"The maximum penalty for fishing in a marine reserve is a $10,000 fine or three months in jail."
The Motu Manawa-Pollen Island Marine Reserve protects 500 hectares of the inner reaches of Auckland's Waitematā Harbour.
"This marine reserve includes intertidal mudflats, tidal channels, mangrove swamp, saltmarsh and shellbanks," Prior said.
"Auckland's marine reserves are very special places and it's up to all of us to look after them for future generations."
DoC encouraged anyone who knew anything about the illegal net to come forward.
"Any information received will be kept anonymous," Prior said.
"Anyone who has seen people breaking conservation rules, such as fishing in a marine reserve or putting marine wildlife at risk should report the behaviour with as much information as possible to 0800 DOC HOT."
In the Auckland region, marine reserves are located at Cape Rodney-Okakari Point (Goat Island), Tāwharanui, Long Bay-Okura, Te Matuku (Waiheke), and Motu Manawa-Pollen Island. All marine reserves are no take reserves.
Marine reserves are the highest level of marine protection established under the Marine Reserves Act 1971.
The main aim of marine reserves is to create areas as true to natural marine habitats and life. This means it is an offence to touch or take anything from a marine reserve.