Anglers Turned Bounty Hunters - Ethics and Effectiveness of the

Anglers Turned Bounty Hunters - Ethics and Effectiveness of the Lees Ferry Brown

Trout Incentivized Harvest and Other Fish Bounties Across the United States

Gabriella Rich

A Thesis Presented in Partial Fulfillment

of the Requirements for the Degree

Master of Science

Approved October 2023 by the

Graduate Supervisory Committee:

Matthew K. Chew, Co-Chair

James P. Collins, Co-Chair

Rachel Bryant

ARIZONA STATE UNIVERSITY

December 2023

ABSTRACT

Across the United States, placing bounties on fish is a management method that is

used to remove an unwanted population. Bounties involve anglers being paid to catch a

certain species, and they are offered for either population reduction or research. There are

several factors involved in designing a fish bounty discussed in this thesis. Fish bounties

are interesting in the sense that there is no “right way” to offer them. Each bounty has to

be tailored to individual populations in order to achieve the desired goals. The first part of

this thesis is a review of fish bounties across the United States, followed by a discussion

of their effectiveness.

The Brown Trout Incentivized Harvest at Lees Ferry is a topic of controversy and

is the main subject of this thesis. The National Parks Service began this program in 2020

and is currently paying anglers $33 for every brown trout (Salmo trutta) they catch and

turn in to the agency. This program was started in order to reduce the population of

piscivorous brown trout at Lees Ferry, for concern they will disperse 60 miles

downstream to where there is a population of protected humpback chub (Gila cypha).

There are many opinions related to this incentivized harvest.

One way to analyze this situation is to look at it from an animal rights perspective.

Martha Nussbaum has created her Capabilities Approach to explain what rights animals

are entitled to, as they are creatures deserving of the ability to flourish. This is helpful to

assess which decision regarding brown trout and humpback chub is best.

ACKNOWLEDGMENTS

I would like to express my gratitude to my committee for their continued support

and taking an interest in my ideas. Firstly, I want to thank Dr. Matt Chew for making

learning so enjoyable and giving me the opportunity to pursue my research. I also want to

thank Dr. Jim Collins for his encouragement throughout my project to make it the best it

could possibly be. Lastly, I want to thank Dr. Rachel Bryant for introducing me into the

exciting world of ethics and for our great conversations. I truly appreciate everything my

committee has done for me.

TABLE OF CONTENTS

Page

LIST OF TABLES……………………………………………………………...…………v

LIST OF FIGURES………………………………………………………………………vi

LIST OF ACRONYMS………………………………………………………………….vii

CHAPTER

1 - INTRODUCTION……………………………………………………………….…….1

PART I. FISH BOUNTIES IN THE UNITED STATES

2 - FISH BOUNTIES……………………………...………………………………2

2.1 What are Fish Bounties?………...…………………………………….2

2.2 Fish Bounties in the United States…………………………………….2

2.3 Fish Bounty Analyses…………………………………………………8

2.4 What Makes A Fish Bounty Effective?……………………...………10

PART II. LEES FERRY AND THE BROWN TROUT INCENTIVIZED HARVEST

3 - THE PROBLEM……………………...………………………………………13

3.1 Introduction…………………………………………………………..13

3.2 Setting the Scene……………………………………………………..14

3.3 Brown Trout Incentivized Harvest…………...………………………15

3.4 Why Are Brown Trout Being Removed?……………………………16

3.5 Environmental Assessment………………..…………………………17

3.6 Timeline of Events………………………………...…………………18

3.6.1 Beginning with the Dam…………………………………………...18

3.6.2 Start of the Harvest………………………………………………...20

CHAPTER Page

4 - HOW DID WE GET HERE?.…………………………….....……………….21

4.1 Glen Canyon Dam……………………………………………………21

4.2 Fish Species………………………………………………………….23

4.3 Fish Stockings……………………………….……………………….24

5 - DISCUSSING THE PROBLEM…….…………………………..…………...26

5.1 The Idea of Nativeness……………………………………………….26

5.2 Colorado River Life After the Dam………………………………….28

5.3 Issues…………………………………………………………………28

5.4 Current Bounty Numbers………………….…………………………30

5.5 Bounty Efficacy…………………...…………………………………30

PART III. ETHICS

6 - ETHICAL ARGUMENTS…………………………………………………...31

6.1 Introduction of Ethical Arguments…………………………………..31

6.2 Capabilities Approach…………………………………….………….34

6.3 Animal Rights and the Capabilities Approach……………………….36

7 - THE CENTRAL CAPABILITIES………………………………………..….39

7.1 Applying the Central Capabilities……………………………………39

7.2 Discussion……………………………………………………………43

7.3 Conclusions…………………………………………………………..44

REFERENCES……………..……………………………………………………………46

LIST OF TABLES

Table Page

1. List of Fish Bounties by Criteria……………………………….………………….7

2. Water Temperature Data at Several River Sites. Crlf is Colorado River Lees

Ferry. Based on Hourly Averaged Data………...…………..……………………22

LIST OF FIGURES

Figure Page

1. Colorado River Fish Monitoring in the Grand Canyon, Arizona…..……..……..15

2. Historic Water Temperature (Degrees Celsius) Data at Lees Ferry…..…………22

3. Lees Ferry Daily Mean Turbidity During 2016. Also Shows Pre-dam Turbidity

from Other Known Data…………………………………………………………23

4. Brown Trout CPUE by Season at Lees Ferry. Graph From AZGFD. Unpublished

Data……………………………………….…...…………………………………31

vii

LIST OF ACRONYMS

ARTs - Animals Rights Theories

ASAP - Automated Standard Application for Payments

AZGFD - Arizona Game and Fish Department

CA - Capabilities Approach

CFMP - Comprehensive Fisheries Management Plan

CPUE - Catch Per Unit Effort

DNR - Department of Natural Resources

EA - Environmental Assessment

EIS - Environmental Impact Statement

ESA - Endangered Species Act

GCDAMP - Glen Canyon Dam Adaptive Management Program

IUCN - International Union for Conservation of Nature

LTEMP - Long-Term Experimental Management Plan

NPS - National Parks Service

PIT tag- Passive Integrated Transponders

TWRA - Tennessee Wildlife Resources Agency

USFWS - United States Fish and Wildlife Service

USFS - United States Forest Service

USGS - United States Geological Survey

Chapter 1. INTRODUCTION

The Lees Ferry reach of the Colorado River is the site of the Brown Trout

Incentivized Harvest offered by the National Parks Service (NPS). Brown trout (salmo

trutta) are being targeted for concern that they will travel downstream of Lees Ferry to

where there is a population of humpback chub (Gila cypha), which are listed as

“threatened” under the Endangered Species Act. Humpback chub are Colorado River

natives that almost went extinct due to the creation of Glen Canyon Dam, competition for

food and habitat from nonnative fish, and the use of piscicides (Miller, 1968). Currently,

they may be threatened by brown trout.

The Brown Trout Incentivized Harvest is problematic for several reasons.

Humpback chub are a warm-water species. Before the dam, the Colorado River had high

temperatures and turbidity. After the dam, it now stays cold year-round with little to no

turbidity. The humpback chub have now been confined to areas of the river with

temperatures they can tolerate. Once Glen Canyon Dam was completed, brown trout were

able to travel from Bright Angel Creek up the river to Lees Ferry and establish a

population once the dam made the river suitable for trout. It seems as if the brown trout

are being punished by the humans who brought them there in the 1920s. There are also

many who are against the Brown Trout Incentivized Harvest, such as catch-and-release

anglers, Native American tribes, and business owners.

PART I. FISH BOUNTIES IN THE UNITED STATES

Chapter 2. FISH BOUNTIES

2.1 What are Fish Bounties? Fish bounties involve paying people to catch and

keep a certain species of fish that have been deemed problematic, usually because they

are or could potentially harm another population of fish. They might also be seen as

problematic if they were to disperse to other bodies of water. Several states have had

some kind of bounty placed on a population of fish. Bounties reward anglers for catching

fish to reduce their numbers or provide information for management. For the purpose of

this thesis, fish bounties are grouped into two categories based on the bounty’s goal:

population management and research.

2.2 Fish Bounties in the United States. Fish bounties can be categorized based on

their characteristics: purpose, turn-in requirements, catch method, rewards, and reward

limits. Examples of these are provided in Table 1, which compares all discussed bounties

and contains further information.

Purpose

The most common reason a bounty is placed on a population of fish is for

predator control. Colorado Parks and Wildlife paid anglers $20 for every northern pike

(Esox lucius) caught and turned in. Northern pike are “voracious predator fish” that were

privately (illegally) introduced into Green Mountain and Wolford Mountain Reservoirs

(Hampton, 2020).

The purpose of some bounties is to locate a population and to determine if those

fish are dispersing to other areas. In Illinois, black carp (Mylopharyngodon piceus) began

appearing in rivers they had never been recorded. The Illinois Department of Natural

Resources (DNR) is paying $100 for every black carp turned in with the information on

where it was found. There is a reward limit of ten fish per month per angler. The Illinois

DNR is requiring that carcasses be kept on ice, so they are fresh for analysis (Invasive

Carp Regional Coordinating Committee, 2021).

There are also ecological reasons a bounty is placed on a fish. For example, the

Tennessee Wildlife Resources Agency (TWRA) wants to reduce the number of “Asian

carp” (These include species such as black carp and silver carp (Hypophthalmichthys

molitrix)) because “invasive carp have the capacity to deplete and alter the current food

web of the reservoirs that support natural resources, including highly-valued recreational

and commercial fisheries” (“Invasive carp in Tennessee, information and images,” n.d.).

TWRA has hosted tournaments to encourage the harvest of Asian carp.

Silver carp have an unusual reason TWRA wants them removed. They are a

safety concern since they jump out of the water at boaters and can cause serious injury.

