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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Characterizing marine mammal stranding events along the Texas coast

Mullins, Ruth Louise 10 October 2008 (has links)
The Texas Marine Mammal Stranding Network (TMMSN) is a valuable data resource for the marine mammal community. Limitations of funding and personnel severely impact the ability of the Network to maintain impeccable databases. This research constructed an application to address database complications and focused on investigating the species identification, temporal and spatial trends for stranding events along the Texas coast. From 1980 to 2004, Tursiops truncatus accounted for approximately 80% of all stranding events. The remainder was 20 additional whale and dolphin species known to reside in the Gulf of Mexico. Tursiops truncatus strand along the entire coastline and are the only species stranding in the bays. All other species stranding are most dense along the southern coastline. The temporal scales of events revealed no linear patterns from 1980 to 2004. A unique cyclic fluctuation occurred from 1992 to 1998, including the highest yearly counts and one isolated mortality event in Port Aransas. Attempts to forecast stranding events beyond 2004 were inconclusive due to multiple factors influencing a stranding event. A bimodal seasonal trend was evident, with events peaking in the spring and fall months. Density distributions by decade isolated three frequent stranding areas: Sabine-Galveston-Brazoria counties, Galveston Shipping Channel, and Corpus Christi Shipping Channel. The final aspect analyzed spatial elaboration of events by creating six location values to describe the Texas coastline. Each event was assigned from the geographical location and the orientation of an event along the coastline. Analysis revealed the segregation of Tursiops truncatus in the bays and confirmed earlier results of density distributions. Examining the locations by time revealed a specific incident connected to a mortality event in 1992, accounting for 59% of the stranding events. Location categories were compared to the TMMSN stranding regions and the regions experienced different location frequencies. This study demonstrated how to construct a stronger database and the necessity for database accuracy. Study conclusions demonstrated the need to better isolate and research factors responsible for event distributions in time and space along the Texas coast to forecast the magnitude and location of stranding events to better aid the TMMSN response efforts.
2

Engaging professional mariners in marine mammal conservation

Thorpe, Leah Irene 16 May 2012 (has links)
Due to British Columbia‟s expansive coastline and limited funding for marine mammal conservation, research projects rely heavily on citizen scientists, or volunteers who contribute data. Professional mariners are an important target audience for such projects. In an attempt to increase participation by this sector, I designed a workshop using the Analysis, Design, Development, Implementation and Evaluation (ADDIE) process. I worked closely with four marine mammal conservation societies and conducted an analysis phase with the Canadian Coast Guard (CCG) using a combination of questionnaires and semi-structured interviews. I discovered that there is some awareness of existing conservation programs within the CCG but understanding of these programs as well as basic marine mammal knowledge and identification skills are limited. I also learned the importance of consistent feedback for continued participation and was able to relay information to the societies involved as well as use it to guide the development of my workshop.
3

Interactions between behavioural ecology and relatedness of female bottlenose dolphins in East Shark Bay, Western Australia

Frere, Celine Henria, Biological, Earth & Environmental Sciences, Faculty of Science, UNSW January 2009 (has links)
Female mammals play a central role in determination of social structure and are thus central to understanding the overall fission-fusion grouping pattern characteristic of many delphinid societies. Focusing specifically on female-female relatedness and association patterns, I have analysed more than 17 years of group composition, behavioural data, and genetic information to investigate complex interactions between behavioural ecology and relatedness and to also examine the common social evolutionary theory, that variation in mammalian social systems is typically attributed to five main factors: inclusive fitness, predation pressure, sexual conflict and male harassment, inbreeding avoidance, and resource competition. Overall, I found that female bottlenose dolphin association patterns depend upon the interplay between matrilineal kinship, biparental relatedness and home range overlap, and that female bottlenose dolphins seem to adapt their social strategies to seasonal variation in levels of predation and male harassment. The presence of both high sexual conflict and bisexual philopatry lead me to investigate the extent of inbreeding avoidance. I found that more than 14% of the calves were most likely the product of mating between close relatives, and identified female fitness costs to inbreeding. We were able to show that the effect of inbreeding on females??? fitness occurs via two independent mechanisms: being inbred and having at least one inbred calf. Inbred calves are on average weaned later than non-inbred calves, and a female???s first calf has a higher probability to be an inbred than subsequent calves. Last, I examined whether sociality provides inclusive fitness to female bottlenose dolphins through an investigation of both the additive genetic and social variance components of female calving success using a pedigree-free animal model. I found that variance in calving success of female bottlenose dolphins is best explained by complex genetic and social interactions. Females with high calving success showed both high genetic and social merit; they not only have good genes but also prefer to associate with others of high fitness. This study reveals that both social and heritable genetic variance contribute to fitness trait variance in the wild.
4

