Browsing by Subject "Marine mammals"
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Item Open Access A comparison of Environmental Impact Statement methodologies for assessing sound propagation, density determination and impacts on protected marine mammals: BOEMRE & the U.S. Navy(2011-04-28) Budzynkiewicz, JaimeSound in the world oceans is an increasingly important conservation issue as human impact throughout the oceans continues to grow without signs of abatement. Deep-water background noise is reported to be doubling every decade. In the U.S. two major sources of underwater sound are the seismic industry (regulated by the Bureau of Ocean Energy Management, Regulation and Enforcement (BOEMRE)) and Naval sonar. Both of these agencies are required to follow national environmental protocols, such as the National Environmental Policy Act, (NEPA) in regard to their impacts on the environment. These two sound sources produced (or regulated) by two different agencies generate similar impacts to the marine environment, in particular protected marine mammals that rely on sound for survival. The assessment techniques used, and the transparency of the agencies involved is highly in question for actions that produce similar impacts. This master’s project analyzes the assessment techniques of BOEMRE and the U.S. Navy concerning underwater sound, exposing the inadequacies and successes of each agency. The analysis was conducted by reading and comparing the techniques used in Environmental Assessments (EA) and Environmental Impact Statements (EIS) produced by both agencies from 2004 to the present. A series of recommendations for both agencies was produced to address the need for more streamlined and transparent analyses that will aid in more accurate and dynamic impact determinations for such projects as the upcoming BOEMRE Programmatic EIS in the Atlantic Planning Region. I have also developed a GIS-based tool that aids in spatial analysis of propagating sound within the marine environment to improve analysis of potential impacts. This tool allows acoustic propagation models run in the computational program MATLAB® to be imported and integrated in the GIS program ArcGIS ® through the Python scripting language. The integration of this propagation data into GIS allows for better visualizations of sound propagation in 360° around the source and from an aerial perspective. It also allows for further geospatial analysis with other geospatial data such as habitat suitability and species distribution, which can allow for more adaptive species impact determinations and adaptive management for both sonar and seismic survey situations.Item Open Access A Social and Ecological Evaluation of Marine Mammal Take Reduction Teams(2014) McDonald, Sara L.There have been few efforts to evaluate the actual and perceived effectiveness of environmental management programs created by consensus-based, multi-stakeholder negotiation or negotiated rulemaking. Previous evaluations have used perceived success among participants as a proxy for actual effectiveness, but seldom have investigated the ecological outcomes of these negotiations. Fewer still, if any, have compared the actual and perceived outcomes. Here I evaluate and compare the social and ecological outcomes of the negotiated rulemaking process of marine mammal take reduction planning. Take reduction planning is mandated by the U.S. Marine Mammal Protection Act (MMPA) to reduce the fisheries-related serious injuries and mortalities of marine mammals (bycatch) in U.S. waters to below statutory thresholds. Teams of fishermen, environmentalists, researchers, state and federal managers, and members of Regional Fisheries Management Councils and Commissions create consensus-based rules to mitigate bycatch, called Take Reduction Plans. There are six active Take Reduction Plans, one Take Reduction Strategy consisting of voluntary measures, and one plan that was never implemented. It has been 20 years since marine mammal take reduction planning was incorporated into the MMPA. Early evaluations were promising, but identified several challenges. In the past decade or more, the National Marine Fisheries Service (NMFS) has implemented measures to set up the teams for success.
I used data from formal Stock Assessment Reports to assess and rank the actual ecological success of five Take Reduction Plans (Harbor Porpoise, Bottlenose Dolphin, Atlantic Large Whale, Pelagic Longline, and Pacific Offshore Cetacean) in mitigating the bycatch of 17 marine mammal stocks. In addition, I employed social science data collection and analytical methods to evaluate Take Reduction Team participants' opinions of the take reduction negotiation process, outputs, and outcomes with respect to the ingredients required for successful multi-stakeholder, consensus-based negotiation (team membership, shared learning, repeated interactions, facilitated meetings, and consensus-based outputs). These methods included surveying and interviewing current and former Take Reduction Team participants; using Structural Equation Models (SEMs) and qualitative methods to characterize participant perceptions across teams and stakeholder groups; and identifying and exploring the reasons for similarities and differences among respondents, teams, and stakeholder groups. I also employed SEMs to quantitatively examine the relationship between actual and perceived ecological success, and contrasted actual and perceived outcomes by comparing their qualitative rankings.
