Oregon’s Most Common Fish; Actually Three Different Species

By Anthony Harris

speckled_daceAn astonishing new discovery has surfaced regarding Oregon’s most common fish, the speckled dace. A recent study, to be published in the journal Molecular Phylogenetics and Evolution this week, by Oregon State University researchers revealed the speckled dace isn’t just one, but three distinctly different species. This small minnow is described as the “most common” because it can be found in more ponds, rivers, lakes, streams, and such than any other from Canada to Mexico.

However, not a whole lot is known about the speckled dace, specifically its genetic makeup, and according to OSU Department of Fisheries and Wildlife faculty research assistant Kendra Hoekzema, it’s never been fully investigated. The speckled dace in Foskett Spring is listed as a federally threatened subspecies, meaning they must be investigated every five years, which researchers reviewed. This type of dace was located in an individual spring inside Warner Valley in southeast Oregon.

Hoekzema collected speckled dace from nearby basins, Goose Lake, the Malheur River system, Silver Lake, Stinking Lake Spring, and others in the region. It was through DNA analysis that she and her fellow researcher and study co-author OSU assistant professor Brian Sidlauskas discovered there are three “highly divergent” evolutionary lineages of speckled dace that could be classified as separate species. The Malheur stream dace, Stinking Lake Spring dace, and the remaining dace from four other combined basins made up the new group.

The Stinking Lake Spring dace went its own way, genetically speaking, an estimated 2.5 million years ago, while the dace from Foskett Spring and possibly others remained isolated in the area 10,000 years ago, according to Hoekzema. The researchers would prefer to see the Foskett Spring dace be listed as an “Evolutionary Significant Unit” (ESU), not a subspecies, though this wouldn’t change the way it’s protected.

A biologist for the Oregon Department of Fish and Wildlife, Paul Scheerer has studied population status, trends, and habitat conditions of Foskett Spring since 2005. He and his colleagues are concerned that speckled dace populations have been in serious decline since 2009 due to a habitat change of open water vegetation to an emergent marsh. Reports indicate speckled dace have expanded to new pools and seen a huge rise in population to the tune of about 13,000 fish. The fear is this expansion may lead to catastrophic loss of dace species.

The results of OSU’s study suggests more dace species may be out there, because their geographic ranges are still unknown, especially after discovering three distinct species in isolated desert basins. Hoekzema and others believe more dace research will lead to improved ways to protect and preserve them.