A large saltwater crocodile partial to free meals has been removed from a Townsville beach after apparently being fed by locals.

The 3.8-metre reptile was trapped at Saunders Beach on Thursday after being spotted lurking at local boat ramps and a pontoon in a nearby creek.

Authorities believe the animal was being deliberately fed by anglers, or had become accustomed to helping itself to scraps that were carelessly left behind.

It took 90 minutes to catch it in a baited trap, a strong indication that it was used to feeding on discarded scraps and bait, the environment department said on Friday.

Fishers have been urged to properly dispose of waste in boat ramp bins, or at home.

"The regular feeding of crocodiles can affect their behaviour and encourage the animals to remain in an area, waiting for their next meal," the department said.

Anyone found to have deliberately fed a crocodile can be hit with a $5222 fine.

The croc will be rehomed at a farm or a zoo.