Economic Valuation of Brown and White Shrimps as Forage Species in the Coastal Areas of Texas

2014-2016 - $222,816

Dr. Masami Fujiwara
Department of Wildlife and Fisheries
Texas A&M University
College Station

Dr. Richard Woodward
Agricultural Economics
Texas Agrilife Research
Texas A&M University
College Station

Abstract

We propose to develop a coupled economic and biological model that includes the dynamic behavior of recreational fishers (anglers), stock dynamics of predatory fishes (predators) targeted by the anglers, and changes in abundance of shrimp as food (prey) for the predators. Using information in existing literature, the model will be parameterized for southern flounder (Paralichthys lethostigma), spotted seatrout (Cynoscion nebulosus), and red drum (Sciaenops ocellatus) as predators and brown shrimp (Farfantepenaeus aztecus) and white shrimp (Litopenaeus setiferus) as prey. The joint economic and biological model will allow us to develop a greater understanding of how changes in the predators’ abundance lead to changes in the behavior of anglers, which will feedback to the stock of the prey species. The model will also be used to evaluate the economic value of shrimp as “forage fish” as well as the overall economic value of the predator-prey system. The final product will be introduced as a multistock management tool to the state and federal agencies. The coupled biological and economic model will be used to explore different scenarios with regard to fishery management policy, shrimp availability, and coastal habitat conditions. The policy types to be investigated include seasonal closures, bag limits, size limits, as well as enhancement of the predators by raising them in hatcheries and releasing them into the wild. The model will allow us to gain deeper understanding of how anglers’ behavior changes as indirect responses to these policy changes. Finally, the model will be used to quantify changes in the economic value of recreational fisheries as a response to changes the settlement and survival of both juvenile shrimp and predators, which implicitly reflect the conditions of coastal habitats. The new tool can be used for various management purposes. For example, the model will aid prioritization of wetland restoration effort under the Coastal Wetlands Planning Protection and Restoration Act (see National Research Council 2000, Merino et al. 2010, Admack et al. 2012, Minello et al. 2012). Using the proposed model, the value of increased shrimp production that results from the increased wetland area (Minello et al. 2012) can be estimated more accurately incorporating their effects on predator abundance and anglers’ behavior. The new tool will also aid the allocation of effort for stock enhancement of the game fish species. Currently, hatchery raised juvenile red drum and spotted seatrout are introduced into the wild to enhance the stocks, and a similar program is starting with southern flounder. Successful restocking programs will lead to increased abundance of the three predator stocks in the wild. Our model will allow us to place an economic value on such changes. Developing a trophic interaction models, we must carefully choose species to include. Including too few would omit the important trophic interactions determining their characteristic dynamics. Including too many would make the model too complex to comprehend. In this study, the five species were selected because the potential importance of their interactions is well-documented in the existing literature (Overstreet and Heard 1978, Minello & Zimmerman 1983, Minello et al. 1989, Zimmerman, et al. 2000, Scharf & Schlight 2000), but their dynamics have not been fully analyzed. Other potentially important predator and prey species that interact with the five species (e.g. blue crab) will be included implicitly in the model. Accumulation of data on the five species from recent studies by academic, state, and federal research on these species (e.g. Lassuy 1983, Muncy 1984, Reagan 1985, Rutherford et al. 1989, Stunz 1995, Murphy et al. 1999, Craig et al. 2000, Porch 2000, Scharf 2000, Brown-Peterson & Warren 2001, Watanabe et al. 2001, Levin & Stunz 2005, Glass 2006, Baker & Minello 2010, Neahr et al. 2010, Smith & Scharf 2010, Froeschke, et al. 2011, Hart 2012a 2012b, Powers et al. 2012) makes the proposed study feasible. In the economic component, angler behavior will be modeled using the best available empirical models with strong theoretical foundations. For spotted seatrout and red drum, we will be able to draw on recent econometric models of demand for these recreational species (Haab et al. 2009, 2012) that estimate recreational fisheries demand for target species as a function of, among other things, the catch per unit effort. For flounder, we will rely on other estimates from the literature and conduct sensitivity analysis. The economic model will allow us to predict how angler trips change in response to changes in the stock, affecting angler welfare and also having feedbacks to the biological model.