From Wikipedia [0]: "Canned sardines in supermarkets may actually be sprat (such as the brisling sardine) or round herrings.", and sprat [1] is a different fish, not a sardine [2]. Nobody in Russia or Nordic countries calls "sprat" "sardines" - this is one of the typical misnomers. Sprats are rich in omega-3s, but sardines are not.

[0]: https://en.wikipedia.org/wiki/Sardines_as_food

[1]: https://en.wikipedia.org/wiki/Sprat

[2]: https://en.wikipedia.org/wiki/Sardine