Genetic and endocrine related variability of sea otters, Enhydra lutris /

Larson, Shawn Elizabeth. January 2003 (has links)
Thesis (Ph. D.)--University of Washington, 2003. / Vita. Includes bibliographical references (leaves 94-106).
5

The Steller sea lion (Eumetopias jubatus) decline and the Gulf of Alaska/Bering Sea commercial fishery

Hennen, Daniel Reneau. January 2004 (has links) (PDF)
Thesis (Ph. D.)--Montana State University--Bozeman, 2004. / Title from PDF t.p. (viewed on June 12, 2006). Chairperson, Graduate Committee: Daniel Goodman. Includes bibliographical references (p. 189-207).
6

The role of oxytocin in the maternal behaviour of the grey seal (Halichoerus grypus)

Robinson, Kelly J. January 2014 (has links)
The neuropeptide hormone oxytocin plays an integral role in mammalian reproductive endocrinology and behaviour. It has been utilised to study the physiological factors driving maternal behaviour in both laboratory and domestic mammals, but few studies have successfully detected oxytocin in wild individuals, or linked detected concentrations to the behaviours they exhibit. Phocid seals present an excellent system in which to study oxytocin's effects on maternal behaviour in the wild. The energetic constraints placed on a phocid mother during the dependant period should cause strong selection pressure for behaviour that maximises reproductive success with the least cost to the mother. However in many phocid species, substantial variations in maternal behaviour persist. In order to investigate whether oxytocin plays a role in driving this variation, behavioural and hormonal datasets were collected from grey seal mothers and pups on two breeding colonies in Scotland. A protocol for the detection of plasma oxytocin in phocid seals was successfully developed, along with the methodology to manipulate peripheral oxytocin concentrations to directly test the hormone's impact on behaviour. Both correlatory studies on natural oxytocin concentrations and behaviour in wild mother-pup pairs and manipulation experiments on newly weaned pups show that plasma oxytocin concentrations influence behaviours that makes mother – pup separation less likely. These include increasing the time spent in close proximity to each other, increasing the number of checks performed on the pup and reducing the aggressive behaviour directed towards the other individual. Additionally, plasma oxytocin could be used as an indicator of weak maternal bonds between mother and pup, which resulted in behaviours such as abandonment and fostering. This study highlights the potential of oxytocin for studying variations in behaviours critical to an individual's reproductive success and provides the methodological framework for studies on other wild species to be conducted in the future.
7

Factors Affecting Harbour Porpoise Bycatch Occurrence In the Swedish Skagerrak and Kattegat Seas

Niu, Jingyao January 2019 (has links)
Incidental catch (bycatch) in fisheries is one of the major threats to marine mammal populations worldwide. The harbour porpoise (Phocoena phocoena, Linneaus 1758) is one of the most common cetaceans in northern Europe. Previous studies have reported high bycatch numbers of harbour porpoises in gillnet fishing operations in the North Sea and Skagerrak Sea. With the aim of disentangling the driving factors behind bycatch of harbour porpoises, I looked at the relationship between occurrence of harbour porpoise bycatch and properties of fishery and porpoise density. Parameters of fishing effort, gear characteristics and operations of 951 sets of strings of cod and pollack bottom set gillnets were collected by an on-board observer programme in the Swedish Skagerrak and Kattegat Seas during 1995-1997. Porpoise density data was generated from satellite tracking locations of 116 individuals from 1997 to 2016. Generalised linear models with binomial distribution were applied to identify the relationships between the occurrence of porpoise bycatch and seven explanatory variables extracted as soak time, string length, net height, mesh size, net bagginess, water depth and porpoise density. During the observer programme, a total of 21 porpoises were bycaught during 10,174 km*h of observed fishing effort. The total bycatch was estimated to be 2.6% of the population abundance at that time, i.e. above the maximum sustainable total anthropogenic removal (1.7%). Soak time, string length and water depth were identified to be positively related to bycatch occurrence. The findings provide guidance for bycatch mitigation measures in terms of adjusting fishing operations, improving gear and establishing separate management units. Modelling can be used to predict possible spatio-temporal high-risk hot spots for harbour porpoise as well as other marine-living species to optimise future monitoring efforts.
8

Immunohistochemical fiber typing, ultrastructure, and morphometry of harbor seal skeletal muscle

