Maretarium’s eels are 50 years old!

Maretarium has a unique population of eels born in 1976. This year, they will be 50 years old. There are ten 50-year-old eels in the Maretarium. They are about 120 cm long and weigh about three kilograms. In 2019, one of the eels in this population spontaneously matured the eggs in the Maretarium basin, this was the world’s first case ever outside the eel’s spawning ground, the Sargasso Sea in the Mid-Atlantic.

The eel is somehow familiar to everyone, but on the other hand, there is still a lot to be found out about its life cycle for researchers. In 2023–2027, Maretarium and the Natural Resources Institute Finland are involved in an international research project with researchers from 22 different countries, which aims to determine the factors related to eel reproduction and the vitality of eel fry. The eel populations in Finland and the whole of Europe have declined sharply since the 1970s. The eel is currently classified as a critically endangered species.

In addition to these 50-year-old eels, there are other eels in the Maretarium, ranging in age from 10 to 30 years. The oldest eels found in the Finnish wild have been 72 years old.

The 50th anniversary of eels will be celebrated at Maretarium on Saturday 14.3.2026. At that time, everyone born in 1976 can enter for free. The birthday programme includes eel information at 11 a.m. and 2 p.m. and eel feeding at 3 p.m. All the eels at the Maretarium are unique, and visitors to the celebration get to think about which of the 50-year-old eels resembles her-/himself.