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Wisniewolski W.,Inland Fishery Institute in Olsztyn | Borzecka I.,Inland Fishery Institute in Olsztyn | Buras P.,Inland Fishery Institute in Olsztyn
Archives of Polish Fisheries | Year: 2011

Changes in the ichthyofauna assemblages of three shallow dam reservoirs located in central and eastern Poland are presented based on long-term records of commercial fish catches. As the reservoirs age the evolution in the sizes of the shares of exploited fish species is depicted by temporal trend lines described with regression functions. The species targeted by commercial fishing are assigned to one of four ecological groups-predatory, eutrophying cyprinid, rheophilic, and others, depending on the role they play in the reservoir. Catches of cyprinid fishes from the eutrophying group increased in each of the reservoirs studied as the years passed. This was most notable in the Siemianówka Reservoir since in the period immediately following inundation the slope factor b trend line was 7.25 at r 2 = 0.9. The population of predatory fish was also noted to increase continually in this reservoir, and this was linked to intense stocking with pike, Esox lucius L. The shares of predatory fish in the other reservoirs decreased from inundation onwards, only to stabilize in recent years at minimal levels with slight increasing trends. As time passed from the inundation of the reservoirs the general dependency between the average shares of fish groups in catches was highly significant for all of fish groups identified.

Sarosiek B.,Polish Academy of Sciences | Dryl K.,Polish Academy of Sciences | Judycka S.,Polish Academy of Sciences | Szczepkowski M.,Inland Fishery Institute in Olsztyn | Kowalski R.K.,Polish Academy of Sciences
Journal of Applied Ichthyology | Year: 2015

Acid phosphatase and arylsulphatase are present in the semen of many animal species, including fish. The presence of these two enzymes has also been confirmed in the semen of Siberian sturgeon (Acipenser baerii). The aim of this study was therefore to determine the potential role of acid phosphatase and arylosulphatase in the fertilization process. Tested were the additions of ammonium molybdate (acid phosphatase inhibitor) and AgNO3 (arylsulphatase inhibitor) regarding their effects on the sperm motility spermatozoa rate and the fertilization rate (in two inhibiting variants: enzymes present in spermatozoa, sperm treated; enzymes present in spermatozoa and eggs, sperm + eggs treated). There was no significant deterioration in motility parameters with either of the applied inhibitors. Ammonium molybdate caused a significant decrease in the fertilization rate (sperm + treated eggs from 86.1 to 9.5%); AgNO3 added only to spermatozoa resulted in a complete inhibition of fertilization. Results indicate that the acid phosphatase activity in eggs and arylsuphatase activity in sperm are necessary for the fertilization process in the Siberian sturgeon. © 2015 Blackwell Verlag GmbH.

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