Dr. Brett Johnson's Fisheries Ecology Lab at CSU

Food Web Dynamics in Colorado's Coldwater Reservoirs


INTRODUCTION

Colorado's large coldwater reservoirs have supported some of the finest kokanee and mackinaw fisheries anywhere. However, keeping a sustainable balance between these two sport fish has been a challenge. At Lake Granby, the home of the state record mackinaw for years, the kokanee population crashed and the big macks got skinny. The Granby kokanee population was restarted with eggs from Blue Mesa Reservoir, but now Blue Mesa's kokanee population has declined to dangerously low levels. A crash of Blue Mesa's kokanee population, the state's largest egg source, could spell disaster for the entire state's kokanee fishery, and could even lead to the end of kokanee fishing in Colorado.

CSU's FIsheries Ecology Lab has collaborated with CDOW for over 15 years seeking to unravel the complex factors driving dynamics of fisheries and food webs in Colorado's coldwater reservoirs. The interplay between fisheries management (fish stocking, harvest regulations), water management (dam operations, water level fluctuation) and climate (precipitation, inflow and temperature) provide a fascinating backdrop within which we try to understand why fish populations, and the fisheries they support, vary the way they do.

This website provides some background information to help interested anglers and others learn more about Colorado's coldwater reservoirs, their foodwebs and fisheries, and some of the scientific fundamentals that underlie sound management of these ecosystems.

BASIC CONCEPTS
Simple Food Webs = Delicate Balance

Kokanee - the Key to Good Fishing in Coldwater Reservoirs

It takes a lot of groceries to feed big mackinaw

 

FOR MORE INFORMATION

         Johnson, B. M. and J. P. Goettl, Jr. 1999. Food web changes over fourteen years following introduction of rainbow smelt into a Colorado reservoir. North American Journal of Fisheries Management 19:629-642.


CSU Fisheries Ecology Lab
Colorado Division of Wildlife - Aquatic Research


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