“Turn-In” Requirements

Bounties have varying requirements regarding what part of the fish must be

submitted for the rewards. Since 2018, the Florida Fish and Wildlife Conservation

Commission has been hosting their annual “Lionfish Challenge,” a spearfishing

tournament that runs from June 1st through October 1st. To qualify for the prizes, only

the lionfish (Pterois spp.) tails must be turned in. This allows participants to keep their

catches for consumption. (Lionfish have venomous spines, so the Florida Fish and

Wildlife Conservation Commission provides resources on how to safely filet these fish)

(“Lionfish Challenge 2023,” 2023).

Turning in only the head is a common requirement. If fish are PIT tagged, the tag

is inserted into the fish’s head. Researchers will only need the head to scan for these tags.

Only turning in the head also allows the angler to keep their fish for consumption.

Some bounties require the entire fish for rewards if the carcass is needed for

research or tournament results. The Pacific States Marine Fisheries Commission hosts an

annual “Northern Pikeminnow Sport-Reward Program” to reduce the number of northern

pikeminnow (Ptychocheilus oregonensis) in the Columbia and Snake Rivers. Each

pikeminnow over nine inches is worth between $6 and $10. Fish tagged by the Oregon

Department of Fish and Wildlife are worth between $200 and $500 as an additional

incentive. The entire fish must be submitted to ensure that it meets the minimum length

requirements (“Northern Pikeminnow Sport-Reward Program,” n.d.).

Catch Method

Fishing with line and lure is the most common catch method for fish bounties. A

bounty on lake trout in Idaho requires anglers to catch them with line and lure. People

can fish from shore or from boats (Idaho Game and Fish, n.d.).

There are a few bounties that are spearfishing only. For example, Atlas

Environment, a conservation organization in Texas, has a bounty on armored catfish

(Loricariidae) and tilapia (Oreochromis niloticus) in the San Marcos River. There are

prizes for the most fish, heaviest, largest and smallest fish. Fishing with line and lure is

not allowed, and there are rules regarding what kind of diving gear participants can use

(“Tournaments,” n.d.).

Rewards

There are several different types of bounties that can be offered. These include

cash, gift cards, and merchandise. The Maryland DNR is offering gift cards if anglers

catch a northern snakehead (Channa argus) with a passive integrated transponder (PIT

tag) implanted, which bears an identifying number which allows them to be tracked

(“Tagging study offers money for harvesting northern snakeheads,” 2022).

Cash for every fish (or for “incentive fish” with tags) is a common reward. Idaho

Game and Fish has a bounty on Rainbow Trout (Oncorhynchus mykiss) and Rainbow-

Cutthroat hybrids. A number of these fish have been tagged that are worth between $50

and $1,000. Anglers have the option of submitting the entire fish while will be donated to

local food banks (Idaho Fish and Game, n.d.).

The Flaming Gorge Chamber of Commerce hosts their annual “Burbot Bash”

(Lota lota) at Flaming Gorge Reservoir. The annual “Burbot Bash” enters participants

into a raffle where they can win items such as grills. There are prizes offered based on

size and number of burbot. Cash prizes are also rewarded for tagged fish. Burbot are a

cod-like fish that are piscivorous. They have no burbot predators in Flaming Gorge

Reservoir, which has allowed their numbers to increase (“Catch the ugliest fish in the

west,” n.d.).

Reward Limits

Bounties can offer rewards for a determined number of fish. A bounty on northern

pike in Washington will pay anglers $10 for every head. While rewards will be given out

for every fish, there is a limit of $590 per angler per year. Only northern pike caught in

the Columbia River fisheries are eligible (“Northern pike,” n.d.).

While some bounties offer rewards for every fish, others only offer them for

some. Buckboard Marina and the Wyoming Game and Fish Department hosted a contest

to remove lake trout under 25 inches from Flaming Gorge Reservoir. Only fish with a

PIT tag are eligible for the reward. Green tags (fish tagged in 2020) are worth $100 and

orange tags (fish tagged in 2019) are worth $50. Tags must be taken to Buckboard

Marina. Fish without a tag will not receive the cash rewards (“‘Pup’ulation control

contest back at Flaming Gorge,” 2020).

A number of walleye (Sander vitreus) and lake trout (Salvelinus namaycush) have

been tagged by Idaho Game and Fish in Lake Pend Oreille (Idaho Fish and Game, n.d.).

To entice anglers to participate, a state’s Game and Fish Department or similar agency

will tag a certain number of fish with microscopic tags placed in the heads of each fish.

This high incentive encourages participation.

Table 1

List of fish bounties by characteristics

Fish(es)

Offeror

Reward (limit) required

submission

Purpose

Habitat, source

Northern

Snakehead

Maryland DNR

Giftcards (tagged fish

only) whole fish

Predator Control

River and estuary, Private

intentional introduction

Northern

Pike

Colorado Parks

and Wildlife

Cash (none) head

Predator Control

River, Private

unintentional introduction

Northern

Pike

Colville

Confederated

Tribes (WA)

Cash (Maximum payout

$590/person/year) whole

fish

Predator Control

Lake, Private

unintentional introduction

Northern

Pikeminnow

Pacific States

Marine

Fisheries

Commission

Cash (nine inch length

minimum)

Predator Control

River, Native

Lake Trout

Idaho Game

and Fish

Cash (none) head

Predator Control

Lake, State agency

intentional introduction

Lake Trout

Buckboard

Marina

Merchandise, Cash

(none) whole fish

Predator Control

Reservoir, unspecified

source

Rainbow

Trout

Idaho Game

and Fish

Cash (tagged fish only)

whole fish

Predator Control

River, State agency

intentional introduction

Walleye

Idaho Game

and Fish

Cash (tagged fish only)

head

Predator Control

Lake, Private

unintentional introduction

Lionfish

Florida Fish

and Wildlife

Merchandise (none) tail

Predator Control

Coral Reef, Private

intentional introduction

Black Carp

Illinois DNR

Cash (maximum

10 fish/month/person)

Location Data

River, Private

unintentional introduction

Asian Carp

Tennessee

DNR

Cash (none) whole fish

Ecology;

Boater Safety

River, Private

unintentional introduction

Armored

Catfish

Atlas

Environment

Merchandise (minimum

size) whole fish

Ecological

River, Private intentional

introduction

Tilapia

Atlas

Environment

Merchandise (minimum

size) whole fish

Ecological

River, unspecified source

Burbot

Flaming Gorge

Chamber of

Commerce

Merchandise (minimum

size) whole fish

Predator Control

Lake, Private intentional

introduction

Note. This table includes all information from the fish bounties listed in section 1.2

2.3 Fish Bounty Analyses. Fish bounties vary from the actual type of fish to the

body of water that they are located in. What works for one body of water might not have

any effect on another. This section analyzes two fish bounties that have been evaluated

based on their effectiveness to test if a conclusion can be made about whether or not fish

bounties work. One bounty is on Lake Trout in Lake Pend Oreille. The second bounty is

a spearfishing tournament for an Armored Catfish population in the San Marcos River,

Texas. These are two different bodies of water and two different species.

Lake Trout - Lake Pend Oreille

Lake Pend Oreille in Idaho is 1,158 feet deep and 43-miles-long (“History of

Lake Pend Oreille,” n.d.). The size of the lake trout population has been a cause for

concern and a subject of removal efforts.

Lake trout in Lake Pend Oreille have greatly increased in numbers from 1999-

2006 to “unsustainable levels of predation mortality on Kokanee” (Dux et al., 2019).

Lake trout have also “increased the conservation threat to native bull trout and

jeopardized the popular recreational fishery for kokanee and rainbow trout” (Dux et al.,

2019). Several removal efforts were made between 2006 and 2016 to reduce the number

of lake trout. These included incentivized angling, gill netting, and trap netting. Between

2006 and 2016, a total of 193,982 lake trout were removed. Gill netting contributed 50%

of removal, angling was 44%, and trap netting was 6%. The combined annual cost was

between $307,000 and $796,000. The majority of fish removed were donated to local

food banks.

There are several takeaways from these suppression efforts, an important one

being that angling alone is not sufficient to achieve the goal of reducing the lake trout

population. While angling not only removes fish but also increases annual mortality, it

becomes increasingly difficult for anglers to catch fish as the population declines or fish

begin to move to other parts of the lake.

Another factor of these suppression efforts is the total annual cost. The lowest

amount mentioned above for this case was $307,000 annually. Over eleven years, this

totals $3,377,000. While this includes efforts other than incentivized angling, it is really

important to acknowledge the costs of removal.

Furthermore, a combination of efforts is better than individual ones. The same

results would not have been achieved if only a single method was used. The authors

determined that “suppression can be an effective management action for mitigating

effects of nonnative Lake Trout in large, deep lakes” (Dux et al., 2019).

Armored Catfish - San Marcos River, Texas

The San Marcos River is spring-fed and is home to regionally endemic and at-risk

populations such as the Texas Blind Salamander and the San Marcos Fountain Darter

(“San Marcos River,” n.d.). They are considered at-risk due to the presence of introduced

South American armored catfish.

Armored catfish introductions into the wild arise from aquarium releases. They

are popular in aquariums as they are used for algae control, but outgrow small fish tanks

and are subsequently released. Armored catfish are associated with “bank erosion and

increased sedimentation caused by burrowing behavior, diet competition with native

herbivores, space competition with native macroinvertebrates, and reduction of

periphyton biomass” (Hay et al., 2022). Since there are several populations of federally

threatened fishes in the San Marcos River, Atlas Environment (mentioned above) hosts

spearfishing competitions to reduce the armored catfish population.

Hay et al. (2022) estimated “movement and mortality of [armored catfish] during

a spearfishing removal experiment within an urban, groundwater-dependent ecosystem.”

Armored catfish were tagged by Hay et al. and tracked in response to the spearfishing

tournament to see where and how far they travel, as well as observing their survival.

They found the tournament does suppress the population of armored catfish in the San

Marcos River. Furthermore, they observed that a minimum of 25 fish must be removed

each week in order for the population to decline. They also determined that the armored

catfish do move in response to spearfishing pressure.

