Matching Items (6)
Description
Niche variation among sexes and life stages within a population has been documented in many species, yet few studies have investigated niche variation within demographic groups or across ecological contexts. We examined the extent to which pregnant California sea lions (Zalophus californianus) at each of three breeding colonies target alternative prey resources and habitats. The three colonies are distributed across distinct regions of the Gulf of California, Mexico and have divergent population dynamics. We compared the nature of niche variation among colonies and investigated the fitness consequences of different foraging strategies within each colony. We analyzed the δ13C and δ15N values from fur collected from 206 suckling pups to characterize relative maternal foraging locations (δ13C) and trophic levels (δ15N) during the metabolically demanding late stages of gestation and lactation that occur simultaneously in California sea lions. The δ13C and δ15N values were regressed against pup body condition index values to compare the relative individual-level fitness benefits of different maternal foraging strategies. We found that the nature and extent of niche variation differed among colonies. Niche variation was most pronounced at the two largest colonies that appear to experience the highest levels of intraspecific competition and the variation was consistent with habitat features. One colony (Granito) displayed two distinct foraging groups with indistinguishable median pup body condition values, whereas the second (San Jorge) exhibited continuous niche variation and pup body condition varied in relation to maternal foraging location and trophic level, suggesting disparities among alternative foraging strategies. For the smallest colony (Los Islotes), females occupy similar niches with a few outliers. Body condition values of pups at this colony were most variable, but did not vary with maternal foraging strategy. Our results provide evidence for intrapopulation niche variation among demographically similar individuals during a period of high metabolic stress and reproductive importance. This work suggests possible fitness benefits conferred by alternative foraging strategies, and calls into question the common assumption that members of a population are ecologically equivalent. Future research aimed at understanding animal foraging strategies should consider the nature and extent of niche variation in the context of local ecological conditions.
ContributorsCrawford, Tara Gancos (Author) / Gerber, Leah R. (Thesis advisor) / Ogle, Kiona (Committee member) / Kurle, Carolyn M (Committee member) / Arizona State University (Publisher)
Created2013
Description
Many wildlife species that are essential to human livelihoods are targeted with the aim of extracting short-term benefits. Overexploitation, resulting from failed common-pool resource governance, has endangered the sustainability of large animal species, in particular. Rights-based approaches to wildlife conservation offer a possible path forward. In a wildlife market, property rights, or shares of an animal population, are allocated to resource users with interests in either harvest or preservation. Here, I apply the Social-Ecological Systems (SES) framework (Ostrom, 2009) to identify the conditions under which the ecological, social, and economic outcomes of a conservation market are improved compared to the status quo. I first consider three case studies (Bighorn sheep, white rhino, and Atlantic Bluefin tuna) all of which employ different market mechanisms. Based on the SES framework and these case studies, I then evaluate whether markets are a feasible management option for other socially and ecologically significant species, such as whales (and similar highly migratory species), and whether market instruments are capable of accommodating non-consumptive environmental values in natural resource decision making. My results suggest that spatial and temporal distribution, ethical and cultural relevance, and institutional histories compatible with commodification of wildlife are key SES subsystem variables. Successful conservation markets for cross-boundary marine species, such as whales, sea turtles, and sharks, will require intergovernmental agreements.
