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This paper reports the occurrence of three new fish species, extremely rare in the Baltic Sea, and provides new data on their parasite fauna. The fish collected were Barbus barbus (Linnaeus, 1758), Salvelinus fontinalis (Mitchill, 1814), and Scophthalmus rhombus (Linnaeus, 1758). Their taxonomic identity was confirmed through genetic analyses using DNA extracted from fin clips. The stomach contents were examined, and age was determined by otolith or scale readings. Parasitological examinations focused on the skin, vitreous humour, eye lenses, mouth and nasal cavities, gills, gonads, viscera, and muscles. Furthermore, the changes of fish species composition over 20 years in Pomeranian Bay were analysed. The sequence comparisons against GenBank records revealed that sequences obtained for B. barbus and S. rhombus from Pomeranian Bay represent new rhodopsin barcodes. Record of the juvenile B. barbus in this study is the first in the Baltic Sea. Scophthalmus rhombus is a new host for the ciliate Trichodina jadranica, while Neogobius melanostomus (Pallas, 1814) is a new food item in the diet of S. rhombus in the Baltic Sea. Acanthocephalan Pomphorhynchus laevis found in the adult specimen of B. barbus and myxozoan Myxobolus musculi, noted in the juvenile specimen, have not been recorded previously in this fish species in Polish waters. Species collected as bycatch can potentially be used for monitoring potential changes in the overall fish community structure and biodiversity.

Background. Automated processing of the fish caught on board a ship can potentially lead to a quality control breach. Specimens visibly infected with parasites are processed, frozen, and directed to the market. On the other hand, the removal of the body elements of taxonomic importance (e.g., fins, head, skin) opens gates to variously motivated seafood frauds. We had been alerted by local veterinary authorities about a fish consignment from the Falklands with a substantial volume of muscles with black contents. Materials and methods. The material for the presently reported study were decapitated, finless, and gutted fish delivered to our lab by the County Veterinarian of Szczecin (Purchased by a local importer from a Spanish fish wholesaler). The fish were labeled as “Pseudophycis bachus (Forster, 1801)”, and allegedly came from the Falklands. After thawing, the fish muscles were dissected, focusing on the distinctly black areas, examined following methods commonly used in parasitology, and observed under a dissecting and a compound microscope. Samples were collected also for molecular studies aiming to disclose the fish taxonomic identity. DNA barcoding gene (cytochrome c oxidase subunit I, COX1) was used to perform the genetic characterization for the collected fish specimens. The degree of similarity between the new records (MT318699 and MT318700) and the other records of Moridae species in the GenBank was assessed by building COX1 gene phylogeny. Results. The muscles contained large galls filled with black fluid. The fluid stained the adjacent muscles. Inside each gall, we found a single female of Sarcotaces sp., several “dwarf” males, eggs, and newly hatched nauplius stages. Using the molecular methods, the fish were identified as Mora moro (Risso, 1810). Conclusion. A preliminary veterinary inspection of the catch on board of fishing vessels may help to avoid huge financial losses when a parasitized fish consignment is rejected by veterinary authorities on land. It is evident that the European regulation regarding fish parasites requires an urgent revision. Mora moro does not occur off the Falklands as declared by the wholesaler. This seafood fraud was probably motivated by the urge to conceal a catch from European waters and thus avoid exceeding national fishing quotas. Species of the genus Sarcotaces require a revision backed by molecular methods.

Background. The study is a contribution to Project CELFISH which involves genetic identification of populations of fish species presenting a particular economic importance or having a potential to be used in the so-called commercial substitutions. The EU fish trade has been showing a distinct trend of more and more fish species previously unknown to consumers being placed on the market. Molecular assays have become the only way with which to verify the reliability of exporters. This paper is aimed at pinpointing genetic markers with which to label and differentiate between two populations of splendid alfonsino, Beryx splendens Lowe, 1834, a species highly attractive to consumers in Asia and Oceania due to the meat taste and low fat content. Materials and methods. DNA was isolated from fragments of fins collected at local markets in Japan (MJ) (n = 10) and New Zealand (MNZ) (n = 18). The rhodopsin gene (RH1) fragment and 16 microsatellite DNA fragments (SSR) were analysed in all the individuals. The sequences obtained were processed using the BioEdit and BLAST software, whereas SSR data were processed with the GeAlEX analysis package. Results. The BioEdit software-aided comparison of MJ and MNZ nucleotide sequences of the rhodopsin gene fragments were identical and showed 100% agreement with the alfonsino sequence deposited under access number DQ197832. The preliminary analysis of SSR markers showed all the loci analysed in both populations to be polymorphic, and when randomly selected specimens were assigned to the original populations. The affinity test correctly identified the provenance of all those specimens. Conclusion. The results obtained constitute a tool for molecular differentiation between alfonsino populations collected in the FAO 81 (New Zealand) and FAO 71 (Japan) areas for the purpose of catch quota control and for checking the agreement between the label declaration and the actual product.

