It's been a bumpy opening for the new Bluff oyster season.

The wild oyster season runs from 1 March to August with the first boats harvesting in Foveaux Strait yesterday.

Invercargill-based Barnes Wild Bluff Oysters manager Graeme Wright said harvesters were battling large tides. With disease issues in recent years there are fewer oysters around.

He said Covid-related delays with couriers and struggling restaurants are also making them cautious about how the season will go.

Courier companies have warned customers of possible delays as they cope with staff off work with Covid-19.

"Couriering product around is difficult. Couriers are under pressure and you need to be very careful with a chilled perishable product," Wright said.

"We are feeling our way. We are expecting the food service trade to be well down.

"Normally it's really strong for live oysters, but everyone is being a bit ginger in their ordering. So most of it (oysters) will get mowed down today locally, but we'll try to get a bit away tomorrow, so yeah most probably [not until] Friday to

Auckland," he said.

However, Wright expected oyster numbers should be much higher in coming seasons.

He said during recent pre-season surveys the numbers were "honestly uncountable" - in fact, billions of them, he reckons.

"For the past three summers we've had lots and lots of recruitment (young oysters coming on) but for the 10 summers before that we had little to no recruitment coming in.

"They're funny little creatures and all the stars have to align for things to work for them. But certainly if we stay disease free and bonamia doesn't bite us on the bum, in two or three years oysters will be extremely plentiful I would

imagine."

It takes up to nine years for wild oysters to reach harvestable size.

Wright said in the meantime harvesters will continue to take about half their allowed catch.

The government quota is set at 14.95 million, but Wright expected the industry to perform similarly to last year where it harvested about half that number because that was sustainable.