Sarah Gugele

Research Project E3: Sticklebacks in Lake Constance

The massive increase of the invasive threespine stickleback Gasterosteus aculeatus in Lake Constance in 2013/2014 was, besides the oligotrophication, the decisive factor which negatively affected the stock of native whitefish (Coregonus lavaretus) and perch (Perca fluviatilis). More than 80% (96% in the pelagic zone of the lake – the habitat of whitefish) of all the fish in Lake Constance are represented by sticklebacks. This invasive species acts as a direct competitor for food, especially for whitefish. Sticklebacks also feed on eggs and larvae of other fish species which might represent another threat for native fish species.
This development displays a unique case in fisheries biology for a large, oligotrophic lake like Lake Constance.

The goal of my research project is the examination of the autecology of the invasive threespine stickleback in Lake Constance. The attempt of species differentiation via hydroacoustics for reliable stock assessment will be part of my research. I will also conduct gut content analysis during spawning and stocking time of whitefish to be able to assess possible recruitment effects on whitefish due to sticklebacks feeding on their eggs and larvae. Stable isotope measurements will be used to expand the knowledge of the sticklebacks’ food spectrum.  Another part of my project will be the investigation of seasonal infestation with the parasite Schistocephalus solidus to clarify its role on the standing stock control of threespine stickleback in Lake Constance. Furthermore I will conduct age determinations to gain knowledge about the growth of threespine stickleback. The investigation of the spawning behaviour at Upper Lake Constance constitutes another part of my research project. Furthermore the possibility of different forms of sticklebacks will be examined using geometric morphometrics. Monthly trawl- and gillnet fisheries will be used to detect possible local differences regarding the stickleback distribution, infestation, food spectrum and morphometrics. The attempt to find answers for the mass occurrence of sticklebacks in Lake Constance as well as the deduction and examination of fisheries management possibilities is the applied goal of my research.

Educational background:

Since 10 / 2017 PhD student – University of Constance

Since 6 / 2016 research associate – Fisheries Research Station Langenargen

10 / 2013 – 11 / 2016 Master of Ecology and Biodiversity – University of Innsbruck

10 / 2010 – 07 / 2013 Bachelor of Biology – University of Innsbruck