Protesters will gather outside Mr Bridges' Devonport Rd offices in opposition to the decision, and to present the Tauranga MP with a letter asking immediate action to ban all exploration in the sanctuary.
But Mr Bridges told the Bay of Plenty Times the protest was unlikely to change anything.
"There's negligible risk to the Maui dolphin from petroleum activity and over 40 years of this on the west coast of the North Island or Taranaki there has not been a single reported incident where a Maui dolphin has been hurt by petroleum work."
The marine sanctuary is home to the critically endangered Maui's dolphin, of which there are only 55 in the world.
The revelation comes a week after the International Whaling Commission urged the New Zealand Government to do more to save the species.
"Obviously when you have a industry like the petroleum industry who bring billions of dollars and thousands of jobs, it would be lunacy to shut it down when there's only a very remote risk of harm to the dolphins," Mr Bridges said.
"I deeply care about the environment like all New Zealanders do but I'm very confident that petroleum activity hasn't in the past, and won't in the future, cause any harm to the Maui dolphin."
Green Party Tauranga candidate Dr Ian Mclean, who has a PHD in environmental biology, said oil exploration often used underwater explosions and other highly noisy activity.
"Obviously running away is an option for them but how far they run, no one can answer that," Dr Mclean said.
"The much greater risk is they will have suffer direct physiological injury by swimming inland (and beaching themselves)."
Mr Coffey said he believed the issue was one which transcended politics and struck at the very core of old fashioned Kiwi values. Mr Coffey invited people to join the protest in Tauranga.
Several speakers are expected in addition to a peaceful march from The Strand, starting at 10am.
People are invited to meet at 9.30am at the centre of Devonport Rd.
