.05) in predators compared to nonpredators. Tissue-specific differences were found in PCB accumulation in both fish groups. PCBs were predominantly accumulated in the liver and hard roe. Individual congeners were not distributed homogeneously within the investigated organs and adipose tissue. PCB 153 was present in higher concentrations than the other congeners in all fish organs as well as in adipose tissue comprising an average 31 and 34 % of ΣPCB in predators and nonpredators, respectively. Acanthocephalans, attached to the intestine of perch, absorbed significantly higher concentrations of PCBs (P < 0.001) than the muscles, liver, kidney, brain, and adipose tissue of their host. About 20 times lower amount of PCBs was detected in the liver and almost 3 times in muscles of infected perch. Data on PCB accumulation in perch infected with acanthocephalans demonstrated a decline of PCB values in all organs as well as in adipose tissue compared to noninfected fish. About 20 times lower amount of PCBs was detected in the liver and almost 3 times in muscles of infected perch. Present results could indicate that some parasitic organisms may influence positively their hosts in PCB-contaminated environment.

New ichthyological findings in Armenia

Three new fish species were found in southeastern Armenia. The presence of Kura gudgeon Romanogobio macropterus is reconfirmed after 80 years of absence. Kura roach Rutilus caspicus, Transcaucasian white bream Blicca bjoerkna transcaucasica, and European pikeperch Sander lucioperca were found for the first time. All three species were registered in Aras River. Kura gudgeon was caught in 2008 just before flooding of the Aras Reservoir. The other two species were found during the period of flooding in 2010. Attempts to find Kura gudgeon failed in the Aras River and its nearest tributaries in 2010 after damming and change of the hydrological regime. Probably, penetration of the species from the lower reach of the Aras River to the middle and upper reach became possible owing to subsequent appearance of a broad limnetic zone after damming. Range expansion of widely distributed cyprinid species upstream may lead to the replacement and even disappearance of local endemic forms, the Armenian roach Rutilus schelkovnikovi and the Armenian white bream Blicca bjoerkna derjavini, which inhabit the Mezamor River and its tributaries.

Genetic analysis of a novel nidovirus from fathead minnows

A bacilliform virus was isolated from diseased fathead minnows (Pimephales promelas). Analysis of the complete genome coding for the polyprotein (pp1ab), spike (S), membrane (M) and nucleocapsid (N) proteins revealed that the virus was most like white bream virus (WBV), another bacilliform virus isolated from white bream (Blicca bjoerkna L.) and the type species of the genus Bafinivirus within the order Nidovirales. In addition to similar gene order and size, alignment of deduced amino acid sequences of the pp1ab, M, N and S proteins of the fathead minnow nidovirus (FHMNV) with those of WBV showed 46, 44, 39 and 15 % identities, respectively. Phylogenetic analysis using the conserved helicase domain of the replicase showed FHMNV was distinct from WBV, yet the closest relative identified to date. Thus, FHMNV appears to represent a second species in the genus Bafinivirus. A PCR assay was developed for the identification of future FHMNV-like isolates.

Age, Growth and Some Biological Characteristics of White Bream (Blicca bjoerkna L., 1758) in Uluabat Lake, in Northwestern of Anatolia

Age, Growth and Some Biological Characteristics of White Bream (Blicca bjoerkna L., 1758) in Uluabat Lake, in Northwestern of Anatolia

Host switch and infestation byLigula intestinalisL. in a silver bream (Blicca bjoerknaL.) population

Sampling of the fish community was carried out for 20 years in the Mirgenbach reservoir, in North-Eastern France. The prevalence and the mean intensity of Ligula intestinalis (Cestoda) were analysed in roach (Rutilus rutilus) and silver bream (Blicca bjoerkna) populations, the main two infected species. The aim of this study was to investigate the host switch from roach to silver bream and the consequences of L. intestinalis infestation in silver bream, which is an unusual host for this parasite as Ligula parasitism in silver bream appears to be rare. We analysed in detail the relationships between parasitism index (PI), gonadosomatic index (GSI), perivisceral fat abundance (PFA) and condition index (CI) in the silver bream population. In 1998, prevalence of L. intestinalis highlighted a clear host switch from roach to silver bream. In the silver bream population, young fish were the most severely infected and the impact of plerocercoids appeared to be different depending on the host sex. In male silver bream, plerocercoids drew energy from fat reserves even if GSI was also slightly impacted. On the contrary, in females energy was diverted from gonad maturation rather than from perivisceral fat reserves. No significant difference was observed in terms of CI in either sex.

