The likely world-record hammerhead shark caught in May weighed 1,280 pounds (576 kilograms) because it was pregnant with 55 pups — the most scientists have ever seen.

Scientists at MoteMarine Laboratory, where the shark was taken for a necropsy, said Thursday that 52 were nearly full-term and just a few days from birth. The shark was estimated to be between 40 and 50 years old.

Scientists previously believed that hammerhead sharks gave birth to 20 to 40 pups at a time.

"Although we are thankful that the fisherman gave this unique specimen to Mote, and we are learning a lot about this species from this large female shark, we were saddened to see so many unborn pups inside her so close to birth," said Dr. Robert Hueter, director of Mote's Center for Shark Research.

The shark was caught off Boca Grande on May 23.

Whether the 14.5-foot (4.35-meter) shark is a record catch on rod and reel is still being decided. The International Game Fish Association expects a decision in late July.