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1
Marsh, Jennifer Anne. "Social behavior and ecology of "southern resident" killer whales (Orcinus orca) /." Thesis, Connect to this title online; UW restricted, 2008. http://hdl.handle.net/1773/9081.
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Samarra, Filipa Isabel Pereira. "Functional design and use of acoustic signals produced by killer whales (Orcinus orca)." Thesis, University of St Andrews, 2011. http://hdl.handle.net/10023/2564.
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This study aimed to investigate possible functions of the sounds produced by herring-eating killer whales in the Northeast Atlantic. In this study, I investigated the whistle repertoire of killer whales, which had previously only been studied in British Columbia, where it appeared to be restricted to the audible range. However, I show that high frequency whistles (> 17 kHz) were detected in Northeast Atlantic populations but not in Northeast Pacific populations. These results indicated substantial intraspecific variation in whistle production in killer whales. Little variation was observed in high frequency whistles recorded from three different sites in the Northeast Atlantic, suggesting this signal has a similar function across locations. The estimated active space of high frequency whistles and burst-pulse calls suggested that these are short-range signals used for within-group communication. Source levels of burst-pulse calls were lower than what was previously described in British Columbia, which possibly reflected the fact that these sounds do not need to propagate far because distances between group members are generally short. Calls, high frequency whistles and herding calls produced at different depths did not appear to suffer effects due to increased pressure, such as changing frequency or duration characteristics. Feeding appeared to take place below 10 m of depth, as suggested by the localisation of depth of production of feeding-related sounds. These depths were consistent with those at which tailslaps were produced in Dtags attached to individual whales. Feeding periods were characterised by deep diving, increased sound production and highly non-directional movement. These findings suggested that killer whales in a herring spawning ground use a feeding strategy different from carousel feeding used in herring overwintering grounds. These findings showed that Northeast Atlantic killer whales have a different sound repertoire to other populations, and suggested that they may employ different feeding strategies depending on prey behaviour.
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Stevens, Tracy Alison. "Analysis of mitochondrial DNA restriction fragment patterns in killer whales, Orcinus orca." PDXScholar, 1989. https://pdxscholar.library.pdx.edu/open_access_etds/3928.
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The mitochondrial DNA restriction fragment patterns of killer whales (Orcinus orca) were investigated in order to determine the level of genetic differentiation that exists between killer whales from various geographic locations. Twenty one killer whales were examined, seventeen of which were captive killer whales that originated from the North Atlantic and Northeast Pacific Oceans. Two were captive-born animals and two were killer whales that stranded along the Northeast Pacific coast.
DNA was extracted from blood and/or tissue samples, cleaved with a variety of restriction endonucleases and the DNA fragments were separated by horizontal agarose gel electrophoresis. The DNA was then transferred to nylon membranes and the killer whale mitochondrial DNA was visualized by hybridization to the complete mitochondrial DNA genome of Commerson's dolphin (Cephalorhynchus commersonii). The resultant restriction fragment patterns were analyzed to determine whether mitochondrial DNA variation was present between killer whales from different geographic regions or between communities and pods of killer whales from the same geographic location.
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Miller, Patrick J. O. "Maintaining contact : design and use of acoustic signals in killer whales, Orcinus orca /." Online version, 2000. http://hdl.handle.net/1912/1765.
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Thesis (Ph. D.)--Joint Program in Biological Oceanography (Massachusetts Institute of Technology, Dept. of Biology, and the Woods Hole Oceanographic Institution), 2000.Vita. Includes bibliographical references.
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Volker, Bernt Deecke. "The vocal behaviour of transient killer whales (Orcinus orca) : communicating with costly calls." Thesis, University of St Andrews, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.631228.
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Giles, Deborah A. "Southern Resident Killer Whales (Orcinus orca)| The evolution of adaptive management practices for vessel-based killer whale watching in the Salish Sea, A novel non-invasive method to study southern resident killer whales (Orcinus orca) and vessel compliance with regulations, and The effect of vessels on group cohesion and behavior of southern resident killer whales (Orcinus orca)." Thesis, University of California, Davis, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=3626639.
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This dissertation concerns the southern resident killer whales (Orcinus orca), a genetically isolated population of fish-eating killer whales that frequent the international waters of the Salish Sea between the United States and Canada in the eastern Pacific Ocean. Research was conducted from June 1 to October 31, 2007 and from June 7 to October 31, 2008, between geographic coordinates: 48°12’ to 49° N latitude by 122°43’ to 123°50° W longitude.
The southern resident killer whale population has experienced multiple fluctuations since population surveys were initiated by the Center for Whale Research (CWR) in the mid 1970's. In November 2005, the U.S. National Oceanic and Atmospheric Administration's National Marine Fisheries Service (NMFS), Northwest Regional Office listed the southern resident killer whales as an endangered distinct population segment of the species Orcinus orca under the United States Endangered Species Act (ESA). Several risk factors including reductions in the quantity and quality of prey (salmon), exposure to persistent toxins, and disturbance from vessel presence and associated noise were identified as contributing to the decline of this already small population. With the listing under the ESA, critical habitat was designated in the inland waters around the U.S. San Juan Islands, Washington State and the Canadian Gulf Islands, British Columbia, Canada.
Chapter one, Managing Vessel-based Killer Whale Watching: A Critical Assessment of the Evolution from Voluntary Guidelines to Regulations in the Salish Sea, provides background on the southern resident killer whales and the robust international whale watching industry in the region. This chapter also provides a detailed history of local, state, federal and international vessel laws and guidelines for watching whales in the Salish Sea.
Chapter two, Non-invasive methods to study southern resident killer whales and vessel compliance with regulations, describes a novel equipment package, consisting of a differential GPS integrated with a digital compass and laser rangefinder that allowed me to collect accurate geo-referenced locations and behavioral data on whales and vessels throughout the whale's critical habitat. To improve both the spatial and temporal data on whale-vessel interactions, the information collected with this equipment was used to assess vessel compliance with local, state and federal laws and the regionally accepted best-practices Be Whale Wise Guidelines.
Chapter three, The effects of vessels on group cohesion and behavior of southern resident killer whales (Orcinus orca), discusses research investigating changes in killer whale group cohesion in response to vessel density, distance and mode of operation. Future cetacean studies would benefit from using the equipment and methods presented here, especially in areas that are not conducive to land-based theodolite collected data.
