By Marcus Gay, NM WRRI Student Program Coordinator
The Pecos River in New Mexico is home to pelagic-spawning minnows. These minnows are called pelagic-spawning because they release eggs directly into the water column. As the eggs are released and fertilized, they drift downstream. These fish rely on water temperature and stream flow as environmental cues to initiate spawning; however, dam construction has fragmented the Pecos River and it no longer resembles the historical environmental conditions in which these fish evolved. The effects of unnaturally timed reservoir discharge may interrupt the continuous flow required for pelagic-spawning minnows.
Richard Raymondi, a graduate student at Eastern New Mexico University (ENMU), has been awarded an NM WRRI Student Water Research Grant to test his hypothesis that sustained high flows will negatively affect egg and larval survival for the pelagic-spawning minnow on the Pecos River.
Under the guidance of his faculty advisor Dr. Jesse Filbrun, Raymondi’s project will use a 1,500 gallon stream tank to mimic velocities observed during high-flow reservoir releases and determine if the timing and magnitude of reservoir release is detrimental to eggs and larvae of pelagic-spawning minnows. Plains Minnow specimens have already been collected from the Pecos River and transported back to the Behavior Ecology Lab at ENMU for observation under captivity and to complete spawning tests. The minnows will be fed, separated, and injected with a commercial spawning agent. After spawning occurs in designated aquaria, eggs will be collected using a sieve, counted, and measured. To test the effects of discharge on egg survival, three stream simulation treatments will be conducted in the stream tank using the fertilized eggs. Stream flows for each treatment will be set to mimic a range of flows, replicating velocities directly measured from U.S. Geological Survey gage stations in the Pecos River. Lastly, survival and growth rates in the stream tank experiment will be compared among flow treatments.
The project entitled, Investigating the effects of flow on growth and survival of larval pelagic-spawning minnows of the Pecos River, NM, was presented at the Southern Division-American Fisheries Society meeting in February 2020, and according to Raymondi, will help provide insight to natural resource managers about the potential impacts of reservoir releases on native fish in the Pecos River. As Raymondi explains, “This study will provide natural resource managers information to implement policies that will mitigate potential impacts of management decisions. Water management decisions in New Mexico are inherently complex and should account for the ecological consequences on native fishes. Implementing sound water management strategies benefit all forms of life in New Mexico.”
Originally from Boise, Idaho, Raymondi received his undergraduate degree from Boise State University and plans on graduating with a Master of Science in Biology from ENMU in 2021. After graduation, his goal is to be involved in conservation biology as a fisheries biologist. In Raymondi’s words, “Riverine systems of the Southwest United States are home to some of the most diverse ichthyofauna around, and so I would like to build a career that deepens our understanding of the unique wildlife found here.”