Influence of fish competitors on Lake Trout trophic ecology in sub-arctic lakes

• Author / Creator

  Hulsman, Mark F.

• Competition for prey is known to narrow the trophic niche width of freshwater fishes. Upon release from interspecific competition, the niche variation hypothesis (NVH) predicts that population niche width will expand via increased inter-individual variation in resource use. I compared the trophic ecology, growth, and body condition of Lake Trout (Salvelinus namaycush) in sub-arctic lakes that varied in their competitive regime. Stable isotope analyses indicated that population trophic niche width and inter-individual variation were smaller in lakes with fewer competitors, a pattern inconsistent with the NVH. Further analyses revealed that these patterns were likely due to foraging shifts, as trout consumed primarily littoral resources in lakes with multiple competitors vs. primarily pelagic zooplankton in lakes with one competitor; growth did not differ between lake-types, but populations in the latter lakes were in better body condition. Findings highlight the potential sensitivity of northern Lake Trout populations to colonizing fish species.

• Subjects / Keywords

  • Lake Trout
  • Trophic ecology
  • Sub-arctic
  • Freshwater
  • Resource competition
  • Stable isotope analysis
  • Lake food web

• Graduation date

  Fall 2012

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/R3BB25

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.