Browsing by Author "Read, Andy"
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Item Open Access A Comparative Analysis Approach to Reducing Vessel Strikes on the Florida Manatee(2011-04-28) Rao, LeelaThe Florida manatee (Trichecheus manatus latirostris) is an endangered species, having been listed in the first U.S. federal endangered species legislation in 1967. However, forty years later, they have not been removed from endangered status. Watercraft collisions with manatees have been estimated to have the greatest impact on their population sustainability. These accidents account for about a quarter of manatee deaths every year. The Florida registered boater population has now reached almost one million registered boaters, and the manatee population is growing as well. Consequently, the frequency of manatee-vessel collisions is likely to become even more frequent. A comparison of terrestrial wildlife collision management measures, primarily of ungulates, to the mitigation management schemes for the Florida manatee was undertaken. A unique approach to viewing the problem after decades of management may provide new insights and approaches to reduce occurrence of manatee-boat collisions. Based on the findings from this research, the application of many terrestrial wildlife collision mitigation measures are inappropriate to reduce manatee-boat strikes. However, some of the terrestrial strategies may be appropriate if the manatee population becomes more imperiled. Aggressive management techniques such as marine fencing, seagrass management, and measures to encourage or force boaters to reduce speed may become necessary. Lessons from effective signage from the terrestrial environment can be successfully applied to signage in the marine environment indicating that further work in this area should be a priority for marine wildlife managers.Item Open Access A Review of Aquaculture Gear Characteristics and Impacts on Entanglement Risk for Protected Species(2021-04-22) Eynon, JohnEntanglement in fishing gear is the cause of death for hundreds of thousands of marine mammals and sea turtles every year. There are relatively few documented cases of protected species entanglement in aquaculture gear, but events are likely underreported. Interactions with aquaculture are expected to increase in the United States as demand for seafood drives industry growth, new technologies enable farming further offshore, and clarified regulatory processes reduce barriers to entry. Despite this, little attention has been paid to how characteristics of aquaculture gear impact entanglement risk. This research a) catalogs the gear elements thought to influence detection, contact, entanglement, entanglement sustainment, and/or injury severity, and b) summarizes the state of knowledge on how each identified characteristic influences entanglement risk. I find that many of the characteristics are correlated and/or interact in their influence on entanglement. By highlighting relevant gear elements, this review supports future research into system-specific strategies for mitigating entanglement risk.Item Open Access An Analysis of Gray and Harbor Seal Strandings in Cape Cod, Massachusetts from 1999 to 2012.(2014-04-25) Frungillo, JaimeIn recent years, the number of gray seals, Halichoerus grypus, inhabiting Massachusetts has increased dramatically. In Canada and Scotland, similar increases in gray seal abundance have been accompanied by a concomitant decrease in numbers of sympatric harbor seals, Phoca vitulina. It has been hypothesized, although not confirmed, that interspecific competition between the two species led to a decrease in harbor seal populations. The present study addressed the question of whether gray seals and harbor seal populations are interacting in Cape Cod, MA by analyzing stranding data from Cape Cod in the period from 1999 to 2012, provided by the International Fund for Animal Welfare (IFAW). Gray seal strandings increased 2.9% annually from 1999 to 2012. Harbor seal strandings, on the other hand, increased 8.5% annually until 2004, after which the increased stopped and the number of strandings varied interannually. Strandings were best predicted by species, age class, and month, although age class only affected harbor seal seasonal stranding trends. Seasonal trends in the number of gray and harbor seal strandings caused by human interactions were significantly different. These differences in the stranding record suggest that the two species are interacting ecologically in Cape Cod.Item Open Access Bycatch and Biomass: Mitigating dolphin bycatch while maintaining fish catch in the Virginia Beach pound net fishery(2008-04-18T22:24:11Z) Herman, EliaPound nets are traditional, passive fishing traps that have been used since the 1870s to catch estuarine fish species in the Chesapeake Bay. Most unwanted species captured in the actual pound net can be released alive; however, sea turtles and marine mammals may die if they become entangled in the leader of the net. In 2004, NOAA Fisheries required changes in the construction of pound net leaders in part of the Chesapeake Bay to reduce entanglement rates of sea turtles. To date no actions have been taken to address the bycatch of bottlenose dolphins in pound net leaders. In the summer of 2007, I conducted a pilot study to sample catches of butterfish (Peprilus alepidotus and