Molecular genetic studies on morphologically indistinguishable Myxobolus spp. infecting cyprinid fishes, with the description of three new species, M. alvarezae sp. nov., M. sitjae sp. nov. and M. eirasianus sp. nov.

While studying Myxobolus gill infections of cyprinid fishes, the authors found large, segmented plasmodia in three species: ide (Leuciscus idus), asp (Aspius aspius) and white bream (Blicca bjoerkna). As regards their size and morphology, the spores from these plasmodia corresponded to those of M. dujardini described from chub (Leuciscus cephalus). However, the 18S rDNA sequences of spores from the three cyprinids differed from those of M. dujardini. Based on molecular differences, this paper describes two new species: M. alvarezae sp. nov. from ide and asp, and M. sitjae sp. nov. from white bream. The two new species and M. dujardini had a similar tissue tropism, and infected the multilayered epithelium of the gill filaments. Histological examination of the infected filaments demonstrated that the large plasmodia with multiple buddings were formed from amalgamating small plasmodia. Besides carrying infection in the filamental epithelium, the three above fish species were infected by small intralamellar plasmodia as well. These plasmodia were filled by spores that resembled the roach parasite M. intimus both in morphology and seasonal development. The 18S rDNA sequences of 'intimus-like' spores from ide and asp differed only in some base pairs from spores found in the type host roach, and were identified as belonging to M. intimus. The spores found in white bream, however, showed 3.6-5.0% difference in DNA sequence from those of M. intimus; therefore, they have been described as M. eirasianus sp. nov. The aim of this paper was to demonstrate the importance of using molecular methods for separating and identifying morphologically corresponding or closely similar Myxobolus spp.

The growth and reproduction of white bream (Blicca bjoerkna L. 1758) in an oligo-mesotrophic lake in northwest Anatolia (Sapanca, Turkey)

Growth parameters and the reproduction period of white bream (Blicca bjoerkna L. 1758) sampled from Sapanca Lake were determined monthly between November 2000 and October 2001. Three hundred and fifty white bream specimens caught ranged in age from 1^+ to 9^+ years, and the majority of the samples consisted of individuals of the 5^+-year-old age group. The von Bertalanffy equation was determined as Lt = 22.169 (1 - exp {-0.215[t + 0.986]}), Ø': 2.02 for males and Lt = 31.917 (1 - exp {-0.122[t + 1.087]}), Ø': 2.10 for females. The length-weight relationship was estimated as W = 0.0046 TL exp. 3.315 ± 0.002 for males (r^2 = 0.9653, P < 0.05), and W = 0.0036 TL exp. 3.417 ± 0.002 for females (r^2 = 0.9671, P < 0.05). Regression coefficients for sex were significant (t-test, P < 0.05). The slope (b) significantly differed (ANCOVA, P < 0.05) between months. The fact that the b values for male and female white breams differed from 3.0 indicates that there was positive allometric growth. Sex ratio was 1:1.36 (X^2; P < 0.05). Spawning period of white breams began at the end of April and continued until the beginning of July; water temperature during this period ranged between 13.7 and 28.5 °C.

Specific Activity of 137Cs in the Muscles of Benthophage Fishes Depending on the Mass of a Specimen

Relationship between 137Cs specific activity and the mass of a specimen in benthophage fishes taken from various water bodies of the Kiev region was studied in 1986−2009. In Cyprinus carpio (L.), Carassius auratus gibelio (Bloch), and Carassius carassius (L.), 137Cs specific activity increased with increasing the mass of a specimen. In Abramis brama (L.) and Blicca bjoerkna (L.), vice versa, the specific activity of 137Cs decreased with increasing the mass of a specimen. It is likely that relationship between 137Cs specific activity and the mass of a specimen (age) in benthophage fishes is conditioned by physiological peculiarities of each species.

