Ongoing Research
My research builds micro-foundations for conservation and resource management problems, to address the wellbeing of people who depend on the resources and the health of ecosystems. To solve these challenging problems, I employ dynamic optimization, mathematical programming, and econometrics methodologies. I also look beyond economics for state-of-the-art numerical tools to tackle these often nonsmooth dynamic resource management problems.
Spatial-dynamic model of commercial fishing trip decision-making 2021 Best Student Paper, North American Association of Fisheries Economists (NAAFE), sponsored by NOAA
Comments from Review Committee: This ambitious paper used methods from operations research to develop a model to determine within-trip location choice, effort allocation, and travel path with trip length endogenously determined. The paper extends previous work using an innovative methodology to address a topic with important implications. The paper does a good job of developing the approach and methodology, and presenting the results.
Innovative sources of high-resolution mobility data are enabling new approaches to modeling and measurement of human behavior. With the advent of global positioning data in fisheries, now more than ever we can empirically model fishers’ decision-making. In the short-run, after choosing the fishing gear, fishers decide where to fish, how much to fish and when to return to the port on a given trip. Most of the research investigat ing these decisions has focused on one aspect of the decision at a time (e.g., choosing a fishing location), treating other aspects exogenous. These decisions, however, are interconnected and conditional on the underlying vessel capital stock (e.g., hold and fuel capacity). This research constructs a novel spatial dynamic model of an individual fisher’s trip level decision-making that incorporates simultaneous decisions on location choice, fishing effort to allocate at each location, and travel route. It is motivated by the observations on fishing trips from the Gulf of Mexico’s bottom longline fishery. Simulation results show that technology constraints endogenously determine the trip length. These constraints also impose a shadow price that affects the individual fisher’s choice of location and effort from the outset of a trip.
We compare these optimal spatial patterns with those from a myopic fisher and a partially myopic fisher, where the former makes one choice ahead decisions and for the latter we consider different levels of forward-looking choices (2, 3, and 6 decisions ahead). The myopic fisher does not optimize route planning or consider the technological constraints until it is time to return to port. Both factors result in large reductions in trip profit even though, for example, catches can be the same across the myopic and dynamic fisher. For the partially myopic fisher, the degree of route planning and consideration of technological constraints depends on the level of forward-looking. Not surprisingly, the more forward looking the partially myopic the closer it approaches the dynamic optimal. Building more refined models of trip level spatial decision-making is important for the design and assessment of spatial and aspatial fishery management instruments.
Keywords: fisheries management, location choice, discrete-continuous dynamic choice, mixed integer programming
[Manuscript]Modeling Ecosystem Service Conflicts in China’s Lake Poyang
The paper models the joint management of conflicting ecosystem services in working landscapes. The case study is Lake Poyang, the largest freshwater lake in China, where longstanding local fishing practices have increasingly impinged on the winter habitat of the last surviving Siberian Cranes. The paper constructs an integrated hydro-bio-economic model of the crane-fisher-water system to investigate the comparative impacts of uncoordinated and coordinated management of fishery and crane conservation. The joint model is a 3-state nonsmooth hybrid dynamic problem that is within-year continuous and between-year discrete. It is solved by the novel pseudo-spectral method from aerospace engineering. In general, we find prolonging the fishing season extends the cranes’ winter feeding and enhances survival but at a cost to the fishery. The paper examines compensation schemes for fishery communities that induce crane conservation. With the decline in natural landscape quality, importance grows for working landscapes to buttress ecosystem service. The integrated framework developed for coordinating institutions to maximize returns to ecosystem services in a working landscape applies directly to sustainable development, agricultural and otherwise, which competes for soil, water, and other natural resources in the same way.
Keywords: bioeconomics, endangered species conservation, hybrid discrete-continuous model, pseudospectral method
[Manuscript]Testing for uniqueness of solutions of linear inequality systems (with Bulat Gafarov)
We provide a necessary and sufficient condition for point identification of a parameter defined by a system of linear moment inequalities. We design a specification test, that distinguishes point-identified linear inequality model from a misspecified or set-identified one. It is based on a novel necessary condition that can be reformulated in terms of positive linear dependence and feasibility of the inequalities. We provide a joint testof the necessary conditions. The test is consistent against practically relevant hypotheses of misspecificationor identified set with empty interior. The procedure is based on feasibility check of linear and integralityconstraints, that can be efficiently performed using mixed integer quadratic programming (MIQP) solversin seconds.
Keywords: moment inequalities, mixed integer programming
Impacts of hypothetical closures around the Galapagos on the tuna fisheries in the Eastern Pacific Ocean
Measure the implications of hypothetical spatial closures in the area around the Galapagos on catches, revenue per trip, and the spatial distribution of fishing effort for the purse seine tuna fleet operating in the Eastern Pacific Ocean.
Keywords: fisheries management, decision under uncertainty, marine protected area (MPA), Galapagos