Issue |
Int. J. Lim.
Volume 60, 2024
Special issue - Biology and Management of Coregonid Fishes - 2023
|
|
---|---|---|
Article Number | 23 | |
Number of page(s) | 14 | |
DOI | https://doi.org/10.1051/limn/2024019 | |
Published online | 30 October 2024 |
Research article
The effect of water level changes on the density of newly hatched European whitefish (Coregonus lavaretus (L.)) larvae in unregulated and regulated lakes
1
University of Jyväskylä, Department of Biological and Environmental Science, PO BOX 35 40014 University of Jyväskylä, Finland
2
Fisheries Centre of Häme, Kustaankuja 2 17200 Vääksy, Finland
* Corresponding author: tuula.m.vaananen@jyu.fi
Received:
17
January
2024
Accepted:
26
August
2024
The effect of the water levels during the period from spawning to hatching of whitefish (Coregonus lavaretus (L.)) on the density of newly hatched larvae was examined from a 23-year time series. The density of larvae was estimated in four lakes with contrasting water level regulation regimes in Central Finland using depth zone stratified bongo and tube net sampling in 2000–2022 and 2008–2022. In the regulated Tehinselkä, larval density was also modeled as a function of the whitefish spawning stock, vendace stock indices, and water levels. Larger water level maximum drops during winter were observed in three regulated lakes (41–68 cm) than in the unregulated lake (35 cm). The average larval densities were highest in the unregulated Lake Southern Konnevesi and regulated Tehinselkä, with densities >20 individuals ha−1. The regulated lakes Ruotsalainen and Puula had lower average densities, <10 individuals ha−1. Significant synchrony in the inter-annual variation in the density time series was observed between Tehinselkä and S. Konnevesi as well as Tehinselkä and Ruotsalainen. None of studied water level variables were associated with larval density in any lake. Thus, the small-scale regulation in these Finnish lakes did not show any direct effects on the production of whitefish larvae. Our analysis did not provide information on the potential effects of water level regulation on later life. For example, it did not cover the impact on whitefish food resources or the abundance of competitors and predators regulating whitefish growth and mortality in the juvenile stage.
Key words: Coregoninae / egg incubation / fish larvae / spawning stock indices / water level regulation
© EDP Sciences, 2024
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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