Hay et al. concluded that spearfishing was an effective method for decreasing the

armored catfish population. However, tournaments should be held over the course of

multiple weeks and more than once a year in order to be effective. A certain number of

fish (in this case more than 25 weekly) will need to be removed to reduce numbers.

“Removal of adult fish through spearfishing may also contribute to control of the

population through demographic collapse caused by the removal of adults before they

have the opportunity to spawn” (Hay et al., 2022). Overall, spearfishing can be an

effective method for suppressing (not eradicating) armored catfish in a spring-fed river

ecosystem.

2.4 What Makes a Fish Bounty Effective? As we have seen above, there are

many fish bounties across the United States that are offered for various reasons. While

there is no “right way” to construct a bounty, there are several factors to consider. The

two types of bounties discussed in this section are population reduction and research.

Bounties are limited by funding. It is important to know what the bounty needs to

accomplish and then determine how much that is going to cost. Changes might have to be

made if the amount of funding required is not secured, or sponsors and fundraising might

have to be done. Funding can determine the timeline of the bounty, and the desired

timeline affects how much funding is needed.

South Carolina has a bounty on coyotes. While this is not related to fish, a lot can

be learned about funding. The South Carolina DNR tagged a total of 112 coyotes. Each

tagged coyote is worth $3000. This high incentive has resulted in high participation and

hundreds of thousands of coyotes killed. The Department has stated that this program has

led to a 40% decrease in the coyote population since 2011 (Coyote Harvest Incentive

Program, n.d.). Having high incentives can be one way to increase participation and

reduce the amount of funding needed. The coyote incentive program is costing the

department a total of $336,000 in rewards over eighteen years.

Public outreach is key. Bounties will not work if there is little participation.

Potential participants need to know why the bounty is being offered, how to participate,

and what rewards are available. Educational videos, flyers, advertisements, and blog

posts are good ways to promote a bounty.

For a research bounty, the goal should be to gain an understanding of the

demographics of the unwanted population. Knowing where these fish are located and

what impact they are having on the ecosystem will let biologists know if there is a

problem.

For a population reduction bounty, plans for the bounty should include some kind

of monitoring. The amount of monitoring will be limited by funding. In order to

understand if the bounty is working, biologists need to see a decline in numbers. An

increase in the native or wanted sportfish populations might also be a sign that the bounty

is working. However, it will take time to see this.

The body of water where targeted fish species reside makes a difference regarding

how to structure a bounty. As demonstrated above, eradication is difficult to achieve

unless the population is in a small pond that can be fully drained. If the goal of the bounty

is to reduce a population, the duration of the bounty is important. The spearfishing

tournament at the San Marcos River was determined to be effective when it was held

multiple times a year for more than one week at a time.

Hay et al. (above) cited Havel et al. (2015) when discussing how to suppress

unwanted populations; eradication is only successful when the invasive population is

isolated and the ecosystem is drained or dried. This is why eradication is usually not able

to be accomplished unless the population is in a pond or other small, isolated body of

water. If the population can be suppressed, that can be the best course of action to see a

reduction in numbers and an increase in the populations that are trying to be protected;

control might be the only option.

Offering fishing bounties year-round would be ideal so there is a higher chance of

removing more fish, but short-term bounties with good participation can also be effective.

Extra incentives are a good way to encourage anglers to participate in the bounty. These

could be contest prizes such as raffles and tiered prizes, or extra cash and gift cards.

PART II. LEES FERRY AND THE BROWN TROUT INCENTIVIZED

HARVEST

Chapter 3. THE PROBLEM

3.1 Introduction. The Lees Ferry reach of the Colorado River has been a topic of

controversy due to the presence of a nonnative species, the brown trout (Salmo trutta).

These fish have been a part of the Grand Canyon waterways since 1922 (Brooks, 1931).

The Colorado River is also home to a population of humpback chub (Gila cypha) that

have existed in this river for roughly three million years ( USFWS “Humpback Chub

(Gila cypha),” n.d.). There are predictions that an increase in brown trout at Lees Ferry

will lead to these fish preying on threatened humpback chub. There are currently five

known populations of humpback chub that are all located in the Western United States.

The confluence of the Colorado River and the Little Colorado River is where the largest

population of humpback chub resides (Southwest Biological Science Center, 2016). This

population is the focus of this paper. Lees Ferry is also a blue-ribbon rainbow trout

(Oncorhynchus mykiss) fishery, designated by the AZGFD in 1981 (“Brown Trout

incentivized harvest,” n.d.). Another concern is that an increase in brown trout will lead

to an increase in competition and therefore a decrease in rainbow trout numbers.

There is a population of native fish and a population of nonnative fish that exist

within roughly sixty miles of each other. Even though there is a large distance between

the two, there is concern that a growing population of brown trout will cause them to

disperse downstream to the chub’s territory and begin preying on them. Brown trout are

piscivorous (Yard et al., 2011) and the presence of another species at the Little Colorado

River confluence could cause competition between these fish.

The National Parks Service (NPS) began the Brown Trout Incentivized Harvest in

November of 2020. This bounty program pays anglers to keep and turn in the brown trout

they catch. The goal of this program “is not designed to eliminate brown trout, but to

reduce their numbers to pre-2014 levels” (“Brown Trout incentivized harvest,” n.d.).

These pre-2014 levels will be defined later.

Much of the controversy arises from anglers. There are many anglers who are

against removing the brown trout from Lees Ferry. They do not see a threat to the

humpback chub and enjoy catching these trophy brown trout. Fly fishermen in particular

often practice catch-and-release. There are also several fishing guide services that make

their living by taking people out on the water. If this harvest is unsuccessful, Lees Ferry

will be shocked to remove the brown trout. Since shocking the river does not target only

one group of fish, all fish would be affected and uncatchable until they recover. This

would hinder the blue-ribbon rainbow trout fishery and could have devastating effects for

these businesses. However, anglers on the opposite end of the argument are excited to get

paid to fish. With current gas prices and the rates of lodging, catching a few brown trout

can pay for one’s entire trip plus some.

3.2 Setting the Scene. Figure 1 illustrates the Colorado River and major

tributaries. Water flows from Glen Canyon Dam down to Hoover Dam. For the purpose

of this thesis, the Lees Ferry Reach is defined as starting from the confluence of the Paria

River and ending at Glen Canyon Dam. This is approximately a 15-mile section of river.

Major tributaries that will be discussed are the Little Colorado River and Bright Angel

Creek. Bright Angel Creek is approximately 90 miles below Lees Ferry while the Little

Colorado River is approximately 60 miles downstream.

Figure 1. Colorado River Fish Monitoring in the Grand Canyon, Arizona-2018 Annual Report - Scientific Figure on

ResearchGate. Available from: https://www.researchgate.net/figure/Map-of-the-Colorado-River-in-Grand-Canyon-the-

study-area-is-the-Colorado-River-from-Lees_fig1_333634628 [accessed 22 Jan, 2023]

3.3 Brown Trout Incentivized Harvest. Humpback chub are Colorado River

natives that have been in the river system for over three million years. They were listed as

endangered by the IUCN (International Union for Conservation of Nature) in 1967 due to

diminishing numbers from a combination of Glen Canyon Dam being constructed, the

use of piscicides, and competition from introduced species (Miller, 1968). After major

conservation efforts to protect this species, the USFWS (United States Fish and Wildlife

Service) down-listed the humpback chub to “Threatened” in 2021 (“Endangered and

Threatened Wildlife and Plants” 2021).

Biologists who conduct fish population surveys have been seeing a steady

increase in brown trout numbers at Lees Ferry beginning in 2014. These fish have

established a population and are successfully reproducing (Runge et al., 2018). As

mentioned in section 1.1, there is concern that an increase in brown trout could have

negative effects on the humpback chub if they were to disperse downstream. Looking at

the NPS’s website regarding the bounty, there is also some concern that brown trout will

outcompete the rainbow trout.

The Brown Trout Incentivized Harvest began on November 11, 2020 and is still

taking place. Brown trout must be caught between the confluence of the Paria River and

the Colorado River and up to Glen Canyon Dam. Anglers must have a valid Arizona

fishing license and all state fishing regulations must be followed. Eligible brown trout

must be over six inches long. To turn in your fish, anglers must pick up a data card and

small bag at the fish drop box located at the Navajo Bridge Interpretive Center. As of

October 2023, each brown trout is worth $33. There are also ways to earn extra

incentives. If an angler turns in a brown trout with a PIT tag, they will receive $15 for

every tag. Previously, any brown trout over twenty inches was worth $300.

Funds for the incentivized harvest are distributed monthly by the Glen Canyon

Conservancy, a cooperating association with the NPS. After reaching out to their

Education and Outreach Director, I have been informed that the harvest is funded by the

NPS through a federal Automated Standard Application for Payments (ASAP) grant.

3.4 Why Are Brown Trout Being Removed? The NPS said that the reason for

removing brown trout is due to an increase in numbers as well as an increase in large fish.

These fish could potentially look for food and habitat below the Lees Ferry Reach. Runge

et al. (2018) predicted that there is a 64 percent chance that over the next twenty years

brown trout numbers will increase 3-10 fold. Modeling this population of brown trout

with the humpback chub suggests that brown trout could have a negative effect on the

chub in terms of competition and predation (Runge et al., 2018). Studies have shown that

brown trout exhibit high levels of piscivorous behavior. Yard and others sampled both

brown trout and rainbow trout at the Little Colorado River confluence to assess their

respective levels of piscivory. Brown trout diets were found to mainly consist of fish,

including humpback chub. It is important to note that rainbow trout were also

piscivorous, but their levels are not as great as brown trout (Yard et al., 2018).

Looking at the NPS’s website for the incentivized harvest, they wish to reduce

brown trout numbers to pre-2014 levels. However, it is unclear what this number actually

is. The Environmental Assessment (EA) completed on the Expanded Non-Native Aquatic

Species Management Plan states that the NPS wants to see 25-50% of the current brown

trout population removed every year for the continuation of the harvest.