Structural Equation Models provided a valid framework in which to quantitatively examine social and ecological data, in which the actual ecological outcomes were used as independent predictors of the perceived outcomes. Actual improvements in marine mammal bycatch enhanced stakeholder opinions about the effectiveness of marine mammal Take Reduction Plans. The marine mammal take reduction planning process has all of the ingredients necessary for effective consensus-based, multi-stakeholder negotiations (Chapter 2). It is likely that the emphasis that the National Marine Fisheries Service places on empirical information and keeping stakeholders informed about bycatch, marine mammal stocks, and fisheries facilitated this relationship. Informed stakeholders also had relatively accurate perceptions of the actual ecological effectiveness of the Take Reduction Plans (Chapter 3). The long timeframes over which the teams have been meeting generally have increased cooperation. The professionally trained, neutral facilitators have produced fair negotiations, in which most individuals felt they had an opportunity to contribute. Participant views of fairness significantly influenced their satisfaction with Take Reduction Plans, which significantly affected their perceptions about the effectiveness of those plans (Chapter 2). The mandate to create a consensus-based output has, for the most part, minimized defections from the negotiations and facilitated stakeholder buy-in.
In general, marine mammal take reduction planning is a good negotiated rulemaking process, but has produced mixed results (Chapters 1 and 2). Successful plans were characterized by straightforward regulations and high rates of compliance. Unsuccessful plans had low compliance with complex regulations and sometimes focused on very small stocks. Large teams and those in the northeastern U.S. (Maine to North Carolina) were least successful at reducing bycatch, which was reflected in stakeholder views of the effectiveness of these teams. Take Reduction Team negotiations have not always produced practical or enforceable regulations. Implementation of take reduction regulations is critical in determining plan success and identifying effective mitigation measures, but because of a lack of monitoring, has not been characterized consistently across most teams. Additionally, elements like the "Other Special Measures Provision" in the Harbor Porpoise Take Reduction Plan have undermined the negotiation process by allowing the National Marine Fisheries Service to alter consensus-based elements without consensus from the team, which has led to hostility, mistrust, and frustration among stakeholders.
The final chapter of this dissertation provides recommendations to improve the outcomes and make them more consistent across teams. I based these recommendations on the information gathered and analyzed in the first three chapters. They are grouped into four broad categories - team membership, social capital, fairness, and plan implementation. If the National Marine Fisheries Service implements these suggestions, both perceived and actual ecological effectiveness of marine mammal Take Reduction Teams should improve, allowing these teams to fulfill their maximum potential.
Item Open Access An Analysis of the Potential Acoustic Effects of Cape Wind's Offshore Wind Farm on Marine Mammal Populations(2010-04-29T02:06:38Z) Burgman, JennyOffshore wind farms are an appealing form of renewable energy that are common in Europe but have yet been developed fully in the United States. The Cape Wind project in Massachusetts has proposed the construction of 130 turbines in the Horseshoe Shoal of Nantucket Sound. Despite the potential local benefits of the development, many Cape Cod residents oppose construction of the wind farm. Opposition to this development includes concerns that the noises emitted during all phases of the wind farm’s life cycle will adversely affect populations of marine mammals. In my Master’s project I review and analyze information regarding the acoustic effects of offshore farms and other relevant anthropogenic sound sources. It is difficult to predict fully what effects the Cape Wind project will have on marine mammals in Nantucket Sound. Nevertheless, it is clear that the construction phase would have the greatest potential acoustic impact, including possible displacement; operational sounds are less intense and more likely to result in habituation. Ultimately, however, marine mammals within Horseshoe Shoals do not face any greater risk from Cape Wind than from other anthropogenic sound source in the region.Item Open Access An Assessment of Sea Turtle, Marine Mammal and Seabird Bycatch in the Wider Caribbean Region(2011) Bjorkland, Rhema HyacinthSea turtles, marine mammals and sea birds are vulnerable to higher mortality rates as a direct function of incidental capture (bycatch) in marine fisheries. Their migratory behavior exposes them to multiple fishing gear types and fishing practices and efforts to understand the rates of interaction between these taxa and fishing necessarily entails analysis of data over large spatial areas (ocean-basin) and