Browsing by Subject "Bio-economic modeling"
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Item Open Access BIO-ECONOMIC MODELING OF CONTAMINATED BLUEFIN TUNA AND ATLANTIC MACKEREL FISHERIES DYNAMICS(2009-04-23T20:56:34Z) Press, MichaelFollowing the discovery of acute mercury toxicity from seafood consumption in the 1950s and subsequent research into mercury in the environment, scientists and managers now recognize the health threats of mercury poisoning from seafood consumption, especially in fetuses, infants, and children. Unfortunately, consumers remain confused or uneducated about species-specific mercury concentrations, thus perpetuating the risks associated with contaminated seafood. This study models the bio-economic dynamics of a system involving two species consumed by humans: a highly mercury-contaminated predator, bluefin tuna, and a tuna prey fish with low levels of contamination, Atlantic mackerel. Model scenarios evaluate varying levels of mercury pollution, consumer aversion to mercury, and fishes’ biological resistance to mercury poisoning to determine optimal harvest rates and population sizes for both species. The results demonstrate that while the mackerel fishery remains largely unaffected by the influence of mercury, optimal harvest and population of tuna depend greatly upon their biological resistance to mercury and consumers’ aversion to purchasing mercury-contaminated fish. When resistance to mercury is low, both tuna population and harvest decrease. When consumer aversion is high, harvest decreases and population increases. Increased mercury pollution exacerbates both effects. Due to lack of previous such studies and the paucity of empirical data, this research is both exploratory and qualitative in nature. Effective fisheries conservation and management requires understanding the strength of both fish resistance and consumer aversion to mercury. Future research should address the lack of empirical data, both biological and economic, as well as refine the above model in order to assist managers in appropriate consumer education and setting fisheries management goals that couple sustainability and public health.Item Open Access EVALUATING TRADE-OFFS IN AN ECOSYSTEM-BASED FISHERY MANAGEMENT PARADIGM: AN EXPLORATION THROUGH ANALYSIS OF THE ATLANTIC BUTTERFISH AND LONGFIN SQUID FISHERIES(2013-04-25) Rogers, Anthony; Carlisle, Keith; Wang, JiaxiThe Mid-Atlantic Fishery Management Council, our client for this masters project, is evaluating how best to transition from a primarily single-species management approach to an integrated multi-species management paradigm. In this connection, we explore how economic considerations may be incorporated into an integrated multi-species management approach by focusing on two closely associated stocks managed by the Council: longfin squid and Atlantic butterfish. We take several different approaches in our analysis of the two fisheries, our ultimate objectives being (i) to characterize the behavior of the fleets based upon historical landings data and geospatial analysis; and (ii) to provide the Council with insight into the potential impact of management constraints and ecosystem interactions on economic benefits in the fisheries. To illustrate potential impacts to economic benefits, we develop a two-species bioeconomic model and derive optimal harvest levels for the stocks, taking into account varying degrees of management constraints and ecosystem interactions. Based upon our analysis of landings data, we found that the Council’s allocation of the longfin squid landings quota among trimester management periods is no longer representative of actual landings in the fishery throughout the year. As a result, there is potential that the fishery may be forced to close prematurely in the summer months, thereby reducing economic benefits to participants who are highly dependent on revenues from the fishery. We also found, based upon our geospatial analysis of butterfish landings and butterfish bycatch in the longfin squid fishery, that a statistically significant correlation exists between the distance to shore from the point of catch and the butterfish bycatch rate. With respect to the model, we explored the importance of three parameters not generally included in a single-species model: predation, bycatch by fishermen, and benefits to the longfin squid population of additional butterfish. We found that all three have potential economic impacts. We also found that the amount of the total allowable catch of butterfish allocated to a bycatch cap imposed on the longfin squid fishery is higher than necessary to prevent early closure of the longfin squid fishery and could result in lost revenues in the butterfish fishery.Item Open Access More Value From the Same Fish: Catch Shares, Fishing Behavior, and Revenues(2018) Birkenbach, Anna MarieIn recent decades there has been a great deal of interest in using property rights-based management and economic instruments as a means to extract the same resources at a lower cost, while also meeting certain sustainability goals (e.g., biological targets in fisheries). However, these policies remain quite controversial and are even opposed by some of the very same stakeholders who would stand to gain some of these property rights. In fisheries, this issue has an additional dimension that has not received nearly as much attention as the biological outcomes or the cost savings associated with rights-based management: this is the fact that there are a number of differentiated product types--such as fresh instead of frozen, value-added products, etc.--that have the potential to generate more market value. This motivates a broad question as to what extent we can generate more value from the same fish and how rights-based policies such as catch shares interact with fishing behaviors and markets.
