A dolphin conservation group says the Government isn't keeping to pre-election promises.
Sunday afternoon's March for Maui aims to add pressure on the Government to keep video monitoring fishing fleets to keep dolphins safe.
Chair of Maui and Hectors' Dolphin Defenders New Zealand, Christine Rose, says the march is a public outcry.
"The Government has been immune to the international pressure, the advice of scientists, the beliefs of the public."
Ms Rose says the Government is considering getting rid of an electronic video system vital for monitoring fishing fleets, and this would be a mistake.
"Further coverage is really important to provide scrutiny and properly quantify the number of Maui's dolphins that are being killed in nets."
March for Maui is at Auckland's Silo Park Sunday afternoon.