Background. Monitoring the genetic diversity of fish populations can provide information necessary to determine fishing quotas for the commercially caught species. One of the species subjected to intensive exploitation is the yellowstripe scad, Selaroides leptolepis (Cuvier, 1833), commonly occurring in the coastal waters of Vietnam, Cambodia, Malaysia, and Indonesia. This paper is the third part of a larger project: ”Development of a genetic-based system for identification of food products from fisheries and aquaculture introduced to the European Union customs area”. Materials and methods. Fin fragments of the yellowstripe scad, Selaroides leptolepis, were obtained in 2012 and 2013 from local markets in Vietnam (SVN), Cambodia (SKH), Malaysia (MMY), and Indonesia (MID). The analyses focused on the amplification and sequencing of a fragment of the nuclear rhodopsin gene which utilized as identification label. Subsequently, in the obtained SVN, SKH, MMY, and MID samples, 11 microsatellite regions (SRR) were analysed. Sequence analyses were performed using the BioEdit and BLAST software, while the analysis of the obtained SRR data was conducted using the GenAlEx software. Results. The analysis of the obtained loci variants divided the investigated populations into two genetically homogeneous groups: the Vietnamese–Indonesian group and the Malaysian–Cambodian group. The analysis of genetic diversity revealed statistically significant deviations from the Hardy–Weinberg equilibrium in the investigated populations and indicated the Vietnamese population as the most stable, while the Malaysian population as the least stable. Conclusion. The study provides information on the genetic diversity of the investigated populations and allows assignment of the captured fish to the geographical regions specified. Moreover, indicate that among analysed populations the safest populations were those caught in the local fisheries (continental shelf) of Vietnam and Cambodia due to their high mean genetic diversity.

Exotic species of acipenserid fishes have been frequently encountered in the commercial catches of the Baltic Sea, since the early 1990s. Such sightings are rarely reflected as published records. The present paper provides detailed descriptions of two specimens of Russian sturgeons, Acipenser gueldenstaedtii caught in the Exclusive Polish Economic Zone of the Baltic Sea.

Background. Genetic traceability of seafood as well as population identification using molecular methods provide useful information about the fish origin and are important for protection of overfished populations, as well as for monitoring illegal, unreported, and unregulated (IUU) fisheries. The presently reported study focused on Indian mackerel, Rastrelliger kanagurta (Cuvier, 1816)—a pelagic species with a wide range of distribution—especially important for many tropical countries, such as India, Philippines, and Thailand. This paper is the first part of a larger project: ”Development of a genetic-based system for identification of food products from fisheries and aquaculture introduced to the European Union customs area”. Materials and methods. Samples consisting of fin fragments of Indian mackerel were obtained from local markets in Thailand (MTH), Vietnam (SVN), Cambodia (SKH), and Madagascar (SMG) within 2012–2013. Two genes were analysed: nuclear rhodopsin gene (RH1) and mitochondrial D-loop (D-loop) region through RFLP analysis simulation and sequencing. Additionally, the samples from Cambodia and Madagascar were analysed with eight microsatellite loci (SSR). The data processing was aided by GenAlEx 6.5 and GeneClass2 software. Results. A comparison of the RH1 gene section revealed a total homology among the studied samples. A comparative analysis of D-loop sequences in the studied groups revealed intrapopulational diversity for MTH-, SKH-, SMG-, and SVN samples, at the level of 1, 1, 0.5, and 0.6 percentage points, respectively. Furthermore, the D-loop sequences identified a characteristic restriction site for SMG population. Based on the allele frequencies, we randomly assigned selected individuals to their original populations. GeneClass2 software correctly assigned only 16 out of 21 individuals to either the Cambodian or the Madagascar population, which jointly constituted 76% of all samples. We demonstrated, using AMOVA and GenAlEx 6.5, that the highest level of variability occurred among individuals within the respective populations, while the lowest interpopulation diversity was between the SMG and SKH populations. Conclusion. Our results may help the relevant authorities in the countries of the European Union to identify Indian mackerel and especially its products and trace them to the respective locality. Our findings may also be used for species-specific conservation measures hopefully undertaken by fisheries authorities of the countries where we took our samples. Results on other fish species, prepared in the frames of the same project, will be presented in other papers that will follow soon.