Concentrations of 17 elements in muscle, gills, liver and gonads of five economically important fish species from the Danube River

The Danube River in the vicinity of the city of Belgrade receives large amounts of untreated or poorly treated communal and industrial waste waters. The aim of this study was to assess elemental accumulation patterns in a number of economically important fish species in this area that belong to different trophic levels. Concentrations of 17 elements (Al, As, B, Ba, Cd, Co, Cr, Cu, Fe, Li, Mn, Mo, Ni, Pb, Se, Sr and Zn) were assessed in liver, muscle, gills and gonads of silver carp (Hypophthalmichthys molitrix ), freshwater bream (Abramis brama ), white bream (Blicca bjoerkna ), common carp (Cyprinus carpio ) and wels catfish (Silurus glanis ) from the Danube River in Serbia by the use of ICP-OES. Silver carp specimens were differentiated from the other four species by high concentrations of Al and Fe in the liver. Common carp specimens were differentiated by high concentrations of Zn in gills, muscle and liver. Distribution of elements among different tissues had a consistent pattern among the species. Concentrations of Pb, Cd, As, Zn, Cu and Fe in muscle were at acceptable levels for human consumption, while concentrations of Fe and Zn were above maximum acceptable concentrations in liver and gonads.

Male primer endocrine responses to preovulatory female cyprinids under natural conditions in Sweden

This study investigated two related aspects of male-female reproductive interactions in the family Cyprinidae: (1) whether ovulating female rudd Scardinius erythrophthalmus (subfamily Leuciscinae) induce endocrine and gonadal priming responses in conspecific males, a phenomenon which has been described only in species from the subfamily Cyprininae such as goldfish, Carassius auratus, crucian carp Carassius carassius and common carp, Cyprinus carpio and (2) whether the stimuli mediating these responses are species-specific. Field studies of three sympatric European cyprinids, two leuciscins (S. erythrophthalmus and white bream Blicca bjoerkna) and one cyprinin (C. carassius), were conducted on fishes captured in Sweden in the spawning season and held in net pens under natural conditions. As previously reported in C. carassius, male S. erythrophthalmus increased milt (sperm and seminal fluid) volume and plasma concentrations of the sperm maturation hormone 4-pregnen-17,20β-diol-3-one (17,20β-P) when they were held with female S. erythrophthalmus induced to ovulate by injection of Ovaprim (GnRH analogue plus dopamine antagonist). Male S. erythrophthalmus had larger milt volumes than male C. carassius prior to and following exposure to ovulatory conspecifics, but exhibited a smaller proportional milt increase in response to stimulation, suggesting species differences in sperm allocation at spawning. The presence of female S. erythrophthalmus and B. bjoerkna did not affect milt volumes of C. carassius under two experimental conditions: (1) ovulating S. erythrophthalmus and B. bjoerkna did not increase the milt volumes of C. carassius and (2) S. erythrophthalmus and B. bjoerkna did not interfere with the milt volume increase induced in male C. carassius by ovulating conspecifics. These results suggest that, as in C. auratus, C. carassius and C. carpio (subfamily Cyprininae), female S. erythrophthalmus (subfamily Leuciscinae) release a preovulatory pheromone that exerts priming effects on male hormones and sperm allocation. The findings also indicate that C. carassius discriminate between the reproductive odours of conspecifics and heterospecifics.

