Existing and Planned Monitoring of NonNative Aquatic Species in Lake Powell and 

Below Glen Canyon Dam

Contributors: 

Brian Healy, Clarence Fullard, Charles Yackulic, David Ward, 

Kim Dibble, Jan Boyer, David Rogowski, Kirk Young, Randy 

Van Haverbeke, Ken Hyde, Mark McKinstry

“Managing fisheries is hard: it’s like managing a forest, in which the trees are 

invisible and keep moving around” (J. Shepherd, from an unpublished lecture at 

Princeton University, ca 1978)
Outline

• Fish monitoring techniques 

• Identify source areas

• Description of planned monitoring:

• Objective

• Gear type

• Locations

• Time of year

• Limitations & monitoring gaps
Monitoring 

Techniques

• Electrofishing

• Seining –

• Larval

• Small-bodied

• Trap netting –

• Hoop netting

• Minnow traps

• Angling - catfish

• eDNA

G. Andrejko, AZGFD photo
Location - sources
Location - sampling
Sampling Locations

Grand Canyon – system-wide sampling 

(electrofishing, hoop-netting, angling) 
Location – sampling (seining)

Small-bodied/larval seining
Environmental DNA Project

Objective: Detection of rare native and nonnative species by 

filtering DNA from water sample

Approaches:

• Quantitative PCR

• Species-specific

• Relative abundance

• Metabarcoding

• Community of fauna

• Presence-absence
June 2021 Trip

Map: K. Dibble, USGS
Monitoring Location and Funding 

Source

• System-wide: AMP

• Pearce Ferry, upstream & downstream: AMP/ BOR

• Lees Ferry catch-per-unit-effort: AMP/ BOR

• Lees Ferry TRGD project: AMP

• Little Colorado River HBC sampling: AMP

• Little Colorado River catfish sampling: AMP

• Tributary HBC Translocation & Trout Control: BOR/ NPS

• Hidden Slough GSF monitoring: BOR/ NPS

• HBC Aggregation Monitoring: AMP

• Juvenile HBC monitoring: AMP

• Larval fish monitoring: BOR

• Small-bodied fish monitoring: BOR

• eDNA sampling: FWS/ BOR/ AMP
Sampling Type & Timing

• System-wide: electrofishing, hoop netting, angling- April

• Pearce Ferry, upstream and downstream: electrofishing, hoop netting, angling- February, May, July, October

• Lees Ferry catch-per-unit-effort: electrofishing- March, July, September

• Lees Ferry TRGD project: electrofishing- January, May, October

• Little Colorado River HBC sampling: hoop netting- April, May, July, September, October

• Little Colorado River catfish sampling: angling- May, July

• Tributary HBC Translocation & Trout Control: electrofishing, hoop netting, minnow traps- January, February, May, June July, September, October, November, December

• HBC Aggregation Monitoring: hoop netting , seining- September

• Hidden Slough GSF monitoring: electrofishing, minnow traps- May, July, August

• Juvenile HBC monitoring: electrofishing, hoop netting- May, July, October

• Larval fish monitoring: seining- March, April, May, June, July, August

• Small-bodied fish monitoring: seining- April, May, June, July, August, September

• eDNA sampling: water collection- June
Limitations & 

monitoring gaps

• Gear limitations, e.g.,:

• Size-specific

• Temperature

• Behavior/habitat use

• Turbidity

• eDNA presence/absence

• Infrequent trips targeting 

NNF:

• Glen Canyon slough/hotspot

• Tributary surveillance 

• Catfish angling

• LCR uncertainties:

• Catfish abundance imprecision

• Impacts on eggs/larval native 

fish?:

• Plains killifish? Carp?

Preliminary – do not cite (Healy et al. in revision)