multiple types of fishing activities. The acquisition the requisite data, however, requires considerable resources and many regions in the world are data-poor with respect to bycatch, including the Wider Caribbean Region (WCR) in the west central Atlantic Ocean basin. This dissertation presents the results of multiple strategies used to assess sea turtle, marine mammal and seabird bycatch in the WCR, with a particular focus on sea turtle bycatch. The research incorporated a synthetic review of the literature, expert consultation, statistical techniques, and geospatial analyses to assess the bycatch seascape for the region. I conclude that sea turtle bycatch in the WRC is significantly linked to turtle rookeries, especially those on the continental land mass and in the southern section of the Caribbean basin, in large part because of the near shore artisanal nature of the fisheries and the importance of these habitats for foraging and reproduction. The limited information on marine mammal bycatch does not permit robust inferences, but it clearly identifies threats to at least one vulnerable marine mammal species, the tucuxi (Sotalia fluviatilis). Information on seabird bycatch was even more limited; the most vulnerable seabird populations occur in the higher latitudes (temperate zones) while the seabird populations in the WCR face significant threats from habitat loss and over-exploitation. This dissertation proposes specific recommendations for improving and advancing the information base for a regional, ecosystem-level management and mitigation of bycatch.
Item Open Access Analyzing the Role of Sound in the Endangered Species Act: A Petition for Sperm Whale (Physeter macrocephalus) Critical Habitat in the Gulf of Mexico(2017-04-27) Elliott, BriannaA key feature of the Endangered Species Act (ESA) is the designation of critical habitat for threatened and endangered species. It is challenging to design critical habitat for marine species, however, due to knowledge gaps and the lack of spatial separation between key life functions (i.e. breeding, feeding). The acoustic component of habitat is particularly important for cetaceans, which rely on sound for communication and other essential life functions. Incorporating an acoustic factor into the critical habitat designations of threatened and endangered cetaceans has only occurred once to date. Thus, this project aims to suggest a way to incorporate sound into the ESA framework by drafting a citizen petition to the National Marine Fisheries Service to designate critical habitat for sperm whales (Physeter macrocephalus) in the Gulf of Mexico, largely based on the importance of acoustic habitat to their basic behavior.Item Open Access Assessing Data Requirements for Calculating Sustainable Marine Mammal Bycatch Limits(2022-04-15) May, EvaThe Fish and Fish Product Import Provisions of the Marine Mammal Protection Act extend several domestic marine mammal management tools to foreign fisheries wishing to export their products to the United States. One of these tools is the calculation of bycatch limits for marine mammal populations impacted by fishing operations. Several methods exist for these calculations, with the most ubiquitous methodology being the Potential Biological Removal model. This study explores all calculation methods and their data requirements, categorizing methods based on model structure and input data. Measures and concepts of population size are most crucial to creating bycatch limit models across existing methods. Exporting fishery managers in low-data environments should focus on collecting population abundance data while being mindful of other important factors such as data uncertainties, how models fit into larger regulatory schemes, and conservation objectives. Further, these models are most accurate and impactful when they are updated and grown as more data about marine mammal populations are collected. Data availability is the primary limiting factor in implementing bycatch limit methods, and this work has important implications for comparability determinations for foreign fisheries under the new Import Provisions.Item Open Access Comparing Stakeholder Perceptions With Empirical Outcomes From Negotiated Rulemaking Policies: Is Participant Satisfaction a Proxy for Policy Success?(Marine Policy, 2016) Roady, S; McDonald, S; Lewison, R; Kramer, R; Rigling-Gallagher, D; Read, AEvaluation of natural resource management policies often is made difficult by lack of robust or long-term data on the resource. In the absence of empirical data, natural resource policy evaluation may rely on expert or stakeholder perception of success as a proxy, particularly in the context of policies that depend on multi-stakeholder engagement or negotiated rulemaking. However, few formal evaluations have compared empirical ecological outcomes with stakeholder perception. This study compares stakeholder perceptions of policy outcomes with ecological outcomes from a long-term, ecological dataset as part of the U.S. Marine Mammal Protection Act's Take Reduction Planning process. Structural Equation Models revealed that stakeholder perceptions were significantly