In the 2018 Maryland Assembly general session I testified regarding SB 926. A law that, among other things, identified oyster shell as the preferred substance to be used to create oyster reefs. The supporters of the bill were on point and on message. According to the supporters, oyster shell is the best material for healthy oyster reefs. They had a good idea, that oyster reef criteria are necessary, unfortunately their choice of material is based on a persistent myth.
There is a myth that oyster shell is the best and only substrate for oyster reefs. There is no science to support this and in fact the opposite has been proven. Researchers from the US and around the world have studied reefs made of many different substrates. These researchers (and I was one of them) consistently find that these alternative substrates perform as well — and sometimes better — then reefs made from oyster shell.
This myth may have evolved from the findings that oyster larvae have a higher set rate shell than other substrates. Research has shown that oysters will set on almost anything hard. They set at a higher rate on oyster shell.
But this is just the first day of an oyster’s life. When we look at these reefs over time though oysters shell may start off with a higher number of oysters, these number equalize over time. The results of long term data show that reefs sampled 3, 5, and 15 years after being set show no difference between shell and other materials.
I know that debunking a myth is hard, but the science has proven that there is no difference between oyster shell and other materials when creating a healthy oyster reef. When dealing with the Chesapeake Bay we cannot go forward with what we believe, what we’ve always known, or what we hold dear. We must base our decision on what we can prove is in the best interest of the Bay.
More information on the research regarding alternate material can be found here .