Why oysters are harder to find

Aussie favourite the rock oyster may be harder to find on menus due to a recent hit to supplies.

Severe rain events in northern NSW and South East Queensland have impact harvests across a range of major production rivers.

The main issue facing oyster farmers has been salinity levels, according to NSW Farmers Federation Oyster Committee chair Todd Graham, who also runs a farm on the Mid North Coast's Macleay River.

He explained that rainwater washing into estuaries raised freshwater levels beyond what some oystersxjmtzyw could survive.

“The biggest problem is the rivers go fresh for too long. Oysters need the salt water obviously,” Mr Graham said.

Farmers have seen high mortality levels in areas that experienced sustained heavy rainfall in recent weeks

While larger Sydney rock oysters can handle freshwater for about three to four weeks, back-to-back rain events have been devastating for many harvests.

Low salinity levels following heavy rainfall is more than some oysters can survive.
Low salinity levels following heavy rainfall is more than some oysters can survive. Credit: Supplied

“Just as the salt's coming back into estuaries, then we get another rain event. Basically the ground's so wet, nothing soaks into the ground, it just all goes straight into the estuaries,” Mr Graham said.

Mr Graham was lucky to be able to transfer three million of his juvenile for safe keeping at the National Marine Centre at Southern Cross University in Coffs Harbour.

However, with oysters taking two to three years to fully mature, the knock on effect of shortages may last several seasons.

Mr Graham is hopeful that with Sydney rock oysters being grown all over NSW, those areas lesser hit by recent can compensate for others while they recover.

“We've been affected a lot by the floods recently. Previous to that, fires hit farms down the southern part,” he explained.

“So they're recovering from the fires now and will be able to pick up the slack and then hopefully in the next few years we're all back into full production.”