U.S. Department of the Interior

U.S. Geological Survey

Mapping Submerged AquVegetation in Glen CanyoHydroacoustics—a ProoConceptTheodore Kennedy & Barbara RalstGCMRC
Need for Project

 Understanding what controls den

growth of trout in Lees Ferry is immanaging fishery & downstream 
Need for Project

 Understanding what controls den

growth of trout in Lees Ferry is immanaging fishery & downstream 

 Food availability and habitat com

two of the most important factors determine density and growth of populations
Need for Project

 Understanding what controls den

growth of trout in Lees Ferry is immanaging fishery & downstream 

 Food availability and habitat com

two of the most important factors determine density and growth of populations

 Submerged aquatic vegetation (S

important source of food and habcomplexity in rivers
Major changes in SAV have 

 New species of SAV showed up i

90s

 Chara, Potamogeton, aquatic mosse
Major changes in SAV have 

 New species of SAV showed up i

90s

 Chara, Potamogeton, aquatic mosse

 Initially colonized sandy substrat

to have expanded to hard substra
Major changes in SAV have 

 New species of SAV showed up i

90s

 Chara, Potamogeton, aquatic mosse

 Initially colonized sandy substrat

to have expanded to hard substra

 Best data documenting these tren

from AZGFD qualitative surveys
Major changes in SAV have 

Chara Potamogeton 

Egeria Aquatic Mo
What does it mean?

Changes in species composition of SAV ‘may 

change the aquatic foodbase in the dam taiMcKinney 1996

an expanded Chara/Potamogeton ‘community 

Canyon tailwater may benefit the fish popuproviding cover and an expanded food basMcKinney 1996 

‘...intermediate densities of submerged macro

heterogeneous river substrate (i.e., a varietprovide the most suitable conditions for a tAyers and McKinney 1996 
Not all SAV types created e

 Cladophora supports higher density of 

diatoms than other types of macroalga

 However, a thorough analysis of invert

diatom densities among new SAV typebeen conducted

 Chick and McIvor (1994) found fish den

biomass differed significantly between Lake Okeechobee

 Other SAV types may provide better co

juvenile fishes
Objectives of SAV Project

 Map distribution, density, and co

SAV throughout selected reaches Canyon
Objectives of SAV Project

 Map distribution, density, and co

SAV throughout selected reaches Canyon

 Determine whether invertebrate a

density and composition varies atypes
Objectives of SAV Project

 Map distribution, density, and co

SAV throughout selected reaches Canyon

 Determine whether invertebrate a

density and composition varies atypes

 Develop trout density coverage fo

determine whether trout density iby SAV type or density 
Mapping Methods

 Develop seasonal SAV map at fiv

reaches in Glen Canyon

 Use Biosonics digital echosound

digital GPS to map bottom depth, presence/absence, plant height, ain spring 2007 and winter 2008 

 Conduct additional transects with

reach using underwater video andetermine species composition
Mapping Methods

Hydroacoustics Ou
Mapping Methods

Example Boat TransecTo Develop Map
Mapping Methods

Example SAV Map Developed Using Hydroacoustics
Mapping Methods

Underwater Video
Invertebrate and Diatom Me

 Collect quantitative samples of d

types using SCUBA

 Determine invertebrate and diato

using standard methods
Comparisons with fish distr

 Conduct mapping at same time a

and/or Korman’s trout monitoring

 Develop trout coverage and inter

SAV coverage
Deliverables

 Seasonal base map (Spring 2007 & Win

 Draft of 1st map to be presented to TWG by 

Completed 1st map to be delivered by Dece

Completed 2nd map to be delivered by Sep 3

 Report describing methods, results of 

and diatom research, and relationship distribution

 To be delivered by Sep 30, 2008

 GIS coverage of trout distribution/dens

 To be delivered by Sep 30, 2008
Questions

 What is current distribution of Cla

relative to other SAV types?

 Does the density and species com

inverts/diatoms differ among SAV 

 Is the density/distribution of juve

trout affected by SAV type or den