Look at which fish live in which conditions.

Hot and cold water contain different oxygen levels, and therefore, different types of fish. Fish usually prefer the warmest and most oxygenated layer of water. As the lake gets browner, this phenomenon will increase, and fish habitats will continue to shrink. Old species will disappear (for example, arctic char), and only the newer, or better-adapted species will survive (like pike or perch).

A column of lake water has a top part, or “pelagic zone,” where most of the food web lives, and a bottom, or “benthic” layer, which contains the most waste; mostly dead algae and plants.

- Fish are the lake residents with which we humans are most familiar

- Be it swimming for fun, or fishing to feast, we encounter them a lot

- But as lake water gets browner and warmer, lakes’ ice cover changes.

- So our winter activities like skating or skiing are impacted, too ! Have you heard of lapplandsmästerskapet? It’s an ice fishing competition here on Torneträsk that brings together people from all over Scandinavia, each aiming to catch the biggest fish. It used to be held each May, but due to the changing ice cover of the lake, it must now take place in April: lakes are clearly changing.

arctic char (salvelinus alpinus): loves the cold winter, but struggles in the heat average size / 30 - 50 cm

barbel (barbus barbus): is a culinary archaeologist; will always dig for food! average size / 40 - 60 cm

brown trout (salmo trutta): has trouble seeing where it’s going, making it easy prey average size / 30 - 50 cm

grayling (Thymallus thumallus): is social among fellow grayling, but is not a team player when it comes to other species average size / 30 - 50 cm

minnow (phoxinus phoxinus): has a tiny body but a big appetite, adapting its prey as needed average size / 4 - 8 cm

perch (perca fluviatilis): is able to find food in the dark! average size / 10 - 25 cm

pike (esox lucius): enjoys a warm bath—even big predators like luxury average size / 40 - 60 cm

arctic salmon (salmo salar): can live in the salty ocean, fresh rivers, and fresh lakes, but brown water? No thanks! average size / 70 - 100 cm

During winter, food is rarer and the lake temperature is generally quite low—but it’s a bit warmer at the bottom, so fish tend to move low and slow. During summer, the food is back and the temperatures are warmer at the top, so fish move up and get around.