Ecological Responses to Fish Reclamation Treatments

Science Center Objects

Piscicides have been used in Rocky Mountain stream and lakes to restore native fish populations. In the last two decades concerns over piscicide effects to non-target organisms, primarily aquatic invertebrates, has increased. Although piscicides have been used for more than 70 years the impact to invertebrate assemblages has not been well studied and is largely unknown. Given the importance a restoring native fish assemblages to State and Federal management agencies it is imperative to definitively evaluate impacts of these actions of all aquatic biota.

Designing and implementing a robust scientific study to explore the effects of piscicides on aquatic invertebrates will provide a framework to evaluate alternative actions. We propose a multi-phased research approach to describe the anticipated and actual effects of piscicides to invertebrate communities in Rocky Mountain lakes and streams. To accomplish these goals a combination of field, laboratory and modeling approaches will be used. 

Image: Cutthroat Trout
Cutthroat trout. Public domain.

Collect aquatic invertebrate samples pre- and post-treatment of piscide. Compare invertebrates present and community structure through time with pre-treatment assemblages to determine when invertebrate assemblage trajectories have stabilized and/or have recovered to within the natural range of variation as compared with the pre-treatment assemblages. This will be accomplished by collecting aquatic invertebrate samples at regular intervals pre- and post-treatment and examining existing data at legacy treatment sites. The deliverable will be a final report detailing piscide effects to invertebrates and the recovery of invertebrates in comparison to the pre-treatment invertebrates and when “recovery” of various metrics takes place. Invertebrates will generally be identified to genus and metrics such as total abundance, taxa richness, community composition and genera occurrence analyzed.  Sampling will include:

1. In years when surveys take place there will be two seasonal sampling periods annually (late spring/early summer and early fall).

2. Sampling at four areas including paired lakes (treatment and control) and paired streams (treatment and control).

  • Stream sampling will include collection of samples at five sites (using a Surber sampler).
  • Lake sampling will include collection of 10 samples (three benthic Eckman grabs, three zooplankton net tows and four littoral area samples).

Return to Aquatic Ecology and Contaminants or Aquatic Systems