Assessing Responses of Fish to Habitat Enhancement in Barrenlands Streams, N.W.T., Canada

  • Author / Creator
    Cahill, Christopher L
  • The development of the Diavik diamond mine destroyed pristine lakes and streams in Barrenlands region of northern Canada. Subsequently, several fish habitat compensation projects were undertaken to offset these losses. The M-Lakes project was intended to enhance the productive capacity of a pristine headwater lake-stream system through improved stream channel connectivity among three small (<5 ha), isolated lakes and with the much larger (>57,000 ha) Lac de Gras. Three fishpasses (two gabion-style pool-weir and one nature-like choke-pool) were constructed to enhance inter-lake connectivity in the M-Lakes system. My objectives were to determine if (1) fish ≥ 150 mm were attracted to and passed through fishpasses, (2) fish use of fishpasses was comparable to reference streams before and after construction and to manipulated streams before construction, and to (3) identify environmental correlates to fish passage events when fishpasses allowed for fish movement. I used passive integrated transponder telemetry, and visual and electrofishing surveys to address my objectives for one year before (2011) and two years after fishpass construction (2012-2013). The gabion-style fishpasses limited fish movement and use, while the nature-like fishpass allowed for fish movement and use comparable to reference streams and the stream prior to manipulation. Few consistent correlates with hydraulic conditions and date were identified for passage events of Arctic Grayling (Thymallus arcticus) in the nature-like fishpass, relative to the conditions available. However, I observed strong diel periodicity in Arctic Grayling passage activity as most (95%; 137/144) passage events occurred during evening or early morning (18:00-5:59). My findings provide evidence against using gabion-style pool-weir fishpasses in low-gradient headwater Barrenlands streams, and demonstrate that nature-like fishpasses can be effective tools for enhancing connectivity in these systems. Additionally, this thesis documents the first case of clear diel periodicity in passage activity for Arctic Grayling, which may be a response to avian predation given the shallow depth of the fishpass.

  • Subjects / Keywords
  • Graduation date
    Fall 2014
  • Type of Item
  • Degree
    Master of Science
  • DOI
  • 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.