Since the sixties of the last century, the technology of detecting and catching fish by means of a method known as electrofishing has spread. It is used to survey the distribution of fish in seas and rivers, and then to catch them.
This technique relies on causing a severe electric shock to the fish, so they move randomly until they fall into the nets or suffer a stroke and float on the surface of the water. Due to the environmental dangers of fishing by means of electrocution, many countries have banned its use in hunting and hunting for aquatic organisms.
But recently, a scientific study was released that includes developing an environmentally friendly method for marine and aquatic life, by researchers from Oregon State University, and published by the Journal of the American Environmental Association (The Ecological Society of America (ESA)) in its January 20 issue.
The idea is based on trapping using environmental DNA, as the research team found that using environmental DNA from certain types of fish that are collected from seawater, could be more accurate and safer than fishing using electrocution.
Quantitative and qualitative monitoring
Environmental DNA (eDNA) is the DNA that an organism leaves behind as it moves through the environment in general, which is collected from a variety of environmental samples such as soil, seawater, ice, or even air, rather than taking samples. Directly from an individual object.
The DNA is obtained in the environment surrounding the organism through the interaction of various organisms with the environment, to expel the DNA and accumulate in the surrounding areas.
This method is followed in the waters of seas and rivers by taking a small sample from the water, and through environmental DNA analysis, the presence and abundance of the types of living organisms can be determined through the remains of separate skin, bodily fluids, or excretions that organisms such as fish, insects and other organisms leave behind. This enables the fishermen to know the presence of fish up to a distance of one kilometer from the surface of the water, and from the place where the water sample was taken.
Environmental DNA analysis also reveals endangered animals or organisms, and identifies non-indigenous species in the area, which are those that can cause damage to the ecosystem.
The best way
According to the Oregon State University press release, environmental DNA samples have been used and analyzed for more than a decade, but they have not yet been widely used in industry, water resource management, or trapping, as their use has been limited to collecting water samples at sites. And laboratory tests to check for the presence of DNA of certain types of fish, which the fish regularly release through their secretions and changes in their skin or mucus.
But the applied research study of the university team revealed the advantage of using DNA over the use of electrocution in knowing the quantity and quality of aquatic life and catching them, after conducting a comparative study between scanning by DNA and electrocution, where the university’s scientific team tested the effectiveness of environmental DNA in finding At a point (the last fish) in the water, which is the most distant source fish.
According to the statement, researchers searched for coastal trout as it is the most common fish, which is the highest in riverbeds on the western side of the Pacific Northwest.
To conduct this practical test, the researchers selected 60 coastal streams in Oregon and Washington states, took samples of RNA from the top of the river’s source, and then used electro-fishing every 50 meters to 250 meters above the source of the last point (last fish) recorded for each stream. .
More fish, a safer way
After this test, the researchers found that in streams where electric fishing had not detected trout, environmental DNA samples showed 40% of their presence.
The university statement adds that the RNA revealed fish higher upstream in 31 streams, compared to electric fishing. According to the study, discovering the advantage of using environmental DNA is a discovery that is less troublesome to fish and harmful than electric fishing.
In this regard, Brooke Piñalona, a researcher in the Department of Fisheries and Wildlife at Ohio State University, says that the use of environmental DNA will revolutionize methods and methods of fishing, adding, “by taking a sample of seawater, for example, and using genetic or genetic tools, it can be identified.” The type of fish found in that watery area, and a comprehensive survey of fish in that area can also be conducted.