and positively related to positive ecological outcomes. Also, perceived success and ecological performance rankings of the Take Reduction Plans were comparable for three of the five plans examined. This analysis suggests that for this particular policy instrument, stakeholder perception aligns well with ecological outcomes, and this positive relationship is likely the result of a commitment and support for stakeholder education and engagement. However, even within a single policy analysis, there was variability suggesting that the relationship between stakeholder perceptions and policy outcomes must continue to be evaluated. This study suggests that stakeholder perception can be an accurate reflection of ecological outcomes, but not necessarily a predictor of them.Item Open Access Critical information gaps remain in understanding impacts of industrial seismic surveys on marine vertebrates(Endangered Species Research, 2019-01-01) Elliott, BW; Read, AJ; Godley, BJ; Nelms, SE; Nowacek, DP© The authors 2019. Anthropogenic noise is increasing throughout the world's oceans. One major contributor is industrial seismic surveys-a process typically undertaken to locate and estimate the quantity of oil and gas deposits beneath the seafloor-which, in recent years, has increased in magnitude and scope in some regions. Regulators permit this activity despite widespread uncertainties regarding the potential ecological impacts of seismic surveys and gaps in baseline information on some key species of conservation concern. Research to date suggests that impacts vary, from displacement to direct mortality, but these effects remain poorly understood for most species. Here, we summarize potential effects of seismic surveys, describe key knowledge gaps, and recommend broad-scale research priorities for 3 impacted taxonomic groups: fish, marine mammals, and sea turtles. We also suggest further technological advances, improved mitigation measures, and better policy and management structures to minimize the ecological impacts of seismic surveys in light of scientific uncertainty.Item Open Access DISTRIBUTION OF HIGHLY MIGRATORY MARINE MAMMALS AND SEABIRDS IN THE EASTERN NORTH PACIFIC: ARE EXISITNG MARINE PROTECTED AREAS IN THE RIGHT PLACE?(2003) Freeman, KateTo date, only five marine protected areas (MPAs) have been established along the West Coast of the United States, none of which extend more than 30 nautical miles from shore. These areas do not afford habitat protection for a number of highly migratory and often endangered pelagic seabird and cetacean species found in the Northeastern Pacific Ocean. Using sightings data for fourteen species from a Minerals Management Service Computer Database Analysis System, I analyzed species distribution based on oceanographic season (countercurrent, upwelling, oceanic), year (El Nino, La Nina, neutral), patchiness, bathymetry (shelf, shelf-break, slope, pelagic), and index of dispersion (Gx). The species density data were also compared to areas of existing MPAs to determine how well current MPAs protect these species. The results indicate that current MPAs do not protect the habitats of highly migratory species. I therefore compared existing MPA coverage to suggested MPA locations and found much stronger protection in the suggested areas. Recommendations include not only general areas for improved protection, such as the North Bend, Oregon region, but also specific season and bathymetric features to protect as hotspots within the larger regions.Item Open Access GEOGRAPHIC INFLUENCES ON THE SKIN MICROBIOME OF HUMPBACK WHALES(2016-04-21) Bierlich, Kevin Charles (KC)Assessing the health state of wild marine mammals and their populations is challenging, and there is a growing need to develop reliable proxies for health determination. Climate change and other anthropogenic factors are influencing disease prevalence and virulence in the marine environment and there is a need to improve tools and techniques for monitoring the health status of wild marine mammals that are listed as threatened or endangered. The skin is the largest mammalian organ and serves as the first line of defense between the host and their external environment. Most research has focused on human health and has found that the skin microbiome can serve as a protective mechanism by adding to the skin’s defense against colonization of potential pathogenic bacteria. The skin is relatively well-sampled in marine mammals and may serve as a useful proxy for health status, as demonstrated in humans. However, before skin microbiomes become useful health diagnostic tools for marine mammals, more information is needed about the factors influencing variability within the skin microbial community. I analyzed the skin microbiome of 72 apparently healthy humpback whales primarily from Antarctica, as well as Alaska, Hawaii, American Samoa, and the Gulf of Maine. Phylogenetic and statistical analyses revealed two dominant families of bacteria (Moraxellaceae and Flavobacteriaceae) found on each individual whale. However, there were significant differences in the skin microbiomes amongst whales from different geographic areas, both