It's the biggest aggregation of anchovies seen in near-shore waters in three decades, according to scientists at the Scripps Institution of Oceanography at the University of California, San Diego.
We're a bit late picking up on this (the school was first noticed at Scripps Pier at La Jolla on Monday and the video was shot on Tuesday), but member station KPBS spotted it in a more timely fashion.
KPBS says: "The millions of finger-sized fishes prized on pizzas and in animal feed — also called Northern anchovy — created a dark-blue band in shallow waters just off the coast."
Scripps says "it is unclear why the unusually large school moved into shallow waters off the coast. Members of the Scripps Marine Vertebrate Collection have collected samples for study."
At about 0:40 into the footage, the anchovies school in an interesting way, apparently to avoid a predator. Later in the video, a small shark is seen in their midst.
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