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Duc, Anne-Valérie. "A comparison of the discrete call repertoires of Northeast Atlantic killer whales (Orcinus orca)." Thesis, Uppsala universitet, Institutionen för biologisk grundutbildning, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-157829.
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Although Icelandic and Norwegian killer whales are thought to have been in contact prior to the collapse of the herring stock in the 1960s, the Northeast Atlantic killer whales currently seem to show high site fidelity. So far, photoidentification data have suggested movement of a few individuals between East Iceland and North Scotland, and two calls have been shown to be shared by the Icelandic and Norwegian populations. Based on previous and newly analysed call samples, the aim of this study was to describe the geographic variation in the vocal repertoire of the Northeast Atlantic killer whales. Recordings have been conducted off Southwest Iceland in the summers 2004, 2008 and 2009 using sound recording tags attached using suction cups (Dtags), a 4-element vertical hydrophone array and a 2-element towed hydrophone array. From the 57 hours of recording analysed, 1742 calls were classified. In total, 56 distinct call categories composed of 35 call types and 31 subtypes were identified. This discrete call repertoire contained less biphonic calls but more calls composed of buzzes and/or clicks than the Norwegian repertoire. The reasons for these differences remain unknown. One Icelandic call subtype was defined as a compound call, a type of call that is common in the Norwegian population. The comparison of the different vocal repertoires of Northeast Atlantic showed four good or likely call matches in herring-eating killer whales (one between Southwest Iceland and Shetland, one between East Iceland and Norway, and two between Shetland and Norway). No matches were found between Southwest Iceland and East Iceland. I suggest that the four shared calls are most likely to have come from a common ancestral pod and have been transmitted through vocal learning. Over time, geographic isolation of the groups induced by changes in the migratory patterns of the herring might have been accompanied by divergence in their call repertoires.
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Tavares, Sara B. "Social associations, relatedness and population genetic structure of killer whales (Orcinus orca) in Iceland." Thesis, University of St Andrews, 2017. http://hdl.handle.net/10023/12061.
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In killer whales, fish- versus mammal-eating ecological differences are regarded as key ecological drivers of sociality, but the potential influence of specific target prey characteristics remains unclear. This thesis aimed to study the social patterns and dynamics of Icelandic killer whales feeding upon herring, a schooling prey that undergoes frequent changes in distribution and school size. I used a multi-disciplinary approach combining photo-identification and genetic data to understand the sociality, role of kinship and genetic differentiation within the population. Individuals sighted in summer-spawning and overwintering herring grounds during at least five separate days (N = 198) were considered associated if photographed within 20 seconds of each other. Photo-identified individuals were genotyped (N = 61) for 22 microsatellites and mitochondrial DNA control region (611 bp). The population had weak but non-random associations, fission-fusion dynamics at the individual level and seasonal patterns of preferred associations. The society was significantly structured but not hierarchically. Social clusters were highly diverse and, whilst kinship was correlated with association, it was not a prerequisite for social membership. Indeed, some cluster members had different mitochondrial haplotypes, representing separate maternal lineages. Individuals with different observed movement patterns were genetically distinct, but associated with each other. No sex-biased dispersal or inbreeding was detected. This study revealed that the Icelandic population has a multilevel society without clear hierarchical tiers or nested coherent social units, different from the well-studied salmon- (‘residents') and seal-eating populations in the Northeast Pacific. In the Icelandic population kinship drives social structure less strongly than in residents. These findings suggest effective foraging on schooling herring in seasonal grounds promotes the formation of flexible social groupings which can include non-kin. Killer whale sociality may be strongly influenced by local ecological context, such as the characteristics of the specific target prey (e.g., predictability, biomass, and density) and subsequent foraging strategies of the population.
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Shapiro, Ari Daniel. "Orchestration : the movement and vocal behavior of free-ranging Norwegian killer whales (Orcinus orca)." Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/43229.
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Thesis (Ph. D.)--Joint Program in Oceanography/Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Dept. of Biology; and the Woods Hole Oceanographic Institution), 2008.Includes bibliographical references.
Studying the social and cultural transmission of behavior among animals helps to identify patterns of interaction and information content flowing between individuals. Killer whales are likely to acquire traits culturally based on their population-specific feeding behaviors and group-distinctive vocal repertoires. I used digital tags to explore the contributions of individual Norwegian killer whales to group carousel feeding and the relationships between vocal and non-vocal activity. Periods of tail slapping to incapacitate herring during feeding were characterized by elevated movement variability, heightened vocal activity and call types containing additional orientation cues. Tail slaps produced by tagged animals were identified using a rapid pitch change and occurred primarily within 20m of the surface. Two simultaneously tagged animals maneuvered similarly when tail slapping within 60s of one another, indicating that the position and composition of the herring ball influenced their behavior. Two types of behavioral sequence preceding the tight circling of carousel feeding were apparent. First, the animals engaged in periods of directional swimming. They were silent in 2 of 3 instances, suggesting they may have located other foraging groups by eavesdropping. Second, tagged animals made broad horizontal loops as they dove in a manner consistent with corralling. All 4 of these occasions were accompanied by vocal activity, indicating that this and tail slapping may benefit from social communication. No significant relationship between the call types and the actual movement measurements was found. Killer whale vocalizations traditionally have been classified into discrete call types. Using human speech processing techniques, I considered that calls are alternatively comprised of shared segments that can be recombined to form the stereotyped and variable repertoire.
(cont.) In a classification experiment, the characterization of calls using the whole call, a set of unshared segments, or a set of shared segments yielded equivalent performance. The shared segments required less information to parse the same vocalizations, suggesting a more parsimonious system of representation. This closer examination of the movements and vocalizations of Norwegian killer whales, combined with future work on ontogeny and transmission, will inform our understanding of whether and how culture plays a role in achieving population-specific behaviors in this species.
by Ari Daniel Shapiro.
Ph.D.
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Foster, Emma Anne. "Exploring the mechanisms and functions underpinning the social networks of an endangered population of killer whales, Orcinus orca." Thesis, University of Exeter, 2012. http://hdl.handle.net/10036/3739.
