New research shows the population of bull sharks in the Gulf of Mexico is growing fast.

Researchers say the number of bull sharks is five times larger than it was 20 years ago, according to data at Mississippi State University.

RELATED COVERAGE: Authorities investigating shark attacks at South Padre Island

Over the last 20 years, experts in Alabama surveyed the fish population and saw more and more bull sharks.

"The relative abundance of the bull sharks, of the juvenile bull sharks, increased five-fold over the last 20 years off the coast of Alabama," Lindsay Mullins said. "I definitely suspect that this is something that is not going to be just affecting the coast of Alabama. It's going to be a gulfwide thing wherever bull sharks are found."

RELATED COVERAGE: South Padre island shark attack victim speaks out

Mullins says the rise in Gulf water temperature appears to be a strong factor in the bull shark population. She says data showed the temperature increased by one degree in the last 20 years.