Histological and molecular studies of species of Myxobolus Bütschli, 1882 (Myxozoa: Myxosporea) in the gills of Abramis, Blicca and Vimba spp. (Cyprinidae), with the redescription of M. macrocapsularis Reuss, 1906 and M. bliccae Donec &amp; Tozyyakova, 1984

Although Myxobolus spp. from cyprinid fishes are generally characterised by a strict host-specificity, this study has found that the breams Abramis brama (L.), Blicca bjoerkna (L.) and Vimba vimba (L.) may be infected by the same Myxobolus spp. It is demonstrated that M. macrocapsularis Reuss, 1906, a parasite of the gill filaments of B. bjoerkna, can also infect A. brama. In the same way, M. bliccae Donec & Tozyyakova, 1984, also a parasite of B. bjoerkna, can also occur in V. vimba. The molecular sequences of M. macrocapsularis spores from B. bjoerkna and A. brama were 100% identical. Two of the 18S rDNA sequences of three replicate samples of M. bliccae from B. bjoerkna were 100% identical, whereas the third sequence exhibited a 99.7% similarity with sequences from V. vimba. M. bliccae sequences of spores collected from V. vimba showed a 99.8% similarity to the first two isolates and 99.6% to the third. Data obtained by morphological, histological and molecular biological methods all suggest that Myxobolus spp., known for their strict host-specificity, may sometimes infect several closely related cyprinids.

State of the reproductive system of Cyprinidae from the Teterev River and Kiev Reservoir after the Chernobyl accident

The state of the reproductive system in four species of Cyprinidae from the Teterev River and Kiev Reservoir (Ukraine)—descendants of F3–F6 generations of individuals subjected to the radiation impact because of accident at the Chernobyl Nuclear Power Plant—has been studied. It was shown that 20 years after the accident, there is a wide range of morphofunctional anomalies of this system in fish. The most significant of them are asymmetry and abnormal morphology of gonads; proliferation of connective tissue-sterilization; and mass destruction of sexual cells of different stages of development. Disturbances of reproductive gonads among the studied species are expressed most strongly in bream Abramis brama and rudd Scardinius erythrophthalmus. In the series of studied generations, maximum frequency of occurrence of gonad anomalies in bream and silver bream Blicca bjoerkna was recorded in F3–F4 and that in roach Rutilus rutilus and rudd was recorded in F4–F5, which is determined by the phenomenon of prolonged mutagenesis.

Characterization of Bafinivirus Main Protease Autoprocessing Activities

The production of functional nidovirus replication-transcription complexes involves extensive proteolytic processing by virus-encoded proteases. In this study, we characterized the viral main protease (M(pro)) of the type species, White bream virus (WBV), of the newly established genus Bafinivirus (order Nidovirales, family Coronaviridae, subfamily Torovirinae). Comparative sequence analysis and mutagenesis data confirmed that the WBV M(pro) is a picornavirus 3C-like serine protease that uses a Ser-His-Asp catalytic triad embedded in a predicted two-β-barrel fold, which is extended by a third domain at its C terminus. Bacterially expressed WBV M(pro) autocatalytically released itself from flanking sequences and was able to mediate proteolytic processing in trans. Using N-terminal sequencing of autoproteolytic processing products we tentatively identified Gln↓(Ala, Thr) as a substrate consensus sequence. Mutagenesis data provided evidence to suggest that two conserved His and Thr residues are part of the S1 subsite of the enzyme's substrate-binding pocket. Interestingly, we observed two N-proximal and two C-proximal autoprocessing sites in the bacterial expression system. The detection of two major forms of M(pro), resulting from processing at two different N-proximal and one C-proximal site, in WBV-infected epithelioma papulosum cyprini cells confirmed the biological relevance of the biochemical data obtained in heterologous expression systems. To our knowledge, the use of alternative M(pro) autoprocessing sites has not been described previously for other nidovirus M(pro) domains. The data presented in this study lend further support to our previous conclusion that bafiniviruses represent a distinct group of viruses that significantly diverged from other phylogenetic clusters of the order Nidovirales.

