I have the same question - My guess is at that altitude, temperature, and under an ice sheet, and silt until the lake was drained. Here's the paper: https://ww

I have the same question - My guess is at that altitude, temperature, and under an ice sheet, and silt until the lake was drained. Here's the paper: https://www.cambridge.org/core/journals/antiquity/article/introduction-of-fish-to-the-scandinavian-mountains-by-hunterfishergatherers-5000-bc/29BD68BA540BA600E05E867CBDF4C6D9 https://www.cambridge.org/core/journals/antiquity/article/in...