Residents of Northland have been caught illegally selling crayfish through buy, sell and exchange pages on Facebook.
The sales were discovered by Northland Ministry for Primary Industries (MPI) staff in the past two weeks.
MPI staff were speaking to all involved and warned the public that such sales were illegal.
"We would like to remind the public, it is illegal to offer to sell, sell, trade and purchase seafood that has been recreationally taken," said MPI Acting Northland District compliance manager Stephen Rudsdale.
"People who buy black market seafood also expose themselves to potential health risks, as there is no assurance that this product has been processed or stored hygienically."