Background. The majority of European populations of vimba, Vimba vimba (L.), have been classified into increasing categories of conservation status while Polish populations of this fish are classified as CR (critically endangered) and in fact they are facing extinction. In many rivers in Poland, including the Odra River, restitution efforts of vimba have been undertaken. Monitoring some biological parameters of the population such as the rate of growth (increase in mass and length), age structure, sex structure, and condition nay help to evaluate the success rate of the restitution efforts. Materials and methods. In total, 210 individuals of vimba, caught in the waters of the southern part of the Odra River estuary, mainly in Lake DÄ…bie, between 28 May 2007 and 30 June 2008 were studied as to their age, condition, rate of growth in mass and length. Making use of the linear R–L dependence, the back calculations were made according to the Rosa Lee procedure with a standard of 20 mm. Results were approximated by 5 mathematical models of growth proposed by von Bertalanffy, Ford–Walford, Gompertz, and based on second degree polynomial function and modified power function. Increase in mass was described by a modified von Bertalanffy equation. The condition of the fish was described by the Fulton (K) and Le Cren (Lc) formulae. Results. Females dominated in the material studied, they constituted over 61% of all individuals. In the age structure groups, females were most often found in groups: 10+ (13.33%), 9+, and 11+ (12.86% each). Males were found in the greatest number among 5-, 6-, and 7-year-old fish (4+, 5+, and 6+, respectively). The mean standard length and mass of the vimba fish studied were 306.33 mm and 286.02 g, respectively. The annual increase in length of the fish approximated 20 mm, being the most intense in the first two years of life (23–24 mm). Fulton and Le Cren coefficients of condition were 0.93 and 1.64 and the ranges of these values were 0.69–1.47 and 1.15–2.60, respectively. Conclusion. Analysis of back readings and empirical results proved that the growth of vimba was best approximated by the von Bertalanffy model. Comparative analysis of condition coefficients of the population of vimba in the Odra River estuary and other populations showed that the condition of analysed vimba population in individual years of live was lower.

Background. Asian pangasiids (Actinopterygii: Siluriformes: Pangasiidae), commonly referred to as “panga”, have recently became an important item on the European fish markets. The fish are currently imported from south-east Asia but the growing consumers’ demand is likely to motivate European fish growers to culture the “panga” locally. This in turn could bring about unforeseeable consequences for the aquatic environment. The presently reported study provides the first record of a pangasiid fish (two specimens) from the European natural waters. We attempted to identify the fish through complex morphometric procedures and to study all their parasites, thus determining their potential threat for the environment. Materials and methods. Two specimens of pangasiid fish were captured in a pond, in the city of Szczecin, Poland. The fish were examined following procedures commonly accepted in morphological studies yielding detailed measurements. The key structures were described and illustrated (e.g., the shape of dentition on both the vomerine and palatine plates). The measurements were taken with an electronic calliper and a dissecting microscope (Nikon SMZ 1000), coupled with the Lucia Measurement System. Additionally, during necropsy, selected organs were checked for the presence of parasites. Results. One of the fish specimens hosted the monogenoid parasite, Thaparocleidus caecus, that has never been found in Europe. Metric and meristic characters of fish studied, as well as the presence of monogenoid T. caecus suggest that the fish found were representatives of Pangasianodon hypophthalmus, however, some features, especially those related to the ratio between fins and body or total length, differ markedly from the species description. Comparative analysis suggested that the two specimens collected in Szczecin are hybrids, most likely of P. hypophthalmus with other species, of unknown origin, presumably imported from Thailand. Conclusion. The specific identity of pangasiids imported alive to Europe should be monitored in the future. Additional genetic studies are needed. The monogenoid parasite found on the fish studied poses no threat to the native ichthyofauna (because of its very narrow host-specificity).

Background. The presently reported finding of leopard pleco, Pterygoplichthys gibbiceps (Kner, 1854) (Loricariidae), in open waters of the Brda River in the centre of Bydgoszcz, constitutes the first record of a south-American loricariid fish species in Poland. The specimen found is described and illustrated. The finding is discussed in association with other alien species sightings in Poland. The described leopard pleco is possibly the next example of an emerging alien fish species in inland Polish waters.