Quantifying the ecological impacts of rainbow trout (Oncorhynchus mykiss) escapes

  • Ciara Louise Oonagh McGlade

Student thesis: Doctoral ThesisDoctor of Philosophy


Invasive species are a major threat to biodiversity, with introductions increasing globally at an accelerating rate. Freshwater environments have been identified as more vulnerable to invasive species compared to marine or terrestrial environments, and invasive fish species have been frequently implicated in freshwater ecosystem impacts, with species of the Salmonidae the most widely introduced. Rainbow trout (Oncorhynchus mykiss) ranks among the most widely introduced fishes worldwide due to an extensive history of introductions which continue to occur on a dramatic scale due to accidental escapes from aquaculture and deliberate releases for recreational fishing. Despite the continued high propagule pressure of rainbow trout into many European waters, establishment of reproducing, self-sustaining populations of rainbow trout is relatively rare, prompting research into the potential reasons for the limited establishment of this widespread species. Rainbow trout may also still have ecological impacts, even in early stages of invasion, and many impacts have been observed globally for established populations. This thesis outlines the utility of having a multifaceted approach to studying invasive species and their impacts. Through a combination of field-based, lab-based and a real-world case study I have explored a number of different factors which may limit rainbow trout invasion in Europe. Additionally, I have found evidence of impacts of these transient escapes on components of the native ecosystem including native salmonids, invertebrates and riparian predators.

Thesis is embargoed until 31 July 2024.

Date of AwardJul 2023
Original languageEnglish
Awarding Institution
  • Queen's University Belfast
SponsorsDepartment of Agriculture, Environment and Rural Affairs
SupervisorJaimie Thomas Allan Dick (Supervisor), Sarah Helyar (Supervisor) & Julia Sigwart (Supervisor)


  • Freshwater ecology
  • animal behaviour
  • rainbow trout
  • invasive species

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