Lakes on Gotland - "Träsk"

The lakes on Gotland, locally called "träsk," are shallow and rarely deeper than two meters. However, there are exceptions, such as some of the lakes in Lojsta and the surrounding areas. For example, Ramträsk near Lojsta Castle, which is 18 meters deep, or Sigvaldeträsk in Etelhem (pictured above).

Gotland, once rich in wetlands, now has only about twenty relatively large lakes remaining. Many of the island's extensive marshes were drained in the late 19th century to expand and improve agricultural land.

Due to the limestone bedrock, the lakes are alkaline and have sparse vegetation. Typically, only stoneworts thrive on the calcareous lake bottoms. The shores of these lakes are often lined with reed beds and sedge. Floating plants, such as white water lilies (Nymphaea alba) and spiked water-milfoil, along with bulrush and club-rush, can also be found in some areas.

The greylag goose, which has a strong presence on Gotland, prefers to nest in small water bodies or along suitable coastal shores. In early summer, you can often spot flocks of goslings by the lakes. In September, the geese begin their migration south, returning in February or March. Occasionally, you might also spot little gulls and black terns. Today, few of Gotland's marshes and lakes are protected as nature reserves. Some reed marshes are preserved within the Hall-Hangvar Reserve, while Muskmyr Reserve is located in Sudret.

Gotland's lakes and streams are home to 19 native fish species. Five of these—lamprey, brook lamprey, bullhead, ruffe, and rudd—are freshwater fish that date back to a period when the Baltic Sea was fresh water. Other common species include pike, perch, roach, and sea trout, which migrate up streams and rivers to spawn.