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The aim of the project was to collect and analyze data regarding European eel stocking in Polish inland waters in 2012. Sixty-seven fisheries enterprises that exploited 295,457 ha of waters, including 82,532 ha of waters in the Oder River drainage basin, and 212,925 ha of waters in the Vistula River drainage basin, were surveyed. The number of reared eel released into these waters was 3.4 indiv. ha'1. The mean individual weight of this material was 23 g, the value was 7.96 PLN ha'1., and 83 % of the water surface areas surveyed were stocked. The types of eel stocking material obtained from importers or producers released into these waters comprised 18,799 kg (1,747,433 indiv.) eel fry, of which 9,465 kg (1,559,700 indiv.) were of a unit weight of up to 10 g.
The aim of the study was to determine the state of stocking Polish inland waters with European eel in 2011. Seventy-one enterprises conducting fisheries in 301,522 ha of waters, of which 92,429 ha were in the Oder basin and 209,093 ha were in the Vistula basin, were surveyed with questionnaires. The number of reared eel released into the waters was 3.8 individuals ha"1 with a mean individual weight of 36 g and a value of 8.94 PLN ha"1, while 84% of the total surface area of the waters analyzed was stocked with eel. Using material from importers and/or producers of eel stocking material, enterprises exploiting inland waters and the implementation of the Polish Eel Management Plan saw the release into Polish waters of 27,843 kg (2,737,974 individuals) of eel fry, including 15,645 kg (2,528,521 individuals) of eel with individual body weights of up to and including 10 g.
The health condition of eel, Anguilla anguilla (L.), caught in the Szczecin Lagoon off Trzebież in 1971-1913 and in 6 fishing grounds in 1982-1983 is evaluated. The clinical analysis, anatomo-pathological examinations, and hematologic parameters demonstrated a considerable increase in the incidence of circulatory disorders involving acute or chronic damaging inflammations, dominated by necropoietic lesions in viscera. The extent of pathologic changes is conditioned by, i.a., toxic effects of cyanobacteria (including Microcystis aeruginosa) blooms occurring in the Lagoon′s eutrophic waters.
Fish exposed to 200 and 300 μg/1 PCB′s (Aroclor 1242) for 24 hr demonstrates negative chronotropic effect; increase in the duration of segments and intervals as well as the waves amplitude. A tachycardia was also observed during the experiments. On the other hand, bioaccumulation of PCB′s in the eel fish was depended upon the concentration and time, the level of PCB′s in the liver was significantly higher than the level observed in the other tissues. Also, the descending order of PCB′s accumulated after 24 hr was found in the gills, blood, kidney, liver and muscle, respectively.
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