U.S. Sen. Edward Markey is asking federal agencies to investigate where a leading sustainable seafood distributor actually gets its fish, after an Associated Press investigation found Brooklyn-based Sea To Table was selling tuna labeled as coming from docks where it wasn't landed and with the names of boats that didn't catch it.

Here's how it was supposed to work: Every day chefs and other potential customers get a long list of "Just Landed" seafood identifying what Brooklyn-based Sea To Table can offer from its trusted, waterfront partners — some 60 fishermen and small commercial docks around the country. Chefs order what they want, and the fish is boxed, put on ice and sent via FedEx overnight.

"We send all fish directly from the landing dock to your kitchen," Sea To Table explained.

The growing world of foodies and conscientious consumers cheered them on. Celebrity chef Rick Bayless signed up. So did Roy's seafood restaurants, the Chopt salad chain, dozens of universities and even home meal kits like HelloFresh and Sun Basket. The Monterey Bay Aquarium made them a collaborator, James Beard Foundation singled them out.

But AP reported earlier this week that Sea To Table "partner docks" were often markets that stocked their shelves with fish from up and down the coasts, as well as importers. The distributor also offered species that were farmed, out of season or illegal to catch. And AP traced companies in Sea To Table's supply chain to other parts of the world, where fishermen described working under slave-like conditions with little regard for marine life.

Customers and supporters told AP they were disappointed and confused.

In letters Friday, Sen. Markey, D-Mass., said "Sea To Table has violated the public's trust in seafood by lying about the nature of its product." He asked the National Oceanic and Atmospheric Association and the Federal Trade Commission to investigate. Those agencies are responsible for enforcing seafood fraud and mislabeling laws.

Markey has introduced legislation to combat seafood fraud in recent years and plans to again.

Sea To Table founder and CEO Sean Dimin said the findings are "frankly heartbreaking."

In a letter posted on their website, Dimin said their family business is "dedicated to delivering the highest standard of seafood" but noted there is still work to be done in the "opaque seafood industry." He said they have discontinued a working relation with a supplier while they further investigate.

National Fisheries Institute spokesman Gavin Gibbons said the AP story raises serious concerns.

"It's important to note that willful mislabeling is not just an error, it is fraud, plain and simple," said Gibbons.

Copyright 2018 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.