Scientists from the United States Forest Service and Oregon University recently proved that DNA from samples taken from Northern California and Oregon is useful for estimating genetic diversities of Pacific trout and salmon.
These findings bear significant implications for management and conservation of the species, which human activities and climate change severely threaten.
According to Kevin Weitemier, postdoctoral fellow from Oregon, this is a dearth of such data in the Northwest. So the newly found data would allow scientists access to understand multiple species and populations at once
eDNA offers scientists an opportunity to test whether an organism is present or absent in a given environment, be it water or soil. It is a cost effective, safe and rapid way to alleviate scientists’ need to capture organisms to get their DNA.
The research undertaken by USDA Forest research team and Oregon State is unique because it used samples of eDNA in determining genetic diversities as well as presence and absence of four particular species: chinook salmon, coho salmon, rainbow trout and coastal cutthroat trout. This same team had once developed various techniques that helped to capture the huge sets of genetic sequences over large landscapes.
According to Weitemier, it is important to understand the genetic diversities of species in order to sustain the integrity of their population. He suggests that creating a diverse environment can help them thrive on their own.
He also affirms that it’s essential because their genetic diversities are affected by declines in population and salmonids (hatchery-raised) that are deposited into rivers.
In most of the investigated watersheds, chinook, coho salmon and steelhead have gone through major declines, which makes them of the threatened species. This is unlike the coastal cutthroat that have declined at a less broader rate.
Water samples were collected from 16 sites in Northwestern California and western Oregon in 2017. About five creeks in the following selected watersheds were sampled: Rogue, Deschutes, Williamette, Umpqua and Klamath. Three creeks feeding rivers around the Oregon Coast were also sampled.
They discovered genetic similarities in Klamath watershed and Deschutes watershed located in the south and north respectively. This is the first ever generic corroboration of past hydrological connection once hypothesized between both watersheds, though now disconnected.
There was unprecedentedly high genetic diversity levels in coho salmon despite the fact that the species was only present in the following rivers, the Nestucca, Klamath and Coquille, which were sampled.
They displayed the varying importance of rivers smaller to the sampled ones in terms of diversity, especially coastal cutthroat trouts. These samples analysed were from creeks feeding off the Alsea, Nestucca and Coquille.
Also, the researchers found more evidence of a unique diversity of Umpqua. The cutthroat trout as well as rainbow trout though in smaller quantities genetic variants were found. The Umpqua houses smaller fishes: the Umpqua pikeminnow and the Umpqua chub.
The researchers have plans to continue the research, while working with samples of water the USDA monitoring program has collected.