globally as well as amongst regions within Antarctica. These findings provide support that there is a species-specific microbiome on humpback skin that varies according to geographic factors. This initial characterization of the healthy humpback skin microbiome in Antarctica is helpful for future health diagnostic efforts aimed especially at heath-compromised animals. This research ultimately aims to be the building blocks for exploring how the skin microbiome can be used as a diagnostic tool for monitoring marine mammal health.Item Open Access INCORPORATING PASSIVE ACOUSTIC MONITORING DATA INTO OBIS-SEAMAP: A STRATEGY TO ENHANCE MARINE MAMMAL CONSERVATION(2008-04-24) Rider, SarahOver 60 species of marine mammals reside in United States waters. Assessing each marine mammal stock in the United States is a lengthy, expensive, and complicated task. The use of new technologies, such as passive acoustic monitoring, could help to improve marine mammal survey efforts and decrease data fragmentation. Passive acoustics are particularly useful for monitoring cetaceans in remote areas or in periods of poor weather or darkness. OBIS-SEAMAP, a web-based archive of geo-referenced marine mammal, sea turtle, and sea bird datasets, has established a passive acoustic monitoring initiative as a strategy to enhance marine mammal conservation. The initiative will integrate acoustic data into the archive, which currently contains data collected from traditional visual surveys and telemetry. Acoustic methods can improve the ability to detect and monitor many deep-diving, highly migratory, and cryptic marine mammal species (Burtenshaw et al, 2004). However, challenges associated with geographical representation of acoustic recordings need to be addressed prior to data integration into OBIS-SEAMAP. This paper aims to identify some of these difficulties, including localizing cetaceans spatially in two and three dimensions, species identification, and encouraging collaborative participation from marine mammal researchers. Recommendations have been made to improve data collection methods and the process of incorporating acoustic data into SEAMAP.Item Open Access Incorporating Photogrammetric Uncertainty in UAS-based Morphometric Measurements of Baleen Whales(2021) Bierlich, Kevin CharlesIncreasingly, drone-based photogrammetry has been used to measure size and body condition changes in marine megafauna. A broad range of platforms, sensors, and altimeters are being applied for these purposes, but there is no unified way to predict photogrammetric uncertainty across this methodological spectrum. As such, it is difficult to make robust comparisons across studies, disrupting collaborations amongst researchers using platforms with varying levels of measurement accuracy.
In this dissertation, I evaluate the major drivers of photogrammetric error and develop a framework to easily quantify and incorporate uncertainty associated with different UAS platforms. To do this, I take an experimental approach to train a Bayesian statistical model using a known-sized object floating at the water’s surface to quantify how measurement error scales with altitude for several different drones equipped with different cameras, focal length lenses, and altimeters. I then use the fitted model to predict the length distributions of unknown-sized humpback whales and assess how predicted uncertainty can affect quantities derived from photogrammetric measurements such as the age class of an animal (Chapter 1). I also use the fitted model to predict body condition of blue whales, humpback whales, and Antarctic minke whales, providing the first comparison of how uncertainty scales across commonly used 1-, 2-, and 3-dimensional (1D, 2D, and 3D, respectively) body condition measurements (Chapter 2). This statistical framework jointly estimates errors from altitude and length measurements and accounts for altitudes measured with both barometers and laser altimeters while incorporating errors specific to each. This Bayesian statistical model outputs a posterior predictive distribution of measurement uncertainty around length and body condition measurements and allows for the construction of highest posterior density intervals to define measurement uncertainty, which allows one to make probabilistic statements and stronger inferences pertaining to morphometric features critical for understanding life history patterns and potential impacts from anthropogenically altered habitats. From these studies, I find that altimeters can greatly influence measurement predictions, with measurements using a barometer producing larger and greater uncertainty compared to using a laser altimeter, which can influence age classifications. I also find that while the different body condition measurements are highly correlated with one another, uncertainty does not scale linearly across 1D, 2D, and 3D body condition measurements, with 2D and 3D uncertainty increasing by a factor of 1.44 and 2.14 compared to 1D measurements, respectively. I find that body area index (BAI) accounts for potential variation along the body for each species and was the most precise body condition measurement.
