It can sometimes be difficult, depending on the choppiness of the waves, for pilot Wayne Davis to spot from his two-seater plane the dark silhouettes of great white sharks swimming off the coast of Chatham during research expeditions with the Atlantic White Shark Conservancy.
But there was no missing a giant school of fish this week as he flew near the Monomoy National Wildlife Refuge.
The conservancy, a non-profit based on Cape Cod, shared a photo Friday taken by Davis from his Citabria earlier in the week of what looks to be hundreds — if not thousands — of menhaden, or forage fish.
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The fish are gathered together not far from a lurking great white, forming a shape like a pinpoint on a Google map. The collection of fish creates a striking black dot in the middle of the blue-green Cape waters as though a shadow were cast over the sea.
The conservancy’s nearby boat is dwarfed by the mass of menhaden, which can live to be 12 years old and are known to swim in large schools close to the water’s surface during the spring, summer, and fall, according to the National Oceanic and Atmospheric Administration.
Davis, 69 and a Vietnam veteran, began working with the conservancy and state biologists three years ago, helping them track and tag great whites.
He said that menhaden — or pogies, as fishermen call them — are high in oil. They’re also a tasty treat for grey seals, which are the preferred snack of great whites.
“I can’t imagine eating one,” said Davis. “These fish are nothing but grease, and bones — and smelly.”
Steve Annear can be reached at steve.annear@globe.com. Follow him on Twitter @steveannear.