Spatial and temporal variability of a vendace (Coregonus albula (L.)) population in Lake Pluszne, Poland, based on hydroacoustics and trawl catches
Doroszczyk, Lech; Długoszewski, Bronislaw; Kanigowska, Ewa; Wiśniewolski, Wieslaw; Godlewska, Malgorzata
Observations of vendace (Coregonus albula (L.)) distribution, abundance and biology in Lake Pluszne, Poland, made using hydroacoustics and trawling between 2001 and 2010 are presented. Since 2002, the numerical density of vendace has decreased continuously, while their mean length and weight have increased. Young-of-year vendace were sampled only in 2001 when a strong year class recruited and their subsequent absence indicates that natural reproduction after 2001 has been hampered. The average condition of individual vendace over this time period was low compared with the condition observed in the 1960s. Observed changes in the vendace population were related to worsening hydrological conditions associated with increased eutrophication of the lake.