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A total of 943 Anguilla anguilla (only digestive tract and swim bladder) from 3 areas of the south-east Baltic was examined for parasites. The investigation was carried out in July and August 1982-1990. Ten species of parasites were encountered: Deropristis inflata, Bothriocephalus claviceps, Proteocephalus macrocephalus, Raphidascaris acus, Camallanus lacustris, C. truncatus, Acanthocephalus anguillae, A. lucii, Echinorhynchus gadi and Pomphorhynchus laevis.
The abundance of the eel (Anguilla anguilla) in Europe has been on the decline in recent years, to the extent that this fish species is now considered to be threatened with extinction. Hence, the current implementation of the Eel Management Plan in Poland, whose aim is to restore w stocks of this fish. The main natural habitats of eel are the transitional waters of the Vistula and Szczecin lagoons and lakes in northern Poland. The eel is highly valued by many consumers for the taste and texture of its meat. The aim of the study was to determine differences in concentrations of macro- and microelements and toxic metals in muscles of the eel as a function of each specimen’s length, mass and the origin. The results of the study also served an evaluation of the health benefits and risks to consumers of eel meat with regard to the content of macro- and microelements and toxic metals. Specimens of the eel (Anguilla anguilla) were caught in 2011-2013, in five regions of Poland: the southern Baltic, inland lakes in northeast Poland, the Vistula and Szczecin lagoons, and in the Vistula River. The concentrations of Ca, P, Mg, Na, K, Fe, Sr, Zn and As were determined with optical emission spectrometry. The flameless atomic absorption spectrometry method was used to measure concentrations of Cu, Cd and Pb. The content of Hg and Se were determined with atomic absorption, those of mercury with cold vapour, and of selenium with hydride generation. The concentrations of macro- and microelements in most instances, with the exception of P and Zn, were negatively correlated with the eel’s length and mass, which indicated that small fish contained more minerals than large specimens. The eel is a rich source of phosphorus, zinc, selenium and iron, and it can supply significant quantities of the daily requirements of human consumers for these minerals. The other minerals occurred in eel muscle at levels that ranged from 2 to 6% of human daily requirements. Among the toxic metals, mercury was the cause for concern, while cadmium and lead occurred at low levels in all of the specimens examined regardless of their size. The mean concentration of mercury ranged from 0.147 to 0.273 mg kg-1 and was positively correlated with specimen length and mass. The content of mercury in large eel exceeded 0.500 mg kg-1, while small eel (up to 70 cm) contained lower levels of mercury. Large eel exceeding 70 cm can pose a threat to the consumer’s health because of mercury, and especially its organic from of methylmercury. This is why consumers should limit long-term consumption of larger eel, while it is safe to consume smaller specimens since they contain less mercury and more minerals than do large eel.
The authors investigated the mycoflora developing on the dead glass eel (montée) and elvers (Anguilla anguilla L.)
Background. The decline in the eel population is reflected in the decreased incomes of fishers. This has led to changes in the structure and size of the fishing effort. The fyke nets used in eel catches are multi-species gear. Changes in the fishing intensity and location of this gear impacts local fish resources, as does changing preferred gear for other types. Materials and Methods. The data on the eel landings and the numbers of licences from all the fisheries bases were obtained from the Regional Sea Fisheries Inspectorate. Direct observations of the spatial and temporal deployment of the fishing effort was observed monthly in the 2000–2007 period. The trends of changes in relative eel abundance were identified from fyke net complexes deployed in the eastern fishing grounds. Results. Landings and directed fishing effort differed both seasonally and spatially. The most effective fishing grounds were in the eastern (near the border with Russia) and western parts of the lagoon. The discontinuation of stocking resulted in decreased catches and then in fishing effort. Decreases in eel catches and fishing efficiency were evident except in 2003 at the Piaski and Kąty Rybackie fisheries bases (the northern part of the lagoon). Conclusion. The availability of eel stocks had the greatest impact on fishing efficiency and gear distribution patterns. The reduction of fyke net fishery because of low incomes shifted the focus of the fishery to gill nets targeting pikeperch.
The aim of the study was to determine the prevalence and intensity of infection of European eel, Anguilla anguilla (L.), with nematode and monogenean gill parasites. Fifty individuals obtained from Vistula Lagoon stocking material were examined in August and October 2006. The prevalence of infection with Pseudodactylogyrus anguillae (Yin et Sproston) in August was 52.4%, and in October 17.2%, while the mean intensity of infection in the same periods was 4.0 and 1.2 individuals, respectively. The prevalence of infection with Anguillicola crassus Kuwahara, Niimi et Itagaki was 4.8 (August) and 20.7% (October), while the mean intensity was 1.0 and 2.5 individuals. Releasing parasite-infected stocking material is harmful from the perspective of fisheries management and simultaneously increases the area of occurrence of the parasites.
A new opecoelid trematode, Peracreadium akenovae sp. nov., is described from the highfin moray eel Gymnothorax pseudothyrsoideus (Bleeker) (Anguilliformes; Muraenidae), collected from Moreton Bay off southeast Queensland, Australia. The new species is distinctive in its body shape, transversely elongate irregular testes, vitelline follicles interrupted at the level of the ventral sucker, and diverticulate excretory vesicle. The Muraenidae is a new host family for Peracreadium Nicoll, 1909. Peracreadium is the seventh opecoelid genus reported from temperate eastern Australian marine fishes and this is its first report from Australian waters.
Two species of monogenetic worms of the genus Pseudodactylogyrus, viz., P. bini (Kikuchi, 1929) and P. anguillae (Yin et Sproston, 1948), were recorded on the gills of eel from Strażyn Lake. In order to distinguish these two species the following skeletal elements were examined: length of anchors, length of basal part of anchors, length to the point of anchors, length of anchors except the double bent part of the internal process, length of bar, length of marginal hooks, length of accessory cirrus and length of vagina. Student’s t-test showed statistically significant differences (p<0.01) between some investigated parameters of these two species: length of anchors, length of basal part of anchors, length to point of anchors, length of anchors except the double bent part of the internal process, length of bar and length of marginal hooks. The differences in length of the accessory cirrus and length of vagina were not statistically significant (p = 0.05). The two species have been recorded for the first time in Poland.
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