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This paper presents preliminary results of a comparison of the seasonal activity of lake minnows, Eupallasella percnurus (Pall.), and crucian carp, Carassius carassius (L.), in a few small water bodies. Field studies were conducted based on catches made with baited traps in periods without ice cover from April to December 2006. E. percnurus became active earlier than did C. carassius and their period of intense activity was longer. The first E. percnurus appeared in the traps in early April when the ice was still melting, and these fish were caught at a temperature range of 3.5-29.2°C. C. carassius were caught most abundantly in the beginning of May at temperatures from 15°C; this species was usually noted in traps at a narrower, but higher, temperature range in comparison with the E. percnurus. Additionally, the activity of both these species was similar with regard to weather conditions; both species were less active on cloudy days and when atmospheric pressure was increasing. Source


Kalinowska K.,Inland Fisheries Institute in Olsztyn | Grabowska M.,University of Bialystok
Hydrobiologia | Year: 2016

Ice cover can considerably influence the food web structure and dynamics of lake ecosystems during winter. The aim of this study was to test the hypothesis that, due to unfavourable conditions, abundances of planktonic organisms are low under ice. The components of the microbial loop (nanoflagellates, ciliates) and the classical food web (algae, rotifers, crustaceans) were investigated in a eutrophic lake from January to April, at 7-day intervals. The phytoplankton was dominated by the mixotrophic chrysophyte Synura uvella, which formed an intense phytoplankton bloom. Nanoflagellates (mostly heterotrophic forms) and ciliates (oligotrichs, prostomatids) were present in relatively high numbers. Rotifers were represented by the algivorous taxa (Notholca squamula, Polyarthra dolichoptera) and reached surprisingly high abundances. There were no significant correlations between physical parameters and protists, but correlations were apparent between the thickness of the ice and the numbers of cyanobacteria, diatoms (negative) and chrysophytes (positive). The absence of crustaceans and relationships between rotifers and both algae and nanoflagellates indicate that these groups were probably a crucial factor determining the abundance and composition of the rotifer community. These results suggest that the microbial loop had a central role in the functioning of the ecosystem under ice in this eutrophic lake. © 2016 Springer International Publishing Switzerland Source


Skora M.E.,Inland Fisheries Institute in Olsztyn
Archives of Polish Fisheries | Year: 2012

The Siberian sturgeon, Acipenser baerii Brandt, is reported in the Reda River, which flows into the Puck Bay, for the first time. In total, 12 specimens of A. baerii were caught during monthly surveys in June and July 2006. The fish were captured during downstream movement between 18:00 and 06:00. The specimens collected in Reda River ranged from 10.3 to 15.5 cm standard length (SL). It is hypothesized that the fish originated from one of the hatcheries located on the banks of the Reda River. This is also the first report of Siberian sturgeon in Polish Pomeranian rivers. Source


Mickiewicz M.,Inland Fisheries Institute in Olsztyn
Archives of Polish Fisheries | Year: 2012

The current report was written using data from the 1973-2004 period regarding fisheries catches and stocking. These data come from management logs for 300 lakes with a total surface area of 116,736 ha. In the 1973-1982 period, the mean annual value of catches for all species of fish was 226.33 PLN ha-1, and this was twice as high as that in the 1995-2004 period (113.77 PLN ha-1). Of stocked species, eel, Anguilla anguilla (L.) (46%), and vendace, Coregonus albula (L.) (17%), dominated the value structure of catches in the first decade, while eel (35%), vendace (15%), pike, Esox lucius L., (11%), and pikeperch, Sander lucioperca (L.) (9%) dominated in the second decade. The mean annual value of stocking material of all species in the 1973-1982 period, which was 385.91 PLN ha-1, was more than 7.5 times higher than that in the 1995-2004 period (50.40 PLN ha-1). This difference was determined by the value of eel stocking. With a share of more than 95%, the value of eel stocking dominated decisively in the first decade. In the second decade analyzed, the value of stocked eel (57%), vendace (15%), and pike (14%) dominated. After eliminating the value of eel catches and stocking, the value of stocking in comparison with the value of catches in the first decade analyzed was barely 15%, while in the second decade analyzed it was almost twice as high at 29%. Source


Chybowski L.,Inland Fisheries Institute in Olsztyn
Archives of Polish Fisheries | Year: 2014

The subject of the study was four populations of signal crayfish from Naryjska Struga River and lakes Pobłędzie, Mauda, and Staw Płociczno. The morphometric differentiation of female and male signal crayfish was studied with discriminant analysis. It was confirmed that both females and males from the Naryjska Struga River differ from the crayfish from the three lakes. The characters that best discriminated females were those associated with the cephalothorax and cheliped width, while in males they were those associated with the chelipeds and the abdomen. © Inland Fisheries Institute in Olsztyn, Poland. Source

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