Monday, November 27, 2006

Look what the cat dredged up...

I can’t say that I’m sad to see this:

Researchers have concluded that Asian oysters are susceptible to a parasite that could wipe them out if they were ever planted in the Chesapeake Bay, raising new concerns about a proposal to use the foreign species to revive the region's struggling seafood industry.

The research found that Asian oysters experienced "almost total mortality" when exposed to the parasite Bonamia from the earliest stages of life, said Ryan Carnegie, a scientist at the Virginia Institute of Marine Science, where the study is being done.

Upon taking office four years ago, the Ehrlich administration said it planned to introduce Asian oysters into the bay to help filter the increasingly polluted water and to give struggling watermen a crop to harvest. Diseases and overharvesting have all but destroyed the native oyster populations in the bay.
Although the threat posed the parasite isn’t enough, on its own, to halt the potential introduction of the non-native oyster species, it certainly doesn’t brighten the prospects of this fool-hardy policy.

Because I’m talking about oysters on a local blog, perhaps a little background is in order. The short story of the last 150 years is this: Oysters were once so plentiful in the Chesapeake Bay that they could filter all its brackish water in a couple days and their reefs posed serious navigation hazards; then, a lot of people decided they really liked the taste of oysters, and watermen obliged, tonging and dredging them from the Bay bottom in tremendous quantities. Add two deadly diseases to the mix in the mid-20th century and you have a population of oysters – an essential, maybe even the essential, species in the bay – and an industry that are barely hanging on.

Enter Crassostrea ariakensis: A fast-growing, disease-resistant Asian oyster that can thrive in the Bay’s water. In short, a silver bullet, or so it seemed.

Though the idea of introducing non-native oysters to replenish the Bay’s supply has been around for a while (non-native oyster introduction has proved successful elsewhere, but may have played a role in the presence of the deadly-to-natives diseases we are dealing with today), it really gained steam when Governor Bob Ehrlich took office four years ago.

The Asian oyster was, wrongly, seen as a single solution to a problem with two parts: economy and ecology. It was assumed that the Asian oysters could provide filtering services to the Bay at the same time that struggling watermen could revive their businesses on the backs of the implanted bivalves. Unfortunately, as with all things that seem too good to be true, we’re now finding out it was.

By giving short shrift to the separate-but-connected ecological and economic problems posed by the decline in our native oyster population, we’re destined to develop a series of easy-to-swallow, but terribly ineffective and unsustainable “solutions.”

However, finding the right solution is not really what we need right now. To be sure, each day another waterman closes up shop, the Bay’s health declines, and the myriad other issues caused by these occurences continue toward intractability. But before we can hope for a solution, we must first fully understand the different problems.

Something to keep in mind as we address ecological problems in our own backyards with solutions that are decidedly and unanimously not sustainable. The superficial problem in our county described in the above links is, of course, that our lakes are filling with sediment, but the underlying cause of the problem – the real problem – is the excessive rain runoff sliding across impervious surfaces and scouring our slopes and streambeds. And in a sense, the lakes filling with runoff is actually a solution to another problem, the burying of submerged aquatic vegetation in the Bay.


Anonymous said...

I've never known so much about oysters. Thank you.

It all started when people decided to eat them.

Down with carnivores!

FreeMarket said...

I echo the sentiment against carnivores. I’d like to give a big thanks to the State Government for letting corporate externalizing machines loose in the Bay to kill all of the oysters. Thanks also for granting the fishermen a regulatory environment apparently free of any meaningful harvesting limits.

Anonymous said...

Freemarket, are you saying the shellfish industry is a selfish industry? That's a hard statement to make three times fast.

Page 105 of "Bay, Plain, and Piedmont" discusses the early demise of the Bay's thriving Oyster population

A few more tidbits:

1. The Corps of Engineers is required by law to operate the Conowingo's flood gates in a manner that doesn't restrict Susquehanna flow. If the Corps could instead reduce the reservoir level days ahead of impending serious downpours, the Conowingo could, with that additional capacity, avoid releasing huge amounts of sediment into the Bay during those events.

2. Centuries of erosion in the Lancaster Valley (think inefficient soil preservation do to no regulation/less advanced technology) have wound up in the Bay as silt. Also, a considerable amount of this silt (remaining as upstream streambed remnants from those hundreds of years of clearing and farm runoff) continues to wash downstream and fill the reservoir behind the Conowingo. At present rates, it will be completely full of silt in about 14 years. It's going to be a huge, lengthy, costly cleanup to deal with dozens and dozens of trainloads per day of dredged silt for years thereafter. Where will it be put? Who will pay?

(Closer to home, the U.S.'s former busiest port, HoCo's own Elkridge Landing, became unnavigable due to erosion from forest clearing to harvest timber to fire iron furnaces.)

3. The real problem you mention, excessive rain runoff scouring slopes and streambeds (these beds holding erosion from land clearing of three centuries and years past), can be reversed.

We can require even more onsite stormwater runoff mitigation for developments.

We can require green roofs and cisterns for new development.

We can require transportation system expansions that do not require construction of more impervious surface.

We can build better transportation systems that can allow us to retire then unused lanes on multilane roads, restoring those lands to greenspace.