Charles Yackulic
Science and Products
Rainbow Trout Abundance and Movement in the Colorado River in Grand Canyon
Just below Glen Canyon Dam on the Colorado River is a very popular Blue Ribbon trout fishery known for its rainbow trout. However, approximately 78 miles downstream, near were the Little Colorado River flows into the Colorado River, is a population of endangered humpback chub. The introduced rainbow trout can negatively affect native humpback chub by competing with them for food (immature...
Uncovering the Base of the Food Web: Primary Production Dynamics in the Colorado River
Algae, phytoplankton, and rooted macrophytes represent the base of many aquatic food webs and are known as primary producers. Through photosynthesis, these organisms convert sunlight energy into chemical energy (i.e., carbon) that in turn fuels the growth of animals such as macroinvertebrates and fish. This project uses high frequency measurements of dissolved oxygen, which is a by-product of...
Population Dynamics of Endangered Humpback Chub in Grand Canyon
Construction of Glen Canyon Dam has led to large changes in environmental conditions of the downriver Colorado River. Whereas the pre-dam Colorado River experienced large seasonal variation in temperature and discharge and was highly turbid, the post-dam Colorado River is far less variable in terms of temperature and discharge and is frequently clear. Many nonnative fish species had already...
Understanding Factors Influencing Rainbow Trout Growth in the Colorado River
Rainbow trout is a desirable sport fish that has been introduced in many locations around the world. Although introductions of rainbow trout and other nonnative fishes provide recreational fishing opportunities, they also pose threats to native fish populations. The Glen Canyon Dam Adaptive Management Program has tasked scientists and managers with identifying management options that allow...
SBSC Research on Barred and Spotted Owls Covered by Ecological Society of America
The Ecological Society of America put out a press release on a paper that investigated the relative importance of barred owl competition and habitat on northern spotted owls in an effort to assist managers. The lead author of the paper is Charles Yackulic of the USGS Southwest Biological Science Center.
Barred Owls Ousting Spotted Owls in the Pacific Northwest
An increase in the barred owl population is contributing to the decline of threatened Northern spotted owls, according to models developed by U.S. Geological Survey and U.S. Forest Service scientists.