Trout spawning set to surge in Helsinki-area streams

Brown trout spawning is expected to become more active in streams across the Helsinki metropolitan area this weekend or next week, Yle reports, citing Henrik Kettunen, a project manager with the City of Helsinki.

The fish are easy to spot as they dig spawning nests and compete for mates. Water can splash as they move through shallow stretches, and the largest trout can weigh between 5 and 8 kilograms.

Spawning activity increases when water temperatures fall below 6 degrees Celsius. Rain also encourages trout to move upstream. Kettunen expects “wild action” at many gravel beds in the coming days.

About 20 streams in the metropolitan area support natural trout reproduction. They include Longinoja, Mätäjoki and Haaganpuro in Helsinki; Kylmäoja, Pakkalanpuro and Rekolanoja in Vantaa; and Monikonpuro, Lukupuro and Finnoonpuro in Espoo.

Trout habitat has improved in recent years. Water quality in the Vantaa River system has improved, fish passages and spawning gravel beds have been built, and barriers have been removed. Areas of stones that provide shelter for young fish have also been constructed.

Wild trout are protected year-round in waterways flowing into the Gulf of Finland and in the gulf itself. People looking for trout with a flashlight at night are advised to approach calmly from downstream. Sudden movements or shining a beam directly into the fish’s eyes can startle them.