Spring is a truly busy time in the sea. When the ice cover melts in the Bothnian Bay it’s time for the fish to spawn and lay their eggs in the shallow bays, creeks and lakes.
The perch (Perca fluviatilis) is one of the most common fishes in and around the Balitc Sea and the Bothnian Bay. It lives both in freshwater lakes and streams as well as in the brackish coastal waters. In spring to early summer it comes to the shallow waters where the female lays her eggs. The eggs are encased in a gelatinous coat, up to one meter long band. To prevent the eggs from drifting away they are attached on vegetation. For example tree branches, stems, and old reed thus become important structures for the survival of the eggs.
After approximately 2-3 weeks the eggs hatch. It depends on the water temperature though, the warmer water the quicker they hatch. The young perch spend their first time in sheltered, shallow areas where they feed on plankton. As they grow bigger they move out to deeper waters. Then they also start feeding on insect larvae, small crustaceans and smaller fish. The perch can become up to 20 years old.
Not all fish roe is as easy to identify as the perch’s white “bands”. These small, pearl-like eggs were found attached on stalks of various vegetation, but who they come from we have no idea of!
The only way to find out is to collect some of the eggs and let them hatch. The hatchlings can then be identified by specie. Answer to come!
Written by Linnea Bergdahl, County Administrative Board of Norrbotten