AJ Enriquez and DC Finnoff. (2021). Managing mortality of multi-use megafauna.
Journal of Environmental Economics and Management 107: 102441.



Greater Yellowstone Ecosystem grizzly bears, which are currently federally protected under the Endangered Species Act, are a high-profile multi-use species. As the number of grizzly bears has increased, there have been increases in the number of grizzly bear-human conflicts and human-caused grizzly bear mortalities. A bioeconomic model is constructed in which a representative wildlife agency considers these relationships and maximizes discounted social net benefits by deciding whether to enact direct population control. A linear specification is employed to reflect the realities of negotiated and rigid active management programs. The agency accounts for how stock-dependent benefits and damages adjust along the recovery path, which tracks the natural capital value of a live grizzly bear as the population changes over time. Benchmark results indicate that the grizzly bear population has surpassed the size at which protections ought to have been removed. The natural capital value of an additional animal in the wild, given by its in-situ marginal net benefits, may actually be negative for an interval of time, during which it is optimal for society to continue conserving the species by developing a buffer. The results of the analysis are sensitive to key economic and ecological parameters, especially on the benefits side.


Yellowstone National Park, 2021

Working Papers

The economic value of wildlife tourism and implications of marginal population changes
LA Richardson and AJ Enriquez

Status: In preparation for submission


Wildlife tourism is a highly demanded recreation activity in parks and protected areas globally, yet economic benefit measures are lacking. Estimates of the effect of small-scale losses of wildlife on viewing values are virtually non-existent, leading to a dearth of information crucial for answering key wildlife policy and management questions (e.g., appropriate compensation for incidents of human-caused wildlife mortality). We estimate a travel cost model of bear viewing trips in Yellowstone National Park and demonstrate how the resulting consumer surplus estimate can be incorporated into a model of visitor sightings as a function of wildlife population size to evaluate the effect of marginal population changes on sighting value. Results indicate aggregate values of $6 and $7 million annually for viewing grizzly bears and black bears, respectively. The corresponding marginal values are around $38,000 and $12,000 per single grizzly bear and black bear. Our approach and general findings have significant relevance for incidents of poaching, wildlife-vehicle collisions, and other policy applications in which there is a need to determine how marginal changes in a species' population size affects the economic benefits associated with wildlife resources.

The pain of paying with other people's money
AJ Enriquez, BT Gilbert, and LH Thunström

Status: Invited for revision and resubmission


Spending decisions are at the heart of consumer research, and factors that impact spending have been studied for many decades. So far, research has focused on spending decisions based on own money. However, people often spend money earned by someone else (e.g., partners spend each other’s earned money, government officials spend tax payer money, employees spend employer money, people in need spend social benefits). We take a first step towards understanding how spending depends on who earned the money. We focus on the shortest social distance between consumer and earner - intra household spending - and survey 166 couples on how pain of paying from a fixed purchase is affected by who earned the money. Pain of paying regulates consumer spending; the higher the pain, the lower the spending. We find that people feel higher pain of paying when spending money earned by their partner, compared to when earned by self, suggesting they might be more frugal with money earned by others. Their pain of paying increases if they believe their partner will be unhappy with their purchases. Their ability to accurately predict the partner’s feelings about the purchase increases with partner similarity in spendthriftiness. 

Rare earth element resource evaluation of coal byproducts: A case study from the Powder River Basin, Wyoming.
DA Bagdonas, AJ Enriquez, KA Coddington, DC Finnoff, JF McLaughlin, MD Bazilian, EH Phillips, and TL McCling.

