Fall wild oyster survey: ‘It’s been a nutty year’
The DNR crew wasn’t expecting to finish this year’s survey until the end of November or early December, and the data haven’t been crunched yet. But Tarnowski said they haven’t seen an unusual number of dead oysters so far.
That’s something of a relief, because salinity levels were higher than normal in the Bay again this year, at least through midsummer in much of the Bay, which could have bred more disease. Even so, Tarnowski said, “Mortalities haven’t been extraordinary.”
On the other hand, higher salinity tends to boost oyster reproduction and that doesn’t seem to have occurred, either. Tarnowski said that the number of spat seen in the survey to that point “hasn’t been exceptional — it’s been average.”
“You’d expect to see a much better spat set,” he said.
But while salinity is necessary, he added, it’s clearly not enough by itself. The reproductive process of oysters remains something of a mystery. Despite decades of studies, scientists still don’t know all of the factors that determine how many oyster larvae are generated and how many, after swimming around in the water for two to three weeks, succeed in settling to the bottom and attaching themselves to a hard surface on which they can survive and grow.
“It’s been a nutty year,” suggested Mark Homer, veteran research statistician on the survey crew.
Oysters are apparently not seeing the improvement in the Bay noted in other areas.