American Mussel Harvesters
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How Old Are Those Oysters?

April 21, 2021

While shucking oysters a common question that I hear is, how old are those oysters? Fortunately, I can answer this question with some certainty because I am usually shucking our own Quonset, Beavertail or Umami oysters and have seen the oysters grow from seed to market.

The answer is 2-4 years for our farm site.

We usually get oyster “seed” in the late spring to plant on our farm site. This seed has been spawned over the winter and grown in a hatchery or nursery operation throughout the spring, so it is a bit larger than a penny by the time we receive it on our farm. When we get it, we put it into our own nursery system for the course of the summer to let it grow right at the surface of the water on the abundant phytoplankton that resides there. In the fall we will sort the seed out by size and the larger sizes will go into our grow out gear that sits six feet under the surface of the water, the smaller oysters go back into the nursery system to grow up a bit more.

So, by the time they are a year old the oysters range in size from the size of a penny (some just never like to grow!) up to 2 ½ inches. Keeping our oysters over the winter gives them a good chance to harden their shell, but growth is limited in the winter months for lack of food in the water. Once the spring rolls around and the oysters start feeding again the larger ones that have been in the grow out cages for the longest time will start to get big enough to cull through for market sized oysters. The strategy here is to take the fastest growers out when they reach market size and put the smaller ones back to continue their growth without competition from their big friends. 

By the middle to end of the second summer growing season we can start to pull market sized oysters out of the grow out cages and start to grade out of the nursery system and into the grow out cages from the smaller seed. Hopefully by the end of the second growing season most of the nursery sized seed will have graduated to grow out cages, and hopefully many of them are approaching market size.

This is an abbreviated version of our growth cycle. There are many intermittent steps that go unnoticed to fine tune the oysters. However, to answer the question How old are your oysters? I can say with confidence because I planted them and harvested them that they are 2-4 years old depending on how fast they grew, and when we decide to harvest them.

As soon as I start shucking oysters from other farms my answer gets more generalized because I do not like to speak falsely. Age of market sized oysters vary with each farms’ processes and environmental conditions. Warmer climates have longer growing seasons therefore possibly younger or larger market oysters. Colder climates as you can imagine go in the other direction. Nevertheless, often 2-4 years is a good guess as to how old a market sized oyster is.