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For the majority of social species, group composition is dynamic, and individuals are interconnected in a heterogeneous social network. In this study I investigate the mechanisms underpinning social structure in the endangered southern resident killer whale (Orcinus Orca) population using a long term dataset, and explore the consequences of these. My results demonstrate that resource availability may be an important determinant of social network structure. A significant relationship between the connectivity of the social network and salmon abundance occurred, with a more interconnected network in years of high salmon abundance. As networks are non-random, highly connected individuals may play a key role in population processes such as information and disease transmission. While associations occurred both within and between matrilines, females had a significantly higher number of associates than males, as did older individuals of both sexes. Older males played a more important role in interconnecting the network. The attributes of group leadership were then investigated in matrilines and in individuals. Leadership was not a factor of size or mean age of matriline. However, there was a significant relationship between leadership score and the matriline sex ratio. Individually, females had higher leadership scores than males, and there was a positive correlation between leadership score and age in both sexes. I suggest that the oldest females have the highest 4 leadership scores due to increased ecological knowledge that comes with a prolonged lifespan. Using multi-generational records for two populations of killer whales, I show that both reproductive and post-reproductive mothers increase the survival of offspring, particularly in older male offspring. This is consistent with theoretical predictions, and may explain why female killer-whales have evolved the longest post-reproductive lifespan of all non-human animals. Given the role that individuals of high network centrality can play in population processes, understanding the driving forces behind social network structure is vital when designing effective conservation and management plans.
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Osborne, Richard W. "A historical ecology of Salish Sea resident killer whales (Orcinus orca), with implications for management." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/Nq52767.pdf.
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Barrett-Lennard, Lance Godfrey. "Population structure and mating patterns of killer whales (Orcinus orca) as revealed by DNA analysis." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/NQ61059.pdf.
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CHARLES, William Dantas. "Interações entre orcas Orcinus orca (Linnaeus, 1758) e falsas orcas Pseudorca crassidens (Owen, 1846) com a pesca de espinhel pelágico monofilamento no Atlântico Oeste Tropical." Universidade Federal Rural de Pernambuco, 2007. http://www.tede2.ufrpe.br:8080/tede2/handle/tede2/6544.
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Since 50`s, industrial fisheries have been damaged by cetaceans in all oceans, with different intensity levels. According to specialists, this behavior is named depredation, which occurs when the animals eat the fishes caught by a fishing gear. Killer whale has been cited as an animal that shows this kind of behavior often, otherwise other species as a false killer whale or sperm whale have been recorded doing fishing gear interactions. After the creation of the On Board Observers Program (PROBORDO) it was possible to cover all tuna fleet working in northeast of Brazil, based on Natal-RN, Cabedelo-PB and Recife-PE ports. The covering was made by board observers that get important information to the fisheries dynamic knowledge made by pelagic long line. Interactions between false killer whales and killer whales are cited as an important scientific subject, in relation to these fisheries type, that the present study pretends to show up. Factors like interactions type, groups’ size, qualitative and quantitative descriptions of depredated fishes and spatial location of the interactions were analyzed. The false killer whale showed greater occurrence on the study area than other species, generally within groups of few individuals, however, there were situations that the group was composed by hundreds of individuals. This species showed food preference about the target species of this fisheries kind, in other words, tuna and swordfishes instead of others catched, but in case of low productivity, they feed with squid used as a bait on the hooks. Killer whales were observed in the Tropical Western Atlantic, interacting with the fisheries. Also, there were accidental catches of the cited cetaceans by the fishing gear, what can bring serious damage to the individuals caughted.
Desde a década de 50, a indústria pesqueira vem sofrendo perdas provocadas por cetáceos, em todos os oceanos, com diferentes níveis de intensidade, num comportamento denominado pelos especialistas como depredação, que ocorre quando esses animais se alimentam do peixe capturado pela arte de pesca. Orcas verdadeiras têm sido citadas como as que exibem esse comportamento com maior freqüência, porém outras espécies como as falsas orcas e cachalotes, são registradas interagindo com a pesca. Com a criação do Programa de Observadores de Bordo (PROBORDO) foi possível a cobertura de toda a frota atuneira arrendada que opera no nordeste, sediada nos portos de Natal-RN, Cabedelo-PB e Recife-PE por observadores de bordo, que coletam informações relevantes para o conhecimento da dinâmica da pesca realizada com espinhel pelágico monofilamento. Dentre os assuntos de grande valor científico cita-se a ocorrência de interações entre as falsas orcas e as orcas verdadeiras, com esse tipo de pescaria, que o presente trabalho pretende apresentar. Fatores como o tipo de interação, tamanho de grupo, descrição quali-quantitativa dos peixes depredados e localização espacial das interações, foram analisados. A falsa orca apresentou maior ocorrência na área de estudo, geralmente em grupos de poucos indivíduos, porém houve situações em que o grupo era composto por centenas de espécimens. Elas demonstraram preferência alimentar pelas espécies-alvo deste tipo de pescaria, ou seja, atuns e espadartes em detrimento da fauna acompanhante, mas no caso de produtividade baixa, também se alimentavam das lulas, utilizadas nos anzóis como isca. Orcas verdadeiras também foram observadas na região do Atlântico oeste tropical, interagindo com a pesca. Também houveram capturas dos referidos cetáceos pelo espinhel, o que pode causar danos sérios aos espécimens capturados.
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Ivaldi, Chiara. "Research on the vocal culture of Orcinus orca in the Loro Parque, Tenerife: a pilot study." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2012. http://amslaurea.unibo.it/3220/.
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This research is focussed on the study of Orcinus orca's communication system. The analysis of vocalizations emitted
by marine mammals has started in the '80s and most studies have been carried out in the wild. In this regard the most
studied animal has been common dolphin (Tursiops truncatus) as the numerous presence of captive individuals
worldwide made researches easier to be carried out. Studies about Orcinus orca's vocalizations have mainly been
carried out in the wild (most in British Columbia) because its maintenance in a controlled environment results to be
very difficult, only 17 among parks and oceanaria worldwide have some Orcinus orca (45 overall among which 64%
born in captivity). These researches showed that Orcinus orca emit three main different types of sounds, classified as:
whistles, clicks and calls. Besides, it was discovered that different groups (pods) produce sounds belonging only to the
relevant pod (dialects). It is rare to find two pods sharing some calls. The two pods usually live in adjacent areas and
can form a clan.
This study was carried out in a controlled environment in the Orca ocean structure (Loro Parque, Tenerife, Spain)
where, at the moment (March 2012) 6 individuals are hosted. Here it was developed an automatic sound recording
system. Thanks to the use of suitable mathematical algorithms that allow to isolate only "interesting" sound events that
differ from the "background noise", it was possible to create a database. The visualization of the sound events collected
in the database is carried out with the use of a software. By looking at this output and at the observation register we
could match the animal to the sound produced.
