The lake and reservoir research laboratory and its staff at the Colorado Parks and Wildlife are devoted to understanding and improving fisheries throughout the state. Our focus is on food web structure and how different species assemblages, lake and reservoir characteristics, prey bases and management strategies affect the numbers, growth and condition of sport fish.
We use a combination of new and long-standing techniques to address issues facing sport fisheries in Colorado. For example, we use otoliths (calcified structures in a fish’s inner ear) that grow like tree rings to verify the age of sport fish and how fast they grow in a variety of reservoirs, under a variety of conditions. This information can aid in determining appropriate stocking densities and management actions to maximize the productivity of a given lake or reservoir. We use stable isotope analyses (a technique where we test fish tissue to determine their diet) to evaluate what prey sources are supporting sport fish and producing the highest growth rates and best conditioned fish. We use hydroacoustic/SONAR (2011 SONAR Survey report 
4MB), netting, electrofishing and trapping techniques to quantify sport fish and prey fish populations to help understand predator-prey interactions and how they influence sport fish densities through time.
The data collected with the techniques described above are provided to Colorado Parks and Wildlife biologists so they can make informed management decisions based on the most current scientific information available. The lake and reservoir research laboratory staff also uses a variety of modeling and statistical techniques to interpret the meaning of the data collected. For example, bioenergetics models (a method that uses laboratory-derived fish physiology characteristics to determine consumption based on observed growth rates) are used to provide insight into the mechanisms driving interactions between sport fish and their prey.
One of the most important goals of the lake and reservoir research laboratory is to provide information that aids in addressing fisheries problems facing Colorado’s lakes and reservoirs. We are investigating issues including but not limited to:
- the effects of introduced predators (e.g., walleye, northern pike, smallmouth bass and lake trout) on native species and other prey and sport fish
- kokanee spawning and egg production
- sport and prey fish stocking success
- mercury bioaccumulation in sport fish
- the impacts of nutrient fluxes on lake and reservoir fish communities
- sucker and trout interactions
- control of harmful nonnative species
- developing management plans best suited for individual lakes and reservoirs.
By conducting targeted research using a variety of techniques, we hope to address these and other issues to maintain and potentially improve Colorado fisheries and angling opportunities.
Personnel: Jesse M. Lepak, Ph.D.
Aquatic Researcher IV
Lake and reservoir researcher
Jesse.Lepak@state.co.us