No, I'm not pulling your leg on this one. Sardines get better with age.
It's long been known amongst European a-fish-ianados that most sumptuous sardines are those that have been allowed to mature and mellow for years before they're eaten. During the aging period the fish and the olive oil they're packed in meld together making the sardines more tender and their flavor notably richer. You can start your own cellar with the current vintage, of course, or seed it with a few of these older tins. Supplies very limited.
We get our Portuguese tinned sardines from the La Gondola cannery just outside the town of Porto. Many of the fishermen are the second generation to work for the company. They tin the sardines only during the sardine season with fresh, not frozen, fish. Each tin is still packed by hand with four or five fat fish nestled in olive oil.
It’s almost a forgotten bit of history, but it was Napoleon we have to thank for tinned sardines. He was looking for a portable, shelf-stable food for the troops fighting in his various wars. He conducted a contest and sardines won.
It wasn’t long after when Connétable went into business. The firm is still there today, and the sardines are fished in the same cold Atlantic waters off the Breton coast of France. They are now bedded in extra virgin olive oil which I think is the only upgrade this tinned fish has seen in 162 years. Extra virgin olive oil makes them silkier. The saline sea edge of sardine is still there, but less sharp.
"Aficionados of aged canned fish — the flavors deepen over time — know that 2013 was a very good year for sardines"
New York Magazine