Peprilus triacanthus) and Spanish mackerel (Scomberomorus maculatus) in a Virginia Beach pound net fishery considering modifications to their leaders to reduce dolphin bycatch. Using these observations, I worked with the Virginia Aquarium to design an experiment to test the new leaders during the 2008 fishing season. The primary goal of this experiment is to determine whether the experimental leader will affect the catch of target fish species. From an analysis of dolphin strandings in Virginia from 1997-2004, I found that pound nets accounted for the greatest percentage (50%) of all documented Human Interaction (HI) strandings. I also used geospatial analyses to examine the distribution of bottlenose dolphin strandings that may be associated with bycatch in pound nets. HI stranded dolphins were found significantly closer to the Virginia Beach pound nets than dolphins that stranded for another reason (No HI) or for an unknown cause (CBD). Together these analyses help to improve our understanding of interactions between bottlenose dolphins and the Virginia Beach pound net fishery, as well as the importance of community-based management efforts.Item Open Access Connecting Populations Across Ocean Basins: Genomics of Short-finned Pilot Whales (Globicephala macrorhynchus) in the Western North Atlantic(2022-04-18) Hanson, SophieShort-finned pilot whales (Globicephala macrorhynchus) are widely-distributed throughout the Atlantic Ocean. These whales are capable of traveling large distances, yet their regional movement patterns and population structure are poorly defined, making stock identification and species management challenging. To understand the population structure of these whales, I analyzed genetic relatedness across 56 distinct individuals in three geographic locations: the Caribbean nation of St. Vincent & the Grenadines (n = 17), Florida, USA (n = 7), and North Carolina, USA (n = 36). I generated genetic sequences from tissue samples using double digest restriction site associated DNA sequencing (ddRAD-Seq). I then derived 3,227 single nucleotide polymorphisms (SNPs) from the Freebayes bioinformatics pipeline. To infer population structure, I used a Bayesian clustering analysis implemented in STRUCTURE software. The results indicate that individuals from all of the three sampling locations are genetically similar. This supports the hypothesis that there is substantial gene flow between the eastern Caribbean and southeast United States. It is likely that the Gulf Stream and extensive continental shelf facilitate long-ranging individual or group movement, and thus connectivity. Interestingly, results also indicate a second, genetically-distinct population comprised of three individuals (two from St. Vincent and one from North Carolina). While more sampling is needed to confirm this second population, it is possible that there is a larger oceanic stock in the western North Atlantic. Together, these findings can be used to better inform the management of short-finned pilot whales, which is imperative considering rising anthropogenic pressures, mass-strandings, and the species’ cultural importance in artisanal whaling.Item Open Access Determining the northern range of the NNCES stock of bottlenose dolphins (Tursiops truncatus) through photo-identification(2018-04-27) Young, AlainaThe Roanoke Sound is an important summer habitat for coastal Atlantic bottlenose dolphins, including members of the Northern North Carolina Estuarine System (NNCES) stock. However, our understanding of the northern range of this stock is limited. It has been assumed that the stock occurs northward only as far as the NC/VA border, but there is considerable uncertainty in the location of this boundary. The objective of the present study was to better delineate this boundary by determining the northern range of individual dolphins sighted in Roanoke Sound. I matched individuals with high capture probabilities (n=59) in Roanoke Sound (NC-OBXCDR catalog) with individuals sighted in Norfolk, Virginia (VA-HDR catalog), the Potomac (MD-PCDP) catalog, and Cape May, NJ (NJ-CMWWRC catalog) through the MABDC. Five individuals, all likely females, were matched to VA-HDR, but none were matched to MD-PCP nor to NJ-CMWWRC. Four of the matched individuals were also sighted in the Pamlico Sound. The movements of these dolphins show some degree of seasonality, with sightings in the Roanoke Sound peaking in June but occurring from May to October, and in Virginia only in July and August. The results of my study indicate that the NC/VA border is not the northern boundary of the NNCES stock, but instead that the movement of these dolphins extends into the Chesapeake Bay. Thus, the management of this stock of dolphins should consider the threats, including by-catch, that may occur in this extended range.Item Open Access Evaluating the Effectiveness of Marine No-Take Reserves in St. Eustatius, Netherlands Antilles(2009-04-24T17:20:05Z) McClellan, KatherineMarine reserves, in which exploitation of marine organisms and other human activities are restricted or prohibited, can be valuable tools for marine conservation and fisheries management. No-take marine reserves support greater density, size, and diversity of fishes than exploited areas, with most benefits accruing to heavily exploited species. Protected areas can also export biomass to sustain or increase the