Conservationists are calling on the government to take urgent action in the Hauraki gulf, which has lost more than half its marine life in the last century.
Snapper and crayfish numbers are down more than 80 percent since the 1920s, with 86 percent fewer trevally and sharks.
Fish of the Day host Clarke Gayford says while the Hauraki Gulf is still beautiful, most people don't realise what it has lost.
"It's the shifting baselines, so it's people's perception of what they think is good now versus what it used it used to be like."
He says most people don't consider the ecological knock-on effect of severe declines in particular species.
Mussels and other shellfish act as natural filters for ocean water, but some populations have been decimated by up to 90 percent, lowering overall water quality in the gulf and removing vital links in the food chain.
Sea Change, a plan to address this ecological crisis, was drafted two years ago by a stakeholder working group representing Mana Whenua, conservationists, commercial and recreational fishing, farming and local and central government.
Its recommendations include extending marine reserves, banning destructive fishing practices and addressing the impact of forestry and farming on the gulf.
Toxic waste water runoff from Auckland's aging waterways also poses a threat to marine life, particularly as the population continues to boom.
Auckland Mayor Phil Goff has committed to a multi-billion dollar water infrastructure upgrade to tackle the problem
"It is time we took that issue out of the too-hard basket and tackled that issue and that's what we're doing with our targeted rate on water quality"
The council has introduced a targeted rate of $1.30 a week per household to help pay for a $7 billion dollar upgrade of the city's wastewater network.
Green Minister Eugenie Sage supported the recommendations of Sea Change when they were first drafted and is now promising action in Government.
"There are a lot of overlapping issues, that's why it's taking time. It is one of my priorities as Minister working with colleagues like the Fisheries Minister Stuart Nash. We'll be putting a paper to cabinet shortly."
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