I then use the model to incorporate uncertainty associated with different drone platforms to measure how body condition (as BAI) changes over the course of the foraging season for humpback whales along the Western Antarctic Peninsula (Chapter 3). I find that BAI increases curvilinearly for each reproductive class, with rapid increases in body condition early in the season compared to later in the season. Lactating females had the lowest BAI, reflecting the high energetic costs of reproduction, whereas mature whales had the largest BAI, reflecting their high energy stores for financing the costs of reproduction on the breeding grounds. Calves also increased BAI opposed to strictly increasing length, while immature whales may increase their BAI and commence an early migration by mid-season. These results set a baseline for monitoring this healthy population in the future as they face potential impacts from climate change and anthropogenic stresses. This dissertation concludes with a best practices guide for minimizing, quantifying, and incorporating uncertainty associated with photogrammetry data. This work provides novel insights into how to obtain more accurate morphological measurements to help increase our understanding of how animals perform and function in their environment, as well as better track the health of populations over time and space.
Item Open Access MARINE MAMMALS AND THE EFFECTS OF NOISE: FACTS ABOUT ACOUSTIC SIGNALS AND THE POTENTIAL IMPACTS OF HUMAN SOUND SOURCES(2005) Cornet, Jacquelyn LBoth natural and human-generated sounds fill the marine environment. Biological processes generate natural sound such as wind, rain, and waves. Humans intentionally produce sound when using sonar or conducting seismic surveys as tools to visualize the underwater world. They produce sound unintentionally through oil and gas exploration and extraction, ocean experiments, and shipping. As sound increases in the ocean, scientists and the general public become increasingly concerned about the potential impact of sound on marine mammals. With these concerns in mind, I undertook a project to provide public outreach and education by producing a brochure for National Oceanic and Atmospheric Administration (NOAA), The American Zoo and Aquarium Association (AZA), Consortium for Oceanographic Research and Education (CORE), and the Marine Mammal Commission (MMC) to distribute during their series of public lectures around the United States to increase public knowledge about human-generated noise and marine animals.Item Open Access Mechanistic Habitat Modeling with Multi-Model Climate Ensembles(2013-04-25) Jones, HunterProjections of future Sea Ice Concentration (SIC) were prepared using a 13-member ensemble of climate model output from the Coupled Model Inter-comparison Project (CMIP5). Three climate change scenarios (RCP 2.6, RCP 6.0, RCP 8.5), corresponding to low, moderate, and high climate change possibilities, were used to generate these projections for known Harp Seal whelping locations. The projections were splined and statistically downscaled via the CCAFS Delta method using satellite-derived observations from the National Sea Ice Data Center (NSIDC) to prepare a spatial representation of sea ice decline through the year 2100. Multi-Model Ensemble projections of the mean sea ice concentration anomaly for Harp Seal whelping locations under the moderate and high climate change scenarios (RCP 6.0 and RCP 8.5) show a decline of 10% to 40% by 2100 from a modern baseline climatology (average of SIC, 1988 - 2005) while sea ice concentrations under the low climate change scenario remain fairly stable. Projected year-over-year sea ice concentration variability decreases with time through 2100, but uncertainty in the prediction (model spread) increases. The general decline in sea ice projected by climate models is detrimental to Harp Seal survival, but the effect of the decreased year-over-year variability is less certain.Item Open Access Pacific Island Fisheries and Interactions with Marine Mammals, Seabirds and Sea Turtles(2009-04-24T15:06:07Z) Aylesworth, LindsayThe extent to which Pacific Island fisheries affect marine mammals, sea turtles, and seabirds due to bycatch remains largely unknown. This report attempts to synthesize the existing information relating to fisheries and bycatch of marine mammals, sea turtles, and sea birds in the Pacific Island countries and territories. The Oceania region encompasses the 22 Pacific Island countries and territories including Papua New Guinea (PNG), but excluding Hawaii, New Zealand, and Australia. Tuna is the most important commercial fishery with four target species (albacore, bigeye, skipjack, and yellowfin) and four distinct gear types (purse seine, longline, pole and line, and trollers) (Gillett, 2008). The subsistence and artisanal fisheries located inshore are largely unregulated with little to no monitoring of catch or effort. Bycatch would be extremely difficult to monitor in these fisheries as seabirds, turtles and even some marine mammals are consumed traditionally throughout the Pacific Islands and any unintentional catch would be retained and consumed. Despite efforts in certain areas and on several species, e.g., humpback whales, detailed knowledge of marine mammals, seabirds and sea turtles is at best extremely limited. The