Climate change boosts eutrophication in Gulf of Finland
Professional fisherman Kai Ilves is casting his fishing nets into the sea in splendid isolation off Helsinki’s district of Vuosaari. No other professionals appear on these shores, while amateur fishers hardly ever go fishing in chilly open waters in the first place.
Signs of global warming can already be seen off the Vuosaari shoreline. Over 50 years, the sea water temperature on the Gulf of Finland has risen by 0.5 to 0.8 degrees Celsius.
There is no ice, and tomorrow - March 7th - marks the day of the year when the ice cover of the sea is supposedly at its thickest. After that point, the sun will give off so much heat that the ice created during the previous night will melt during the following day.
Climate change has similar effects to excessive nutrients, in other words the state of the Gulf of Finland will deteriorate further. Actually, some of the perceived signs of eutrophication may already have been caused partly by climate change.
Even though fisherman Ilves is used to going out in all kinds of weather, he regards the current winter as something else again.
”However, I suppose the conditions could be even worse. At least now it is possible to use a boat”, he remarks.
On Tuesday morning, Ilves had a successful fishing trip. He caught a dozen or so trout.
According to statistics, the size of salmon catches has come down, and the same trend is likely to continue, while roach and other coarse fish are occupying the sea.
As the already brackish waters have sweetened, it has been noticed that roach and sprats have become thinner, which has weakened the health of the young sea birds feeding on fish.
The current ill-health of fish is a consequence of impoverished nutrition, namely animal plankton of inferior quality.
Actually, Ilves does not try to catch Baltic herring, but these fish sometimes find their way into perch nets as well.
”I have sometimes caught Baltic herring with only the head, skin and the backbone. Every now and then I also catch first-class specimens”, Kai Ilves reports.
Incidentally, this time grey seals did not come to share the catch with the fisherman. Only one seal was seen to lift its head above the water surface near the islet of Huomenlahja.
"The burbot season came to an end a couple of weeks ago, when a seal was found in one fyke-net”, notes Ilves.
This winter has been the lousiest ever for seals in the Gulf, as there has been a shortage of suitable places for mother seals to give birth to pups. There have been small frozen areas only on the Bay of Vyborg and the Neva Bay off St. Petersburg.
Fishermen do not love seals. In cold winters these greedy mammals cannot reach the fishing nets below the ice, but currently, when the waters are open seals are a nuisance even in the winter months.
According to Antti Halkka, who is preparing a thesis on the effects of climate change on seals, some rumours from St. Petersburg say that a kind of rescue operation for ringed seals is under way in that region. However, he could not give any exact information on the project.
With just a little snow and thin ice, the seals cannot make any snow cave for their new pups, who are then exposed to sharp changes in temperature. The pups of ringed seals weigh just about one kilo, which is why thy are an easy target for gulls, foxes, and ravens, among others.
Grey seals give birth to their pups on the edge of ice, and sometimes also on land. This is what also happens on the western coast of Estonia, in the Archipelago Sea, and in the Archipelago of Stockholm.
Unfortunately, the pups easily die on land as they are exposed to predators, diseases, and stress.
Previously in HS International Edition:
Current winter is warmest of all time in Finland (29.2.2008)
Warm winters could push Baltic seals further to north (31.1.2007)
Ice-free coastal waters in February considered exceptional, even in Southern Finland (13.2.2008)