Brown said while he could have looked for an alternate supplier, he supported Ngāi Tahu’s stance, calling the Bluff oyster a “national taonga”.

“They’re just an extraordinary part of the New Zealand culinary scene … this is an opportunity to set an example. Being a restaurant, we’re kind of a window on what’s going on out there and so if we can get some messaging out, and get people to start thinking about that, then hopefully our children’s children will be able to have a Bluff oyster one day.”

Bluff oyster prices range widely in Auckland restaurants, but at the top end, diners pay $85 a dozen for the shellfish that chefs buy for between $32 and $35.

“When you order a dozen oysters, you’re paying a big price for each one,” Brown said.

“We’ve noticed the decline of Bluff oysters over the last few seasons. It seems like you might get two goodies, three goodies, and half a dozen mediocre and then a few runts … we can’t throw them in the bin because, of course, we’re paying for them.”

Depot had not served whitebait in recent seasons and tuna had been off the menu for years, also because of sustainability concerns, Brown said.

“We’re an oyster bar and I totally understand people may be disappointed that we don’t have Bluff oysters, but we do have lots of other wonderful oysters, and we’re supporting the hardworking aquaculture industry.”

He cited Kerikeri’s farmed “Qyster”, which recently made headlines following the theft of $60,000 of stock, as a worthy alternative for shellfish lovers.

“If you order a dozen, you get a dozen beautiful big oysters. Sometimes with the wild fishery, when you put down a plate of oysters, the first thing you do is look for the goodies. You know, you smash those while everyone else is in the toilet or something!”

Martin Bosley, a Wellington-based chef turned seafood supplier, said his company Yellow Brick Road had historically sold up to 1000 dozen Bluff oysters a week. Today, “I think anybody in the industry that is selling those oysters or eating those oysters would agree they’ve been smaller and they haven’t been landing as many as they have previously”.

He called Brown’s decision “brave” but also said he wouldn’t criticise restaurants serving Bluff oysters sourced from other suppliers.

“The oysters are available. We’re catching oysters, they’re allowed to do it, the Ministry of Primary Industries says the quota is there … it’s just that, at some point, someone’s got to put a stake in the ground.

“When you start to get up to $8 an oyster, you know, it’s got to be pretty special – and I just don’t think the quality is there.”

The more readily available Pacific oyster was a “beautiful” alternative, Bosley said.

“Farming oysters is definitely the future. The Bluff is the last wild commercial oyster fishery on the planet. We absolutely need to protect that. Because when it’s gone, it’s gone.”

Judith Tabron, the chef and restaurateur who initiated Auckland’s “all you can eat” Bluff oyster lunches when the Viaduct’s Soul Bar was under her ownership, said she had not been made aware of any concerns about the Foveaux Strait fishery – nor had she noted any quality issues with the first-grade product her chef was sourcing.

“I rang Bluff, before the season, to talk about it … nobody told me there was a sustainability problem.”

Tabron said there was always a flurry to secure (and eat) Bluff oysters at the beginning of the season, “but I’m expecting it to taper off”.

First Mates, Last Laugh, her new seafood-centric venture, had last week sold around 100 dozen Bluff oysters. A “mixed dozen” featuring Bluffies and the farmed “Qyster” was also popular.

Meanwhile, restaurateur and chef Josh Emett, who operates Gilt and Onslow restaurants in central Auckland and The Oyster Inn on Waiheke Island, said he was taking “a really limited supply” of Bluff oysters this season.

“We might only take as much as five dozen per day. We’re selling 30 to 40 dozen of other oysters, easily, across the board.”

Te Kouma, Kaipara and Marlborough oysters were all popular, as was Waiheke’s Te Matuku (currently in hiatus), Emett said.

“There are still some amazing oysters out there. Maybe the Bluffies just need a breather.”