Question on Oysters

[Slayer]

http://www.somd.com/news/headlines/2010/11865.shtml

Read this article on Southern Maryland news (www.somd.com) and found it interesting. I got a question for someone who may know about Oysters:

In the article, it states that the $20k will buy 2 million Oyster spats. To me, it seems like a good investment as longs as they are protected from harvesting for a long duration of time. However, in the overall "big bucket", how much is 2 million? If they can successfully spawn and be protected, what are some good estimates on what this population will be in 2 yrs, 5 yrs?

Thanks.

Keith

[crabby and son]

It's about the same as a striped bass with several million eggs. Not many will make it 2 years.............Gary

[JohnnyOysterSeed]

Originally Posted by Slayer

http://www.somd.com/news/headlines/2010/11865.shtml

Read this article on Southern Maryland news (www.somd.com) and found it interesting. I got a question for someone who may know about Oysters:

In the article, it states that the $20k will buy 2 million Oyster spats. To me, it seems like a good investment as longs as they are protected from harvesting for a long duration of time. However, in the overall "big bucket", how much is 2 million? If they can successfully spawn and be protected, what are some good estimates on what this population will be in 2 yrs, 5 yrs?

Thanks.

Keith

For this particular methodology of seeding (planting *very* young spat, only 1 or 2 weeks of age - the diameter of a BB), mortality can be pretty high initially - maybe 50% in the first couple months. But as they grow bigger, they become stronger animals - more resistant to various predators (e.g. crabs) - and the instantaneous mortality rate continues to decline as they grow larger. Typically, survivorship to 2 years might be something like 15-25% of the original spat count, and maybe 10-20% to 3 years. So, for the original planting of 2M spat, something like 300K might survive to become adult oysters.

To be clear, survivorship and productivity in *cultured* oysters is much higher than wild oysters. Kinda similar to wild apples vs. orchard apples - take care of them, and they do much better, grow much larger. Cultured oysters will often have 90% survivorship to 3 years (depending on the method of culture, i.e. how much work/care goes into the oysters).

But beyond 2-3 years of age, the diseases Dermo and/or MSX can become a problem... however, the prevalence of the diseases are quite variable (geography and weather patterns greatly influence disease outbreaks and/or intensity). Depending on the body of water, and the weather/climate (drought years, wet years, hot year, cool year) some of the oysters might succumb to disease as young as age 3, or some might live to 10. Charles County waters are all low salinity (assists the oysters in combating disease: good for oyster longevity), so I'd expect that oysters planted here would have a very good chance of living to 5 years or better.

But salinity itself is a bit of a Catch-22: low salinity is good for oyster longevity, but it's bad for oyster reproduction. Conversely, high salinity is good for oyster reproduction, but bad for longevity.

So making predictions about a particular oyster population is kinda like predicting the weather: generally, the weatherman is pretty accurate with the forecast for today, a little bit less so for tomorrow, halfway decent for day 3 , spotty at 4 days, and just pulling the forecast outta his ass for anything beyond that. With oyster plantings, we can be pretty good at predicting survivorship for this year and into next, OK into the 3rd year, and increasingly shaky beyond that.

And if anyone wants to buy oyster spat, lemme know... Even 2 million (the figure from the article) is doable if you're so inclined.

[Slayer]

Thanks for the explanation JohnnyOysterSeed. Still sounds like a good program for the limited investment the county is making. Wish they had more to put in.