The first brown trout at Lees Ferry were discovered in 1984 by the Arizona Game

and Fish Department (AZGFD). Up until that year, there were no findings. 2012 resulted

in a catch per unit effort (CPUE) of 0.35 (Runge et al., 2018), which is a good

representation of brown trout catch rates beginning in 2000. Catch rates began to increase

significantly starting in 2014. While there is no distinct number of brown trout that the

NPS wants to see, one can speculate that they wish to see CPUE similar to 2012 and

prior.

Due to the current knowledge that brown trout could potentially migrate

downstream and prey on humpback chub, the NPS wants to reduce their numbers in order

to protect the chub and other native species, as well as to preserve the rainbow trout

fishery.

3.5 Environmental Assessment. The EA on the Expanded Non-Native Aquatic

Species Management Plan in Glen Canyon National Recreation Area and Grand Canyon

National Park below Glen Canyon Dam contains all information regarding the potential

impacts of all removal strategies on the Colorado River ecosystem. There are many

potential management strategies listed in the EA that fall under five categories: targeted

harvest, physical controls, mechanical controls, biological controls, and chemical

controls. Each management strategy is also categorized based on risk using a tiered

method. A Tier 1 strategy is least intensive and is non-lethal or can have beneficial use.

An increase in tier number corresponds to an increase in intensive management. The

incentivized harvest is categorized as Tier 1.

3.6 Timeline of Events. There are two separate timelines I will discuss in this

section. The first is not directly related to the brown trout incentivized harvest, and will

be briefly touched on, but includes important information for understanding some of the

programs and groups that have been formed in order to address issues relating to

humpback chub and nonnative species. The second timeline focuses on the incentivized

harvest.

3.6.1 Beginning with the Dam. After the dam’s completion in 1963, there was

federal and public concern regarding how the dam was impacting resources downstream.

The Department of the Interior and the Bureau of Reclamation put together an

environmental impact statement (EIS) on the operation of Glen Canyon Dam. In 1995,

the Final EIS Operation of Glen Canyon Dam was released, which analyzed its impacts

on environmental and cultural resources. An important takeaway from this EIS is it notes

that nonnative trout do have a negative impact on humpback chub. The dam itself is also

another reason for their decline. The EIS focuses on flows from the dam and how those

flows could potentially be managed to reduce the number of nonnative trout.

In response to the Final EIS Operation of Glen Canyon Dam, the Glen Canyon

Dam Adaptive Management Program (GCDAMP) was created to study and analyze the

concerns from the EIS. The GCDAMP is responsible for implementing the Grand

Canyon Protection Act of 1992, which states that Glen Canyon Dam must be operated in

a way to “protect, mitigate adverse impacts to and improve the values for which Grand

Canyon National Park and Glen Canyon National Recreation Area were established.”

Since the EIS, there have been several programs in place to reduce the number of

nonnative fish in the mainstem Colorado River, as well as its tributaries. In 2011, the

Bureau of Reclamation prepared the Non-Native Fish Control Downstream from Glen

Canyon Dam. The goal was to reduce impacts of nonnative fish on humpback chub,

as well as their habitat. Some of the actions proposed in this program included reducing

emigration of brown trout and rainbow trout from their source populations. It also

mentioned electroshocking parts of the river to remove nonnative fish. The Bureau of

Reclamation recommended that this project continue from its start in 2011 until 2020.

After the 2011 program came the Comprehensive Fisheries Management Plan

(CFMP). Proposed by the NPS in 2013, it lists goals to maintain a thriving native fish

community and to maintain the recreational rainbow trout fishery at Lees Ferry.

There were several alternatives listed in the EA, but Alternative 2 was the favored

strategy. It included translocation of humpback chubs to other tributaries, encouraged the

public to harvest any nonnative fish caught, detection monitoring, and nonnative fish

removal trips.

After the CFMP came the Glen Canyon Dam Long-Term Experimental

Management Plan (LTEMP) in 2016. This plan outlined how the dam and the river would

be managed over the next twenty years. The NPS and Bureau of Reclamation are the

agencies leading this program. To summarize, there were several alternatives listed for

how to manage flows from the dam to conserve resources downstream of Lees Ferry.

The current program that this thesis focuses on is the 2018 Expanded Non-Native

Aquatic Species Management Plan, where a harvest is first mentioned. The NPS is the

lead agency of this program. The goals are to “prevent, control, minimize, or eradicate

potentially harmful nonnative aquatic species.”

3.6.2 Start of the Harvest. As mentioned in section 1.3, beginning after 2014 is

when an increase in brown trout numbers was noticed. In response to this increase, the

GCDAMP and the Adaptive Management Work Group called upon the NPS and other

cooperating agencies to hold a workshop in order to determine causes for the brown trout

increase, as well as possible management strategies and their potential impacts. This

workshop took place in 2017. Some of the management options listed in the workshop’s

whitepaper included mechanical removal (electroshocking), brown trout angling

regulations, management flows, and stocking YY brown trout. The information in this

whitepaper contributed to the framework of the 2018 “Brown Trout in the Lees Ferry

Reach of the Colorado River - Evaluation of Causal Hypotheses and Potential

Interventions” from Runge et al.

The paper by Runge et al. goes further in depth about what form an incentivized

harvest would take. They mention that, through education and outreach, a harvest could

gain more support from anglers for harvesting nonnative fish. An incentivized harvest is

one of the six potential management strategies listed and evaluated in their report.

The Expanded Non-Native Aquatic Species Management Plan EA evaluates the

proposed action for managing nonnative species. They have been categorized in a tiered

approach, with the incentivized harvest classified as Tier 1.

An increase in brown trout raises concern for the humpback chub’s continuation

in the Colorado River. While brown trout could pose a major threat to these fish, it is

important to discuss how trout ended up in the Colorado River as they are not native to

this area. Humpback chub in the Colorado River have not only faced predation from

trout, but also habitat loss from Glen Canyon Dam.

Chapter 4. HOW DID WE GET HERE?

The problems have been outlined and solutions are already in place. But how did

we end up in this situation? Trout are not native to the Colorado River systems, so how

did they get there?

4.1 Glen Canyon Dam. Traveling up the Lees Ferry Reach is quite simple if you

have access to a boat. At the Lees Ferry Boat Ramp, you will launch your boat into fast-

moving water that has little to no turbidity and will also be fairly cold (depending on the

time of year). Approximately 14 miles up the river from the boat ramp, you will arrive at

Glen Canyon Dam. Construction of Glen Canyon Dam began in 1956 and was finished in

1963 (“Glen Canyon Unit,” n.d.). If you were to travel to Lees Ferry before 1956, the

Colorado River would be unrecognizable.

Available temperature data for Lees Ferry dates back to 1991 and is shown in

Table 2

. The second line of the table, CRLF, is data at Lees Ferry. The average lowest

temperature is 44.7 degrees Fahrenheit, while the average highest temperature is 61.7

degrees Fahrenheit. Since 1991, we can see that temperature throughout the year does not

greatly fluctuate.

CRBD: Colorado River Below the Dam

CR030: Colorado River Mile 30

CR033: Colorado River Mile 33

Table 2. Voichick, N., & Wright, S. (2007). Water temperature data at several river sites. Crlf is Colorado River Lees

Ferry. Based on hourly averaged data. USGS. Retrieved from https://pubs.usgs.gov/ds/2007/251/ds-251.pdf.

Looking at available temperature data at Lees Ferry before the creation of Glen

Canyon Dam shows that it is quite different from the range of current temperatures.

Figure 2 before 1963 has a much greater variation in temperatures. Lowest temperatures

approached 32 degrees Fahrenheit and the highest temperatures were around 82 degrees

Fahrenheit.

Figure 2. Historic water temperature (degrees Celsius) data at Lees Ferry.Voichick, N., & Wright, S. (2007). Daily

water temperatures measured or calculated at the Usgs' stream gage located at Lees Ferry 1949-2005. USGS.

Retrieved from https://pubs.usgs.gov/ds/2007/251/ds-251.pdf.

Turbidity can help to paint a picture of what the Colorado River looked like

before and after Glen Canyon Dam. Figure 3 shows daily average turbidity at Lees Ferry

through 2016. Pre-dam turbidity data was estimated from known data. There is a large

difference in the level of turbidity pre and post Glen Canyon Dam. The Colorado River

used to be very turbid. Native fish have adapted to and thrived in these conditions for

millions of years. The creation of the dam, which greatly reduced turbidity, is one reason

why humpback chub faced extinction.

Figure 3. Voichick, N., Kennedy, T., Topping, D., Griffiths, R., & Fry, K. (2016). Lees Ferry daily mean

turbidity during 2016. Also shows pre-dam turbidity from other known data. USGS. Retrieved February 6, 2023, from

https://pubs.usgs.gov/fs/2016/3053/fs20163053.pdf.

4.2 Fish Species. Humpback chub are Colorado River natives that have been in

the river system for over three million years. This warm water fish species grows to be

around eighteen-inches long on average and weighs roughly 2.6 pounds. Their diets are

varied, consisting of insects, crustaceans, plants, and occasionally small fish (USFWS,

n.d.). They are a warm water species and require temperatures over 60 degrees Fahrenheit

in order to spawn (National Parks Conservation Association, n.d.).

Brown trout are native to Europe and West Asia and have been introduced across

the United States. As mentioned earlier, they were first introduced to the Grand Canyon

water systems in the 1920s. They range widely in size, some being over twenty-four

inches. They are a coldwater species, but can tolerate warmer temperatures compared to

other trout species (Fuller et al., n.d.). They consume insects and are opportunistic feeders

of other fish. As they grow older, they are more likely to feed on other fish as their main

source of food (“Brown Trout,” n.d.). These fish are commonly found in waters that

range from 41 degrees Fahrenheit to 77 degrees Fahrenheit (Fuller et al., n.d.).