Comparative karyological analysis of four diplozoid species (Monogenea, Diplozoidae), gill parasites of cyprinid fishes

The present study has revealed new data on chromosome complements of diplozoid parasites, namely Diplozoon paradoxum from freshwater bream Abramis brama, Paradiplozoon bliccae from white bream Blicca bjoerkna, Paradiplozoon sapae from white-eye bream Ballerus sapa, and Paradiplozoon nagibinae from zope Ballerus ballerus. Particularly, D. paradoxum is characterized by four pairs (2n=8) of long (up to 22.1 μm) chromosomes: pairs 1, 2, and 3 are metacentric and pair 4 acrocentric. Karyotypes of three Paradiplozoon species are nearly identical in number and morphological classification of chromosomes, each comprising diploid number of 14 one-armed chromosomes of very similar length ranging up to 12.5 μm in P. bliccae, 9.2 μm in P. sapae, and 9.9 μm in P. nagibinae. All four species are similar in their total complement length, ranging from 64.4 to 50.4 μm. Interspecific differences were found in location of secondary constriction: it is situated on short arm of the 1st chromosome pair in D. paradoxum, on long arm of the 7th pair in P. bliccae and on long arm of the 4th pairs in P. sapae and P. nagibinae. Phylogenetic interrelationship within the diplozoids and hypothetic karyotype evolution is here discussed.

Flood duration determines the reproduction success of fish in artificial oxbows in a floodplain of a potamal river

Janáč M, Ondračková M, Jurajda P, Valová Z, Reichard M. Flood duration determines the reproduction success of fish in artificial oxbows in a floodplain of a potamal river. Ecology of Freshwater Fish 2010: 19: 644–655. © 2010 John Wiley &amp; Sons A/S.Abstract – Fish reproduction was studied in six man‐made water bodies (borrow pits) adjacent to the channelised Dyje River (Danube basin) over five seasons. Terrestrial vegetation provided spawning and nursery habitats when inundated by raised water levels in the borrow pits (hereafter referred to as ‘floods’). The diversity of 0+ fish and the density of 0+ cyprinids (mainly Abramis bjoerkna, Scardinius erythrophthalmus and Rutilus rutilus) in June–October were positively correlated with flood duration in previous months. The density of 0+ Perca fluviatilis was independent of the flood duration. The density of spawners and predators did not influence the diversity of 0+ fish and the density of 0+ cyprinids. Receding flood and associated lack of shelters resulted in decreasing density of 0+ cyprinids, numbers sometimes decreasing to zero. Prolonged floods facilitated the survival of 0+ fish and resulted in high 1+ cyprinid density in the following season. Specific hydromorphological conditions (e.g., the presence of shallow littoral zone or flooded vegetation) are necessary to enable successful spawning and provide shelters for 0+ fish in artificial water bodies.

Behavioural Study of Polyandrous Spawning inBlicca bjoerknaUnder a Controlled Environment

This study describes the reproductive behaviour of silver bream, Blicca bjoerkna, in an aquarium environment with hormonal injection, constant temperature and natural photoperiod conditions. The results revealed that the reproductive behaviour of silver bream was polyandrous with courting tactics including a high level of tactile stimulation and following behaviour developed by the males, but without territorial or aggressive acts. The individual participation of males in mating acts showed a significant positive correlation with the individual participation of males in following a female. A successful spawning act included trembling movements and violent splashing while eggs and sperm were released on plants. The female mated with one to five males without an active inter- and intra-sexual selection.

Karyotype analysis in white bream (Blicca bjoerkna transcaucasica) from north coast of Iran.

Preparation of chromosome spreads and karyotype analysis in Blicca bjoerkna transcaucasica were carried out using 0.01% solution of colchicines and Phytohaemagglutinin (PHA) (20 µg g-1 body weight). The gill and kidney tissues were collected and let to stand in a hypotonic solution of 0.075 M KCl and then treated with a fixative (Carnoy's solution) in three steps. The chromosomes spreads were then stained with 5% Giemsa solution for 20 min and examined under a light microscope. Appropriate metaphase plates were photographed in order to prepare karyotype. The size of the chromosomes (short and long arms), relative length of chromosomes and centromere index were calculated. Chromosome spreads from gill tissue cultures which were colchicine treated with PHA, had a well defined size, shape and number of chromosomes for karyotype analysis. Based on the 76 metaphase plates studied, chromosome count in 59 metaphase plates was 2n=49.74±0.25. By arranging homologous chromosomes beside each other the chromosome formula was calculated as 6 pairs of Metacentric, 10 pairs of Sub-Metacentric and 9 pairs of Sub-Telocentric (2n=6M+10+Sm+9St) and the chromosome arm number (NF) was 100. The largest chromosome in this species was a pair of metacentric chromosomes. On the basis of the number and type of chromosomes, the karyotype obtained for this species conformed to the findings of other researchers, but the chromosome formula was different, which could be attributed to the existence of different populations for this species.

