Surging demand for seafood has led to the growth of farmed fish. In 2020, roughly 49 percent of seafood eaten worldwide was farmed rather than caught, up from 13 percent in 1990. Seabed monitoring is crucial to maintaining the health of captive animals, but such tracking may be time-consuming and labor-intensive. Now, advancements in environmental DNA analysis are simplifying the process in a way that American fish farms can adopt.
Scottish researchers are using environmental DNA analysis to monitor the ocean surrounding fish farms without using much equipment or manpower. Scotland is home to over 200 fish farms, and salmon is the dominant farmed species. Salmon producers are working with the Scottish Environment Protection Agency to test the use of environmental DNA to simplify the fish farming process going forward.
Fish farms (or aquaculture) are often found in marine environments, although they can also be established on land or in freshwater bodies. Some marine operations may contain fish in cage-like structures far offshore, but others use simple net pens in shallow waters. These marine farms can be found worldwide, and in the United States, they are concentrated in states like Mississippi, Washington, and California.
A marine fish farm operation means the farmed animals interact with ocean conditions and the underwater environment. Monitoring seabed conditions helps keep the surrounding environment from being impacted by farmed fish while maintaining the health of the captive animals. The Environmental Protection Agency mandates such monitoring for American fish farms. Monitoring methods include taking pictures and videos of the surrounding ocean and seabed, gathering samples to assess water quality, using echo sounders (a mechanism miming echolocation) to get a quick glimpse of the surrounding area, and other techniques.
Environmental DNA (eDNA) analysis is much more straightforward. Mimicking the DNA analysis techniques developed for crime scene forensics, scientists gather a sample of seawater or seabed sediment and run it through a machine. That one sample can signal which bacterial species are prevalent, and a model is then used to predict the health of the surrounding area based on the existing bacteria. Researchers take the info from the sample and use it to rate the area through the Infaunal Quality Index, a standard ecological benchmark.
“At the moment, we sample the seabed followed by sieving and sorting sediment to identify species, but it is a time-consuming, labor-intensive process that hasn’t been updated for 30 years or so,” explained Stephen Macintyre, head of the environment at Mowi Scotland, the United Kingdom’s largest salmon provider. “The DNA-based approach will enable us to understand our environmental performance much quicker, almost in real time, and take action where required to improve the environmental picture.”
This use of eDNA in Scottish fish farming is part of a six-year project. Once complete, the project results will be presented to area regulators for approval as a standard practice for seabed monitoring. The currently used processes will also be turned into an open-source toolkit for other fish farms, including those in American waters.
Using eDNA instead of traditional monitoring methods would be more efficient and likely save money. Scotland’s farmed fish industry spends approximately £1 million (U.S. $1.3 million) on seabed monitoring annually. While researchers involved with the project did not estimate how much money eDNA analysis would save, they noted that it is much more cost-effective than currently used monitoring methods. The United States has a much larger farmed fish industry than Scotland and could see significant savings if this approach is widely implemented.
Monitoring through eDNA would also be a win for animal welfare. While the global animal welfare community does not love fish farming, these operations are not going away soon. Thus, every effort should be made to provide humane conditions for farmed fish, mollusks, and other sea creatures. With the ability to provide nearly real-time results, eDNA analysis could allow fish farm operators to quickly make adjustments that impact the well-being of whichever species is contained in that area.
America’s fish farming industry contributes approximately $4 billion annually to our economy. Advancements in using eDNA for seabed monitoring could save the industry money, simplify fish farming operations, and improve conditions for the captive animals in American waters.
The views and opinions expressed are those of the author’s and do not necessarily reflect the official policy or position of C3.