ContributorsSturm, Melanie (Author) / Minteer, Ben A (Thesis advisor) / Gerber, Leah R. (Thesis advisor) / Perrings, Charles (Committee member) / York, Abigail (Committee member) / Arizona State University (Publisher)
Created2014
Description
This dissertation consists of three substantive chapters. The first substantive chapter investigates the premature harvesting problem in fisheries. Traditionally, yield-per-recruit analysis has been used to both assess and address the premature harvesting of fish stocks. However, the fact that fish size often affects the unit price suggests that this approach may be inadequate. In this chapter, I first synthesize the conventional yield-per-recruit analysis, and then extend this conventional approach by incorporating a size-price function for a revenue-per-recruit analysis. An optimal control approach is then used to derive a general bioeconomic solution for the optimal harvesting of a short-lived single cohort. This approach prevents economically premature harvesting and provides an "optimal economic yield". By comparing the yield- and revenue-per-recruit management strategies with the bioeconomic management strategy, I am able to test the economic efficiency of the conventional yield-per-recruit approach. This is illustrated with a numerical study. It shows that a bioeconomic strategy can significantly improve economic welfare compared with the yield-per-recruit strategy, particularly in the face of high natural mortality. Nevertheless, I find that harvesting on a revenue-per-recruit basis improves management policy and can generate a rent that is close to that from bioeconomic analysis, in particular when the natural mortality is relatively low.
The second substantive chapter explores the conservation potential of a whale permit market under bounded economic uncertainty. Pro- and anti-whaling stakeholders are concerned about a recently proposed, "cap and trade" system for managing the global harvest of whales. Supporters argue that such an approach represents a novel solution to the current gridlock in international whale management. In addition to ethical objections, opponents worry that uncertainty about demand for whale-based products and the environmental benefits of conservation may make it difficult to predict the outcome of a whale share market. In this study, I use population and economic data for minke whales to examine the potential ecological consequences of the establishment of a whale permit market in Norway under bounded but significant economic uncertainty. A bioeconomic model is developed to evaluate the influence of economic uncertainties associated with pro- and anti- whaling demands on long-run steady state whale population size, harvest, and potential allocation. The results indicate that these economic uncertainties, in particular on the conservation demand side, play an important role in determining the steady state ecological outcome of a whale share market. A key finding is that while a whale share market has the potential to yield a wide range of allocations between conservation and whaling interests - outcomes in which conservationists effectively "buy out" the whaling industry seem most likely.
The third substantive chapter examines the sea lice externality between farmed fisheries and wild fisheries. A central issue in the debate over the effect of fish farming on the wild fisheries is the nature of sea lice population dynamics and the wild juvenile mortality rate induced by sea lice infection. This study develops a bioeconomic model that integrates sea lice population dynamics, fish population dynamics, aquaculture and wild capture salmon fisheries in an optimal control framework. It provides a tool to investigate sea lice control policy from the standpoint both of private aquaculture producers and wild fishery managers by considering the sea lice infection externality between farmed and wild fisheries. Numerical results suggest that the state trajectory paths may be quite different under different management regimes, but approach the same steady state. Although the difference in economic benefits is not significant in the particular case considered due to the low value of the wild fishery, I investigate the possibility of levying a tax on aquaculture production for correcting the sea lice externality generated by fish farms.
The second substantive chapter explores the conservation potential of a whale permit market under bounded economic uncertainty. Pro- and anti-whaling stakeholders are concerned about a recently proposed, "cap and trade" system for managing the global harvest of whales. Supporters argue that such an approach represents a novel solution to the current gridlock in international whale management. In addition to ethical objections, opponents worry that uncertainty about demand for whale-based products and the environmental benefits of conservation may make it difficult to predict the outcome of a whale share market. In this study, I use population and economic data for minke whales to examine the potential ecological consequences of the establishment of a whale permit market in Norway under bounded but significant economic uncertainty. A bioeconomic model is developed to evaluate the influence of economic uncertainties associated with pro- and anti- whaling demands on long-run steady state whale population size, harvest, and potential allocation. The results indicate that these economic uncertainties, in particular on the conservation demand side, play an important role in determining the steady state ecological outcome of a whale share market. A key finding is that while a whale share market has the potential to yield a wide range of allocations between conservation and whaling interests - outcomes in which conservationists effectively "buy out" the whaling industry seem most likely.
