A1 Refereed original research article in a scientific journal
Trends in vendace (Coregonus albula) biomass in Pyhäjärvi (SW Finland) relative to trophic state, climate change, and abundance of other fish species
Authors: Helminen Harri, Sarvala Jouko
Publisher: FINNISH ZOOLOGICAL BOTANICAL PUBLISHING BOARD
Publication year: 2021
Journal: Annales Zoologici Fennici
Journal name in source: ANNALES ZOOLOGICI FENNICI
Journal acronym: ANN ZOOL FENN
Volume: 58
Issue: 4-6
First page : 255
Last page: 269
Number of pages: 15
ISSN: 0003-455X
DOI: https://doi.org/10.5735/086.058.0411
Self-archived copy’s web address: https://research.utu.fi/converis/portal/detail/Publication/67225577
Catches of vendace (Coregonus albula) from Pyhajarvi, a boreal lake in SW Finland, were exceptionally high for decades. Gradually, however, eutrophication and climate warming significantly changed the lake environment. From the 1970s to the 2010s, total phosphorus and chlorophyll a levels increased two- and threefold, respectively, while the average June-September surface temperature increased by 0.34 degrees C decade'. The highest population biomass of the young-of-the-year vendace in autumn, 6-18 (mean = 14) kg ha(-1). was recorded in 1973-1989, a period of sustainable fishery. Overfishing in 1990-1999 reduced autumn biomass of young-of-the-year vendace biomass to 3-11 (mean = 6) kg ha(-1), allowing the competing planktivores perch (Percafluviatills), roach (Rutilus rutilus), and smelt (Osmerus - eperlanus) to increase and consume a larger part of the plankton resources. Eutrophication and climate warming appear to have favoured these species, and the new resource division persisted even after the vendace population recovered.
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