Oyster quality of concern as season nears

Photo: ODT files
Photo: ODT files
Signs are not good for a booming Bluff oyster season.

A pre-season stock assessment survey was recently completed by Barnes Wild Bluff Oysters, and though the results of the survey are several months from being available, anecdotal evidence points to the 2023 season being in the same boat as the last — what some called the worst oyster season in 26 years.

The season opens next Wednesday.

Barnes Wild Bluff Oysters manager Graeme Wright said while there was no doubt about warming water temperatures, he was unsure how that would affect the shellfish.

The situation in Fouveaux Strait was very similar to what was seen this time last year.

"The quality last year was really poor, but I think there’s a whole range of factors involved. It’s very much a cyclic fishery, and it’s happened before."

There were well-documented records dating back to about the 1950s, and there were years when oyster quality had been very poor, he said.

Graeme Wright
Graeme Wright
"Oysters are sedentary, they rely on plankton in the water, and for some reason there just didn’t seem to be the food availability.

"It’s been quite a different summer ... Southland has officially been in a drought, and environmentally the conditions are quite different. I think it’d be foolish to think that those are environmental changes or varying seasons don’t have an effect on the sea as well as they do on land."

Bluff Oyster Festival chairman John Edminston said it was hard to know how the season would play out until it began, but the weather was definitely a worry.

"With these heatwaves and bits and pieces and global warming that they’re talking about and, and all this, it’s got to be concerning. You’d be a fool to ignore it."

"The quality wasn’t very good last year ... But there’s lots of places that have been surveyed that seem to think that the quality is a lot better than last year. So we’ve just got to wait and see."

Earlier this month, MetService oceanographer Dr Joao de Souza said that while New Zealand waters had seen almost uninterrupted marine heatwaves for a couple of years, the warming had now reached new levels.

"Extreme marine heatwaves are just that — extreme.

"It’s the highest category in existence for marine heatwaves, reflecting how unusual this level of warming is, both in New Zealand and internationally."

Fiordland Marine Guardians chairwoman Rebecca McLeod said concerning accounts were coming in from around the country of widespread kelp die-offs, algae mats smothering reefs, sponges "melting" and signs of ill health in fish.

"The big unknown is how the marine life in coastal Fiordland will respond to these repeated heatwaves," she said.

"A few years ago no-one was talking about marine heatwaves — instead researchers were talking about the effects of climate change as possible sea-level rise and maybe ocean acidification."