European Sardine

You leave the relief of the rocks and, in the blue, a silvery mass suddenly crosses your field of vision. Hundreds of sardines change direction almost together, then the school stretches and closes again.

But behind this familiar image lies an astonishing capacity: the sardine possesses two feeding strategies. Experiments conducted directly on Sardina pilchardus showed that it can filter water to retain small planktonic prey, then switch to more targeted capture when prey are larger.

In the Bay of Marseille, sixteen months of study of its diet also revealed great flexibility in the choice and size of its prey, compatible with the use of these two strategies. The school also changes location with the light: in sectors of the Aegean Sea, acoustic tracking observed rapid descent at dawn and ascent at dusk.

Even its reproduction conceals an organization invisible to the diver. The sardine spawns in several episodes and, in populations studied in the central Aegean Sea and the Ionian Sea, females in the process of spawning were temporarily separated from other females, accompanied by numerous males ready to reproduce.

Just a few meters from you, what seemed to be merely a silvery cloud suddenly becomes a moving crowd, which feeds, moves and reorganizes before disappearing into the blue.