Distribution patterns, annual density changes, growth and mortality of pikeperch [iSander lucioperca/i (L. 1758)] fry following oligotrophication of a reservoir

0583728 - BC 2024 RIV US eng J - Journal Article
Jůza, Tomáš - Blabolil, Petr - Čech, Martin - Draštík, Vladislav - Hejzlar, Josef - Kočvara, Luboš - Muška, Milan - Peterka, Jiří - Sajdlová, Zuzana - Tušer, Michal - Vašek, Mojmír - Kubečka, Jan
Distribution patterns, annual density changes, growth and mortality of pikeperch [iSander lucioperca/i (L. 1758)] fry following oligotrophication of a reservoir.
Ecology of Freshwater Fish. Roč. 32, č. 4 (2023), s. 724-734. ISSN 0906-6691. E-ISSN 1600-0633
R&D Projects: GA MŠMT(CZ) EF16_025/0007417; GA MZe QK22020134
Institutional support: RVO:60077344
Keywords : diel vertical migrations * stizostedion-lucioperca * winter mortality * perca-fluviatilis * ichthyoplankton * oligotrophication * overfishing
OECD category: Ecology
Impact factor: 1.8, year: 2022
Method of publishing: Open access
https://doi.org/10.1111/eff.12718

Until 2006, the Lipno Reservoir had the largest catches of pikeperch in the Czech Republic, but since 2007 it has partially collapsed. This collapse was preceded by oligotrophication, when phosphorus concentrations declined by 25%. Conservation measures from 2009 to 2015 partially improved the population from 2015, but pikeperch biomass did not reach previous levels. Unsuccessful spawning and low survival of pikeperch fry were suspected as possible reasons. Pelagic trawling for pikeperch younger juveniles in June and older juveniles in August indicated that extreme mortality in the first year of life, rather than limited spawning, was the reason for low pikeperch recruitment. Large interannual differences in pikeperch density were observed in both spring and summer, and the growth was generally low. Pikeperch fry density changed over a trophic gradient with the highest densities in the eutrophic upper reservoir parts, while differences between depths were much less pronounced due to the lack of temperature and oxygen depth stratification in summer. Oligotrophication of the reservoir in recent years is probably partly responsible for the high mortality and slow growth of pikeperch fry that are still zooplanktivorous, resulting in a lower probability of surviving their first winter. Given the changing conditions in the reservoir, measures should be taken to strictly conserve populations to maintain self-sustaining pikeperch populations in the Lipno Reservoir.
Permanent Link: https://hdl.handle.net/11104/0351724