U.S. Department of the Interior

U.S. Geological Survey

Invasive Aquatic Spe

Management Plan 

Development and Up

Short Term Strategy and Long T

By

Kara Hilwig

and

Matthew Andersen, Lew Coggins, Dan Gwinn, 

USGS, SBSC, GCMRC
Overview

1. Plan purpose and need2. Scope of Plan3. Information challenges4. Short term approach5. 2007 field study6. Long term approach7. Integration
Purpose and Need

Nonnative fish implicated in decline of native fPlan to develop management actions:

Reduce nonnative fish abundanceReduce negative impacts to native fishe

Concern for implementation of TCD/SWS:

Intended to benefit native fishes, but ma

water nonnative fishes

©www.answersingenesis.org 
Scope of Plan

Management plan includes:

 Aquatic species

 Nonnative fish

 Small and large bodied species Warm, cool and cold water species

 Crayfish

 Geographic scope:

 Mainstem Colorado River in Grand C Identification of sources of nonnativ

Canyon
The Unknown

Unknowns: How do we respond?

 Species of greatest risk? Can monitoring protocols to 

detect changes?

 Effective capture/reduction 

methods?

 Feasibility of control or 

abundance reduction?
Response Plan

Develop contingency plan: Respond to nonnative populati

expansions

 Current monitoring methods:

 Detect large changes in nonnative fi Not effective for capture/control 

 Plan based on literature review o

methods (mechanical or operational)

 May not have answers if/when inc

occurs
Response Plan for Tro

Management of rainbow trout in 

the LCR aggregation

 Rainbow trout effectively 

reduced with electrofishing

 Monitor trout CPUE Implement removal to maintain 

target abundance 

 Reduce predation/competition 

on natives Trout 
2007 Field Study

Combined Warmwater Invasives/Sonic 

 Target species posing greatest risk to  Criteria:

 Currently in Grand Canyon  Warm water expansion potential Current capture methods ineffective

 FY07 Funding sufficient to study one  Channel catfish fits these categories f
2007 Field Study

Study Goals and Objectives:

1. Investigate capture 

probabilities of channel catfish

 Determine proportion of 

population captured

2. Evaluate three gear types

 Large mesh hoopnets Electrofishing with ‘catfish 

settings’

 Standardized angling
2007 Field Study

Study Goals and Objectives:3. Investigate feasibility of using 

sonic technology to track fish movements in Grand Canyon

Data goals:

 Habitat preferences  Diurnal, seasonal movement 

patterns

 Application to other species Species habitat overlap

Surgically 
 Target particular nonnative species 

 Currently in Grand Canyon  Warm water expansion potential Current capture methods ineffective

 Monitoring and management:

 Abundance Movement  Investigate effective capture methods Develop novel methods

 Avoid ‘body count’ method

 Quantify proportion of population 

removed

 Identify and quantify native response

F

Color

Long Term Strategy

Development of Effective Capture M
Long Term Plannin

Develop Risk Assessment

Identify nonnative species 

of greatest risk to natives

 Efficient application of limited 

resources

1. Environmental tolerance and life 

history review

2. Existing control measures3. Identify negative impacts and 

interactions

 Predation or competition Spatial and temporal overlap
Long Term Plannin

Development of Risk Assessment

4. Utilize temperature-based bioenergetics 

model to inform risk assessment

 Petersen and Paukert (2005) identify 

bioenergetics model as useful tool to investigate risk from nonnative fishes in Grand Canyon

 Assess impacts to juvenile and 

adult natives

 Identify relative importance of 

impacts

Incorporate Valdez assessment
Applications of Bioenerg

 Investigate species interactions

 Designate predators, prey, and competitors Degree of impact, one species and age clas Identify consumption demand or food limita Define spatial and temporal factors

 Evaluate importance of environmental 

(e.g., temperature, food limitation or quality, en

 Investigate Predator/Prey cycles Rebuild history

 Invasions, management actions

 Forecast future
Long Term Plan – Bioenergetic

Primary production

Zooplankton 

Juvenile humpback 

chub

Hypothetical Example
Hypothetical risk assessment 

Blue Fish ExampleResults from Bioenergetics 

Model inform risk assessment:

 High predation risk High invasion risk High susceptibility to 

control 

High predation and invasion risk reduced with:

 Effective control of 

recruitment (river level fluctuation)

 Effective capture of 

adults with electrofishing

Recommendation: Control 
Hypothetical risk assessment 

Predation vs. Competition ExampleBioenergetics model for Age 1+ study fis Red fish population exerts high compe Moderate predation risk from purple fiOther risk factors: Red fish risk amplified by Low suscep

 No current effective capture/reduction met

Recommendation: Control red fis
Integration

 Foodbase and nonnative fish 

programs:

 Model data inputs similar  End products slightly different

 Foodbase is collecting:

 Food availability Diet composition

 Gut contents Isotope analysis

 Programs are also collecting 

small bodied and juvenile fish:

 Abundance  Capture probability
Summary of Approac

Short term approach

 Response plan

2007 Field study

 Investigate capture methods Improve monitoring and control  Quantify effectiveness and response Study results inform long term approach

Long term approach

 Expand knowledge of monitoring 

and controlling nonnatives

 Identifying impacts to natives Products:

 Risk assessment document Management plan