This dissertation--and the larger body of ongoing work from which these chapters are drawn--addresses this broad question through a series of specific ones: Do the theoretical underpinnings of revenue-side benefits hold true empirically across a range of catch share fisheries? Do we observe longer fishing seasons post-catch shares, and, if so, does this translate to higher prices/revenues for fishermen through improved market timing, reduced market gluts, and changes in the mix of fresh versus frozen products? Do fishermen respond to revenue-maximizing opportunities that vary not only across time and but also across space once catch shares afford them the flexibility to do so? How do fishermen trade off revenue- and cost-side incentives across target species in multispecies and mixed-management settings? And what do these underlying preferences and behavioral drivers tell us about predicted micro-level responses to new proposed policies? The ultimate goal of this work is to inform the design of rights-based and other management policies so as to maximize the value generated from the resource, and, in so doing, help to minimize the tradeoffs between economic and conservation goals.
The first paper systematically evaluates the theory that rights-based management can lead to higher revenues in fisheries through improved market timing. While follow-on work in Kaczan, Birkenbach, and Smith (2018) explicitly tests for increases in prices received by fishermen for their catch, this paper lays the groundwork by first testing the mechanism underlying hypothesized price increases: namely, that catch shares slow the "race to fish." By securing each individual's right to a portion of the total catch, catch shares theoretically remove the competitive incentives leading to compressed seasons and market gluts and instead give fishermen the opportunity to strategically time their catch to market demand. However, existing evidence of these outcomes comes from selected examples only. In this paper, we analyze natural experiments to test whether catch shares reduce racing in 39 U.S. fisheries. We compare each fishery treated with catch shares to an individually matched control before and after the policy change. We estimate an average policy treatment effect in a pooled model and in a meta-analysis that combines separate estimates for each treatment-control pair. Consistent with the theory that market-based management ends the race to fish, we find strong evidence that catch shares extend fishing seasons on average. This evidence informs the current debate over expanding the use of market-based regulation to other fisheries.
The findings in the first paper, though strong, present a puzzle: if seasons tend to expand for catch share-treated fisheries, why do we observe counter-examples among individual species in multispecies complexes? For example, the season for the New England cod fishery lengthens, but the corresponding season for New England haddock contracts, relative to matched controls. Single-species theory of catch shares and associated market incentives cannot account for these mixed results; thus, the second paper adapts existing theory to more nuanced multispecies settings. We generate predictions about within-season behavior in multispecies fisheries with individual fishing quotas, allowing features such as stock aggregations, effort constraints, and various demand schedule slopes. Numerical results show variation in harvest patterns, including season length, acceleration or delay of harvests, and sequencing individual species harvests. Specifically, we find: 1) harvests for species with downward-sloping demand tend to spread out; 2) spreading harvest of a high-value species can cause lower-value species to be harvested earlier in the season; and 3) harvest can be unresponsive or even respond negatively to biological aggregation when fishermen balance incentives in multispecies settings. We test these predictions using panel data from the Norwegian multispecies groundfish fishery and find evidence for all three.
The third paper dives deeper into the anomalies in the first and empirically tests the new theoretical predictions of the second in a real-world multispecies, mixed-management setting. While a growing body of work seeks to evaluate the impact of catch share programs and other fisheries policy interventions using treatment effects models, these approaches can only identify the net effects of the policy change and not the mechanisms underlying them. As a result, these models may have limited relevance for proposed new (out-of-sample) policies. To learn how catch shares influence micro-level decision-making on the water, we develop and estimate a structural discrete choice model of individual vessel behavior. This work seeks to improve our understanding of how catch shares--and the policies that they replace--influence species targets, timing of fishing activity, and the value generated from the resource. To allow study of inter-species substitutions in pre- and post-rationalization, we implement this model using fine-scale commercial fishing data from before and after the start of the Northeast Multispecies Sector Program. We predict stock-specific production at the vessel-day level in first-stage regressions and use these predictions in a second-stage discrete choice model of targeting decisions that controls for weather, costs, and prices. From this second stage we recover structural parameters that capture how policies affect micro-level incentives. We use these parameters to simulate the effects of removing input restrictions and replacing them with catch shares and to predict behavioral responses to alternative policy specifications.
While the first three papers explore how quota-holding fishermen respond to changing economic opportunities across time, the fourth asks the same question with respect to space. In theory, rights-based management allows fishermen to not only target fish when their value is highest, but also to land and sell them where they will fetch the highest price. But apart from generating potential revenue-side gains, landing decisions also matter to fishery managers looking to incorporate non-efficiency goals, such as equity- or community-focused initiatives, into their quota systems. For example, managers may implement price premiums at disadvantaged landing communities to support commercial fishing activity and the local businesses (e.g., restaurants and processors) that rely on it. Predicting the outcomes of such policies requires an understanding of how fishermen decide where to land their catch, which has received little attention relative to fishing location choices. In this paper, we develop a discrete choice model of landing site choices, using groundfish vessels in Finnmark, Norway as our empirical application. We find that, while fishermen are highly responsive to travel distance, expected revenues are not a consistent driver of landing location choices, which instead reveal a high degree of state dependence. These results suggest that policies altering price incentives to redistribute landings would not be sufficient to draw fishermen away from their preferred landing sites.