Rainbow trout are a freshwater fish that thrive in colder temperatures. They are

native to North America, but were first introduced to Arizona in 1880. Their diet consists

of both aquatic and terrestrial invertebrates and they also occasionally eat small fish and

eggs. They have a pink lateral line with green and white scales, giving them an almost

“rainbowlike” appearance (USFWS, n.d.). Their optimum temperature range is between

50 and 60 degrees Fahrenheit (Piper et al., 2010).

4.3 Fish Stockings. Now it is easier to understand the conditions of the Colorado

River before and after Glen Canyon Dam. The highest temperatures of the Colorado

River would not have been suitable for trout, as they are cold water fish. The dam made it

possible for trout to exist at Lees Ferry. However, trout have been stocked long before

Glen Canyon Dam into tributaries below the Lees Ferry Reach. The species that have

been stocked into Lees Ferry and Colorado River tributaries are Westslope cutthroat trout

(Onchorhynchus clarkii lewisi), brook trout (Salvelinus fontinalis), sockeye salmon

(Oncorhynchus nerka), coho salmon (Oncorhynchus kisutch), and cutthroat trout

(Oncorhynchus clarki).

The first documented trout stockings in the Grand Canyon occurred in 1922.

Brown trout were backpacked into Bright Angel Creek, which is a tributary to the

Colorado River located roughly ninety miles downstream of Lees Ferry (U.S. Department

of the Interior, 2022). This was decades before the creation of Glen Canyon Dam, so the

Colorado River itself was still muddy and turbulent; not ideal for trout, but Bright Angel

Creek provided a suitable coldwater habitat. This creek is also a spawning location for

several of the Colorado River’s native species, such as the Flannelmouth Sucker and the

Blue Sucker (U.S. Department of the Interior, 2015). Having new species introduced into

these spawning habitats created additional competition.

While rainbow trout and brown trout are currently the only trout species in the

Colorado River and surrounding tributaries, the NPS as well as the AZGFD

experimentally stocked other species of trout in the early 1900s. A Grand Canyon trout

stocking program began in 1922 and was concluded in 1930. Five creeks were stocked

with rainbow trout, brown trout, Westslope cutthroat trout, and brook trout (Brooks,

1931).

After the completion of Glen Canyon Dam in 1963, the temperature of the

Colorado River dropped to where trout would be able to survive. The AZGFD began

stocking several different species into the Lees Ferry Reach for recreational purposes.

Rainbow trout, sockeye salmon, coho salmon, brook trout, and cutthroat trout were

stocked between 1964 and 1998. All species except for rainbow trout were stocked one

time, with rainbow trout being stocked regularly until 1998 when these fish were able to

reproduce naturally (Runge et al., 2018). The AZGFD, as well as the Glen Canyon

National Recreation Area have been studying and managing this population of rainbow

trout in order to create a blue-ribbon rainbow trout fishery (“Nonnative Fish,” 2022).

With the drastic change in the Colorado River environment, the brown trout that

were stocked into Bright Angel Creek have since been able to disperse into the main stem

of the river and travel the ninety miles to Lees Ferry. With an abundance of food in this

area, brown trout have been able to spawn and increase in numbers at this section of the

river.

The Colorado River is now more suited for trout than for warm water species such

as the humpback chub. With the current water conditions, it will be difficult and

potentially impossible for humpback chub to return to their native range.

Chapter 5. DISCUSSING THE PROBLEM

5.1 The Idea of Nativeness. When reading the NPS website regarding the

incentivized harvest, you will see the terms “native” and “nonnative.” What do these

titles really mean? Nativeness is associated with a sense of belonging, but there is no

agreed upon meaning of the word.

It is difficult to find a universal definition of “native.” A quick online search

defines ‘native’ as “a species that arrived in a habitat naturally, without the aid of

humans” (Bialowas, n.d.). However, the answer is more complex than this. There are

many factors to consider when deciding if a species is native. Ken Thompson discusses

the first uses of the word ‘native’ in his book Where Do Camels Belong? The Story and

Science of Invasive Species. One of the first definitions comes from H.C. Watson who

was a botanist from the mid-nineteenth century. He used the term to describe plants that

were an aboriginal species with no human introductions. But there are possible

exceptions to this definition. Some species that were once native to an area have gone

extinct and then later reintroduced through human intervention. This human intervention

contradicts our previous definition that a species is native if they have not been

introduced (Thompson, 2015). Does this make them nonnative even though they were

native at some point in history?

Some also define native species as those that evolved in a given area (i.e. the

humpback chub having evolved in the Colorado River). However, a species could also be

native if it evolved elsewhere but ended up in a new area without human intervention

(Simberloff, 2013). Human intervention seems to be a key factor.

To add another possible definition, Carthey and Banks (2012) bring to our

attention the possibility of an alien being able to become native. They say that native

wildlife are often naive regarding the predatory nature of introduced animals since they

do not know anything about them. This naivete could be a factor in determining if a once

alien species can become native. It is important to note that this only really applies to

prey species. The authors argue that once native prey species have learned that an

introduced species is bad, the introduced species then becomes native.

Going back to the idea of belonging, Chew and Hamilton (2010) raise questions

about what it means not only for something to belong, but to not belong. They mention

the case of the northern snakehead, where eradication efforts (as we have seen in Part I)

are underway in the U.S. because these fish are labeled as alien. Originally from Asia,

these fish have been brought to America and have been released into Maryland water

systems. If we say that these fish belong in Asia, are we talking about the habitat they

have evolved in? What if their habitat in America is very similar if not the same to their

habitat in Asia? It seems like when we say something does not belong, we are referring to

where they are located geographically. However, their habitats in these different

continents could be very similar. One could then argue that these fish belong in the U.S.

because they belong in this type of habitat.

The purpose of this section is not to go in-depth about defining the word ‘native.’

It is important to acknowledge that while this word does not have a concrete definition, it

is still used to persuade people to look at different populations of animals a certain way.

‘Nonnative’ and ‘invasive’ have a negative connotation. Many label animals as these

terms to justify removal efforts, often before fully understanding the impacts these

animals really have on their ecosystem.

5.2 Colorado River Life After the Dam. Humpback chub are native to the

Colorado River that was known for high turbulence and widely varying temperatures. A

large reason for their decline is Glen Canyon Dam and how it modified their environment

into something completely different. Their habitat was lost and a new one was made

which suited nonnative trout. What it really comes down to is that humans have created a

new environment that is not as suitable for native fish as it is for trout, whether this was

intentional or not. Before 1924, the only fish species one would find in the Colorado

River and tributaries would mainly be suckers and chubs.

5.3 Issues. There are other removal efforts that could have been done besides an

incentivized harvest; one of them being to repeatedly electroshock the entire Lees Ferry

Reach. One major reason why this has not been done is that Native American tribes in the

area, such as the Pueblo of Zuni, are against the mechanical taking of life. The Pueblo of

Zuni has spiritual connections to aquatic species. This is one reason why shocking the

river to remove brown trout has not been done (Runge et al., 2018).

Shocking the river does not only affect one species; all fish, insects, and other

organisms in the river are hindered by this type of management effort. There are several

fishing guide services who take anglers fishing at Lees Ferry. Repeatedly shocking the

river would make Lees Ferry unfishable for extended periods of time. Electroshocking is

likely to cause hemorrhaging (Walsh et al., 2004) and potentially lead to some mortalities

(Habera et al., 1996). While death is not a common outcome of electroshocking, guides

are still concerned that repeated shocking will stress the rainbow trout to the point where

it becomes incredibly difficult to fish for them.

From an angler perspective, opinions of managing trout are across the board. The

NPS sought public comment on their Expanded Non-Native Aquatic Species Plan in

2017. They received a total of 422 responses that consisted of individual comments,

comments from different environmental and angling groups, and comments from federal

agencies and stakeholders. Out of these comments, 219 noted that they (being both

individuals and groups as well as agencies) are against electroshocking Lees Ferry which

is one of the proposed management strategies to remove brown trout. 185 comments were

against any kind of trout removal. Out of these 185 comments, there were numerous

responses from anglers who enjoy catching brown trout and do not want to see them

removed. Many have also noted that these fish bring in people from all over the world to

fish here which supports the local economy. Not only do people enjoy brown trout for

their intrinsic value, they also see an economic benefit from them as well.

However, 31 comments supported some kind of encouraged take of nonnative

trout, whether this be a bounty or getting rid of limits on the amount of brown trout an

angler can keep. Not only was there some initial support regarding an encouraged take,

we can look at how many anglers have participated in the bounty since it began. From

November 2020 to June 2023, a total of 836 anglers have turned in brown trout. On the

NPS’ website for the incentivized harvest, they also list the top ten anglers of 2021.

Angler #1 has caught a total of 53 fish and made $3,841. Although we may not know

exactly how the anglers who participated feel about the bounty, they have still

participated in the program and therefore can assume that there is support for its

continuation.

5.4 Current Bounty Numbers. As of June 2023, a total of $410,743 has been paid

out to 836 anglers. A total of 5,237 brown trout have been removed with over half of

those fish (3,226) being between twelve and eighteen inches.

5.5 Bounty Efficacy. As the brown trout incentivized harvest is still taking place,

it is difficult reach a conclusion regarding its effectiveness. The graph below is

unpublished data from the AZGFD. It shows a significant increase in the CPUE of brown

trout since 2019. However, it is unclear if this increase is in response to the incentivized

harvest. The bounty could also not be working for several reasons. There could be low

participation, ideal spawning conditions from high flow events, plenty of food (rainbow

trout), and slightly warmer temperatures.

Figure 4. Brown Trout CPUE by season at Lees Ferry. Graph from AZGFD. Unpublished data.

If the bounty does not work, the next step taken by the NPS will be to repeatedly

electroshock Lees Ferry. Based off the graph, it appears that the incentivized harvest may

not be reducing the number of brown trout that the NPS wants to see. This action will

most likely face more backlash than it already has. While the NPS has attempted to try

other removal strategies than electroshocking, it may have to be done.

