802 research outputs found
Assessing the effectiveness of conservation measures : resolving the "wicked" problem of the Steller sea lion
No full text“Wicked” problems are those that are complex and that change when solutions are applied. Many conflicts in conservation fall in to this category. The study approached the problem of how to constrain the apparent wickedness of a problem in the conservation management of a species by using simple empirical indicators to carry out iterative assessment of the risk to a population and to document how this risk evolves in relation to the addition of new data and the implementation of management actions. Effects of high levels of uncertainty within data and also concerning population structure were examined through stochastic simulation and by exploration of scenarios. Historical trends in the example used, the Steller sea lion, showed rapid declines in abundance in some regions during the 1980s. The current total population is 130,000-150,000 Steller sea lions through Alaska and British Columbia and this number has been stable since about 1990 in spite of regional differences in population dynamics. Regional differences in the sequence of changes in the number of pups and non-pups, suggested that an internal re-distribution of juveniles could have happened between 1980 and 1990. Current productivity also appears close to the long term mean. Stochastic population projection using various scenarios showed that, based upon this history, the risk of extinction for the population has declined and is below reasonable thresholds for considering the population to be endangered.Peer reviewe
Thermoregulation in Steller sea lions: an experimental approach
No full textDue to the character of the original source materials and the nature of batch digitization, quality control issues may be present in this document. Please report any quality issues you encounter to [email protected], referencing the URI of the item.Includes bibliographical references (leaves 123-137).Issued also on microfiche from Lange Micrographics.The availability of baseline thermal flux data is important for testing hypotheses of endangered species such as the Steller sea lion (Eumetopias jubatus), whose numbers have declined since the 1960s by more than 80% in portions of their range. The overall objective of this study was to quantify heat flow in Steller sea lions under controlled conditions at various water temperatures, flow speeds, and for stationary versus foraging animals. Heat flux and skin temperature data were collected from seven captive Steller sea lions using heat flux sensors (HFSs) with embedded thermistors. Optimal sensor placement was determined using infrared thermography to measure the major pathways of heat flow along the surface of the animals. Experiments were conducted on swimming animals in a large habitat tank with and without a harness to test for effects of increased hydrodynamic drag, and on stationary animals in a temperature controlled swim flume. In the latter, measurements were taken at three water temperatures (9.0 �� 0.2 ��C, n=5; 7.0 �� 0.2 ��C, n=5; and 4.0 �� 0.0 ��C, n=5) and five current settings (0, 0.2, 0.4, 0.8, and 1.0 m/s). The novel sensor attachment technique designed and utilized in this study allowed for the collection of heat flux data independent of human manipulation during actual measurements. Results from infrared thermography and HFSs revealed consistent spatial patterns in heat loss for foraging animals, suggesting that the body trunk plays an important role in temperature regulation. Mean heat flux for animals swimming with a harness was significantly greater than mean heat flux for unencumbered animals, and heat flux increased with decreasing water temperatures. These data provide insight into the thermoregulatory responses of Steller sea lions, and show that although animals lose more heat in colder water, they also unload rather than conserve excess heat when swimming with drag. These data represent valuable new direct measurements of heat flux for Steller sea lions in water using animal-borne heat flux sensors, and may be useful for comparison with other swimming otariids
Thermoregulation in Steller Sea Lions: a modelling approach
No full textDue to the character of the original source materials and the nature of batch digitization, quality control issues may be present in this document. Please report any quality issues you encounter to [email protected], referencing the URI of the item.Includes bibliographical references (leaves 114-127).Issued also on microfiche from Lange Micrographics.The Steller sea lion, largest of the otariids, is currently listed as endangered, in parts of its range, due to a substantial population decline over the past three decades. The most prominent hypothesis for this decrease is a reduced juvenile survival resulting from increased nutritional stress. Consequently, energetic demands are unable to be met by energy input. To better understand this relationship, an energetics model using relevant published data incorporating environmental conditions commonly experienced