But just the fact that they have to plant the oysters should tell you something, they aren't growing without (As Crabby and son put it) "Humans managing the natural resources" If the oysters in the severn are doing as great as you claim, why do they need to plant them?
When was the last big commercial harvest in the severn? (I really don't know, but its probally been a long time) you would think they would be able to rebuild by now without planting, it must not be as simple as just leaving them alone.
Also, is Dermo or mx not a problem in the Severn? no oysters are dying?
What helps oysters in the Severn is also what necessitates man's intervention. The lower salinity keeps disease down, but also keeps reproduction way down. The historical oyster bars in the Severn developed over many thousands of years, with maybe one year in twenty being good enough to result in significant reproduction. So, unless we want to wait a few thousand more years, man must intervene to speed up the process. A few decades of no commercial involvement won't do it. The same is probably true north of the Bay Bridge. Below that, however, oysters can (and do) more rapidly reproduce. Salinity is higher, but as the Pax oysters show (the Pax oysters are in an environment that should be just as saline as the mid-Bay), disease may take some oysters but enough survive to carry on.
Even in very saline environments, if the oysters are left alone (Lynnhaven Inlet), enough will survive, then pass along their good genes, to eventually mount a recovery.
So, I think everyone here is correct to some degree. Some species, in some areas, will thrive again if simply given a break ( e.g., Redfish…or Bald Eagles). Others need a hand. Of course, giving things a hand costs money, so we ought to choose carefully where that money goes. Based on what I know (which admittedly is far less than many here), I'd say that oysters ought to be the focus of most of our species restoration. The ability of filter feeding bivalves to clean the water is awesome -- and well documented. We can create huge areas of oyster beds for a fraction of the cost of other pollution control initiatives (most of which are so eye-wateringly expensive that they'll never be done). We just need to get a number of well-intentioned folks on the same page.
Unfortunately, here's an example of why that's so hard. The Severn recently became eligible for at least a few million in federal funds. That money would allow the re-creation of the majority of oyster reefs that existed in the Severn at the beginning of the 20th century. Some estimates put that amount of oysters, assuming that the survival rate is within the normal range, at a level on par with the temporary zebra mussel spike of '04, which had a very significant impact on water clarity. Instead, that money is being split dozens of ways, none of it towards oyster restoration, assuming any goes to the Severn at all since various groups are now fighting over it. Spread across rain barrels, rooftop gardens for a few restaurants and a couple landscaping projects, the Severn will probably see no noticeable benefit.
