From farm to your table, oysters offer a sustainable choice

Summer 2016

Kari Eckdahl is currently spending a year as a California Sea Grant Fellow working in NOAA Fisheries’ California Aquaculture Program Office. The California Sea Grant State Fellows Program matches highly qualified graduate students with host agencies in the state. She shares her observations in this column.

My time as a Sea Grant Fellow with NOAA Fisheries’ California Aquaculture Program Office has opened my eyes to the role that marine aquaculture can play in providing a healthy, sustainable source of food, and what NOAA Fisheries is doing to promote it.

You may have heard of “Farm to Table” in terms of vegetables, but there’s a similar concept in shellfish aquaculture. Oyster farms deliver fresh, healthy, protein-packed oysters to your table, and the popularity of their products is growing. The value of oyster production in Washington, Oregon and California has doubled in the last 15 years, hitting a record high of almost $63 million in 2014, the last year with data available.

That makes oysters one of the most valuable shellfish on the West Coast, important both to the economy and to the people who love to eat them.

man holding tiny oyster seed

Oyster farms receive tiny "seed" oysters from hatcheries. Photo courtesy Ed Anderson Photography

As part of my NOAA fellowship, I learned a lot that surprised me. Did you know that more than 95% of oysters consumed worldwide are farmed? That is a good thing when it comes to local oysters. NOAA Fisheries’ FishWatch rates oysters a smart seafood choice because they are sustainably farmed and harvested under U.S. and state regulations.

I saw this for myself during a tour of Hog Island Oyster Farm, owned and operated by John Finger and Terry Sawyer, in Tomales Bay in Northern California. They explained that farms usually get “seed” oysters from hatcheries when they are about 2 millimeters in size and then place them in a bay either in floating mesh bags or an apparatus called a FLUPSY (FLoating UPwelling SYstem).

A FLUPSY looks like a barge, and is up to about 100 feet long with walkways down the center and sides. Between the walkways a row of bins hangs down into the water and holds the oysters. A large paddlewheel at each end of the bins forces nutrient-rich water towards the oysters.

oyster farm seen from a distance with low tide in foreground

Oysters grow on racks at Hog Island Oyster Farm in Tomales Bay, California.

Once the oysters reach about ¼-inch in size, the farm moves them into larger cages or bags where they continue to grow. Depending on the species, an oyster can take one to three years to reach harvest size.

The tour showed me what makes oyster farming so sustainable. Oysters do not require feed or fresh water. Oysters are filter feeders so they eat the microscopic algae and nutrients already suspended in seawater. An oyster can filter up to 50 gallons of water in a day and actually help improve water quality of bays by filtering out excess nutrients and sediments.

Since oysters continually filter water within the bay, farmers are particularly concerned about water quality. Oysters cannot be harvested and sold from bays that contain harmful chemicals, bacteria, or phytoplankton species that cause Harmful Algal Blooms (HABs).

This is one area where NOAA Fisheries provides support for oyster farmers. For example, NOAA Fisheries scientists are developing an early warning system for HABs using an Environmental Sample Processor (ESP). An ESP, also called a “lab in a can,” can collect and analyze water samples in a bay in real-time. The ESP uses DNA technology to detect harmful algae and bacteria in the water. It can then relay the data to farmers via radio, satellite, or even their cell phone.

Scientists are hoping to couple the ESP with weather forecasts to provide farmers advance warning of red tides in the future. The idea is that with enough notice, farmers can pull their oysters out of the water before a bloom occurs, preventing a substantial economic loss.

As a fellow in the NOAA Fisheries Aquaculture Program located in the Sacramento office, I have a hand in helping guide shellfish farmers who are navigating the regulatory permitting process, and in providing them access to science resources such as the ESP.

The Hog Island tour ended fittingly with shucking and eating oysters while gazing out on Tomales Bay. Prior to starting this fellowship I had probably only eaten about a handful of oysters in my life. Since February, I have eaten dozens of oysters. It makes me feel good to know I am eating something healthy, sustainable, local, and delicious!