Browsing by Author "Dunn, Daniel"

Now showing 1 - 5 of 5
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    Assessing the potential of Important Marine Mammal Areas to address connectivity and promote marine mammal conservation
    (2018-05) Alberini, Amalia
    This study examines and identifies the potential of marine mammal scientific data tools, namely the Important Marine Mammal Areas (IMMAs) and the Migratory Connectivity in the Ocean (MiCO) system, can have in contributing towards advancing current knowledge on marine mammals. This report examines how these tools can significantly improve the synthesis and availability of existing marine mammal data in different ocean regions, using two case studies, the Mediterranean Sea and the Southwest Pacific Ocean. Chapter 1 integrates the migration data stemming from the MiCO system and other available data on the two main migratory species, the sperm and fin whales to develop hypotheses for their migratory patterns in the Mediterranean Sea. The existing data is combined with the IMMAs designed for the two species in the region to identify the migration status and connectivity between these areas. Based on the findings, we propose scientific methodologies to be conducted to better account for the entire life-history of key migratory species. Chapter 2 assesses the potential of IMMAs in strengthening existing scientific knowledge and promoting marine mammal conservation at the national scale using two case studies in Palau, in the Southwest Pacific Ocean. This study represents an initial attempt to examine the potential of establishing an IMMA to foster and advance marine mammal research and to provide the baseline for management decisions for marine mammal conservation in a poor-data region. This is the first study done to explore how the presence of IMMAs in an ocean region where limited data exists can contribute to increasing and complementing science, policy, and management efforts to address existing knowledge gaps on marine mammals. Based on the main gaps identified, general and specific recommendations at all levels are provided to address main threats on marine mammal species. Overall, this study provides evidence for the first time that the MiCO system and IMMA process, if combined and fully integrated, can contribute to a more comprehensive and holist understanding of the dynamic nature of marine mammals and ultimately to the design of area-based management planning for the effective conservation of marine mammal habitats in the oceans.
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    Evaluating Electronic Methods of Fisheries Monitoring, Control, and Surveillance
    (2018-04-27) Blondin, Hannah
    Management of the world's fisheries has become an increasingly important issue over the last several decades as numerous stocks have begun to decline, some more rapidly than others. Electronic Technologies encompass a suite of new technologies that can be used to monitor catch, gear usage, reporting, bycatch, and vessel activity. Within this paper, I summarize findings from a three-part study on the evaluation of electronic technologies in fisheries monitoring, control, and surveillance (MCS) world-wide. In Part I, I focus on the various electronic methods that are currently employed within managed fisheries. Further, I describe the distribution of programs that use these methods across the globe, focusing particularly on Remote Electronic Monitoring (REM) and Vessel Monitoring Systems (VMS). Part II is an extensive literature review on the utilization of REM within fisheries management. Specifically, I analyze successes and failures of the use of REM in fishery MCS programs. Additionally, I make recommendations on the application of the technology to fisheries management worldwide in support of the Environmental Defense Fund (EDF) Fishery Solution Center's Global Electronic Monitoring Project. In Part III, I take a deeper look into VMS by analyzing VMS data from mid-water trawling vessels in Sierra Leone. I use a Hidden Markov Model (HMM) to spatially distinguish between fishing activity and non-fishing activity to 1) determine the distribution of mid-water trawling effort of 16 vessels in Sierra Leone waters and 2) determine if industrial vessels may be fishing illegally in the Inshore Exclusive Zone (IEZ) limited to artisanal fishing only.
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    Habitat Modeling of Invasive Blue Catfish in the Patuxent River, Chesapeake Bay
    (2019-04-25) McCabe, Patrick
    Invasive blue catfish (Ictalurus furcatus) populations have expanded to many tributaries of the Chesapeake Bay, negatively impacting native species through predation and competition. To mitigate this problem, the state of Maryland has recently launched programs to aid the growth of the commercial fishery targeting the species to reduce the negative ecological impact of blue catfish while also benefitting the local economy. However, little is known about habitat use and movement of invasive blue catfish within these tributaries. This study presents a predictive model of blue catfish habitat use within the Patuxent river utilizing acoustic telemetry and a binary Boosted Regression Tree (BRT) modelling approach to identify seasonal habitat and movement as well as abiotic environmental covariates that may influence its distribution. Salinity had the largest relative influence on the BRT models, followed by depth and water temperature. Acoustic telemetry and model results reveal that primary blue catfish habitat is in the freshwater upper reaches of the Patuxent during the winter and late summer, with some individuals observed year-round. Downstream shifts in presence probability occurred in spring/early summer and fall, possibly associated with spawning and feeding respectively. Model results predict that blue catfish are most often present, and thus likely have the greatest ecological impacts, in tidal freshwater areas of the Patuxent and management should concentrate fishing effort in this area.
