Monday (11/11/13) saw the South Coast get a welcome rain event. In particular Narooma received over 100mm which is the heaviest rain we have had since last April. The district was quite dry and oyster farmers like land based farmers need some rain but hopefully not excessive amounts which can cause flood damage.This amount is fine and let me explain why.
The feeding rate of oysters is water temperature dependent. In these southern waters ocean sea temperatures are rising as the East Australian Current pushes down along the coast from the north. Presently water temperatures are approximately 18 degrees and increasing. Combined with rainfall such as we have had nutrient levels increase in the estuaries and rivers encouraging natural microscopic algae and plankton to grow. When it is dry we don’t have so much nutrient input and these organisms are restricted in growth.
So with these conditions oysters and other wild shellfish increase their feeding rate and with the increased availability of food hopefully shellfish will flourish. This takes a few weeks to occur as we need good ocean water exchanges to take place to help promote this natural blooming of microorganisms. It looks promising for the coming festive season and oyster farmers in this region have been filling up their leases with stock for the coming summer and autumn sales.
At present sales are temporarily suspended due to this rainfall. Along with nutrients contaminants can be washed into rivers and estuaries where the oysters are grown. It takes a week or so for the oysters to flush these out and oyster farmers monitor the water and test the oysters to make sure they are safe for human consumption. All commercial oyster farmers by law have to harvest and sell there oysters under strict protocols laid down by the NSW Food Authority which complies with world standards. This has been in existence for many years and underpins the commercial viability of oyster farming.
This has been a very timely rain event and even though we are closed for commercial sales at the moment, the short term pain will have a much greater long term gain.