Anglers are calling for volunteers to help them fight a predatory crayfish which is driving out native species.
The American signal crayfish is more aggressive
The hunters are meeting at Barton Mills service station on the A11 on Saturday morning and will spend the day scouring the River Lark for the intruder.
They will be tracking and catching the giant and aggressive American crayfish which they say can make a tasty meal.
Guy Belcher from Forest Heath Council says the aim is to reduce the numbers of American crayfish in the river.
"The population of the native British species is in decline because its bullish American cousin is driving it out of its traditional territory.
"The British crayfish may even become an endangered species," he said.
The Lark Angling and Preservation Society has organised the 'Crayfish Day' and is looking for volunteers to help them.