by sea lions in the wild has been constructed for otariids, focusing on Stellers. This predictive, individual-based physiological model allows the assessment of heat loss, from which costs of thermoregulation can be estimated for both aquatic and terrestrial habitats. The main aim of this system is to incorporate possible interactions between a number of factors, including the compensatory effects of the heat increment of feeding, the heat generated by locomotion, and the effect of body condition. Under the environmental conditions tested in water, Steller sea lions appear to require additional energy for thermoregulation, unless they are moving and generating additional heat as a result of the locomotion. While resting in air sea lions are within their thermal neutral zone during sunny conditions on clear days. However, when there is a lack of direct solar radiation, either at night or when it is cloudy, or under very cold conditions, sea lions must generate extra heat for thermoregulation. These costs are in part offset if the sea lion has recently fed and is therefore generating additional energy from the heat increment of feeding. For all the conditions tested, smaller sea lions, or those with poorer body condition, are most at risk from the effects of the cold and incur the greatest thermoregulatory cost. Using this model, the physical and environmental conditions under which sea lions utilize extra energy for thermoregulation can be established in addition to the key factors that may ultimately cause an energetic imbalance in Steller sea lions
Németek kisebbségben III. - a Közép-európai Német Kisebbségi Tudományos Gyűjtemény tudományos konferenciája ( = Deutsche in der Minderheit III. - Konferenz der Wissenschaftlichen Sammlung für deutsche Minderheiten in Mitteleuropa )
No full textUngarnsprachiges Programm:
9.00-10.30: TÖRTÉNETI ÉS JOGI ÁTTEKINTÉS (Elnök: Johann Reichenberger)
- Lea-Katharina Steller, Waldkraiburg: A Kárpát-medencei német kisebbség kormányzattörténete
- Anna M. Loerinczy, Berlin: A nemzetiségi önkormányzatok jogi háttértörténete
11.00-12.30: HATÁSVIZSGÁLAT I. (Elnök: Lea-Katharina Steller)
- Katharina Engelhardt, Berlin: Az adatletiltás az ajánlásgyűjtés gátja
- Györe Erzsébet, Budapest: A nem ottani lakóhellyel rendelkező nemzetiségi jelöltek hatása a közösségre
13.00-14.30: Munkaebéd
14.30-16.00: "Weg der Geschichte": a híres városnéző séta Waldkraiburgban, majd kávé
16.00-17.30: HATÁSVIZSGÁLAT II. (Elnök: Katharina Engelhardt)
- Andreas Obermeyer, Landshut: A nem magyar állampolgárságú, de nemzetiségiként regisztrált szavazók hatása a közösség életére
- Eva Wagner, München: A külképviseleteken miért nem lehetséges országos nemzetiségi önkormányzati képviselőkre szavazni?
17.30-20.00: ÖSSZEFOGLALÁS (Elnök: Lea-Katharina Steller)
- Svédasztal, elemző beszélgetések, vita
- Johann Reichenberger, Mühldorf am Inn: A megválasztott kisebbségi önkormányzatok közösségépítő lehetősége
Seasonal abundance and diversity of nearshore fishes around Steller sea lion haulouts of Kodiak Island
No full textThesis (M.S.) University of Alaska Fairbanks, 2003Nearshore fishes around haulouts are potential prey for Steller sea lions, especially pups, as they learn to forage and supplement their milk diets during weaning. Visual surveys in July and November 2001, and March, May and July 2002 were used to quantify spatial and temporal variation in fish diversity and abundance around two Steller haulouts and two control sites. SCUBA divers sampled depths of 9, 15, 21, 27, and 33 m. Concurrent habitat surveys were used to quantify substrate, macroalga and benthic invertebrate cover. Steller haulout sites had fewer fish than control sites, but similar species richness and species composition at the 9, 15 and 21 m depths during the summer sampling periods. In winter, fish were fewer but more evenly distributed. Habitats were not significantly different between Steller haulouts and control sites. All sites had seasonal cover of canopy forming kelp, and overstory algal cover was heavy down to 21 m. At approximately 27 m the habitat changed abruptly from kelp-covered bedrock to bare gravel and shell hash. While nearshore fish are an important component of Steller diets, results from this study do not indicate that fish assemblages at haulouts are substantially different from other headland sites
Hydrodynamic drag in steller sea lions (Eumetopias jubatus)