only bycatch mortality estimates are from the commercial tuna fishery indicating around 265 marine mammals, 100 seabirds and 900 sea turtles are killed per year (Molony 2005). The main challenge to identifying and quantifying bycatch of sea turtles is the lack of observer coverage. Information on population structure and occurrence of marine mammals, sea turtles, and seabirds in the region should be a priority. Bycatch language should be written into national tuna management programs and industry should be involved in discussions to mitigate bycatch at the WCPFC. Other recommendations include research into the catch and effort in subsistence and small-scale fisheries as well as mandatory workshops for commercial vessel owners on bycatch handling and training as part of a licensing scheme.Item Open Access Soundscape Ecology of Hawaiian Spinner Dolphin Resting Bays(2016) Heenehan, Heather LeighSound is a key sensory modality for Hawaiian spinner dolphins. Like many other marine animals, these dolphins rely on sound and their acoustic environment for many aspects of their daily lives, making it is essential to understand soundscape in areas that are critical to their survival. Hawaiian spinner dolphins rest during the day in shallow coastal areas and forage offshore at night. In my dissertation I focus on the soundscape of the bays where Hawaiian spinner dolphins rest taking a soundscape ecology approach. I primarily relied on passive acoustic monitoring using four DSG-Ocean acoustic loggers in four Hawaiian spinner dolphin resting bays on the Kona Coast of Hawai‛i Island. 30-second recordings were made every four minutes in each of the bays for 20 to 27 months between January 8, 2011 and March 30, 2013. I also utilized concomitant vessel-based visual surveys in the four bays to provide context for these recordings. In my first chapter I used the contributions of the dolphins to the soundscape to monitor presence in the bays and found the degree of presence varied greatly from less than 40% to nearly 90% of days monitored with dolphins present. Having established these bays as important to the animals, in my second chapter I explored the many components of their resting bay soundscape and evaluated the influence of natural and human events on the soundscape. I characterized the overall soundscape in each of the four bays, used the tsunami event of March 2011 to approximate a natural soundscape and identified all loud daytime outliers. Overall, sound levels were consistently louder at night and quieter during the daytime due to the sounds from snapping shrimp. In fact, peak Hawaiian spinner dolphin resting time co-occurs with the quietest part of the day. However, I also found that humans drastically alter this daytime soundscape with sound from offshore aquaculture, vessel sound and military mid-frequency active sonar. During one recorded mid-frequency active sonar event in August 2011, sound pressure levels in the 3.15 kHz 1/3rd-octave band were as high as 45.8 dB above median ambient noise levels. Human activity both inside (vessels) and outside (sonar and aquaculture) the bays significantly altered the resting bay soundscape. Inside the bays there are high levels of human activity including vessel-based tourism directly targeting the dolphins. The interactions between humans and dolphins in their resting bays are of concern; therefore, my third chapter aimed to assess the acoustic response of the dolphins to human activity. Using days where acoustic recordings overlapped with visual surveys I found the greatest response in a bay with dolphin-centric activities, not in the bay with the most vessel activity, indicating that it is not the magnitude that elicits a response but the focus of the activity. In my fourth chapter I summarize the key results from my first three chapters to illustrate the power of multiple site design to prioritize action to protect Hawaiian spinner dolphins in their resting bays, a chapter I hope will be useful for managers should they take further action to protect the dolphins.
Item Unknown Spatial Relationships among Hydroacoustic, Hydrographic and Top Predator Patterns: Cetacean Distributions in the Mid-Atlantic Bight(2016) LaBrecque, ErinEffective conservation and management of top predators requires a comprehensive understanding of their distributions and of the underlying biological and physical processes that affect these distributions. The Mid-Atlantic Bight shelf break system is a dynamic and productive region where at least 32 species of cetaceans have been recorded through various systematic and opportunistic marine mammal surveys from the 1970s through 2012. My dissertation characterizes the spatial distribution and habitat of cetaceans in the Mid-Atlantic Bight shelf break system by utilizing marine mammal line-transect survey data, synoptic multi-frequency active acoustic data, and fine-scale hydrographic data collected during the 2011 summer Atlantic Marine Assessment Program for Protected Species (AMAPPS) survey. Although studies describing cetacean habitat and distributions have been previously conducted in the Mid-Atlantic Bight, my research specifically focuses on the shelf break region to elucidate both the physical and biological processes that influence cetacean distribution patterns within this cetacean hotspot.