The third substantive chapter examines the sea lice externality between farmed fisheries and wild fisheries. A central issue in the debate over the effect of fish farming on the wild fisheries is the nature of sea lice population dynamics and the wild juvenile mortality rate induced by sea lice infection. This study develops a bioeconomic model that integrates sea lice population dynamics, fish population dynamics, aquaculture and wild capture salmon fisheries in an optimal control framework. It provides a tool to investigate sea lice control policy from the standpoint both of private aquaculture producers and wild fishery managers by considering the sea lice infection externality between farmed and wild fisheries. Numerical results suggest that the state trajectory paths may be quite different under different management regimes, but approach the same steady state. Although the difference in economic benefits is not significant in the particular case considered due to the low value of the wild fishery, I investigate the possibility of levying a tax on aquaculture production for correcting the sea lice externality generated by fish farms.
ContributorsHuang, Biao (Author) / Abbott, Joshua K (Thesis advisor) / Perrings, Charles (Thesis advisor) / Gerber, Leah R. (Committee member) / Muneepeerakul, Rachata (Committee member) / Schoon, Michael (Committee member) / Arizona State University (Publisher)
Created2014
Description
Despite years of effort, the field of conservation biology still struggles to incorporate theories of animal behavior. I introduce in Chapter I the issues surrounding the disconnect between behavioral ecology and conservation biology, and propose the use of behavioral knowledge in population viability analysis. In Chapter II, I develop a framework that uses three strategies for incorporating behavior into demographic models, outline the costs of each strategy through decision analysis, and build on previous work in behavioral ecology and demography. First, relevant behavioral mechanisms should be included in demographic models used for conservation decision-making. Second, I propose rapid behavioral assessment as a useful tool to approximate demographic rates through regression of demographic phenomena on observations of related behaviors. This technique provides behaviorally estimated parameters that may be applied to population viability analysis for use in management. Finally, behavioral indices can be used as warning signs of population decline. The proposed framework combines each strategy through decision analysis to provide quantitative rules that determine when incorporating aspects of conservation behavior may be beneficial to management. Chapter III applies this technique to estimate birthrate in a colony of California sea lions in the Gulf of California, Mexico. This study includes a cost analysis of the behavioral and traditional parameter estimation techniques. I then provide in Chapter IV practical recommendations for applying this framework to management programs along with general guidelines for the development of rapid behavioral assessment.
ContributorsWildermuth, Robert (Author) / Gerber, Leah R. (Thesis advisor) / Collins, James (Committee member) / Smith, Andrew (Committee member) / Arizona State University (Publisher)
Created2012
Description
In the face of increasing anthropogenic threats to marine systems, marine reserves
have become a popular tool to promote sustainable fisheries management and protect marine biodiversity. However, the governance structures that determine marine reserve success are not well understood. The response of resource users to reserve establishment, as well as the socioeconomic, institutional, and political contexts in which they occur, are rarely considered during reserve implementation. I use the Coupled Infrastructure Systems (CIS) framework to better understand the interdependencies between social, economic, natural, and institutional processes affecting reserve implementation and performance efficacy in the Gulf of California, Mexico. I used a combination of interviews, qualitative case study comparisons, and systematic conservation planning tools to evaluate the role of different infrastructures, institutions, and governance for marine reserve efficacy in the Gulf of California, Mexico. At a local scale, I assessed stakeholder perceptions, preferences, and knowledge on reserves in the Midriff Islands sub-region of the Gulf. My results show differences in fisher perceptions about the use of reserves for biodiversity conservation and fisheries management, misconceptions about their location, and non-compliance behavior problems. At the regional scale, I explored the trajectories of reserve implementation and performance. I show that capacity-building programs and effective collaboration between non-profit organizations, environmental, fisheries, and other government authorities are essential to coordinate efforts leading to the provisioning of infrastructure that enables effective marine reserves. Furthermore, these programs help facilitate the incorporation of fishers into diversified management and economic activities. Infrastructure provision tradeoffs should be carefully balanced for designing scientifically-sound reserves that can achieve fisheries recovery objectives and incorporating stakeholder engagement processes during the planning phase that allow fishers to include their preferences in a way that complements proposed reserve network solutions. Overall, my results highlight the importance of multiple infrastructures in understanding the dynamics of interacting action situations at various stages of marine reserve implementation and operation. I identify strengths and weaknesses within marine reserve systems that help understand what combinations of infrastructures can be influenced to increase marine reserve effectiveness and robustness to internal and external challenges, as well as delivering benefits for both nature and people.
