Threats to Arctic charr - species interactions and climate change

Climate change, in combination with competition and predation from other fish species, are potential threats to Swedish Arctic charr populations. In this project, I will use multiple approaches to identify critical factors affecting charr.

The interaction between charr and brown trout – and how it has changed over the last decades – will be investigated with the help of historical data, interviews, and new sampling efforts.

Arctic charr occurrence, densities, and population structures will be examined both across environmental gradients of temperature and nutrient availability, and in relation to fish community composition.

Using existing regional data and a space-for-time substitution approach, I will quantify climate impacts on charr, and climate-induced changes its interactions with trout, and other species.

Time-series of charr growth patterns and abundances will be analyzed, to help disentangle mechanisms causing observed changes, and methods will be developed to extract additional information on charr growth from otoliths.

A size-structured population model will be used to identify key mechanism driving the charr-trout interaction, and to investigate how harvest strategies should be modified depending on whether trout is present or not. The influence of different lake characteristics and harvesting regulations will also be considered in the model.

The project will identify current threats to Arctic charr and develop monitoring and management actions in our lakes.