overall yield of adjacent fisheries. These effects can be especially significant for organisms with small home ranges, such as coral reef fish. Although there are many benefits to creating marine reserves they are also costly to manage and can infringe on people’s recreation and livelihoods. For marine reserves to be used as management tools, a comprehensive knowledge of the ecosystems is needed and reserve impacts should be regularly monitored. St. Eustatius Marine Park and two no-take marine reserves were established by the Statian government in 1996 to promote dive tourism and sustainable fisheries. No fisheries study was carried out prior to reserve implementation to determine the status of fish stocks. In the summer of 2008, surveys were undertaken inside and outside the marine reserves to census reef fish and habitat to establish a current baseline and to evaluate the effects of the marine reserves on reef fish populations. The data that was collected was used to answer three questions about the current state of the Marine Park: 1) are there habitat related differences between reserve areas and non-reserve areas or between reef types? 2) do fish density, diversity, or biomass differ between protected and unprotected sites or between reef types? and 3) do habitat characteristics, reserve status, or reef type influence fish density, diversity, and biomass? This study determined that habitat differences among the survey sites affected reef fish populations more than reserve status. However, the no-take reserves may still be important for protecting reef fish populations. The two reserves have been in place for more than 10 years and it is unknown what happened to fish populations during that time. Future research, employing the methods of this study, can be used to monitor reef fish populations and habitat over time to better determine if the reserves are having beneficial effects.Item Open Access Evaluation of Thermal Characteristics of Secondary Warm-Water Sites for the Florida Manatee(2010-04-30T19:05:50Z) Loomis, Caroline PittWhile the threat of collisions with recreational watercraft continues to be a serious concern for the Florida manatee population, a growing threat in the future is likely to be the loss of available winter habitat. Manatees are at risk of illness or death in water temperatures less than 20°C. To meet their thermoregulatory needs, manatees rely on sources of warm-water habitat. Currently the majority of the population is utilizing thermal discharges at coastal power plants to stay warm during winter cold periods; however, most of these power plants are expected to close down in the next t20 to 50 years. Since 1998 the Florida Fish and Wildlife Conservation Commission (FWC) has collected time-series temperature data at various sites used by manatees in winter. The goal of my project was to evaluate the thermal characteristics of 10 suspected warm-water sites in southern Florida to assess their potential suitability as winter habitat for manatees. Sites were assessed based on how frequently they were at temperatures considered threatening to manatee health and mortality, and on how many consecutive days they remained below these threshold temperatures. Delta-T and regression analysis were also used to compare the temperature of potential warm-water sites to that of nearby ambient sites. The results of this analysis will be used to make recommendations to the FWC about which sites might provide suitable warm-water habitat and should be further investigated with more detailed monitoring efforts in the future. This information could be used to meet the agency’s long-term goal of creating a protected network of warm-water habitat throughout the state.Item Open Access IMPLICATIONS OF HISTORICAL CHANGES IN FIXED FISHING GEAR FOR LARGE WHALE ENTANGLEMENTS IN THE NORTHWEST ATLANTIC(2003) Kozuck, AmandaNorth Atlantic right whales (Eubalaena glacialis) are one of the most critically endangered large whales in the world, with an estimate of 300 animals remaining. Despite international protection from whaling since 1935 and an endangered status listing under the United States Endangered Species Act, this population has been in decline since the 1990s. Factors hindering recovery include entanglements in fishing gear and ship collisions. Today, lobster pots and gillnets are most commonly implicated in large whale entanglements, especially those of right and humpback (Megaptera novaeangliae) whales. However, other fixed fishing gear presents entanglement risk to large whales, such as crab pots and slime eel gear. Entanglements typically occur when whales come into contact with lines attached to the gear; any body part can be involved. I present historical data tracking changes in fishing line and fixed fishing gear, as well as changes in fishing practices, from the mid-1940s to the present in the Northwest Atlantic. The introduction of synthetic materials to the fishing industry in the 1950s, coupled with government subsidies and legislation for domestic fishery expansion, led to dramatic increases in fishing effort and efficiency. These attempts to promote the development of the U.S. fishing industry have created entanglement risk for large whales. In 2002, eight right and eleven humpback whale entanglements were documented; two deaths resulted, one of each species. This suggests that existing protective measures are inadequate. I briefly examine current regulations and provide suggestions for further measures to reduce the conflict between large whales and fixed gear fisheries.