Pacific Shellfish Institute works with Alaska shellfish growers to address emergency rainfall closures

Many Alaskan shellfish farms are located far from population centers in pristine coastal waters. In June of 2016, Alaska Department of Environmental Conservation (ADEC) implemented a blanket emergency closure policy for remote shellfish growing areas any time two or more inches of rain falls within a 24-hour period. It rains quite often in Southeast Alaska, and the 2016 policy caused the extended closure of three remote shellfish growing areas in southeast Alaska, including Rocky Bay Oysters owned by John Kiser.

Oyster farming equipment in water at low tide.
Rocky Bay Oyster rafts and farm equipment at low tide. Photo taken from Mosman Island by Bobbi Hudson, August 2019.

These closures can result in thousands of dollars of lost revenue. Recognizing that frequent or extended closures could significantly hamper efficient shellfish production, Bobbi Hudson, Director of the Pacific Shellfish Institute, started working with Kiser at Rocky Bay Oysters in 2017 on a Sea Grant funded project to better understand how rainfall is affecting water quality and closure criteria.

Hudson and Kiser started collecting water samples at multiple sites near his farm to generate water quality data following a heavy rainfall. So far, Hudson and Kiser’s research has detected low water quality on the first day following a heavy rainfall. Water quality is better at the four-foot depth–where oysters are grown–than it is on the surface. Water quality at the surface substantially improved in the days succeeding a rainfall event.

man stands on wooden raft and lowers a rope into the water
Biologist Andy Suhrbier lowers a sampler to profile water conditions at the Rocky Bay Oyster farm site at Etolin Island in August 2019. Photo by Bobbi Hudson.

While this project was underway, the value of this research was underscored when Rocky Bay Oysters was closed again for two months in September and October of 2020. This closure was instituted by ADEC during a period of heavy rains. Although Rocky Bay Oysters survived the disruption, not every farm can survive a two-month closure.

Researchers plan to continue water sampling to build adequate data to understand water quality at Rocky Bay Oysters. They will also expand sampling to sites around Prince of Wales Island. This information is needed so that managers can refine decisions about farm closure timing and duration, and farmers can better plan growing and harvest activities to maximize product safety as well as ensure operational efficiency and profitability.

With increasing rainfall events linked to climate change, partnerships among farmers, researchers, and managers are more important than ever. This research may be able to prevent emergency closures after heavy rainfall events and inform more refined solutions that work for both the management agency and shellfish farmers. This work can help ensure a successful future for shellfish farming in Alaska.

Jesse Gordon and Anne Gore contributed to this story.