Three situations were detected and studied: 1) Chosen alone: the animal chooses to go to the recording pool but it is
free to move to another pool with other individuals. 2) Put alone: the animal is put alone in the recording pool. 3) With
other orcas: more animals are together in the recording pool.
The statistic analysis show that animals emit more vocalizations when they are in the situation "Chosen alone".
The research will continue in order to observe eventual differences in the individual repertoire of each Orcinus orca.
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Sharpe, Deborah Lynn. "Call types of Bigg's killer whales (Orcinus orca) in western Alaska| Using vocal dialects to assess population structure." Thesis, Alaska Pacific University, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10104546.
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Apex predators are important indicators of ecosystem health, but little is known about the population structure of Bigg’s killer whales ( Orcinus orca; i.e. ‘transient’ ecotype) in western Alaska. Currently, all Bigg’s killer whales in western Alaska are ascribed to a single broad stock for management under the US Marine Mammal Protection Act. However, recent nuclear microsatellite and mitochondrial DNA analyses indicate that this stock is likely comprised of genetically distinct sub-populations. In accordance with what is known about killer whale vocal dialects in other locations, I sought to evaluate Bigg’s killer whale population structure by examining the spatial distribution of group-specific call types in western Alaska. Digital audio recordings were collected from 33 encounters with Bigg’s killer whales throughout the Aleutian and Pribilof Islands in the summers of 2001-2007 and 2009-2010. Recorded calls were perceptually classified into discrete types and then quantitatively described using 12 structural and time-frequency measures. Resulting call categories were objectively validated using a random forest approach. A total of 36 call types and subtypes were identified across the entire study area, and regional patterns of call type usage revealed three distinct dialects, each of which corresponding to proposed genetic delineations. I suggest that at least three acoustically and genetically distinct subpopulations are present in western Alaska, and put forth an initial catalog for this area describing the regional vocal repertoires of Bigg’s killer whale call types.
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Nichol, Linda M. "Seasonal movements and foraging behaviour of resident killer whales (Orcinus orca) in relation to the inshore distribution of salmon (Oncarhynchus spp.) in British Columbia." Thesis, University of British Columbia, 1990. http://hdl.handle.net/2429/29634.
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Sightings and acoustic recordings from 1984 to 1989 of northern resident killer whales (Orcinus orca) from Johnstone Strait off north eastern Vancouver Island and from King Island on the central British Columbia coast were analysed to examine the hypothesis that northern resident whales move seasonally in their range to areas where salmon are available. Killer whales were most abundant in Johnstone Strait between July and October and infrequent during the remainder of the year. The increase in whale abundance during summer coincided with the migration of salmon (Oncorhynchus spp.) from offshore into Johnstone Strait. The occurrence near King Island in spring 1989 of the same resident whales that are seen in Johnstone Strait during summer, coincided with runs of sockeye and chinook salmon.
During July, August and September of 1984 through 1988, killer whale sightings were recorded virtually daily in the Johnstone Strait. Observations of killer whales in Johnstone Strait during the summer of 1988 showed that whales foraged along shore and in areas of strong current where salmon occur in high densities. Of the 16 killer whale pods in the northern resident community, however, less than half were present more than 15% of summer days (1984 to 1988). Regression results between numbers of whale days per week from each pod and numbers of salmon per week showed that the occurrence pods that were present on more than 15% of summer days in Johnstone Strait was positively and significantly associated with the abundance of sockeye and pink salmon (six pods). In addition to these, the occurrence of one pod that spent less than 15% of summer days in the Strait was positively and significantly associated with chum salmon.
Together these results support the hypothesis that northern resident killer whales select their habitat seasonally to feed on available salmon. The results also lead to the hypothesis that within the northern resident community each pod has a seasonal home ranges.Land and Food Systems, Faculty of
Graduate
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Fung, Charissa W. "Cranial shape correlates with diet specialization in northeast Pacific killer whale (Orcinus orca) ecotypes." Thesis, University of British Columbia, 2016. http://hdl.handle.net/2429/59077.
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Resident, transient (Bigg’s), and offshore killer whales (Orcinus orca) live in sympatric and parapatric ranges in the northeast Pacific Ocean. These ecotypes have different vocal repertoires (Ford and Fisher, 1982; Ford, 1991; Yurk, 2002), echolocation use (Barrett-Lennard et al., 1996), foraging strategies (Bigg et al., 1987; Ford et al., 1998; Baird et al., 1992; Deecke et al., 2002; Ford et al., 2011), and sociobiology (Ford and Fisher, 1982; Bigg et al., 1987; Deecke et al., 2000; Baird and Whitehead, 2000; Riesch et al., 2012). Genetic studies corroborate the behavioural evidence that the resident and transient (Bigg’s) populations are reproductively isolated despite the absence of any geographic or temporal barrier (Stevens et al., 1989; Barrett-Lennard, 2000; Hoelzel and Dover, 1991; Morin et al., 2010). The behavioural segregation between the sympatric ecotypes is apparently maintained by cultural mechanisms alone, which is extremely unusual among non-human mammalian species (Barrett-Lennard, 2000; Riesch et al., 2012). These ecotypes also exhibit dramatic resource polymorphisms: resident killer whales feed exclusively on fish, transient (Bigg’s) killer whales primarily hunt marine mammals (Bigg, 1982; Baird et al., 1992, Ford et al., 1998) and offshore killer whales are thought to feed on fishes including Pacific sleeper shark (Somniosus pacificus) (Ford et al., 2011). We do not know if cranial features related to capturing and processing prey have evolved to reflect the dramatic dietary specializations observed in these three ecotypes. The goal of this research was to determine whether there has been divergence of cranial morphology among the three ecotypes. To this end, I measured and compared cranial shape using traditional and geometric morphometrics techniques. I found that transient (Bigg’s) killer whales that bite and tear apart large mammals have more robust cranial skeletons than the piscivorous resident and offshore killer whales that handle smaller prey items. I found that resident and transient (Bigg’s) killer whales are distinguishable based on skull width, rostral width, and mandibular shape, and that offshore killer whales have a more variable morphology that precludes identification based on cranial shape alone.Science, Faculty of
Zoology, Department of
Graduate
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Lachmuth, Cara Leah. "A model-based approach investigating killer whale (Orcinus orca) exposure to marine vessel engine exhaust." Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/7566.