PART III. ETHICS

Chapter 6 – ETHICAL ARGUMENTS

6.1 Introduction of Ethical Arguments. Animals having their own rights is not a

new idea. However, this idea is more complicated than simply saying that animals have

rights. There are many different theories regarding to what extent having rights means

when it comes to nonhuman creatures. For this project, I will be focusing on Martha

Nussbaum’s Capabilities Approach (CA).

Before diving into Nussbaum’s ideas, I would like to discuss a few ethical

theories that can be applied to animal rights and why I am not focusing on them. The first

theory that is not specifically about animal rights, but can be applied, is ecoholism. The

ideas of ecoholism place emphasis on populations, species, and communities over the

value of the individual. Aldo Leopold, in his book A Sand County Almanac includes a

discussion of the land ethic which is an example of this theory. Species have a biotic right

to continue their existence, as they are important to their environment.

“Any credible variety of ecoholism must contain rules that are weighted in favor

of ecosystems and species” (Gendin, 1988). This theory is not inclusive in the sense that

emphasis is placed on the species or the population as a whole. In the case of natives

versus invasives, I think an individualistic approach would be more inclusive. Labeling

an entire group can be very harmful. In the case of the humpback chub and the brown

trout, ecoholism could argue that protecting humpback chubs is more important because

they are a native species. Native species are valued more in some parts of society.

Another is utilitarianism. According to this theory, “utilitarianism is generally

held to be the view that the morally right action is the action that produces the most good

(The History of Utilitarianism, 2009).” It is a form of consequentialism since

consequences of outcomes are evaluated. In this theory, whichever outcome produces the

most good or the most happiness is the right outcome. The interests of all parties are

considered equally important. These will be analyzed to determine which outcome

delivers the greatest amount of happiness when deciding.

The main reason why I am not taking a utilitarian approach regarding the Lees

Ferry incentivized harvest is due to the fact that a group of animals must be harmed if it

maximizes overall good. In this case, it would seem justified to harm brown trout in order

to save native fish. Humpback chub are also protected under the Endangered Species Act,

so this could be another justification as to why it's okay to do whatever necessary to

protect them. Utilitarianism sees all parties’ interests as equal (Beauchamp et al., 2013).

However, compared to Nussbaum’s theory, “the CA does not single out human moral

powers as more crucial than other aspects of animal living…” (Nussbaum, 2022) as

utilitarianism does. In her chapter regarding utilitarianism, Nussbaum points out some of

the positives of this theory, such that creature’s interests must be treated equally, even

though the interests themselves may differ. While she does not discredit the theory,

Nussbaum believes there is more to animals than their abilities to feel pain and pleasure.

Utilitarians see animals as a means to an end.

Animal Rights Theories (ARTs) are just as the name suggests: animals are

entitled to rights. Within ARTs, there are several supporting theories that explain the

extent to which animals have rights. Tom Regan, in his book A Case For Animal Rights,

makes the argument that animals who are subjects of a life have inherent value and

therefore should have respectful treatment. An animal who is a subject of a life is able to

have welfare interests, beliefs and desires, perception, as well as the ability to pursue

their desires and goals (Regan, 2010). He makes a distinction between moral agents and

moral patients; moral agents are accountable for their actions as they have sophisticated

abilities, while moral patients lack this. But both deserve respectful treatment.

I do think that Regan’s theory could be useful for discussing the Lees Ferry

Incentivized Harvest, since he does agree that moral patients should be treated with

respect. However, Nussbaum’s theory builds much more on this by defining to what

extent and what kind of rights animals are owed.

6.2 Capabilities Approach. Martha Nussbaum has built upon the Capabilities

Approach that describes human rights by defining her central capabilities. However, she

also uses the Capabilities Approach to defend the rights of animals. To understand her

way of thinking, I first want to describe it in terms of human rights as she does in

Creating Capabilities.

The central idea of the Capabilities Approach is flourishing. Humans have the

right to flourish because they are creatures with dignity. Flourishing looks different to

each individual. It is things that we have access to and can act upon that allow us to live a

good life. The ten central capabilities (discussed later) that Nussbaum describes are

things that allow a life to be worthy of human dignity. Working through an example

might help us to better understand flourishing. Let’s look at exercising. We know that

exercising helps us to be healthy and have fewer health-related problems later in life.

However, an individual might not want to exercise and they have a right not to do so. All

of a sudden, if the government starts forcing every person to exercise, the right of people

being able to make their own decisions is taken away. Choosing to exercise allows us to

flourish; not exercising is not flourishing. But, if exercising is something an individual

wants to do, then they should be able to do so. If an individual does not want to exercise,

they should also be able to do so. Having the ability to choose is what’s important. When

it comes to a life worthy of human dignity, respect is important. Another example that

involves animals would be a fish having access to a habitat that is within their optimal

temperature range, gives them the ability to move freely, and interact with their own

species. This must be provided for the fish and should not be infringed upon. However,

the fish can choose to be in a habitat that is not suitable and would not make them

flourish. They get to make that choice, as long as the opportunities are provided.

Humans have dignity. Each of us, from an individual standpoint, should have the

rights and freedoms to flourish and live dignified lives. When Nussbaum talks about a

life worthy of human dignity, that is recognizing that we all have capabilities which

should not be taken away. We must respect every individual as they are worthy of equal

respect. We may not all act in the same way, but we must have the freedom to make our

own choices as we have the ability to act upon different capabilities.

Recognizing that a life is worthy of human dignity also involves seeing people as

an end and not a mere means to an end. The distinction between the two is that being an

end means that a person has rights that should be respected while being seen as a mere

means to an end is someone using them to get something they want. While a server at a

restaurant is a means to getting your food, they have their own lives outside of the

restaurant. The functionings that they partake in allows them to flourish in their own way.

This makes them an end and they deserve respect.

There are three important factors involved in the Capabilities Approach:

functioning, capability, and flourishing. These three factors relate to each other but are

different. A function is realizing what we are capable of. For example, health is a

function. Capabilities are “...a set of (usually interrelated) opportunities to choose and to

act” (Nussbaum, 2013). Capabilities might seem like abilities, but they are more than

that. They are also “the freedoms or opportunities created by a combination of personal

abilities and the political, social, and economic environment” (Nussbaum, 2013).

Functions are what we do in response to realizing capabilities or acting on these

capabilities.

A good way to view Nussbaum’s Capabilities Approach is to think of flourishing

as an umbrella and dignity, being an end, and having rights fall under the umbrella.

Dignity is a very important aspect of the Capabilities Approach, and having dignity leads

to a right to flourish. Now that we have discussed the Capabilities Approach, we can look

into Martha Nussbaum’s ideas and what kinds of rights sentient beings have. When

framing her Capabilities Approach, Nussbaum describes ten specific requirements of a

life for human dignity. I will not be going into great detail about each, but will explore

some of these requirements when discussing animal rights. The ten requirements are life,

bodily health, bodily integrity, senses and imagination and thought, emotions, practical

reason, affiliation, other species, play, and control over one’s environment. These central

capabilities are rights every individual has that should never be taken away or limited.

These rights should be guaranteed for all and need to be respected when a government is

making decisions that could impact the livelihoods of its citizens. Having a definitive list

of capabilities is incredibly important for decision makers so they do not have to infer

what kind of rights everyone is entitled to. Instead, they are laid out and constitutions can

be written in respect to these rights.

6.3 Animal Rights and the Capabilities Approach. Many of us recognize that

animals are sentient beings. Nussbaum argues that animals have dignity and are

deserving of the rights that allow them to flourish (in their own ways). Humans should

make a commitment to animals to protect their rights and to respect them as dignified

creatures. Animals are not simply a mere means to an end. They too have capabilities and

can act upon them accordingly. Humans often feel obligated to protect animals, as we

look at them with a sense of wonder and see creatures worthy of respect. While we may

not agree as to what extent to offer this protection, the Capabilities Approach can ensure

that individual lives are respected.

The ten requirements that Nussbaum has listed for her Capabilities Approach

regarding human lives also apply to animal lives. Some of the requirements seem quite

obvious for animals, such as living a life that is of normal length, not being subjected to

unnecessary killing (i.e. for clothing), and being able to live with other species. A few of

her requirements, however, might not seem on the same level as humans and for these

she goes into greater detail. It might be difficult to comprehend when she says that

animals have a right to senses, imagination, and thought. How can animals have such a

complex way of thinking? Compared to some animals such as primates and elephants

who we know have complex brains, it might not make sense to say that a fish or a bird

has these same rights. Senses, imagination, and thought include things like acting in ways

that bring animals pleasure as well as freedom to move wherever they please. Confining

animals or taking away parts of their environment that they enjoy would be taking away

this right. This is a big issue in zoos. Zoo staff will combat this by offering enrichment

opportunities that would mimic an animal’s natural environment. Another requirement

that is difficult to understand in terms of animals is affiliation. Nussbaum defines this as

animals having the right to form bonds and different kinds of relationships. It also has to

do with forming relationships with humans (i.e. domesticated animals such as dogs

needing to be cared for and wanting to be around humans).

In Chapter 6 of Justice for Animals, Nussbaum takes on the issue of determining

if fish are sentient beings. As previously explained, sentient creatures are subjects of a

life who are capable of emotions and acting on their capabilities. She outlines the

“standard animal package” which is the requirements for an animal to be a “subject of a

theory of justice.” The qualities of the standard animal package are sentience, emotion,

cognitive awareness of objects, and movement towards the good and away from the bad.

Nussbaum concludes that “Fish, as we’ve seen, are definitely sentient creatures, and

beyond that, creatures of striving and flourishing, creatures to whom my theory applies”

(Nussbaum, 2022).

Nussbaum goes on to discuss the interruption argument from Utilitarians which is

when an animal dies or their life is interrupted before adult functioning is reached.

Animals can be aware of their development. However, she claims that this does not

extend to fish because “they live in a perpetual present with no prolonged projects to be

interrupted…” Fish will only be wronged if they experience a painful death or do not get

to reach maturity. If they get killed humanely, then that will not wrong them.