Invasive fish species in the largest lakes of Scotland, Northern Ireland, Wales and England: the collective UK experience

An invasive species is defined as an alien (or introduced or non-native) species whose establishment and spread threaten ecosystems, habitats or species with harm. Such threats to UK lake fish communities have long been appreciated and this review assembles case histories, including new data, from the largest lakes of Scotland, Northern Ireland, Wales and England to examine the hypothesis that at least some of these introductions have become invasive. Loch Lomond in Scotland has experienced six introductions [chub (Leuciscus cephalus), common bream (Abramis brama), crucian carp (Carassius carassius), dace (Leuciscus leuciscus), gudgeon (Gobio gobio) and ruffe (Gymnocephalus cernuus)], of which the most significant has been that of the percid ruffe, which has been implicated in a recent decline of the native coregonid whitefish (Coregonus lavaretus). In Northern Ireland, the introduction of the cyprinid roach (Rutilus rutilus) to Lough Neagh has apparently had a negative impact on some overwintering waterfowl, although the native coregonid pollan (Coregonus autumnalis) remains abundant. Llyn Tegid in Wales has received three introductions [rudd (Scardinius erythrophthalmus), ruffe and silver bream (Blicca bjoerkna)], although no impacts on the native whitefish or other fish populations have been observed. In England, individuals of at least 12 native and non-native fish species have been brought to Windermere for the purpose of live-baiting, although only those of the cyprinids roach and common bream have established abundant populations. At the same time, the native salmonid Arctic charr (Salvelinus alpinus) has declined markedly while the native esocid pike (Esox lucius) has shown changes in abundance, distribution and individual condition, although these developments have not been shown to be causally linked. None of these introductions were sanctioned by appropriate fisheries or other regulatory bodies and almost all of them probably arose from the release or escape of live-bait used by pike anglers. Of the 10 species introductions documented here, four (common bream, gudgeon, roach and ruffe) have established abundant populations and two of these (roach and ruffe) have apparently caused or currently threaten harm, supporting the hypothesis that at least some of these introductions have become invasive.

Otolith retrieval from faeces and reconstruction of prey-fish size for Great Cormorant (Phalacrocorax carbo) wintering at the East Dongting Lake National Nature Reserve, China

The food composition of Great Cormorant (Phalacrocorax carbo) was studied by analyzing 360 faecal samples collected from their roosting sites at the East Dongting Lake National Nature Reserve in south-central China during November 2008 and January 2009. A total of 223 fish otoliths were retrieved. Only sagittal otoliths (N = 74) with intact margins, good medial relief, and well-defined sulcus were used to identify the prey-fish species and to reconstruct prey-fish size. Through shape indices and elliptical Fourier analyses, these otoliths were identified as belonging to two cyprinid fish species, crucian carp Carassius auratus (72%) and white amur bream Parabramis pekinensis (28%). The otolith size (maximum length, Lo)—prey-fish size (standard length, Ls) relationships determined for the two fish species were Ls = −19. 5 + 37.1 Lo (N = 74; R2 = 0.95; P < 0.05) for crucian carp and Ls = −31.9 + 36.9 Lo (N = 70; R2 = 0.97; P < 0.05) for white amur bream. The back-calculated Ls from the otoliths retrieved from the faeces were 96.2 ± 10.2 mm (range 72.7–110.4 mm) for crucian carp and 86.3 ± 10.4 mm (range 74.1–104.6 mm) for white amur bream. Based on setnet sampling of the fish community near roosting sites, crucian carp and white amur bream were found as the first and second most abundant species. Great Cormorants were very selective for the size range of prey. These results demonstrate that analysis of otoliths retrieved from faeces can be an effective, inexpensive, and non-invasive method to identify prey-fish species and to estimate prey-fish size in studies of diet composition for piscivorous birds.