Cooperative Research Units
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Effects of water chemistry on lake trout embryos and fry


September 2015 - August 2019


Introductions of nonnative lake trout into lakes of the northwestern United States have often posed serious threats to native fish assemblages because lake trout are keystone predators that directly or indirectly affect all other sympatric fishes as well as other taxa. The illegal introduction of lake trout into Yellowstone Lake in Yellowstone National Park is the most highly publicized instance of this fishery resource issue. The native Yellowstone cutthroat trout of Yellowstone Lake are threatened with extirpation by the presence of this large piscivore. Currently, intensive gillnetting is the primary method of lake trout suppression used by fisheries managers in Yellowstone National Park. Although highly successful in capturing subadult and adult lake trout, Yellowstone cutthroat trout are frequently caught unintentionally as well. The development of alternative suppression methods to be used in concert with intensive gillnetting is highly desired by park managers. Suppression methods that target lake trout embryos and larvae in spawning substrates have not been investigated extensively. Targeting these immobile early life stages may become increasingly effective as larger, free-swimming lake trout become rarer and Yellowstone cutthroat trout bycatch in gill nets increases. Currently, experiments are underway at Yellowstone Lake to test the efficacy of electricity for killing lake trout embryos in situ and limited and somewhat inconclusive tests of the effects of high-intensity sound from seismic air guns on lake trout embryos were conducted at Priest Lake, Idaho. However, no controlled, laboratory or field experiments have been conducted to systematically evaluate the effects of a variety of candidate chemical and mechanical methods to induce mortality of lake trout embryos and to evaluate the influence of developmental stage on susceptibility; the ideal treatment would be easy to apply, safe to handle, have limited environmental persistence, and would not bioaccumulate. The objectives of this multi-year study are to conduct controlled laboratory and field experiments to systematically evaluate the effects of a variety of candidate chemical and mechanical methods (e.g., hydrogen sulfide, NaCl salinity, piscicides, silt, collagen film, calcium carbonate, and sound/physical pressure delivered by seismic air guns) on mortality of lake trout embryos and larvae and to evaluate the influence of developmental state on susceptibility.


Current Staff

Federal Staff: 101

Masters Students: 239

Phd Students: 154

Post Docs: 55

University Staff: 241

5 Year Summary

Students graduated: 695

Scientific Publications: 1962

Presentations: 4417



Funding Agencies

  • USDOI National Park Service


Cooperative Research Units Program Headquarters Cooperators

  1. U.S. Geological Survey