See it: Massive 900-pound ocean sunfish found dead on Cape Cod beach

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FILE: NECWA Sunfish Rescue

NECWA volunteers struggle to save a juvenile sunfish that weighs between 500 and 600 pounds. Adults weigh around 4,000 pounds said Carson.

THE TAKEAWAY

• A massive, roughly 900-pound ocean sunfish was found dead in Wellfleet after becoming stranded in Cape Cod’s shallow, tidal waters.
• The vulnerable species faces seasonal stranding risks as it migrates along the East Coast toward warmer southern waters.
• Researchers collected tissue, data and photographs from the fish to help fill gaps in scientists’ understanding of ocean sunfish biology and ecology.

WELLFLEET, Mass. – A massive ocean sunfish, estimated to weigh more than 900 pounds, was found stranded on a Cape Cod beach earlier this week, a tragic sight that’s unfortunately all too familiar this time of year as the vulnerable species migrates toward warmer southern waters.

The adult female ocean sunfish washed ashore at the mouth of the Herring River in Wellfleet, Massachusetts, on Cape Cod’s inner shore along Cape Cod Bay.

The sunfish was found at the mouth of the Herring River in Wellfleet Harbor, on Cape Cod’s inner shore along Cape Cod Bay.

(New England Coastal Wildlife Alliance)

The massive sunfish, one of the ocean’s gentle giants, known to bask at the surface and dive into deep waters, was found dead on the beach by someone walking along the shoreline.

The species ranges across tropical and temperate oceans worldwide, from Iceland to Chile, and annually migrates to warmer wintering waters.

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Ocean sunfish can weigh more than 2,000 kilograms, or about 4,400 pounds. At roughly 900 pounds, the fish captured in tragic images was still an impressive giant.

The fish’s ovary alone weighed 13.2 pounds, researchers said.

Wellfleet Harbor’s narrowing inner waters and extreme tidal swings can trap migrating ocean sunfish, leaving them stranded on shallow flats as the tide recedes.

(New England Coastal Wildlife Alliance)

Volunteers with the New England Coastal Wildlife Alliance (NECWA), a grassroots wildlife nonprofit, responded to the stranding — an unfortunately familiar sight this time of year.

Each year, healthy ocean sunfish meet the same unfortunate fate on their migration journey south to warmer wintering areas during the fall.

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While following the Atlantic coast on their seasonal migration, ocean sunfish can become trapped in Cape Cod Bay, where the peninsula’s hook-shaped coastline and dramatic tides funnel them into the shallow, narrowing waters of Wellfleet Harbor.

The stranded female ocean sunfish was estimated to weigh about 900 pounds.

(New England Coastal Wildlife Alliance)

For these open-ocean fish, the harbor can become a deadly trap.

Ocean sunfish accustomed to deeper waters can be caught by shallow waters and retreating tides, where they can strand and die, like what happened to the massive adult female sunfish recovered earlier this week.

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The gentle giants that inhabit tropical and temperate waters worldwide are classified as "Vulnerable" on the IUCN Red List, the world’s most comprehensive inventory of species’ extinction risks and conservation statuses.

Despite their vulnerable status, ocean sunfish are among the most prolific breeders known. A single female can produce roughly 300 million eggs — one of the highest reproductive outputs among vertebrates, according to the NOAA.

"So sad to see that she died, but her death is not in vain," NECWA officials said.

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NECWA said researchers collected data and tissue samples, along with photographs documenting the tragic scene, to share with scientists worldwide and help answer basic questions about ocean sunfish biology and ecology.