A father of two in Florida died after he swam out to help a seagull he hooked while fishing ... and ended up drowning.

William "Stone" Romberg -- a hospitality manager -- died while fishing down in Panama City Beach on Sunday ... according to a GoFundMe set up for his family.

His friend, Heidi Fortner, says Romberg was fishing at an inlet when his cast caught a seagull. Concerned for the bird, she says he jumped into the water to untangle the animal.

Unfortunately, Fortner says the hook and the bird became attached to Romberg's hand. He tried to swim to shore ... but the strong current dragged him out, and he drowned.

Romberg is survived by his wife, Taylor, and two children ... girls aged 3 and 1. The GoFundMe set up to support them has already raised $116K and counting.

He was 31.

RIP