In Chapter One I review biologically important areas for cetaceans in the Atlantic waters of the United States. I describe the study area, the shelf break region of the Mid-Atlantic Bight, in terms of the general oceanography, productivity and biodiversity. According to recent habitat-based cetacean density models, the shelf break region is an area of high cetacean abundance and density, yet little research is directed at understanding the mechanisms that establish this region as a cetacean hotspot.
In Chapter Two I present the basic physical principles of sound in water and describe the methodology used to categorize opportunistically collected multi-frequency active acoustic data using frequency responses techniques. Frequency response classification methods are usually employed in conjunction with net-tow data, but the logistics of the 2011 AMAPPS survey did not allow for appropriate net-tow data to be collected. Biologically meaningful information can be extracted from acoustic scattering regions by comparing the frequency response curves of acoustic regions to theoretical curves of known scattering models. Using the five frequencies on the EK60 system (18, 38, 70, 120, and 200 kHz), three categories of scatterers were defined: fish-like (with swim bladder), nekton-like (e.g., euphausiids), and plankton-like (e.g., copepods). I also employed a multi-frequency acoustic categorization method using three frequencies (18, 38, and 120 kHz) that has been used in the Gulf of Maine and Georges Bank which is based the presence or absence of volume backscatter above a threshold. This method is more objective than the comparison of frequency response curves because it uses an established backscatter value for the threshold. By removing all data below the threshold, only strong scattering information is retained.
In Chapter Three I analyze the distribution of the categorized acoustic regions of interest during the daytime cross shelf transects. Over all transects, plankton-like acoustic regions of interest were detected most frequently, followed by fish-like acoustic regions and then nekton-like acoustic regions. Plankton-like detections were the only significantly different acoustic detections per kilometer, although nekton-like detections were only slightly not significant. Using the threshold categorization method by Jech and Michaels (2006) provides a more conservative and discrete detection of acoustic scatterers and allows me to retrieve backscatter values along transects in areas that have been categorized. This provides continuous data values that can be integrated at discrete spatial increments for wavelet analysis. Wavelet analysis indicates significant spatial scales of interest for fish-like and nekton-like acoustic backscatter range from one to four kilometers and vary among transects.
In Chapter Four I analyze the fine scale distribution of cetaceans in the shelf break system of the Mid-Atlantic Bight using corrected sightings per trackline region, classification trees, multidimensional scaling, and random forest analysis. I describe habitat for common dolphins, Risso’s dolphins and sperm whales. From the distribution of cetacean sightings, patterns of habitat start to emerge: within the shelf break region of the Mid-Atlantic Bight, common dolphins were sighted more prevalently over the shelf while sperm whales were more frequently found in the deep waters offshore and Risso’s dolphins were most prevalent at the shelf break. Multidimensional scaling presents clear environmental separation among common dolphins and Risso’s dolphins and sperm whales. The sperm whale random forest habitat model had the lowest misclassification error (0.30) and the Risso’s dolphin random forest habitat model had the greatest misclassification error (0.37). Shallow water depth (less than 148 meters) was the primary variable selected in the classification model for common dolphin habitat. Distance to surface density fronts and surface temperature fronts were the primary variables selected in the classification models to describe Risso’s dolphin habitat and sperm whale habitat respectively. When mapped back into geographic space, these three cetacean species occupy different fine-scale habitats within the dynamic Mid-Atlantic Bight shelf break system.
In Chapter Five I present a summary of the previous chapters and present potential analytical steps to address ecological questions pertaining the dynamic shelf break region. Taken together, the results of my dissertation demonstrate the use of opportunistically collected data in ecosystem studies; emphasize the need to incorporate middle trophic level data and oceanographic features into cetacean habitat models; and emphasize the importance of developing more mechanistic understanding of dynamic ecosystems.
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