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The summer habitat of the southern resident population of killer whales (Orcinus
orca) in British Columbia and Washington experiences heavy traffic by vessels involved in
whale-watching, sport fishing, other recreational activities, and shipping. Behavioural
changes caused by vessel proximity and the impacts of vessel noise have been previously
documented, but this is the first study to assess direct impacts of air pollutant emissions from
vessel traffic. The concentration and composition of air pollutants from whale-watching
vessels that southern resident killer whales are exposed to during the peak tourist season were
estimated, as were the health impacts of the exposure. Specifically, the study a) estimated
the output of airborne pollutants from the whale-watching fleet based on emissions data from
regulatory agencies, b) estimated the vertical dispersion of such pollutants based on air
stability data collected in the field and from climatological sources, c) used a dispersion
model incorporating data on whale, vessel, and atmospheric behaviour to estimate exposure,
and d) examined the likely physiological consequences of this exposure based on allometric
extrapolation of data from other mammalian species. The results of these exercises indicate
that the current whale-watching guidelines are usually effective in limiting pollutant
exposure to levels just at or below those at which adverse health effects would be expected in
killer whales. However, under ‘worst-case’ conditions and even under certain ‘average-case’
conditions the pollutant levels are much higher than those predicted to cause adverse health
effects. With this information, recommendations are made for further studies that would fill
in missing information, and increase confidence in the models, and the predicted impact on
the southern resident killer whales. Recommendations for limiting killer whale exposure to
air pollutants are also provided.
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Reisinger, Ryan Rudolf. "Abundance and predatory impact of killer whales at Marion Island." Diss., University of Pretoria, 2011. http://hdl.handle.net/2263/27643.
Full textAbstract:
Killer whales are the oceans’ apex predator and are known to have important effects on ecosystems. At Subantarctic Marion Island, southern Indian Ocean, they have only been studied opportunistically, resulting in limited knowledge of their ecosystem impact here. This dissertation describes the prey and seasonal abundance, estimates the population size and assesses the predatory impact of killer whales on seals and penguins at Marion Island, using dedicated and opportunistic shore-based observations and photographic identification, from 2006 to 2009. During 823 sightings of killer whales at Marion Island (2006 to 2009) 48 predation events were recorded; in only 10 cases could prey be identified. Killer whales fed on fur seals, elephant seals and penguins. Constant effort (dedicated) observations (259 hours, 2008 to 2009) showed that killer whale abundance, which peaked in September to December with a secondary peak in April to May, is linked to the abundance of seals and penguins. Mark-recapture analyses were performed using nearly 10 000 photographs taken from 2006 to 2009. Following careful quality control criteria 37 individuals were identified and a population size of 42 (95% CI = 35-50) individuals estimated using the open population POPAN parameterization in the software program MARK. The analytical approach is more rigorous than that used in any previous population size assessment at Marion Island. Finally, the above data were integrated to assess whether top-down control of seal and penguin populations at Marion Island is generally plausible using a simple process of elimination. Based on published data I predicted the energetic ingestion requirements of adult male and female killer whales as 1 394 MJ.day-1 and 1 028 MJ.day-1, respectively. Expanding these requirements to the 37 killer whales photographically identified at Marion Island, the population requires 40 600MJ.day-1. Based on available energy density and mass data, I predicted the energy content of available seal and penguin prey and calculated the rates at which killer whales would consume these prey in various scenarios. Penguins and Subantarctic fur seals are relatively insensitive to killer whale predation owing to their large population sizes (10 000s to 100 000s), conversely, the smaller populations (100s to 1 000s) of Antarctic fur seals and southern elephant seals are sensitive to predation, particularly the latter as they have a high energy content (approximately 2 000 to 9 000 MJ). Populations of these seals are currently increasing or stable and I conclude that presently killer whale predation is not driving population declines, although they clearly have the potential for regulation of these smaller populations. Thus, if population sizes were reduced by bottom-up processes, if killer whale diet shifted, or if prey availability changed, top-down control by killer whales could become significant. This study provides baseline information for the informed management and conservation of killer whales at Marion Island, identifies avenues for further research, and provides a foundation for the continuation of structured and dedicated killer whale research at Marion Island.Dissertation (MSc)--University of Pretoria, 2011.
Zoology and Entomology
unrestricted
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Matthews, Cory. "Longitudinal Diet Studies of Arctic Whales." Marine Biological Association of the United Kingdom, 2013. http://hdl.handle.net/1993/30149.
Full textAbstract:
An animal’s foraging ecology can vary over a range of temporal scales, mirroring seasonal and longer term changes in prey availability, as well as ontogenetic shifts in diet and distribution. Obtaining individual-based, longitudinal diet information through direct observation, however, is logistically challenging for marine mammals that pursue and consume prey underwater, and are often widely distributed. Isotopic profiling along continuously growing tissues like teeth and baleen, which archive dietary inputs at the time of growth in their stable isotope composition, allows for chronological dietary reconstructions over multi-year timespans. This thesis reports longitudinal diet studies of three Arctic whale species, killer whales (Orcinus orca), bowhead whales (Balaena mysticetus) and beluga whales (Delphinapterus leucas), derived from serial isotopic measurements along teeth and baleen. Study objectives varied by species, but general goals were to characterize seasonal, ontogenetic, and/or individual diet variation.
Results revealed similar trophic-level diet, but regional spatial separation, among eastern Canadian Arctic/Northwest Atlantic killer whales. However, isotope and tooth wear differences between two individuals and the rest of the sampled whales suggested potential specialisation on sharks, while the other whales likely had diets comprising marine mammals. Cyclic isotopic variation along Eastern Canada-West Greenland bowhead whale baleen was consistent with year-round foraging, although at a reduced rate during winter. Resting zooplankton could be an important food resource outside of periods of peak productivity, and accessibility likely drives winter habitat selection. Isotopic cycling did not differ between female and male bowheads, or among age classes, indicating similar seasonal foraging patterns despite reported spatial segregation throughout their summer range. Individual beluga whales from three eastern Canadian Arctic populations varied in timing of ontogenetic diet shifts (i.e. weaning age), as well as overall trophic position, which could reflect size-specific energetic requirements and foraging capabilities. Population-specific beluga whale diet trends over a period of several decades likely reflected climate-related expansions of southern forage fish. Collectively, findings of seasonal, ontogenetic, and/or individual diet variation contribute a greater understanding of intrapopulation variation in foraging ecology of these species, and of large-scale structuring of Arctic marine ecosystems.
