In enviable weather, on the south-east coast of Australia, a stainless steel punt glides over Merimbula Lake towards an oyster lease, with passionate young oyster farmer Dom at the helm. It’s a romantic picture of tranquil beauty and a life close to nature, attuned to the rhythm of the tides. But Dom’s father Chris, whose knowledge goes back forty years, swears the water’s getting warmer, storms more severe, and diseases more of a worry. Indeed, the oyster has been called the canary in the estuary, for the death of an oyster can reveal environmental changes or pollution that might have gone unnoticed.
Dom is the lake warden – he monitors the water and oysters for disease. His degree in Aquaculture hasn't prepared him for the shock when the samples he’s collected are dead. His parents reassure him that they and the oysters have weathered droughts, floods and tough times, but conditions are changing, and there's tension in paradise over what might happen in the lake if Dom and his wife and farming partner Pip move to growing a different species of oyster.
The only oyster it’s legal to harvest from the lake is the gourmet’s delight, the Sydney Rock Oyster, but it’s slow growing and vulnerable to pollution, changes in temperature and increasing diseases. In the oyster’s three year life, it has to be hauled out of the lake thirty-six times, put through the industrial grader and back out into the lake until it’s grown to a size that looks good on a plate. Dom and Pip know the care, frustration, sense of humour and hard physical work that it takes and they've got two lovable energetic young sons to bring up as well. Switching to the much faster growing non‑native Pacific Oyster looks very tempting indeed.
When Pip journeys to a giant food trade show in Guangzhou, China, she finds the smog’s too thick to see the sky, but she’s heard that people watch the sunrise on a screen, and wealthy customers pay big money for oysters whose image is purity, blue skies, clear air and vivid sunsets. Pip takes a Sydney Rock Oyster off the tray of crushed ice and shucks it with ease using a short knife that could impale the hand of a novice. An eager potential buyer forks the oyster to his mouth. There's a smile on Pip’s face. She knows her oysters taste of the lake back home and there’s nothing better. After all the hard work, passing out a plate of oysters feels like a celebration – even a tiny miracle.
Back on the lake, Dom and Pip are keen to go to China to secure a contract, but Chris worries they'll get too dependent on a fickle market overseas and lose the markets they've got at home. Their good friend and fellow farmer, known locally as Sponge, warns that the non-native Pacific Oyster spawn more, eat more and grow faster, and if Dom and Pip switch to farming them, they could take over the lake and starve out the Sydney Rock Oysters. These arguments are heated. Dom and Pip want to make the right decisions, but no-one can predict the flow-on effects for their livelihood, the lake or the oysters.