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    Longitudinal analysis of historical seabird bycatch data in the North Pacific
    (2018-04-26) Poulin, Sarah
    Historical ecology is used by researchers to help understand how past interactions between people and their environment have shaped contemporary conditions. Though recent science has responded to the many management challenges of the ocean, the lack of analysis and limited availability of archival data hinders our ability to place current ocean impacts in the historical context of exploitation. All 22 species of albatross and several species of petrels are currently listed as Near Threatened or Threatened by the IUCN with bycatch cited as the main threat. However, there are very few publicly available datasets on the interactions between fisheries and seabirds before the 1990’s. The purpose of this project was to explore and analyze historical data collections from the Smithsonian and the USGS. These overlooked records contain seabird band return cards that specify extensive information from as early as the 1940’s on seabird bycatch occurrences in the North Pacific. With the inclusion of this new information, more thorough management may be implemented that accounts for the longitudinal gaps of modern day bycatch records through complementing current data sources with archival datasets.
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    SPATIAL DISTRIBUTION AND MIGRATORY CONNECTIVITY OF SHARKS IN THE GULF OF MEXICO
    (2019-04-13) Whitten, Meredith
    Since the 1950s, highly migratory shark species worldwide have experienced severe declines, with some populations in the Gulf of Mexico showing decreases of more than 90%. As a result, there is a clear need for better data and tools to inform the spatial and temporal management of shark populations. In recent years, the use of satellite and acoustic tracking has increased, but there has been limited critical assessment of the current state of knowledge resulting from these studies. In partnership with The Nature Conservancy’s Migratory Blueways Project, this study aims to fill this gap through 1) a comprehensive, systematic literature review of available telemetry data and 2) a comparative analysis of multiple methods for processing satellite telemetry data. The literature review analyzed telemetry tagging papers for 10 species of highly migratory sharks in the Gulf of Mexico: Whale sharks, silky sharks, great white sharks, great hammerheads, scalloped hammerheads, tiger sharks, bull sharks, oceanic whitetips, shortfin makos, and longfin makos. These species were chosen based on their highly migratory behavior and the level of threat to their populations. The review used the very broad search terms “shark” and “Gulf of Mexico” which returned over 1000 results. After filtering the results for relevancy, only 15 telemetry tagging studies for these species were identified. Two of the most threatened species, oceanic whitetips and silky sharks, had no coverage in the literature. The date range for the papers was 2008-2019, with an increasing trend in number of publications over time. Many species were missing tagging data from regions of the Gulf of Mexico, with no tagging occurring in the southwestern Gulf. Scalloped hammerheads showed a heavily male skewed sex ratio in the individuals tagged, indicating missing information about female behavior. Recommendations from this review include better collaboration between institutions to help reduce costs of collecting data and to increase the amount of data available. The second part of this research compared methods for processing satellite telemetry data used by The Nature Conservancy (TNC) and the Migratory Connectivity in the Ocean (MiCO) projects on the same dataset of 12 hammerhead sharks. TNC utilized a line density method, while MiCO utilized state-space modeling to generate kernel density estimates (KDE). TNC’s work was conducted using Python coding language, while MiCO uses R packages. The results showed that the overall products are similar, with the TNC product covering 22% more area of the Gulf, likely due to MiCO’s more rigorous filtering methods. TNC’s methods were faster but are less supported by scientific literature, so MiCO’s methods are likely preferred for making management decisions. Overall, choosing a method depends on the expertise and intentions of the user group. Introducing more data from other spatial regions of the Gulf would contribute to developing better products for use in conservation and policy.