In the late summer months immediately after obtaining my oyster garden, I spent most of my time mucking off sea squirts and struggling to make sure the cage had enough water flow. Luckily, as the weather got colder, the sea squirts have stopped growing so prolifically. In November and December, I was pleasantly surprised to see the oyster cage was almost the same as when I left it, relatively clean and sea squirt-free.
This year, we were asked to collect measurements on the oysters’ growth in three months: July (when I received my cage), December and April. You are supposed to check your cage once a month to make sure the rope is in good condition, but the data submission is optional outside of those mandatory months. So, I popped open the cage last weekend and began culling through the oysters for the first time since July.
Originally, we placed 300 oysters in the cage, 250 in the large compartment and 50 in the small compartment. The subset of 50 oysters is the set to be measured. Unfortunately, a good chunk of the oysters were clearly dead, gaping open with no oyster in sight (probably eaten long ago by sea worms). I felt a twinge of grief as I counted the dead ones–24 empty shells, nearly half of the original set. The oysters in the large compartment looked like they’d suffered about the same mortality rate.
I set aside the surviving oysters and measured each from bill to hinge. They were significantly larger than before, an average of 54.5 mm in length, compared to 41.5 mm in July. One oyster had grown into the corner of the cage and I couldn’t dislodge it, so I simply left it alone.
I’m not sure what the mortality rate for oysters normally is, but having half of them die in just 6 months seems pretty severe. Good thing I’m not dependent on oysters to make a living! Granted, the water conditions in NYC harbor are pretty challenging for oyster growth. We’ll have to compare the growth data with other locations around the city, and to see how many of the oysters survive until April.