I disagree with this argument. If fish are creatures in which the Capabilities

Approach extends to, it seems hypocritical to justify killing them. One of the most

important things that fish do is spawn. Salmon spawn once and then die, so they must be

able to reach maturity in order to spawn. Other fish, such as Gila Trout, can spawn

multiple years. Would it be okay to let them spawn once and then kill them? There would

seem to be a gray area in determining when it would be acceptable to end their lives. It is

also difficult to ensure that they die a painless death. Getting struck in the head with some

kind of mallet is one way to have a quick death, but the person might not use enough

force and cause the fish to suffer. If the Capabilities Approach applies to an animal,

killing should not be justified. A fish needs to reach maturity and to spawn in order to

flourish. This is part of their reproductive rights.

Extending the central capabilities to nonhuman creatures is an important way to

explain what kind of rights they are entitled to and how this will influence decisions.

Things like habitat modification and animal research will need to make sure that they are

implemented in a way so that these rights are not being violated.

To summarize, animals are creatures that deserve to live a dignified life. Just like

humans, they are capable of living dignified lives which in turn gives them the

opportunity to flourish. Flourishing to an animal may not look the same as human

flourishing, but nonetheless they are still entitled to this right. Applying the ten central

capabilities will make sure that their rights are recognized and protected.

Chapter 7 – THE CENTRAL CAPABILITIES

7.1 Applying the Central Capabilities. While humpback chub and brown trout are

both fish, their requirements for flourishing are different. Humpback chub are a warm

water species and have evolved in turbulent, fast-moving water. They also need cooler

temperatures from tributaries to spawn. Brown trout live in cold temperatures, and need

these cold temperatures to spawn. A few similarities that these two species share for

flourishing are the capability to move freely and interaction with other members of their

species.

I will now use Nussbaum’s improvements to the Capabilities Approach to discuss

the Lees Ferry Brown Trout Incentivized Harvest. This is one way we can evaluate the

ethics of this bounty program. To do this, I would like to look at the central capabilities

with regard to both the humpback chub and the brown trout.

Brown Trout. As brown trout are the ones being targeted by the bounty, there are

many rights that are being violated. Let us look at the capabilities that are potentially

being violated;

1. Life. Animals have a right to continue living their lives. However, there are some

gray areas regarding killing animals for population control which is happening at

Lees Ferry. If these killings were painless, we could argue that naturally they

would die a painful death so ending their lives before they could be harmed by

other animals or starvation could be justified. However, we do not really know

how these fish are being killed. Often when anglers keep fish they will attach

them to a stringer until they die of stress, hit them on the head with a rock (this

could be a quick and painless death if done correctly), or throw them into a

container while they are alive. If all anglers killed them quickly and painlessly,

then Life would not be violated. However, this is not the case.

2. Bodily Integrity. “Animals have direct entitlements against violations of their

bodily integrity by violence, abuse, and other forms of harmful treatment…”

(Sunstein et al., 2006). Placing a bounty on an animal instantly subjects them to

harm. Even if the reasons seem justified, the fact is brown trout are still being

killed. And, as mentioned in the first capability about life, they may be killed

inhumanely.

3. Emotions. Fish are capable of feeling fear. They see people or predators and will

quickly swim away. Being pulled out of the water onto land where they cannot

live for very long can be quite stressful. Then, there’s being thrown into a cooler

or placed on a stringer. Left to die a prolonged death, their right to having their

emotional needs (not feeling fear) are not met.

4. Affiliation. Brown trout are entitled to be able to form relationships with both

animals and humans. At the bare minimum, they must be protected from

humiliation. The bounty can be a cause for humiliation. These fish, who were

simply living their lives, are now seen as bad because of humans. While fish do

not know that they are being humiliated, the bounty is still violating them by

making them a target.

5. Other Species. Animals have the right to live with other species (even predators)

and are allowed to live cooperatively with them. Brown trout and humpback chub

have been in the same ecosystem since 1924.

6. Control over One’s Environment. For humans, this right is defined in material and

political terms. For nonhuman animals, it has to do with a political justice that

treats animals with respect. It also involves respecting territory. The bounty does

not treat brown trout with respect as they have been labeled as ‘invasive’ which

makes people dislike them and want them gone. Again, fish have no perception of

respect but being labeled as invasive makes them a target for anglers.

The incentivized harvest on brown trout violates six out of the ten central

capabilities. Even violating one of these violates the rights that brown trout have to live a

dignified life. While the bounty may seem justified in its reasoning, brown trout are still

being harmed. From a utilitarian standpoint, killing brown trout might seem like the best

outcome to save the humpback chubs. However, looking at Nussbaum's approach, we do

not rank outcomes. All animals have rights and deserve to be treated with respect.

The reason for wanting to remove brown trout from Lees Ferry is fear that they

will lead to humpback chub going extinct. However, we know that predation has only a

small impact on why they became endangered in the first place. The major reason has to

do with Glen Canyon Dam. Let us look at how changing the chub’s environment violated

their rights by taking the same approach that we did for brown trout:

1. Life. Humpback chub are warm water fish. Suddenly living in much colder

temperatures is a major stressor. If they were not able to find somewhere tolerable

to live, death would follow. If the dam were not built, this would never have been

an issue.

2. Bodily Health. This includes reproductive health. Humpback chub spawning is

dependent on temperature; they need warmer temperatures for the process to

begin. The now colder water limited the areas in which they could spawn.

3. Bodily Integrity. Being able to move freely falls under bodily integrity. The dam

limited where these fish were able to go by regulating the amount of water now

available as well as changing the temperature.

4. Practical Reason. Although to different extents, sentient beings are able to form

goals and plan their lives. They may not be consciously aware of these plans, but

still have a right to live the life of a fish. The dam made this far more difficult

than in their natural habitat.

5. Other Species. There are other warm water fish species in the Colorado River.

The new temperatures had a drastic effect on them as well. These two species

would now have to fight for space and form negative relationships with each

other.

Glen Canyon Dam has violated five out of the ten central capabilities. While there

are other factors that impacted their numbers, the fact that their natural environment is

gone is major.

7.2 Discussion. Now that we know both of these populations have been wronged

in some way, is the NPS taking the most ethical actions? The bounty obstructs six of the

brown trout’s central capabilities. This in itself is wrong, according to the Capabilities

Approach. Killing, from the perspective of the NPS, must be justified then if it means

‘saving’ a native population. The NPS has a duty under the ESA to protect the humpback

chub population. This must outweigh their wellbeing over brown trout. However, just

because it is justified does not mean it will do no harm. What we can do versus what we

should do are completely different. Brown trout are only a sliver of the humpback chub’s

story and why they are listed as endangered.

Nussbaum argues that violating even one of these rights is unacceptable. Both

humpback chub and brown trout have also had their rights violated. Their circumstances

are a bit different. The chub’s rights were violated by the completion of Glen Canyon

Dam. They do face predation from nonnative trout species, but the dam is the major

reason for their decline; these nonnative trout species would not be able to survive in the

Colorado River with no dam. Removing the dam would be the best way to restore their

habitat while making the Colorado River unsuitable for trout. This is very unlikely to

happen, as several states rely on Glen Canyon Dam for hydroelectric power. On the other

hand, brown trout are being wronged by the incentivized harvest. They are being killed

for simply living.

Is there a right decision? Killing brown trout is unethical. But what if brown trout

do become a huge issue for the chubs? Do we owe it to the chubs to make sure they have

the ability to flourish since we took their natural habitat away? It is very difficult to

answer these questions. If we even attempt to do so, one of these groups will be wronged.

This leads us to discuss tragic moral conflict. There is no perfect solution, and we might

have to make decisions that we do not fully support. One way to combat this would be

taking a slight utilitarian approach since some kind of decision has to be made. A list of

choices could be made and the one that violates the least number of rights could be the

right decision. This is called tragic conflict, where an individual or population will be

harmed no matter the choice.

7.3 Conclusions. In the situation at Lees Ferry, it is difficult to determine which

action is the best. Killing brown trout could potentially keep the humpback chub from

facing more predation. But placing a bounty on brown trout is taking away their right to

flourish by causing potentially painful and early deaths. However, the chubs are also

being wronged in several ways, all of which are due to Glen Canyon Dam.

There are several options; continue with the harvest, remove the dam, or do

nothing. Continuing with the harvest will continue to wrong the brown trout, but could

reduce potential predation on the humpback chub. Removing the dam would be extreme,

but that could restore the Colorado River to its original state. This would be ideal for the

chubs and would prevent trout from being able to survive, but would be very expensive

and reduce power for millions of people. Doing nothing could result in several things.

There would most likely be an increase in brown trout. However, it is unclear at what

point they would begin to move downstream. And if they did, how long it would take

them to cover the 60 miles to where the humpback chub are. Doing nothing could also

result in nothing happening. Perhaps the brown trout will never move

downstream. Or if they did, perhaps humpback chub numbers would not drastically

decrease.

The right choice in this situation, after analyzing it using Nussbaum’s theory,

would be the one that violates the least number of rights. Knowing all of the

uncertainties, it might be best to stop the incentivized brown trout harvest and see if there

really will be a problem. This does run the risk of brown trout establishing a population

in the same area as the humpback chubs. However, conservation actions such as

translocations have significantly help the humpback chub to increase their range. The use

of weirs or nets could be one way to prevent brown trout from reaching the chubs. It is

going to be very difficult to protect the humpback chub from predators that humans

introduced into a river that is no longer suitable for them. There is not a decision that can

be made in which all parties will have no rights violated; the right to flourish will be

taken away from some.

REFERENCES

Beauchamp, T. L., Frey, R. G., & Matheny, G. (2013). Utilitarianism and Animals. In

The Oxford Handbook of Animal Ethics. essay, Oxford University Press.

