Oysters versus Wilderness: what’s the “right” choice?

Being a nature-lover at heart, most of the time when I hear about a new National Park or designated wilderness area, I’m happy. However, I wasn’t so sure about the recent wilderness designation of California’s Drakes Estero (just north of San Francisco). The problem is not that it’s protected—I’m all for preserving wilderness areas for the purposes of species’ habitat protection, biodiversity, recreation, and just to make sure there’s no development in some of our beautiful natural areas— but rather that in designating it as official wilderness, it necessitated the shut-down of a historic oyster farm (open since 1932) that provides about 40% of California’s commercial oyster supply. The root of the problem, I believe, lies in how we define and view wilderness.

On Nov. 27^th 2012, Secretary of the Interior Ken Salazar gave Drakes Bay Oyster Company 90 days to shut down operations for good, since it lies within Point Reyes National Seashore, and is therefore in violation of the National Park’s mission and regulations. Drakes Bay Oyster Company has been producing commercially-sold oysters since 1932. They pride themselves on being a sustainably-run family business, a model of sustainable local farming. They use no artificial inputs, chemicals, or feed, and are ranked as a “best choice” on the Monterey Bay Seafood Watch list. This does not mean that there are no negative environmental impacts of oyster farming in Drakes Bay—all human activities and interactions with nature come with some associated cost-benefit trade-off. The question is, what is that balance? The United States Wilderness Act of 1964 defines wilderness as “an area where the earth and its community of life are untrammelled by man, where man himself is a visitor who does not remain”—this definition leaves little room for alternative uses of official wilderness. And therefore, when Salazar made the decision to officially turn Drakes Estero into a federally designated wilderness area, the oyster farm had to close.

Clem Miller
(or Bates from Downton Abbey?)

Point Reyes National Seashore was first established in 1962 by Clem Miller, a congressman from Marin County who envisioned an area protected from residential development, but that would keep the historic ranching and oyster farming as part of the multi-use park. (This was one of the reasons that it wasn’t originally designated as a National Park.) Being a scientist, I wanted to understand the science behind these decisions, and whether the environmental benefit of closing the oyster farm outweighed the benefit of maintaining a locally sustainable farm that employed about 30 people and provided almost half of California’s oysters. (And since I’ve only recently come round to realizing that oysters are in fact utterly delicious, it is even more sobering to think that there may be a serious shortage of them in the near future).

Anne and I enjoying the fruits of the sea in Seattle 

So, what are the negative environmental impacts of oyster farming? There have been limited scientific studies done on Drakes Estero and the impact of oyster production, but there are some (as well as many studies on oysters in other systems). One potential problem is increased nutrient load in the sediment as a by-product of filtration. Oysters are filter feeders, gathering particles of phytoplankton and nutrients from the water with their cilia. The problem is that all this particulate matter and nutrients is then transferred (i.e. excreted) into sediment, creating potential anoxic (low oxygen) conditions and smothering native eelgrass beds. However, studies in Drakes Estero have shown high flushing rates with the ocean, so excess/toxic sediment does not seem to be a problem. The presence of the oyster company could also negatively impact California harbor seal populations, which have their breeding grounds in the estuary (20% of CA harbor seal populations comes there to breed). The threat to seals is from human disturbance and the use of company motorboats rather than the oysters themselves—seals will react when humans come within 90 meters. However, this impact is not solely limited to the oyster company—hikers and kayakers could have a similar negative impact. And there are potential ways to mitigate these disturbance impacts, including the creation of large buffer zones or closing specific areas during breeding season (March-June).

California harbor seals

Oysters being transported in Drakes Estero

Colonial sea squirt (Didemnum)

One common complaint about the Drakes Bay Oyster Company is that it farms non-native oysters—the Pacific oyster from Japan (Crassostrea gigas). This species is now prevalent along the west coast, having been introduced in the early 1900s (for aquaculture purposes) after overfishing caused depletion of native Olympic oyster (Ostrea lurida) populations. Introducing one non-native species usually brings others—associated parasites and epibionts—and there is currently a large population of non-native colonial sea squirt (Didemnum vexillum) in Drakes Estero. As with any non-native species, the concern is that the population will reproduce on its own and expand, and may negatively impact (or out-compete) native species. This is a risk associated with the Pacific oyster itself, and the potentially expanding Didemnum population. However, it seems that at the moment, Didemnum is more of a nuisance than anything else, fouling marine equipment and, perhaps its biggest sin, being ugly.

As well as negative impacts, oysters offer significant benefits, both to the local ecosystem and economy. Oysters can increase water clarity by filtering up to 55 gallons of water a day—to put that in perspective, this is ~110 times what the average human drinks in a day, by an organism ~1/680 our size. In fact, many areas including the Chesapeake Bay are working on large projects to re-establish native oyster populations, both for economic and water quality benefits. One potential benefit of oyster aquaculture in Drakes Estero is that it could mimic the historical ecological benefits of the Olympic oyster (i.e. water filtration and creation of substrate habitat for fish and invertebrates). How well they might mimic the native oysters’ benefits depends on their relative abundance and biomass compared to historic populations of Olympic oysters (which is of course not well documented). But native oyster beds were likely integral to the original functioning of Drakes estuary, before they were destroyed by humans (an original alteration of the ecosystem). Which begs the questions… what is “wilderness”? What state exactly are we trying to restore? The “wilderness” of the early 1900s? Or some mythical wilderness of the 1500s that we can merely imagine (but that was managed, and altered, by Native Americans)?

Impressive historic native Olympic oyster reefs

So what is my final take on this issue? I’ve gone back and forth several times. The trade-offs, as I see it, are between deciding to preserve the land as wilderness, thereby prioritizing the value of nature and species protection, or trying to conserve the land while allowing multiple uses. Even full wilderness designation does not completely guarantee that animals will not be disturbed—the National Seashore gets over 2 million visitors a year, and the area relies on revenue from recreation. And there is the additional consideration of the economic benefits of the oyster farm, both in jobs and revenue. Without Drakes Bay Oyster Company, the Bay Area would have to import ~38,000 pounds more oysters each week in order to meet demand, which will in turn generate more carbon. Given all the trade-offs, minimizing the impact of the oyster farm through strict regulations, while allowing it to still provide important jobs and revenue for the region seems like it would be a good, and attainable, solution.

In the end, the decision about whether to close Drakes Bay Oyster Company is not a simple one. It’s a decision that has even divided avid environmentalists in the local community. It’s one of those decisions that should make us pause and re-examine what exactly we are trying to accomplish with designated wilderness areas. We need to protect natural areas for many reasons, but we also need to provide food and jobs for millions of people. And perhaps most importantly, if we want people to want to protect nature (a decision, I believe, that ultimately comes from the heart), then we need to live with nature.