Effects of High Density Competitors to Early Life History Steelhead


Predation? Resource competition? Let's find out!

Summary

My second chapter is centered around investigating direct effects of the invasive rusty crayfish on a population of threatened steelhead using stable isotope analysis and other laboratory-based methods. In the summer of 2023, I led a field season in the South Fork of the John Day River which is home to a dwindling population of roughly 600 summer-run steelhead. State and tribal biologists currently lack the capacity to further investigate how the relatively recent invasion could be affecting the species of high concern. By reconstructing the aquatic food web and leveraging the unique isotopic signature held by Pacific salmon, I can understand critically important ecosystem dynamics like competition for resources and predation of steelhead eggs by crayfish. With this work, I hope to contribute to a knowledge gap regarding invasive crayfish species in Western waterways and open systems in particular.

Field Season

Dayville, OR - Over 5 weeks, my technicians and I got to know the South Fork of the John Day River in and out. Like any other ecologist, I am inexplicably fond of the natural world and subsequently love this part of research. Each day presented valuable challenges that allowed me to leverage my prior experiences in high-stress, uncontrollable scenarios. The multi-month stint rewarded me with incredibly valuable data - including habitat characteristics, fry distribution, crayfish density, community composition of macroinvertbrates, and tissue samples (periphyton, filamentous algae, steelhead fry (APPS #26934), crayfish, benthic macroinvertberates).

Summary Statistics:

  • 1 tick bite
  • 2 tires flattened
  • 4 rattlesnakes encountered
  • 30 sites surveyed
  • 394 steelhead fry counted
  • 3,888.3 meters snorkeled
  • Far too many rusty crayfish

field First day in the field (L-R: Dr. Julian Olden, Claire Vaage, Ben Culver, Spencer Kubo)

SciComm

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