In 1964, the Lees Ferry tailrace on the Colorado River was given birth by the completion of Glen Canyon Dam, which impounded Lake Powell. Subsequent water releases from the bottom of Lake Powell changed the once highly turbid, warm waters of the Colorado River into a constant cold (46-50°F), clear flowing river. Shortly after completion of the dam, the Arizona Game and Fish Department stocked rainbow trout (Oncorhynchus mykiss) in the 15-mile Lees Ferry reach and, in 1981, began to manage this section of river as a Blue Ribbon trout fishery. The trout began to flourish in the Lees Ferry reach from 1970-1985 when catches of rainbow trout above 10-pounds were not uncommon, and angler pressure was relatively low. In 1991, however, the Bureau of Reclamation implemented the Record of Decision flow regime, which consisted of higher minimum and more stable flows and allowed for increased trout reproduction and survival. Under these conditions, a huge population of trout developed causing individual fish growth rates to decline. Quite simply, there was a large number of fish competing for limited space and food items, resulting in a fishery where trout less than 14-in were dominant.
In 2000, the Arizona Game and Fish Department began a long-term monitoring program sponsored by Grand Canyon Monitoring and Research Center (http://www.gcmrc.gov/) to determine the effects of Glen Canyon Dam operation on the trout fishery at Lees Ferry and to make recommendations for improving this fishery. Since 2000, our data collection has shown an increase in the general health of all trout age classes (especially since 2002). This increase in fish health is usually associated with an increase in growth rates. There has been a marked increase in catch rates of young-of-the-year fish in recent years. With successful spawning and recruitment continuing to occur, fishing conditions in Lees Ferry are improving.
The Lees Ferry tailrace is located in Marble Canyon, Arizona and covers the 15-mile section of the Colorado River from Lees Ferry upstream to Glen Canyon Dam.
The Research Branch of the Arizona Game and Fish Department currently conducts nighttime electrofishing surveys 3 times per year at Lees Ferry to monitor the rainbow trout population. We use two 16-foot inflatable boats with a crew of 3 on each boat. During each sampling trip, 9 fixed sites are sampled along with 27 randomly selected sites over the span of 3 nights using an electrofishing system mounted to each boat. Throughoutthe Lees Ferry reach, rainbow trout are given individually numbered tags allowing us to identify individual fish and gather information such as growth and movement if the fish is ever captured again. All fish collected during each sampling trip are measured, weighed, and checked for sexual maturity. Sampling surveys are conducted at night as fish tend to move towards the shoreline after sunset, and electrofishing is most effective in shallow water.
Benefits of Management:
The data collected from each sampling survey enables us to detect changes in the rainbow trout population over time. From this data, we can take action to ensure Lees Ferry
remains a world-class fishery.
This project is funded by the USGS Grand Canyon Monitoring and Research Center as part of ongoing research activities.
For more information
Andy Makinster, Arizona Game and Fish Department
506 N. Grant St. Suite L, Flagstaff, AZ 86001.
Phone: (928) 226-7677 E-mail: email@example.com
Bill Stewart, Arizona Game and Fish Department
5000 W. Carefree Highway, Phoenix, AZ 85086
Phone: (623) 236-7368 E-mail: firstname.lastname@example.org