Watson, Rebecca Reiko 30 September 2004 (has links)
There is strong evidence that the skeletal muscles of pinnipeds are adapted for an aerobic, lipid-based metabolism under the hypoxic conditions associated with breath-hold diving. However, regional variations in mitochondrial density are unknown, and the few fiber typing studies performed on pinniped skeletal muscles are not consistent with an aerobic physiological profile. Thus, the objectives of this study were to (1) reexamine the fiber type distribution throughout the primary locomotory muscles of the harbor seal, and (2) to better understand the density and distribution of mitochondria in the locomotory muscles. Multiple samples from transverse sections of the epaxial muscles and a single sample of the pectoralis muscle of wild harbor seals were analyzed using immunohistochemical fiber typing and electron microscopy. Fiber typing results indicated that harbor seal epaxial muscles are composed of 47.4% type I (slow twitch, oxidative) fibers and 52.8%, IIa (fast twitch, oxidative) fibers. No fast twitch, glycolytic (type IIb) fibers were detected in the epaxial muscles or the pectoralis muscle. Mean volume density of mitochondria [Vv(mt,f)] was 5.6%, which is elevated over what would be predicted for a terrestrial mammal of similar mass. The elevated Vv(mt,f) had a high proportion of intermyofibrillar mitochondria, a trait not normally found in the muscles of terrestrial mammals with elevated Vv(mt,f). These results provide further evidence that the elevated mitochondrial volume density in pinniped muscle decreases the oxygen diffusion distance between myoglobin and mitochondria to facilitate aerobic respiration in working muscles. In addition, analyses of heterogeneity revealed that the regions of the epaxial muscles that were located deep within the muscle showed a significantly higher Vv(mt,f) relative to those regions that were superficially-located. In contrast, there was no significant heterogeneity of fiber type detected in either plane of the epaxial muscles. Thus, there was a fine-scale pattern of spatial heterogeneity of Vv(mt,f) within the epaxial muscles that does not manifest in fiber type distribution, indicating that the fibers have similar oxidative capacities.
9

Historical population genetics of Callorhinus ursinus (Northern fur seals) from the Aleutian Islands

Fang, Ying January 2009 (has links) (PDF)
Thesis (M.S.)--University of North Carolina Wilmington, 2009. / Title from PDF title page (February 16, 2010) Includes bibliographical references (p. 82-86)
10

Immunohistochemical fiber typing, ultrastructure, and morphometry of harbor seal skeletal muscle

Watson, Rebecca Reiko 30 September 2004 (has links)
There is strong evidence that the skeletal muscles of pinnipeds are adapted for an aerobic, lipid-based metabolism under the hypoxic conditions associated with breath-hold diving. However, regional variations in mitochondrial density are unknown, and the few fiber typing studies performed on pinniped skeletal muscles are not consistent with an aerobic physiological profile. Thus, the objectives of this study were to (1) reexamine the fiber type distribution throughout the primary locomotory muscles of the harbor seal, and (2) to better understand the density and distribution of mitochondria in the locomotory muscles. Multiple samples from transverse sections of the epaxial muscles and a single sample of the pectoralis muscle of wild harbor seals were analyzed using immunohistochemical fiber typing and electron microscopy. Fiber typing results indicated that harbor seal epaxial muscles are composed of 47.4% type I (slow twitch, oxidative) fibers and 52.8%, IIa (fast twitch, oxidative) fibers. No fast twitch, glycolytic (type IIb) fibers were detected in the epaxial muscles or the pectoralis muscle. Mean volume density of mitochondria [Vv(mt,f)] was 5.6%, which is elevated over what would be predicted for a terrestrial mammal of similar mass. The elevated Vv(mt,f) had a high proportion of intermyofibrillar mitochondria, a trait not normally found in the muscles of terrestrial mammals with elevated Vv(mt,f). These results provide further evidence that the elevated mitochondrial volume density in pinniped muscle decreases the oxygen diffusion distance between myoglobin and mitochondria to facilitate aerobic respiration in working muscles. In addition, analyses of heterogeneity revealed that the regions of the epaxial muscles that were located deep within the muscle showed a significantly higher Vv(mt,f) relative to those regions that were superficially-located. In contrast, there was no significant heterogeneity of fiber type detected in either plane of the epaxial muscles. Thus, there was a fine-scale pattern of spatial heterogeneity of Vv(mt,f) within the epaxial muscles that does not manifest in fiber type distribution, indicating that the fibers have similar oxidative capacities.

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