The annual duck race encourages participants to buy a £1 plastic duck and race it across the River Irwell to raise money for children’s charity Brainwave.
However, because of pollution levels in the river, the ducks can’t be returned, meaning they have caused concerns for environmental campaigners.
After the race, Gaskells dispatched two trucks to collect the ducks which were then transported to its headquarters in Liverpool.
Two ducks were taken to Polymers UK in Newton le Willows to research how the ducks can best be recycled.
Denise Banks, commercial director at Gaskells Waste, said: “We have a zero waste to landfill pledge and are always looking for the best ways to re-use and recycle waste.
“Five thousand plastic ducks is definitely a bit of a tricky task.
“Some plastics are actually quite difficult to recycle, but we’re confident with the tests being carried out, we will be able to give those ducks a new lease of life”