No full textDrag forces acting on Steller sea lions (Eumetopias jubatus) were investigated from \u27deceleration during glide\u27 measurements. A total of 66 glides from six juvenile sea lions yielded a mean drag coefficient (referenced to total wetted surface area) of 0.0056 at a mean Reynolds number of 5.5x10(6). The drag values indicate that the boundary layer is largely turbulent for Steller sea lions swimming at these Reynolds numbers, which are past the point of expected transition from laminar to turbulent flow. The position of maximum thickness (at 34 % of the body length measured from the tip of the nose) was more anterior than for a \u27laminar\u27 profile, supporting the idea that there is little laminar flow. The Steller sea lions in our study were characterized by a mean fineness ratio of 5.55. Their streamlined shape helps to delay flow separation, reducing total drag. In addition, turbulent boundary layers are more stable than laminar ones. Thus, separation should occur further back on the animal. Steller sea lions are the largest of the otariids and swam faster than the smaller California sea lions (Zalophus californianus). The mean glide velocity of the individual Steller sea lions ranged from 2.9 to 3.4 m s(-)(1) or 1.2-1.5 body lengths s(-)(1). These length-specific speeds are close to the optimum swim velocity of 1.4 body lengths s(-)(1) based on the minimum cost of transport for California sea lions
Variation of mitochondrial control region sequences of Steller sea lions: the three-stock hypothesis
No full textSequence variation of a 238 bp segment of the mitochondrial control region was analyzed for 1,568 Steller sea lions (2.8% of the estimated species population) sampled from 50 rookeries representing nearly every locality at which Steller sea lions are known to breed in significant numbers. Haplotype diversity (H = 0.9164 �� 0.0035) was high and nucleotide diversity (�� = 0.00967 �� 0.00586) was moderate. No evidence was observed for significant genetic bottleneck effects. Rookeries were grouped into regions and stocks to examine structure at different spatial scales. F- and ��-statistics were computed for all pairwise comparisons of rookeries, regions and stocks. Significant (P<0.05) divergence of eastern stock (southeastern Alaska to California) animals from western stock animals was supported in analyses at all spatial scales. Likewise, rookeries and regions from Asia were found to be significantly different from all other western stock rookeries. This was most clearly demonstrated using ��-statistics at the regional level. The Commander Islands clearly associate with Alaskan western stock rookeries, not with the Asian rookeries. Within each of the three stocks there is significant isolation by distance among rookeries. This relationship does not hold for inter-stock comparisons indicating that there are important barriers to gene flow among stocks. Mitochondrial DNA analysis supports the recognition of three stocks for appropriate conservation of the species. The currently recognized eastern stock is unaffected, but the western stock is now partitioned west of the Commander Islands yielding a western stock which ranges from Prince William Sound west to the Commander Islands, and an Asian stock including rookeries from the Kamchatka Peninsula, Kuril Islands, and Sea of Okhtosk
Three-dimensional photogrammetry as a tool for assessing morphometrics and estimating body mass of Steller sea lions
No full textDue to the character of the original source materials and the nature of batch digitization, quality control issues may be present in this document. Please report any quality issues you encounter to [email protected], referencing the URI of the item.Includes bibliographical references (leaves 54-55).Issued also on microfiche from Lange Micrographics.A technique was developed to indirectly assess morphometrics and to estimate body mass of Steller sea lions (Eumetopias jubatus using three- dimensional (3D) photogrammetry. 3D computer wireframes of thirty-five Steller sea lions of various age classes were generated from multiple time-synchronous digital photos. Overall average estimates of standard length and axillary girth were within ��2.8% and ��4.2% of physically measured dimensions, respectively. Average estimates of standard length and axillary girth from wireframes based on ideal body postures were within ��1.7% and ��3. 1% of physically measured dimensions, respectively. These measurements were used to estimate body mass by applying previously existing regression equations. Regressions of physically measured mass on photogrammetrically estimated body volume yielded a predictive model. Body mass estimates using this model were on average within 10.5% (with a 95% confidence interval of ��2.35%) of the physically measured mass. The use of 3D photogrammetry decreases many of the problems associated with camera and body position encountered with two-dimensional photogrammetric techniques. This technique can be used to estimate the body mass of free-ranging, active sea lions, eliminating the need for sedation, heavy weighing equipment, and animal disturbance
Characterizing the winter movements and diving behavior of subadult Steller sea lions (eumetopias jubatus) in the north-central Gulf of Alaska
No full textRecent studies indicate a 70% decrease in the Alaskan Steller sea lion (SSL) population
(ca. 5% per year) since the early 1980's. In accordance with a 1997 status classification of the
Western Steller sea lion (WSSL) stock as endangered, the "critical habitat" for the species was to
be defined. This habitat has now been designated to include 10-20 nautical mile buffer zones
around most rookeries and haulouts in the Gulf of Alaska (GOA) and Aleutian Islands. However,
these zones were based on limited, summer, foraging data.
