Seals in the Baltic Sea
While the Baltic Sea - the small brackish sea surrounded by Sweden, Denmark, Finland, Poland, Estonia, Latvia, Lithuania and Russia (Kaliningrad) - has only one cetacean, the endangered Baltic harbour porpoise, it has three species of seal. They are the harbour seal, the grey seal, and the ringed seal.
The Baltic is the youngest sea on Earth. Only 8000-9000 years ago, it was a great freshwater lake, known as “Ancylus lake”, which was only connected to the Atlantic through what is today Vänern (the largest lake in Sweden and western Europe), as Denmark and southern Sweden were a solid landmass.
With an average depth of 60 meters and only brackish, not true salt water, it is still practically a large "salt-ish" lake, only now it has direct connection to the Atlantic ocean.
In its short life, it has seen more wars than any other sea (there are reportedly over 5000 wrecks of ships, planes, and others, on the bottom), and has become one of the most polluted seas in the world. [source]
Shipping lanes use sonar on a frequency that disturb the porpoises’ ability to feed, and make mothers and calves lose themselves in the noise. This combined with the same threat small cetaceans face all over the world - drowning in gill nets - has resulted in the Baltic harbour porpoise being reduced to around 500 animals, and is considered critically endangered by the IUCN.
Harbour seal - Phoca vitulina
Called knubbsäl in Swedish, spættet sæl in Danish, foka pospolita in Polish, and seehund in German, is a common seal in the northern hemisphere, found all the way to the Bay of Biscay, Florida, and California. Globally, they number upwards of 500 000 animals, while in the Baltic, there are only around 1000. In the nearby waters of the west coast of Sweden, however, there are another 14 000.
By the turn of the 20th century, there were 5000 harbour seals in the Baltic, and 16 500 in the waters west of the Baltic. They do not ranger further north than the Gotland-Stockholm area, and do not range east, to the Baltic countries.
They have been protected in the Baltic since 1966, but have still experienced drops in population due to diseases, including a 1988 outbreak of canine distemper.
Grey seal - Halichoerus grypus
The grey seal is the largest pinniped in the Baltic, and unlike the harbour seal, they range to the northernmost coast, and deep in the Gulf of Finland. They are recognizable not just by their size, but also by their long, straight profile.
They are called gråsäl in Swedish, gråsæl in Danish, kegelrobbe in German, szarytka morska in Polish, dlinnomordyy tyulen in Russian, pilkasis ruonis in Lithuanian, pelēkais ronis in Latvian, hallhüljes in Estonian, and halli in Finnish.
Global population figures say anything from “up to 300 000″ to “at least 600 000″. The IUCN states there are 316 000 mature individuals - meaning there are additional juveniles, so some 400 000+ is likely.
Their range is much smaller than that of the harbour seal, being only found in the north Atlantic, surrounding the British Isles, Iceland, eastern Canada, the coast of Norway and northern Finland, and of course, the Baltic.
They give birth to their pups on sea ice, but are for some reason not as badly affected by loss of sea ice as other seals, as they can just as well go to land to give birth on shore.
Today, there are around 40 000 grey seals in the Baltic sea.
Around 500-1000 are shot every year, between Sweden, Finland, and Estonia, as a measure of population control, though strangely, it is referred to as a “protective hunt”. When talking about land predators like wolves or bears, protective hunting is only about killing specific individuals that are being troublesome - a quota of several hundred animals is simply that, a cull, or population control.
The seals are of course blamed on fish stocks failing - even though the seals are less numerous now than they were in the past. By the turn of the 20th century, there were around 100 000 grey seals in the Baltic. And according to a 2010 study, humans take seven times as much fish out of the Baltic sea, as the seals do.
I had no idea about this cull of seals in Sweden until I researched for this article, trying to find information about possible natural predators of seals in the Baltic. As there are no killer whales or large sharks there, presumably, seals are on the top of the food chain. Unless one factors in that seals and humans have probably shared the Baltic coasts for the same time span, and been "exploited" by humans the whole time.
Regardless of one’s personal opinion on hunting seals, I find it strange that organizations campaigning to protect our wolves, bears, lynx, wolverines and eagles, have never said a word about protecting our marine predators.
Ringed seal - Pusa hispida
Called vikare in Swedish, norppa in Finnish, viigerhüljes in Estonian and pogainais ronis in Latvian, the ringed seal has a great range, encircling all of the northern part of the northern hemisphere, going as south as Nova Scotia and Maine. In the Baltic, they are only found in the upper parts, not overlapping with the range of the harbour seal, as they are dependent on ice.
The worldwide estimate is that there are around two million ringed seals, and they are one of the most frequently hunted seals in Canada.
A third of the adult females are sterile because of pollution levels in the Baltic sea, but despite this, they are increasing in population. There are upwards of 20 000 ringed seals in the Baltic. At the turn of the 20th century, there were 200 000.
Unlike the grey seal, when there is no ice to give birth on, there are less pups born. Whether that is because the pups are born in water and drown, or if the fetuses are lost, is unknown, as is the cause why the ringed seals simply don’t give birth on land as the grey seal does when needed.
Just like the others, the ringed seal has an annual quota hunt. The latest is 300 seals, 130 of which in Sweden (and in 2019, 440 harbour seals in Swedish waters). This is the permitted quota, though, not how many will actually be killed.
The three seal species in the Baltic stand at 20%, 40% and 10% of what their population was 120 years ago, yet are being blamed for the fall of fish stocks in the most polluted sea in the world.
Seals in the Baltic have no other predator besides for humans, and since we have been living together in that sea since the beginning, one could argue humans are a "natural predator" of the Baltic seals.
The hunting is done sustainably, and whatever one thinks of it, far more important issues for the seals are the pollution (such as PCBs and industrial and farm runoffs), and fishing gear entanglements.