By Alexa Martinez, MNWR Wildlife Biologist
When visitors are asked ‘what is the first species that comes to mind when you think of a refuge system?’ it’s not a shocker to hear birds, fish, mammals and reptile species. But sometimes what is forgot are the species no one pays attention too or are aware of, such as insects, micro invertebrates, mussels, and certain plant species. It’s our job as refuge staff, especially in the biology department, to be aware and understand what is going on in the ecosystem, including those that don’t have the spotlight.
Even though these underdogs are not always highlighted, doesn’t mean they are forgotten. Recently at Malheur National Wildlife Refuge, staff from Fish and Wildlife Service, Oregon Department of Fish and Wildlife, and Xerces Society connected together to help have a better understanding of a certain species…freshwater mussels. Particularly, Western Ridge mussels.
Malheur NWR is known to have all three native species of fresh water mussels: Western Ridge, Western Pearlshell, and floater spp. Mussel survey have been conducted in the past at Malheur NWR, but never consistently monitored. Our goal was to have an updated general understanding where mussel colonies were located, their conditions, numbers, and where different species were located. We predominantly tried to target Western Ridge since this species is being petitioned to become enlisted.
Snorkel and visual scoping surveys were conducted around 8-10 locations (mostly road crossings or dam sites) along the Blitzen River. The Blizen River was chosen since it had been surveyed in the early 2000’s (Al Smith), mid 2015 (Linda Beck and Al Smith) and again in 2018 (Emilie Blevins). Sections of the river are known to have the preferred habitat where mussels can be found as well as the adequate water flow. All three species (Western Ridged, Western Pearlshell and floater spp.) were observed throughout the surveys. We also found high densities of the western ridged mussel in many locations. Of the surveyed locations, five were identified to have high potential to be good long term monitoring site locations. This is super important for the refuge to know incase populations begin to deplete and staff can go back to these locations for future monitoring. Because, we found few historic records of floater shells being found in the lake, we decide to survey around the mouth of the Blitzen and a few potential lake site but did not locate any live mussels or shells.
Overall, we noticed most of our Western Ridge colonies were located within the Buena Vista Unit and near by the refuge headquarters area. While Western Pearlshell were found near the south end of the refuge in our P-Ranch Unit. Floaters were found sporadically throughout the Blitzen River but higher concentrations were noticed in the south end of the refuge. We hope with this information we can have an update our baseline data and increase our knowledge of how these colonies are doing in the future.