The primary objective of this study was to characterize juvenile SSL diving behavior
and habitat use along the Kenai Peninsula and Prince William Sound (PWS) from winter to
spring. Fifteen free ranging, subadult SSL of both sexes were captured and equipped with
satellite telemeters at five haulout sites in PWS and Resurrection Bay, Alaska. Telemeters
transmitted for an average of 122 days (range 38-181 days). A total of 11,692 locations were
received and 217,419 dives recorded.
All sea lions exhibited localized movements parallel or close to shore (3-15 km
offshore). Young of the year (YOY) exhibited high site fidelity. Older juvenile sea lion lions
were less restricted in their movements and traveled greater distances (200-400km) visiting a
variety of islands, buoys, and other locations in PWS.
Most dives were short (mean duration = 1.1 min) and shallow (mean depth = 10.8 m),
with animals diving to an average maximum depth of 193 m. During winter (January and February), many dives (>40%) occurred during the daytime (0900-1500 LT). However, by April
and May this pattern shifted and the animals made most of their dives (>40%) during the night
(2100-0300 LT). This relationship was more pronounced for dives deeper than 20 m and
coincided with the seasonal increase in photoperiod.
Subadult SSL, especially YOY, remained within the 20 nautical mile coastal zone during
winter and spring. Shallow, nearshore waters provide important habitat during this critical
period of transition to nutritional independence. However, more conclusive data on SSL
foraging ecology is necessary to better understand locations and depths preferred by the species
Milk fatty acid composition of perinatal and foraging Steller sea lions: examination from pup stomachs
No full textThesis (M.S.) University of Alaska Fairbanks, 2014.To investigate the relationship of milk fatty acid composition between perinatal and foraging Steller sea lions and within each maternal state (i.e., perinatal or foraging), milk samples were collected in 2010 and 2011 via gastric intubation from Steller sea lion pups on a small rookery in the central Gulf of Alaska. Subsamples of initial milk samples were taken over four hours post-collection to examine changes of fatty acids within milk over time. Maternal states of lactating females of sampled pups were determined via remotely operated video cameras on the rookery. Fatty acid composition within milk, collected from Steller sea lion pup stomachs, did not change over the four hour post-collection period, and thus milk fatty acids were not modified within milk over time. Milk fatty acid composition between Steller sea lion maternal states was different, and thus can be utilized to distinguish between perinatal and foraging Steller sea lions of the same geographic region. In the absence of direct observations, this study demonstrated the use of a viable method to determine maternal state. Milk fatty acid composition remained relatively constant within perinatal Steller sea lions, suggesting steady mobilization of fatty acids from blubber to milk, and within foraging Steller sea lions, implying females forage in the vicinity of the rookery and on similar prey species. Differences in milk fatty acid composition between maternal states, including differences in the relative percentages of polyunsaturated fatty acids, may have implications for growth and development of offspring. For lactating Steller sea lions, foraging after the perinatal period is important for continued delivery of fatty acids needed by young pups.Preface -- Steller Sea Lion Life History -- Lipids and Fatty Acids -- Essential Fatty Acids -- Milk Lipid and Fatty Acid Composition -- Milk Lipid Digestion via Gastric Lipase -- Introduction -- Materials & methods -- Sample Collection -- Behavioral Observations -- Lipid Extraction and Fatty Acid Analysis -- Milk Fatty Acid Stability Over Time -- Interannual Comparison -- Statistical Analyses of Maternal States -- Results -- Milk Fatty Acid Stability Over Time -- Interannual Comparison -- Spatial Separation of Perinatal and Foraging Females -- Milk Fatty Acid Composition Between Perinatal and Foraging Females -- Milk FA Composition Within Perinatal and Foraging Females -- Discussion -- Milk Fatty Acid Stability Over Time -- Distinguishing Between Perinatal and Foraging Females -- Milk Fatty Acid Composition Within Perinatal and Foraging Females -- Differences in Fatty Acids Important for Pups Between Maternal States -- Importance of Food Resources -- Conclusion -- Conclusion -- Literature cited -- Appendices
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