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SAN DIEGO – A huge school of anchovy amassed near Scripps Pier in La Jolla Tuesday and few graduate students snorkeling in ocean got a unique underwater view.

Students from Scripps Institution of Oceanography, UC San Diego used a GoPro camera to capture video of the anchovy school off the coast of San Diego.

“Multimillions” of the 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 when first spotted Monday.

Scripps scientists say they haven’t seen such an aggregation in more than 30 years, but were unclear why the large school moved into shallow waters off the coast.

Phil Hastings, a marine biology professor and curator of the marine vertebrate collection at the UC San Diego-connected Scripps, said the school swam north and was mostly dissipated this evening.

He had no explanation for the huge swarm 15 meters to 100 meters wide and extending from Scripps Pier to a distant point north. But he noted that the water temperature at Scripps Pier hit 74 degrees today, “pretty much the warmest water the species has been reported in.”

Hastings said he doubted the mystery of their appearance will be solved.

“I don’t think we’ll be able top ferret it out,” he said. But for history’s sake, Scripps has collected specimens for preservation.

The band of 6- to 7-inch fish, which feed on plankton, was first spotted Monday by lifeguards, Hastings said. Hastings called the stragglers that remained today “bait balls.”

Photos showed surfers paddling out for a view below, and video was posted on the Scripps website.

Northern anchovy is harvested mainly for use as bait in other fisheries and sometimes processed into fish meal, “but it once supported a multimillion-dollar fishery as catch was sold for human consumption, for bait, and for reduction into meal, oil and soluble protein,” according to the NOAA.

Northern anchovy has been fished off the West Coast since at least 1916, the agency says.

Watch the video and about 1:50 minutes in you’ll see what the anchovy school looks like up-close.

Anchovy school at Scripps Pier, July 8, 2014
Anchovy school at Scripps Pier (Credit: Scripps Institution of Oceanography, UC San Diego)