Status: Invited for revision and resubmission


Domestic rare earth element sources and production are limited in the United States and currently rely on final processing overseas. Increasing demand and resource security has led to significant investigation into domestic rare earth element resources. Much of the existing research focuses on unconventional potential ore stocks, including coal and coal byproducts. This investigation focuses on coal byproducts generated as ash from coal-burning power stations. Wyoming’s Powder River Basin hosts the largest U.S. coal stocks for energy production, providing approximately 40% of all thermal coal mined in the country. In Section I, we study Powder River Basin coal byproducts for rare earth element concentrations and compare the data to current alternative resource knowledge. We find that the coal byproducts are consistently high enough in rare earth element concentration (above the current Department of Energy 300 ppm cutoff grade) to warrant consideration as a promising potential resource. Rare earth element behavior within the host coal seams is also considered in an effort to better understand resource prospecting and ore body description. In Section II, we evaluate the economic feasibility of rare earth extraction from coal byproducts using net present value analysis and the rare earth concentrations data from Section I. We calculate the break-even ash-to-oxide output and input unit costs for four coal stations in the Powder River Basin. All stations have break-even unit costs that are higher than the mine-to-oxide operating cost reported for a traditional rare earth element mine. This is a promising result, especially given that it is more costly to refine rare earths from mined material than from ash. The results are highly sensitive to rare earth prices: given low long-term prices, none of the stations can feasibly break even. In Section III, we summarize federal policy considerations in rare earth element resource development. Recent policy developments, which have focused on rare earth element-specific funding legislation, paired with the results from Sections I and II, suggest a robust opportunity for development of Wyoming-based coal byproducts as a partial solution to current domestic rare earth element shortfalls and strategic needs.

Free riding toward personal protection: Relating parental cooperation behavior to vaccine hesitancy
AJ Marchal, AJ Enriquez, MD Ehmke, and CA Camargo, Jr.

Status: In preparation for submission


Small urban clusters and rural communities, which have historically had low vaccination rates, are especially vulnerable to healthcare system overloads. We conducted a study in which parents from these locations participated in a voluntary contribution mechanism experiment and then answered survey questions about influenza vaccinations. We observe whether parents’ cooperative actions in the experiment (i.e., contributions to a shared group account) relate to their flu vaccination decisions for themselves and their children. We classify different player-types based on parents’ propensities to cooperate and react to their partners’ actions, including “free riders” (keep the majority of tokens), “contributors” (contribute the majority of tokens), and “responders” (adjust contributions based on partners’ actions). We also control for the intensity of reciprocation among all players. We find that free riders and parents who tend to reciprocate are most likely to vaccinate, which is a departure from previous literature. The findings shed light on the behavioral motives behind people’s vaccination decisions. Policies that amplify free riding and reciprocation may increase vaccination rates, which would be critical for mitigating the damaging effects of COVID-19 and other preventable diseases.

In-Progress Survey Projects

Nonmarket valuation of grizzly bears in the Greater Yellowstone Ecosystem
AJ Enriquez, SC Newbold, and DC Finnoff


  • Use stated preference components (i.e., choice experiments) to estimate people’s willingness to pay for changes in the following grizzly bear-related attributes: chance of seeing a grizzly bear, risk of being injured by a grizzly bear, number of grizzly bear-human conflicts, and grizzly bear extinction probability

  • Use a revealed preference component to estimate people’s aggregate demand for recreational trips to the area as a function of trip cost, grizzly bear-related attributes, and other key control variables

  • Integrate the stated and revealed preference components with a utility-maximization framework that can be used to derive people’s average willingness to pay for future grizzly bear management policies

  • Compare average willingness to pay between locals and non-locals

Completed Work:

  • Obtained Institutional Review Board approval

  • Pretested the survey by running five focus group sessions and a one-on-one interview

  • Secured funding for an expected sample size of 2,500 respondents

  • Communicated with and sought feedback from grizzly bear experts in three agencies

  • Finalized the experimental design and conducted power analysis and simulations in R

  • Programmed and administered the survey in Qualtrics

  • Currently analyzing the data

Preferences for Wind Energy in Wyoming
AJ Enriquez and RW Godby


  • Elicit Wyoming residents’ attitudes about competing energy sources, including fossil fuels and renewable energy

  • Determine what drives Wyoming residents’ preferences for (or against) wind energy

