Herring is an important food fish, but suffers from the effects of climate change. The decrease in salt content has changed the diet of herring.
A new explanation is being found for the poor condition of herring in the Archipelago Sea.
Back in the 1980s, herring was twice as plentiful as it is now. Reasons for the silverfin’s weight loss have been searched for a long time.
There are several factors behind this, but the latest observation is the decrease in iodine concentration in the Baltic Sea.
Heavy rains dilute the Baltic Sea
It has already been observed that a decrease in salinity is harmful to herring.
At the turn of the millennium, it was noticed that climate change has an effect on the life of herring. Due to climate change, the amount of precipitation has increased and with it the salinity of the Baltic Sea water has decreased.
When water moves away from the Baltic Sea more regularly, salt pulses occur less frequently. When no new salty water comes from the Danish straits, the salinity of the Baltic Sea water is further diluted.
Due to the lower salinity, the diet of the herring has changed. Because of that, the herring lives in constant hunger. In 40 years, the herring has lost up to 50 percent of its weight.
Iodine has also decreased in the Baltic Sea
Recently, researchers discovered another reason for herring’s weight loss. Like salt, the iodine content of the Baltic Sea has been decreasing and it is also believed to affect the growth of herring.
– Iodine is the most important raw material for the thyroid hormone thyroxine. There appear to be indications that thyroxine levels in herring have decreased.
People at the university have studied iodine concentrations in herring meat, roe eggs and gonads. The iodine observation still needs to be verified, and its investigation will continue at Seil.
_Corrected 6/9/2022 growth hormone to thyroid hormone._
_You can discuss the topic with the Yle ID. The discussion ends on September 7 at 11 p.m._
The condition of the back sea herring has deteriorated: \”We can even talk about starvation\”