An illegal gill net was recovered from the River Great Ouse near Ely after it became entangled in the propeller of a boat.
The Environment Agency's Fisheries Enforcement Officer (FEO) say the net, which was discovered on Saturday morning, is believed to have been set late Friday evening.
"Our FEO managed to release some bream which had been caught, seized the net and then assisted the boat owner," said an Environment Agency spokesperson.
"A huge thank you to the boat owner for not only reporting this illegal fishing instrument to our hotline number but also helping to release some of the fish caught."
It comes after 96 people were found fishing and eight offence tickets were issued across Cambridgeshire as part of a clampdown during the close season.
Environment Agency (EA) fisheries enforcement officers patrolled more than 70 locations with Cambridgeshire police’s rural crime action team (RCAT) over 10 weeks between March 15 and June 15.
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