for people, fish and tiny ‘mammoths’

Not the largest and not the deepest. And yet Vättern may be the most unique lake in Sweden. The lake has its own unique character, with great depths and clear, cold, nutrient-poor water. Its location in southern Sweden allows for an ecosystem with a very unusual combination of southern and northern species. There are even traces here from the last ice age, such as Vättern's small 'mammoths' that are still swimming in the lake.

When the ice withdrew after the last ice age, about 11,000 years ago, Vättern wasn’t a lake, but a bay in the Baltic Sea. It was only as the land rose that Vättern took on its current form and its inhabitants were closed off from the sea. Animals still remain in the lake from that time. Fish like smelt, char and the fourhorn sculpin, but also small crustaceans. These animals are called glacial relicts and they have been able to survive in Vättern because of the cold water – hence calling them ‘mammoths’.

"Shrimp-like Mysis relicta is fascinating, not least because of its exceptional ability to move between the lake bottom and surface. Such movement probably surpasses what all other freshwater invertebrates can do.”

– Björn Kinsten, Sweden's expert in glacial relict crustaceans. Mysis relicta is one of the crustaceans remaining from that time. It’s only up to three centimetres long, but despite its tiny size it has a huge swimming capacity. At dusk it swims from the bottom of Lake Vättern to the surface layer to feed on plankton. A distance that in Vättern can reach up to 100 metres every night. At dawn it swims back to shelter in the dark depths and so reduce the risk of being eaten itself by hungry fish.

Another crustacean that survives from the past is the small Monoporeia affinis. It resembles a pale shrimp and thrives in the deep waters of Lake Vättern. It isn’t uncommon to find several thousand individuals within a single square metre, at a depth of 120 metres. The bottom of Lake Vättern is so rich in oxygen that it’s teeming with life, even so far below the surface.

These small crustaceans play an important role in the ecosystem of the lake, including as fish food. In Sweden's lakes there are a total of seven species. All seven species are only found together in the waters of Lakes Vättern, Vänern och Stora Le.

As survivors of the ice age, these crustaceans are adapted to a colder climate and dependent on cold water. Climate change is increasing the water temperature in Vättern. Whether these "mammoths" will still be found in Lake Vättern in 100 years is not certain.

Unique ecosystem in Lake Vättern

It isn't just glacial relicts that make Vättern's ecosystem unique. The water in Vättern is cold, pure and clear. And the flora and fauna are rich and unique in many ways. Many of the species found here are rare in southern Sweden, and can usually only be found in northern Sweden and the mountains.

Beneath the surface of the water are a range of naturally reproducing fish unique in our part of the country. Here, cold water species such as grayling, trout and burbot swim together with the country's largest stock of char. In the open water, the predators' favourite food, smelt and vendace, swim in large schools to try to avoid being eaten. In their turn, predatory fish such as char and trout can also become prey for the larger pike that live in the lake.

"Sport fishing in Vättern offers exciting and unique fishing for char, trout and pike – something we must protect!"

– Hanna Eriksson, Sportfiskarna

Visitors to Vättern can experience world-class fishing. Char-fishing and pike-fishing from a boat, and salmon fishing from land, offer incredible experiences, but for the inexperienced angler it's a good idea to go out with one of the local fishing guides first. Vättern boasts both a world record for lake salmon and the Swedish record for pike, with two fish weighing over 20 kg.

Vättern is a fantastic lake in many ways, and a huge natural asset. It also provides drinking water for almost 300,000 people, and many people use the lake for fishing and outdoor activities. Vättern isn’t the largest lake, nor the deepest – but it is still unique in Sweden.

NOTE! Recently, an invasive new species was discovered in Vättern, which is known as the 'Killer shrimp' Read more about this on page 46.

Underwater meadows: Because Vättern is such a clear lake, light filters quite a long way down into the water, allowing underwater plants to thrive. These 'meadows' are a fantastic habitat for small fish and fry, and are the reason why the whole of Vättern has been designated as a Natura 2000 area.

vättern's ‘to-do list’ – which ones have you checked off?

■ Swimming in Lake Vättern

■ Take a walk to a place with a great view

■ Visit one of the many nature reserves around the lake

■ Go skating in the North Vättern archipelago

■ Go out on Vättern – take a boat, kayak if weather permits, or take a trip on the steamer Trafik

■ See spawning trout and char in the autumn

■ Try land fishing for salmon

■ Visit the aquarium in Motala and see our fish up close

Learn more about Vättern!

Due to its unique characteristics, Lake Vättern also faces some challenges in the future. Do you want to know more about Lake Vättern’s health and how we measure it? Or are you going fishing?

Also visit:

• vattern.org

General information, in cooperation between the Lake Vättern Society of Water Conservation, Leader Vättern and the County Administrative Boards around Vättern.

• vätternliv.se

A portal about Lake Vättern, its ecosystem, environmental conditions and challenges.

There's also a section where you can find fun activities for children of all ages.

• svenskafiskeregler.se

Here you can find out which fishing rules apply to recreational fishing in Swedish coastal areas and the country's five largest lakes.