April 29, 2013
Although it’s relatively small for the moment, the Maryland portion of the Chesapeake Bay is about to experience a huge increase in oyster aquaculture. I had the opportunity to attend the University of Maryland’s Shellfish Aquaculture Conference this month. The conference had more than 150 attendees consisting of a few researchers and government officials, but more importantly a large majority were current owners of aquaculture leases or interested lessors. The conference included talks from current successful aquaculture operators and organizers as well as information about how to start an oyster aquaculture site in Maryland and how best to advertise to wholesale retailers and individual buyers. I was thoroughly convinced after attending this conference that the industry will be growing very soon.
Aquaculture, or fish farming, is rapidly becoming how most humans across the globe access seafood. For many, aquaculture has become a concern because of its potential for economic and environmental degradation, especially in developing countries. Aquaculture sites that raise finfish such as salmon in open water net pens are often considered analogous to concentrated animal feeding operations (CAFOs); both create similar environmental concerns, which include delivering high volumes of feed to the farming site as well as releasing an excess of animal waste. Different from on-land feeding operations is that the waste in open water aquaculture cannot be collected and composted and so disperses out of the farming site much more easily. This can significantly increase the occurrence of algal blooms, sometimes known as red tides, which is a major problem in coastal regions where aquaculture is most often performed. Such algal blooms can seriously damage the surrounding environment by lowering the amount of available oxygen and can sometimes cause die-offs at the aquaculture site itself.
It is important however to distinguish shellfish aquaculture from finfish aquaculture. Shellfish aquaculture does not carry the same threat of generating more concentrated animal waste, and is arguably beneficial for environments oversaturated with nutrients. Oysters, clams, scallops, and mussels are all bivalve mollusks that are well known for their filter-feeding properties. These species will take up most particulate matter in the water, including excess nitrogen and phosphorus.
As we look to Maryland and the Chesapeake Bay, growing oysters at high-density may not be at all unusual. The Bay was once densely covered with oyster reefs that were natural filters for the bay, able to filter all the water in the bay in a few days. The bay is thought to now only have 1 percent of the oyster population it once maintained, and is unarguably filled with excess nutrients. The case for oyster aquaculture in Maryland is therefore two-fold: provide a healthy source of protein and omega-3 fatty acids to a national population that is demanding more seafood, and at the same time help restore the Chesapeake Bay to a more balanced ecological state. The Chesapeake is ripe for the aquaculture industry seeing as the bay is one of the largest estuaries in the world and there are plenty of unused or un-leased waters in the bay. Virginia has already jumped on the shellfish aquaculture bandwagon and has been quite successful so far. Not to be outdone by their neighbor state, the leaders of the conference made it very clear that, “Maryland oyster aquaculture is open for business!”
While oyster aquaculture seems to be a win-all situation, it is important to step back and first consider the potential issues that surround shellfish production in the Chesapeake Bay. The bay is not what it used to be, and there are many more complex water pollution concerns than there were 100 years ago. Beyond the increase in human wastewater, there are now contaminants of emerging concern, which include pharmaceuticals, personal care products, and antibiotic-resistant bacteria. The last contaminant is of particular concern, as antibiotics used in CAFOs are often finding their way into animal waste. This waste is often left untreated, and can become runoff pollution in many of the bay’s tributaries in the Delmarva region.
Oysters are expected to help restore the bay’s oxygen levels by taking up the excess nitrogen and phosphorus, which comes from livestock and dairy farms in Pennsylvania and the Delmarva region. However these filter-feeders may also take up all the other water pollutants already mentioned, many of which may not harm the animal itself or be visibly noticeable to the harvester, but are harmful to humans and can cause acute and chronic illness if consumed. Concern over shellfish contamination has always been present and the FDA has worked hard to set strict regulations concerning the food safety of oysters and other shellfish. However testing is never perfect, and predicting how oysters will uptake such pollutants coming from an increasingly dense population should be of primary concern as the shellfish aquaculture industry continues to grow.