  • Use a set of economic experiments in which respondents assign credits to signal how important they find various impacts from potential future wind energy developments. The impacts span the following categories: economic considerations, electricity generation, effects on wildlife, effects on climate and environment, and physical characteristics, location, and viewshed

Completed Work:

  • Obtained Institutional Review Board approval

  • Pretested the survey by running four focus group sessions

  • Secured funding for an expected sample size of 800 respondents

  • Programmed and administered the survey in Qualtrics

  • Currently analyzing the data


BIOECON XXII Annual Conference
September 2021 in Jackson, Wyoming

Presenter: "The economic value of wildlife tourism and implications of marginal population changes"

UW-CSU Graduate Student Symposium
April 2019 in Laramie, Wyoming

Presenter: "Bioeconomic grizzly bear management"

International Institute of Fisheries Economics & Trade Biennial Conference
July 2018 in Seattle, Washington

Presenter: "From the shore or from the water? Enforcement of resource rights under discrete enforcement technologies"

Abstract: Poaching is a major problem under the Chilean system of territorial use rights in fisheries (TURFs). Organizations of artisanal fishers that are granted spatial property rights through TURFs combat poaching by establishing their own enforcement. Although an organization must protect its benthic resources against poachers from both within the organization (“insiders”) and outside of the organization (“outsiders”), existing literature has shown that fishers are more concerned about enforcement against outsiders. Organizations know that their enforcement is imperfect - increasing enforcement increases the probability that poachers will be caught but does not guarantee that poachers will be caught. This probability depends on an “effectiveness of enforcement” parameter. With a high effectiveness of enforcement, an organization’s enforcement is more likely to lead to poacher capture. Using an optimal control framework, we analyze how a representative organization maximizes expected profit by choosing its levels of harvest and enforcement, over time. The organization incorporates the poacher’s best-response function, in which a poacher’s decision of how much to illegally harvest is influenced by the organization’s harvest and enforcement levels, the size of the stock, and exogenous parameters. In the case where the organization chooses positive levels of both harvest and enforcement, there are multiple equilibria in the steady state. One equilibrium is associated with a high level of stock while the other is associated with a low level. We show comparative dynamics on key parameters, including the effectiveness of enforcement.
Geological Society of America Annual Meeting
September 2016 in Denver, Colorado

Presenter: "Economic feasibility of rare earth element extraction from Wyoming coal ash/char"

Abstract: The State of Wyoming is the largest producer of coal in the U.S. Uncertainty over the future of this resource has caused the state to recognize the importance of diversifying its mineral industry. Recent research shows a potential remedy: coal by-products, such as fly ash, can contain recoverable amounts of Rare Earth Elements (REEs). By producing REEs from fly ash, Wyoming can diversify and add to its revenue streams. There is global demand for REEs, as they are utilized in the production of a diverse array of modern goods and technology. Application of Net Present Value (NPV) analysis allows determination of the potential profitability of REE extraction from Wyoming coal-fired power station ash. The NPV analysis considers REE concentrations in six ash samples from two basins, the Powder River Basin and the Green River Basin. A challenge for NPV analysis of these samples is the lack of REE-from-coal-ash processing and refining cost estimates in the literature. To overcome this hurdle, the NPV analysis is structured to determine the maximum unit cost that a coal station can incur and still break even. For each station, this cost is calculated in two ways: as an input cost per pound of ash, and as an output cost per pound of Total Rare Earth Oxide (TREO). In addition to the unit cost, the analysis also provides the potential revenue and maximum capital cost for each station. Subsequent sensitivity analysis then allows for comparison of the results under scenarios that range from low to high yield and low to high REE concentrations. With the assumptions made, five of the six coal stations have breakeven unit costs that exceed the value of 1.17 US$ per pound TREO, which is the mine-to-oxide operating cost reported by the hard-rock mine company Molycorp. Under these results, REE recovery from Wyoming coal by-products appears economically promising.