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Wright, Brianna Margaret. "Kinematics and acoustics of foraging behaviour by a specialist predator, the northern resident killer whale (Orcinus orca)." Thesis, University of British Columbia, 2014. http://hdl.handle.net/2429/47014.
Full textAbstract:
Foragers with narrow dietary niches often exhibit specialized hunting behaviours that improve their efficiency for capturing preferred prey, but can leave them vulnerable if the abundance of this prey declines. I examined the specificity of foraging behaviour by a highly selective predator, the northern resident killer whale (Orcinus orca), which specializes on Chinook salmon (Oncorhynchus tshawytscha). Northern residents are undoubtedly well adapted to capture Chinook, however, their hunting tactics have never been described due to the challenges of quantifying underwater behaviour. To address this research gap, I deployed archival tags (DTAGs) on 32 killer whales to measure their acoustic and kinematic behaviour during foraging dives. Reconstructed 3-dimensional tag tracks indicated that foraging and non-foraging dives were kinematically distinct. While engaged in hunting behaviour, whales dove deeper, remained submerged longer, swam faster, increased their dive path tortuosity, and rolled their bodies more than during other activities. Maximum foraging dive depths reflected both the deeper vertical distribution of Chinook (compared to other salmonids), as well as the tendency of these fish to evade predation by diving steeply. Inferences from whale movements further revealed that salmon engaged in other anti-predation strategies, including increasing swim speeds and evasive manoeuvring. DTAG records also provided the first definitive link between echolocation and prey captures by resident killer whales, who displayed significantly higher clicking rates and spent proportionally more time echolocating prior to capturing a fish than they did afterward. Rapid ‘buzz’ click sequences were often produced before fish captures, which is consistent with their hypothesized function of close-range prey targeting. Furthermore, prey handling ‘crunches’ were usually detected following kills and, with buzzes, provide possible acoustic proxies for capture attempts and successes that could be used to estimate foraging efficiency. My thesis determined that northern resident killer whales possess specialized foraging behaviours for targeting Chinook salmon. The specificity of these behaviours may make the whales less effective at capturing other types of fish. If northern residents have limited flexibility to modify their foraging behaviour to successfully exploit other prey types when Chinook availability is reduced, prey capture efficiency (and thus per capita energy intake) could decline.
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Vester, Heike Iris [Verfasser], Julia [Akademischer Betreuer] [Gutachter] Fischer, Marc [Gutachter] Timme, André [Gutachter] Fiala, Julia [Gutachter] Ostner, Eckhard W. [Gutachter] Heymann, and Christian [Gutachter] Roos. "Vocal repertoires of two matrilineal social whale species Long-finned Pilot whales (Globicephala melas) & Killer whales (Orcinus orca) in northern Norway / Heike Iris Vester ; Gutachter: Julia Fischer, Marc Timme, André Fiala, Julia Ostner, Eckhard W. Heymann, Christian Roos ; Betreuer: Julia Fischer." Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2017. http://d-nb.info/1131875729/34.
Full text
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Kuker, Kathryn. "A re-evaluation of the role of killer whale (Orcinus orca) predation in the decline of sea otters (Enhydra lutris) in the Aleutian Islands." Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/5637.
Full textAbstract:
Sea otters in the Western Aleutian Islands have experienced a drastic population decline
since the 1990s and Estes et al. (1998) hypothesized that killer whale predation is responsible.
This hypothesis has not been challenged nor tested empirically. The aim of this study was
twofold: 1) to conduct a literature review of the evidence that killer whales caused the sea otter
populations to decline, re-examining alternative explanations, and 2) to empirically test the
"killer whale prédation hypothesis" by comparing sea otter behavioural responses to artificial
killer whale cues (playbacks of killer whale vocalizations and blows) in the Aleutian Islands to
the response of sea otters to the same cues in British Columbia, where they do not suffer
intensive killer whale prédation. The literature review revealed that the existing data are
inconclusive and further research into other possible causes is needed. For example, high
contaminant levels observed in sea otters coupled with intensive military occupation in the
Aleutian Islands warrants further investigation into the role that toxins have played in the health
of otters. Increases in shark populations in the Aleutian Islands concomitant with the sea otter
population declines also calls for further research into alternative marine predators. The
empirical test revealed that sea otters in the Aleutian Islands responded to both treatment and
control playbacks of killer whale vocalizations while the sea otters in British Columbia did not.
This suggests that there is some form of environmental difference between the two sites, but,
because sea otters did not respond more strongly to the sounds of killer whales than to controls,
it does not support the notion that killer whale prédation caused the discrepancy. This is the first
experimental evidence that killer whales may not have preyed on sea otters to the extent
suggested by Estes and colleagues, if at all. Together, the results from the review and the
playback experiments indicate that the situation is more complex than previously acknowledged
and fiirther research into alternative mechanisms driving the sea otter population down is
required to ensure proper conservation and management of the species.
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Janc, Anaïs. "Comportement des capitaines, des orques Orcinus orca et des cachalots Physeter macrocephalus dans le contexte de compétition autour de la pêcherie palangrière à la légine australe Dissostichus eleginoides dans les eaux subantarctiques françaises." Thesis, La Rochelle, 2019. http://www.theses.fr/2019LAROS033.