Bialowas, M. (n.d.). Native Species: Definitions and Examples.

https://study.com/learn/lesson/native-indigenous-species.html

Bright angel creek trout reduction project. National Park Service. (2015).

https://www.nps.gov/grca/learn/nature/trout-

reduction.htm#:~:text=Bright%20Angel%20Creek%20is%20now%20an%20important%

20spawning,of%20fish,%20and%20they%20preferentially%20consume%20native%20fi

sh.

Brooks, J. P. (1931). Official Report on Stocking Canyon Streams with Fish. In Nature

Notes - Grand Canyon (Vol. 5, p. 48). U.S. Dept. of the Interior, National Park Service.

Brown Trout incentivized harvest. (n.d.). https://www.nps.gov/glca/planyourvisit/brown-

trout-harvest.htm

Brown Trout. Glen Canyon Dam Adaptive Management Program. (n.d.).

http://gcdamp.com/index.php/Brown_Trout

Carthey, A. J., & Banks, P. B. (2012). When does an alien become a native species? A

vulnerable native mammal recognizes and responds to its long-term alien predator. PLoS

ONE, 7(2). https://doi.org/10.1371/journal.pone.0031804

Catch the ugliest fish in the West. Burbot Bash (ice fishing). (n.d.).

https://www.burbotbash.com/

Chew, M. K., & Hamilton, A. L. (2010). The rise and fall of Biotic Nativeness: A

historical perspective. Fifty Years of Invasion Ecology, 35–47.

https://doi.org/10.1002/9781444329988.ch4

Coyote Harvest Incentive Program. SCDNR - Wildlife - Coyotes Biology and Control

Program. (n.d.). https://www.dnr.sc.gov/wildlife/coyote/coyoteincentive.html

Dux, A. M., Hansen, M. J., Corsi, M. P., Wahl, N. C., Fredericks, J. P., Corsi, C. E.,

Schill, D. J., & Horner, N. J. (2019). Effectiveness of lake trout (salvelinus namaycush)

suppression in Lake Pend Oreille, Idaho: 2006–2016. Hydrobiologia, 840(1), 319–333.

https://doi.org/10.1007/s10750-019-3913-z

Endangered and Threatened Wildlife and Plants; Reclassification of the Humpback Chub

From Endangered to Threatened With a Section 4(d) Rule. (2021, October 18). Retrieved

January 8, 2023

Fuller, P., Larson, J., Fusaro, A., Mackled, T. H., Neilson, M., & Bartos, A. (n.d.). Brown

trout (Salmo trutta) - species profile.

https://nas.er.usgs.gov/queries/FactSheet.aspx?speciesID=931

Gendin, S. (1988). Animal rights and ecoholism are not compatible. Between the Species:

An Online Journal for the Study of Philosophy and Animals, 4(1).

https://doi.org/10.15368/bts.1988v4n1.5

Habera, J. W., Strange, R. J., Carter, B. D., & Moore, S. E. (1996). Short-term mortality

and injury of rainbow trout caused by three-pass AC electrofishing in a Southern

Appalachian Stream. North American Journal of Fisheries Management, 16(1), 192–200.

https://doi.org/10.1577/1548-8675(1996)016<0192:stmaio>2.3.co;2

Hampton, R. (2020). $20 for Northern Pike at Green Mountain and Wolford Reservoirs.

Colorado Parks and Wildlife.

https://cpw.state.co.us/Lists/News%20Releases/DispForm.aspx?ID=2773

Hay, A., Riggins, C. L., Heard, T., Garoutte, C., Rodriguez, Y., Fillipone, F., Smith, K.

K., Menchaca, N., Williamson, J., & Perkin, J. S. (2022). Movement and mortality of

invasive suckermouth armored catfish during a spearfishing control experiment.

Biological Invasions, 24(10), 3119–3131. https://doi.org/10.1007/s10530-022-02834-2

History of Lake Pend Oreille. Lake Pend Oreille Idaho Club. (n.d.).

https://lpoic.org/history/

Idaho Fish and Game. (n.d.). Angler Incentive Programs.

https://idfg.idaho.gov/fish/angler-incentives

Invasive carp in Tennessee, information and images. in Tennessee, Information and

Images. (n.d.). https://www.tn.gov/twra/wildlife/fish/invasive-carp/#concern

Invasive Carp Regional Coordinating Committee. (2021). Keep, Cool, Call. What to do if

you capture a black carp.

Leopold, A. C. (1966). A Sand County Almanac. O.U.P.

Lionfish Challenge 2023. Florida Fish And Wildlife Conservation Commission. (2023).

https://myfwc.com/fishing/saltwater/recreational/lionfish/challenge/

Miller, R. R. (1968). Freshwater Fishes. In Red Data Book (Vol. 4, Ser. Pisces). IUCN.

National Parks Conservation Association. (n.d.). Humpback chub.

https://esa.npca.org/humpback-chub/

Northern pike. CCT Fish & Wildlife. (n.d.). https://www.cct-fnw.com/northern-pike

Northern Pikeminnow Sport-Reward Program. Save a salmon (and make money doing it)

|. (n.d.). https://www.pikeminnow.org/background/save-a-salmon-and-make-money-

doing-it

Nussbaum, M. C. (2013). Creating capabilities: The Human Development Approach.

Belknap Press of Harvard University Press.

Nussbaum, M. C. (2022). Justice for animals: Our collective responsibility. Simon &

Schuster.

Piper, R. G., McElwain, I. B., Orme, L. E., McCraren, J. P., Fowler, L. G., & Leonard, J.

R. (2014). Broodstock, Spawning, and Egg Handling. In Fish hatchery management.

essay.

“Pup”ulation control contest back at Flaming Gorge. Wyoming Game and Fish

Department. (2020). https://wgfd.wyo.gov/Regional-Offices/Green-River-Region/Green-

River-Region-News/Pup%E2%80%9Dulation-Control-Contest-back-at-Flaming-Gorge

Reclamation, B. of. (n.d.). Glen Canyon Unit. https://usbr.gov/uc/rm/crsp/gc/

Regan, T. (2010). The case for animal rights. University of California Press.

Runge, M. C., Yackulic, C. B., Bair, L. S., Kennedy, T. A., Valdez, R. A., Ellsworth, C.,

Kershner, J. L., Rogers, R. S., Trammell, M. A., & Young, K. L. (2018). Brown trout in

the lees ferry reach of the Colorado River—evaluation of causal hypotheses and potential

interventions. Open-File Report. https://doi.org/10.3133/ofr20181069

San Marcos River. San Marcos River | City of San Marcos, TX. (n.d.).

https://sanmarcostx.gov/3420/San-Marcos-River

Simberloff, D. (2013). General Introduction. In Invasive species: What everyone needs to

know. Oxford University Press.

Southwest Biological Science Center. (2016, December). Population Dynamics of

endangered humpback chub in Grand Canyon. https://www.usgs.gov/centers/southwest-

biological-science-center/science/population-dynamics-endangered-humpback-

chub#overview

Sunstein, C. R., Nussbaum, M. C., Wise, S. M., Posner, R. A., Singer, P., Diamond, C.,

Francione, G. L., Epstein, R. A., Rachels, J., Rogers, L. J., MacKinnon, C. A., Anderson,

E., Kaplan, G. T., Wolfson, D. J., Sullivan, M., Favre, D. S., & Nussbuam, M. C. (2006).

In Animal rights: Current debates and New Directions. Oxford University Press.

Tagging study offers money for harvesting northern snakeheads. Natural Resources

News. (2022). https://news.maryland.gov/dnr/2022/05/24/tagging-study-offers-money-

for-harvesting-nort

Thompson, K. (2015). A short history of nativeness. In Where do camels belong? the

story and science of invasive species. Profile Books.

Tournaments. Atlas Environmental. (n.d.).

https://www.atlasenvironmentaltx.com/tournaments

U.S. Department of the Interior. (2015, February). Bright angel creek trout reduction

project. National Parks Service. https://www.nps.gov/grca/learn/nature/trout-

reduction.htm

U.S. Department of the Interior. (2022, January). Nonnative fish. National Parks Service.

https://www.nps.gov/glca/learn/nature/nonnativefish.htm

U.S. Fish and Wildlife Service. (n.d.). Humpback chub (Gila Cypha): U.S. Fish &

Wildlife Service. FWS.gov. https://fws.gov/species/humpback-chub-gila-cypha

US Fish and Wildlife Service. (n.d.). Rainbow trout (Oncorhynchus mykiss).

https://www.fws.gov/species/rainbow-trout-oncorhynchus-mykiss

Voichick, N., & Wright, S. (2007a). Daily water temperatures measured or calculated at

the USGS’ stream gage located at Lees Ferry 1949-2005. USGS. Retrieved from

https://pubs.usgs.gov/ds/2007/251/ds-251.pdf.

Voichick, N., & Wright, S. (2007b). Water temperature data at several river sites. CRLF

is Colorado River Lees Ferry. Based on hourly averaged data. USGS. Retrieved from

https://pubs.usgs.gov/ds/2007/251/ds-251.pdf.

Voichick, N., Kennedy, T., Topping, D., Griffiths, R., & Fry, K. (2016). Lees Ferry daily

mean turbidity during 2016. Also shows pre-dam turbidity from other known data.

USGS. Retrieved February 6, 2023, from

https://pubs.usgs.gov/fs/2016/3053/fs20163053.pdf.

Walsh, M. G., Winkelman, D. L., & Bahr, R. J. (2004). Electrofishing injury and short-

term mortality in hatchery-reared rainbow trout stocked into an Ozark stream. North

American Journal of Fisheries Management, 24(1), 316–321.

https://doi.org/10.1577/m03-002

Yard, M. D., Coggins, L. G., Baxter, C. V., Bennett, G. E., & Korman, J. (2011). Trout

piscivory in the Colorado River, Grand Canyon: Effects of turbidity, temperature, and

fish prey availability. Transactions of the American Fisheries Society, 140(2), 471–486.

https://doi.org/10.1080/00028487.2011.572011