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 Patterns of odontocete depredation and bycatch in pelagic longline fisheries.(2022) Fader, Joseph EmersonThe leading threat to the conservation of whales and dolphins worldwide is incidental mortality (or bycatch) in fisheries. In longline fisheries, these interactions are commonly driven by an attraction to feed on bait or fish secured on fishing gear, a process known as depredation. Depredation is particularly common and costly in longline fisheries, where bait and catch are typically unprotected prior to gear retrieval. Bycatch of depredating whales can occur when animals become hooked or entangled in the gear while attempting to remove bait or catch. Depredation, and associated bycatch, is an exceedingly difficult problem to solve in open-ocean, or pelagic, longline fisheries, because the behavior often occurs at depth or at a large distance from the fishing vessel. Evidence of depredation may consist only of large stretches of missing bait or fish heads on hooks, because odontocetes have eaten the bodies of captured fish. Observations of bycatch are also rare and depend on on-board observers to carefully report details of the interactions.In my dissertation, I examined two longline fisheries in the United States heavily impacted by depredation and bycatch of cetaceans: the Hawai‘i deep-set longline fishery depredated by false killer whales (Pseudorca crassidens) and the Atlantic pelagic longline fishery depredated by short-finned pilot whales (Globicephala macrorhynchus). These two interactions are data rich (relative to most other pelagic longline fisheries), with detailed observations of cetacean-fishery interactions and long-term, dedicated behavioral research programs focused on the two depredator species. Both fisheries also benefit from resources and institutional will as a consequence of legislative mandates to reduce bycatch by the U.S. Marine Mammal Protection Act. Nevertheless, managers and stakeholders in both fisheries have struggled to fully resolve the problem. I used a variety of different data sources and interdisciplinary methods to better characterize depredation and bycatch interactions in both fisheries, with the ultimate goal to identify potential mitigation solutions that may help reduce the negative impacts of depredation and bycatch on both whales and fishermen. In my first chapter, I reviewed common mitigation approaches to depredation and bycatch by marine mammals, and I conducted a case study analysis on the management process and its effectiveness in addressing depredation in the two focal fisheries. I identified past successes and failures and summarized the current situation for both fisheries and where bycatch management is going next. The next two chapters focused in-depth on the Hawai‘i deep-set pelagic longline fishery and depredation interactions by false killer whales. I first analyzed data collected by fisheries observers and from satellite-linked transmitters deployed on false killer whales to identify patterns of odontocete depredation that could help fishermen avoid overlap with whales. I identified several broad-scale patterns of depredation but found the best indicator of depredation to be the occurrence of depredation on a previous set of the same vessel. I identified spatiotemporal scales of this ‘repeat’ depredation and analyzed satellite-tagged false killer whale data to better understand fine scale whale movement that may be relevant to avoiding depredation. I brought this information together to provide simple recommendations to fishermen that could reduce the occurrence of depredation from 18% to 9% on average (a 50% reduction). Next I used the same fishery-dependent data sources (observer-collected and logbook data) and a novel, multi-stage modeling approach to derive quantitative estimates of catch losses by depredating odontocetes in the Hawai‘i deep-set longline tuna fishery. Although depredation is relatively rare and variable on a per set basis, I estimated the total lost biomass and economic value of the top three catch species to average 100 t and one million USD per year, respectively. I also identified broad-scale spatiotemporal patterns where the relative losses of depredation by odontocetes are expected to be greatest, providing additional recommendations for how fishermen may be able to minimize costs of depredation. My final chapter focused on the Atlantic pelagic longline fishery and depredation and bycatch of the short-finned pilot whale. I conducted a baseline analysis of pilot whale behavior from a rich satellite tag dataset, identifying a previously undetected diel behavioral pattern and adding additional novel insights to a growing body of research on this population of whales. I then described a novel behavioral state that occurred when whales were in close proximity to fishing activity (< 50 km). Although the resolution of these data precluded a detailed characterization of depredation events, my observations that whales change their behavior when in the proximity of vessels may help inform move-on rules that fishermen could employ to reduce the occurrence of depredation and bycatch.
Item Open Access