Full textAbstract:
La surexploitation des ressources halieutiques entraîne une compétition croissante entre les pêcheries et la biodiversité marine. Cette compétition donne lieu à des interactions de type déprédation (consommation des poissons directement sur le matériel de pêche par les prédateurs marins). La déprédation engendre des conséquences i) socio-économiques pour les pêcheries (diminution des rendements) ; ii) écologiques pour les prédateurs marins (risques accrus de capture accidentelle ou d’exposition à une réponse létale) et iii) écosystémiques (impacts sur les ressources cibles et auxiliaires). Cette thèse propose d’étudier, sur une des pêcheries des plus lucratives, des plus sélectives mais également des plus exposées à la déprédation, les mécanismes décisionnels (capitaines) et comportementaux (prédateurs marins) impliqués dans la déprédation exercée par les orques (Orcinus orca) et les cachalots (Physeter macrocephalus) sur la pêcherie à la palangre démersale ciblant la légine australe (Dissostichus eleginoides) dans les Zones Économiques Exclusives françaises des îles Crozet et Kerguelen, océan Indien. Par une approche originale combinant éthologie humaine et animale sur fond de théorie de l’approvisionnement optimal à deux échelles spatio-temporelles, nous montrons que i) cette déprédation est marquée avec une compétition d’autant plus importante que les capitaines sont expérimentés ; ii) les odontocètes ajustent leur comportement naturel pour bénéficier de l’apport de nourriture issue des pêcheries ; iii) aucune prise de décision ne permet simultanément un haut rendement de pêche et une déprédation réduite. Ces résultats soulignent l’importance de la pression exercée par les pêcheries sur les ressources naturelles et la pertinence de futures évaluations bioéconomiques et socio-écosystémiques pour assurer la viabilité économique des pêcheries et la durabilité des ressources naturelles exploitées et auxiliairesOverexploitation of fisheries resources leads to increasing competition between fisheries and marine biodiversity. This competition gives rise to depredation-type interactions (consumption of fish directly on the fishing gears by marine predators). Depredation has i) socio-economic consequences for fisheries (reduced yields); ii) ecological for marine predators (increased risk of bycatch or exposure to a lethal response) and iii) ecosystems (impacts on target and auxiliary resources). This thesis proposes to study, on one of the most lucrative fisheries, the most selective but also the most exposed to depredation, the decisional mechanisms (captains) and behavioural (marine predators) involved in the depredation exerted by the orcas (Orcinus orca) and sperm whales (Physeter macrocephalus) on the demersal longline fishery targeting Patagonian toothfish (Dissostichus eleginoides) in the French Exclusive Economic Zones of the Crozet and Kerguelen, Indian Ocean. By an original approach combining human and animal ethology against the backdrop of optimal foraging theory at two spatio-temporal scales, we show that i) this depredation is marked with a competition all the more important as the captains are experienced; (ii) odontocetes adjust their natural behaviour to benefit from the supply of food from the fisheries; (iii) no decision-making simultaneously allows high fishing yield and reduced depredation. These results highlight the importance of fisheries pressure on natural resources and the relevance of future bio economic and socio-ecosystem assessments to ensure the economic viability of fisheries and the sustainability of exploited and ancillary natural resources
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Tixier, Paul. "Déprédation par les orques (Orcinus Orca) et les cachalots (Physeter Macrocephalus) sur les palangriers à la legine australe dans la ZEE de l' archipel de Crozet." Thesis, Aix-Marseille, 2012. http://www.theses.fr/2012AIXM4096/document.
Full textAbstract:
C'est dans le contexte délicat du milieu marin, marqué par l'écroulement des stockshalieutiques et la conservation urgente des espèces de prédateurs marins, que s'inscrit cette étude sur la déprédation (i.e. prélèvement des poissons capturés) par les orques et les cachalots sur la pêche à lapalangre dans la ZEE de l'Archipel de Crozet.Le premier objectif a été d'évaluer les conséquences socio-économiques du phénomène. Entre 2003 et2010 les orques ont interagi avec un total de 43,3% des palangres relevées et les cachalots avec 57,5%,les deux espèces étant présentes simultanément sur 27.8% des palangres (n=5438). Les orques, seulesou associées aux cachalots ont été estimées prélever 926 ± 76 tonnes de légines sur l'ensemble de lapériode, représentant un taux de déprédation de 17,7%.Trois facteurs opérationnels ont été identifiés comme faisant varier la déprédation par les orques : i)utilisation de palangres courtes (<5000m) en absence d'orques, ii) déplacement du navire sur desdistances supérieures à 40nq pour quitter une zone confrontée à la déprédation et changer de zone, iii)utilisation de vitesse de remontée des hameçons à bord supérieures à 50 H.min-1.Le deuxième objectif de cette étude a été d'évaluer les conséquences démographiques de ladéprédation sur la population d'orques de Crozet. Le suivi à long terme des individus a permis demettre en évidence des réponses différentielles des unités sociales en fonction de leur degréd'interaction avec les pêcheriesOver the last 50 years, fisheries have undergone a major decline worldwide. With an increasedcompetition for resource, depredation (i.e. removal of catches on fishing gear) has recently become amajor case of conflict between humans and marine predators. In this study I focused on thedepredation on Patagonian toothfish fisheries by killer and sperm whales in the Crozet EEZ. The firstpart of the study aimed at assessing the socio-economic consequences of this issue. Killer and spermwhales have interacted with 43.3% and 57.5% of longlines (n=6751) respectively from 2003 to 2010.Killer whales, alone or co-occurring with sperm whales were responsible for an estimated loss of 926± 76 tons of toothfish over that period, which represents 17.7% of the total catch.Three operational factors were identified as influencing significantly depredation levels: i) the use ofshort longlines (<5000m) in absence of killer whales, ii) the displacement of vessels on distances>40nq to leave the whales behind and iii) the use of longline hauling speed > 50 H.min-1.The second aim of the study was to investigate the consequences of depredation on the Crozet killerwhale population. The long term monitoring of individuals showed divergent demographic trajectoriesrelated to the depredation level of matrilines. During the 1990s, matrilines interacting with fisherieshave undergone a high mortality due to lethal interactions with illegal fishing vessels using explosivesto repel the whales
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Barrett-Lennard, Lance. "Echolocation in wild killer whales (Orcinus orca)." Thesis, 1992. http://hdl.handle.net/2429/1263.