have become a popular tool to promote sustainable fisheries management and protect marine biodiversity. However, the governance structures that determine marine reserve success are not well understood. The response of resource users to reserve establishment, as well as the socioeconomic, institutional, and political contexts in which they occur, are rarely considered during reserve implementation. I use the Coupled Infrastructure Systems (CIS) framework to better understand the interdependencies between social, economic, natural, and institutional processes affecting reserve implementation and performance efficacy in the Gulf of California, Mexico. I used a combination of interviews, qualitative case study comparisons, and systematic conservation planning tools to evaluate the role of different infrastructures, institutions, and governance for marine reserve efficacy in the Gulf of California, Mexico. At a local scale, I assessed stakeholder perceptions, preferences, and knowledge on reserves in the Midriff Islands sub-region of the Gulf. My results show differences in fisher perceptions about the use of reserves for biodiversity conservation and fisheries management, misconceptions about their location, and non-compliance behavior problems. At the regional scale, I explored the trajectories of reserve implementation and performance. I show that capacity-building programs and effective collaboration between non-profit organizations, environmental, fisheries, and other government authorities are essential to coordinate efforts leading to the provisioning of infrastructure that enables effective marine reserves. Furthermore, these programs help facilitate the incorporation of fishers into diversified management and economic activities. Infrastructure provision tradeoffs should be carefully balanced for designing scientifically-sound reserves that can achieve fisheries recovery objectives and incorporating stakeholder engagement processes during the planning phase that allow fishers to include their preferences in a way that complements proposed reserve network solutions. Overall, my results highlight the importance of multiple infrastructures in understanding the dynamics of interacting action situations at various stages of marine reserve implementation and operation. I identify strengths and weaknesses within marine reserve systems that help understand what combinations of infrastructures can be influenced to increase marine reserve effectiveness and robustness to internal and external challenges, as well as delivering benefits for both nature and people.
ContributorsMancha Cisneros, Maria del Mar (Author) / Gerber, Leah R. (Thesis advisor) / Abbott, Joshua K. (Committee member) / Anderies, John M. (Committee member) / Torre, Jorge (Committee member) / Arizona State University (Publisher)
Created2017
Description
Cetacean-based ecotourism is a popular activity and an important source of revenue for many countries. Whale watching, a subset of cetacean-based ecotourism, is vital to supporting conservation efforts and provides numerous benefits to local communities including educational opportunities and job creation. However, the sustainability of whale-based ecotourism depends on the behavior and health of whale populations and is therefore vital that ecotourism industries consider the impact their activities have on whale reproductive behavior. To address this statement, behavioral data (e.g. direction change, breaching, slap behaviors, diving, and spy hops) were collected from humpback whales (Megaptera novaeangliae) in Las Perlas Archipelago off the Pacific coast of Panama to determine if vessel presence had an influence on whale behaviors. Studies were recorded during their breeding season from August through September in 2019. Based on 47 behavioral observations, higher boat density corresponded with humpback whales changing direction which is believed to be a sign of disturbance. This result is important given Panamanian regulations implemented on February 13 of 2007 prohibit whale-based tourism from disturbing whales, which is measured as changes in behavior. Because there is no systematic monitoring of whale watching activity to enforce the regulations, there is currently little compliance among tour operators. The integration of animal behavior research into management planning will result in more effective regulation and compliance of conservation policies.
ContributorsAmrein, Arielle (Author) / Gerber, Leah R. (Thesis advisor) / Guzman, Hector M (Committee member) / Polidoro, Beth (Committee member) / Arizona State University (Publisher)
Created2020