By Evan Harding of 
Willie Calder, skipper of Bluff oyster boat Argosy, says the 2023 season was the worst since he began dredging for the delicacy in Foveaux Strait in the mid-1970s. Photo: Stuff / Kavinda Herath
The quality of Bluff oysters in Foveaux Strait was "terrible" this season, with many oysters appearing to starve to death in the ocean, an experienced fisherman says.
The quota of 7.5 million oysters was reached about a week ago, with the season officially ending for the 10 oyster boats on 31 August.
Willie Calder, a Bluff oyster fisherman in Foveaux Strait for nearly 50 years, said the quality of oysters for the first month of the season in March was better than last season [which was a poor season]. But the quality from April onwards deteriorated.
"They were just as bad as last season, if not worse.
"Worst I have seen, and I have been doing it since 1975."
The catch rate was similar to last season, but a lot of oysters were starving to death, said Calder, skipper of oyster boat, Argosy.
"The oysters in the shell were probably only half as big as they should have been ... it wasn't a good season at all, quite terrible."
About 21 percent of the oysters his boat caught were second grade [small] oysters, whereas it was usually around 5 percent of the take.
Calder said in 1962 and a season early in the 1970s, thousands of oysters were dumped due to their poor quality. The 2022 and 2023 seasons were not quite as bad as those years, he said.
"They came right quick [in 1962 and about 1971], so hopefully history can repeat itself."
There was minimal phytoplankton [grass of the sea] in Foveaux Strait for the oysters to feed on during the 2023 season, he said.
Greg Mead, skipper of Bluff oyster boat Southern Enterprise says the Bluff oysters in Foveaux Strait looked hungry later in the 2023 season. Photo: Stuff / Kavinda Herath
Southland had experienced two summers of dry conditions and the oysters had been poor both years, with Calder saying they tended to thrive in years of heavy rainfall.
The past two seasons of poor quality oysters coincided with La Nina weather patterns, but an El Nino weather cycle was coming and the oysters were generally better quality in such cycles.
"Hopefully that fixes the problem, it's all in nature's hands."
Barnes Wild Bluff Oysters manager Graeme Wright said demand for Bluff oysters was relatively strong but the quality of oysters in 2023 "wasn't what we like" - though slightly better than the 2022 season.
"We had a lot more second grade oysters than what we normally would."
He confirmed there was a lack of phytoplankton in the water for the oysters to feed on.
"It's almost like they [oysters] are starving."
Wright said traditionally a good mutton bird season meant there would be a good Bluff oyster season. Mutton birds fed on small fish called krill, which in turn fed on phytoplankton.
"The last couple of years there's been no mutton birds around Foveaux Strait. If there's no mutton birds it means there's no krill which means no plankton ... there's some environmental things that are out of sequence at the moment."
He added it was a wild fishery that had cycles.
"Overall not a bad season, just the quality isn't where we like it."
There was a slight increase in the endemic strain of bonamia, an oyster killing disease, in Foveuax Strait this season, but it wasn't significant. "It's still very low percentages."
The fishery would continue to be monitored so stakeholders could try to understand what drove the changes, Wright added.
Greg Mead, skipper of Bluff oyster boat Southern Enterprise, said the oysters looked hungry in Foveaux Strait late this season.
"You have to keep eating to stay fat."
- This story was first published byStuff