Full textAbstract:
Echolocation by odontocete whales has been demonstrated in captive settings many times, yet little is known about its use and function in the wild. In this thesis, I describe echolocation sounds in pods of killer whales (Orcinus orca) off the coasts of British Columbia and Alaska. I examine the relationships between echolocation and water clarity, ambient noise, and behavioural activity. I compare echolocation by two populations with different feeding habits and foraging patterns. The study provides new insight into the functional role of odontocete echolocation, and into the relative contributions of vision and passive listening to spatial perception and prey detection. Underwater recordings were made during 111 encounters with killer whales. Known members of the resident (fish-eating) population were photographically identified 85 times, and transients (mammal eaters) 23 times. Click sounds characteristic of echolocation were identified in the recordings aurally, and by spectrographic and waveform analysis. Most clicks occurred in series (trains), but isolated clicks were occasionally detected. Echolocation behaviour differed strikingly between residents and transients. An echolocation index (EI) was defined as the average percentage of time that an individual produced click trains. The mean EI for residents was 4.24%, 27 times greater than for transients. The duration of resident click trains averaged 6.83 s, compared to 0.86 s for transients. Resident click trains were comprised of evenly spaced clicks, whereas transient trains had uneven click spacing. Transient individuals used isolated clicks once every five minutes, four times as often as residents. For resident killer whales, EI values were significantly higher during foraging and travelling than during other behavioural activities. In residents, EI declined with group size. This was also true of transients, for the recordings in which click trains were detected. Transient EI levels were significantly higher when close to shore than when offshore. No relationship between EI and ambient noise level was found for either residents or transients. Residents increased the amplitude of their clicks in response to increasing ambient noise levels. No relationship was found between water clarity and EI for either type of killer whale. I suggest that the differences in echolocation behaviour between residents and transients are accounted for by their different prey. Fish have little or no aural sensitivity in the frequency range of killer whale clicks. Marine mammals are able to detect clicks, and may use them to evade killer whale attacks. The use of isolated clicks and short, irregular, quiet click trains makes transient echolocation less detectable by marine mammals than the echolocation used by residents. Passive listening is probably the principal technique that transients use to locate prey, whereas residents use echolocation in combination with passive listening when foraging. Vision is not a major factor in locating prey, but may be used by either whale type during pursuits. Finally, I suggest that both residents and transients obtain much of their positional and orientational information using passive listening alone.
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Yurk, Harald. "Vocal culture and social stability in resident killer whales (Orcinus orca)." Thesis, 2005. http://hdl.handle.net/2429/16898.
Full textAbstract:
The killer whale (Orcinus orca) is one of the few species for which vocal culture is actively involved in the development and maintenance of the social organizations of populations. In particular, the social structure of one form of killer whales, called residents, is a good example of this involvement. Resident societies are characterized by associations of groups with highly stable membership, which allow an in-depth examination of the association between vocal culture and the nested social hierarchy of that population. Resident killer whales live in small populations where inbreeding is a threat to their genetic diversity. Genetic and cultural evolution may be closely linked in killer whales, as has been proposed for a number of other cetaceans with matrilineal social structure. To test for a possible link between genetic and cultural evolution in killer whales, I investigated vocal similarities and differences among mixing and non-mixing resident groups and between two ecotypes, residents and transients. First, I examined whether clans exist among resident killer whales in Southern Alaska. Vocal clans had been previously identified in British Columbia but not in Alaska. Two acoustically distinct clans were recognized, each of which was monomorphic for a different mitochondrial D-loop haplotype based on results of a separate genetic study. Thus, acoustic similarities within these cultural groups reflect common matrilineal ancestry, which suggests that clan-based social structure is a fixed characteristic of resident killer whales. Second, I examined the similarity of vocal repertoires between residents and transients, and among clans and communities within residents. Call type similarity does not exist above the clan level. To investigate vocal similarity above the clan level, I split calls into syllables, and compared their distribution among population levels. Structural variation of upper frequency syllables characterized vocal variation among clans of the same community, while usage of distinct lower frequency syllables reflected divisions among communities and between residents and transients. Third, I examined syntax, the ordered arrangement of syllables, among clans of resident communities. I found that vertical transmission of syllable order in matrilines is important for the distinctiveness of call type repertoires and leads to clan-specific syntax rules. Previous work has shown that mating mainly takes place between clans. Because syntax similarity appears to be negatively correlated with sociality among clans, resident killer whales may use syntax variation to choose mates with low levels of genetic relatedness. The link between vocal culture and social structure likely influences mate choice in resident killer whales. This link leads to gene-culture co-evolution in killer whales and makes them excellent candidates for studies of cultural taxonomy.Science, Faculty of
Zoology, Department of
Graduate
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Osborne, Richard. "A Historical ecology of Salish Sea "resident" killer whales (Orcinus orca) : with implications for management." Thesis, 1999. https://dspace.library.uvic.ca//handle/1828/9090.
Full textAbstract:
The purpose of this study is to explore the implications of the historical perspective when it is linked to the ecological concept of adaptive management. The vehicle for this exploration is a genetically distinct population of killer whales (Orcinus orca), whose core coastal habitat includes the inland waters of Georgia Strait, Juan de Fuca Strait and Puget Sound; a geographic region referred to as the “Salish Sea.” This stock of killer whales, known as the Southern Resident Community, is unique in having a detailed scientific record that spans over two decades and recently this population was listed as “threatened” by the Committee on the Status of Endangered Wildlife in Canada (April 1999).
The goal of this study is to take account of the specific ecological history of this killer whale population, and provide an assessment of the resiliency of this stock to withstand present levels of human impacts.
In Chapter 1 the academic concepts of historical ecology and adaptive management are reviewed in preparation for their application as theory. Chapter 2 is an inventory of the ecological domain, in which the focal population is assessed by temporally measurable indicators o f its ecological status: population dynamics, feeding ecology, and habitat use. In Chapter 3 temporally measurable indicators of stress such as predation, disease, food resource depletion, toxic exposure, surface disturbance, and underwater noise are examined for their impact upon the carrying capacity of the
environment of the whales. Chapter 4 plots both sets of indicators historically as trends in variation from the Sample Mean at different time scales (months, years, decades, centuries), and indexes them in terms of perturbations from the historical norm.
In Chapter 5 four basic types of historical trends in environmental impacts are identified that are directly relevant to evaluating the resilience of the management unit. These are: (1) Relic impacts - potential impacts that are no longer present, but may account for present conditions. (2) Adapted impacts - potential impacts that have been around long enough for the management unit to have adapted to them. (3) Cumulative impacts- potential impacts that accumulate slowly in the environment or life history of the management unit before exerting environmental resistance. (4) New impacts - potential impacts with which the management unit has not had previous experience.
These four historical criteria allow the manager to identify the most sensitive impacts for present conditions, and identify scales of management for restorative intervention. This resiliency index should have application for most types of ecological systems, or management units, because it describes very generalized types of temporal outcomes, independent of scale and life history pattern of the management unit.
In terms of the focal population of killer whales in this study, the historical assessment suggests that: 1) these whales are presently a remnant population due to killing and capture by European settlers from the turn of the century to the 1970s; 2) they have bio-accumulated toxins during the highest historical periods of environmental pollution in the Salish Sea, and this toxic exposure will continue to increase for the whales over the next few decades; 3) this killer whale population has never previously experienced a lack of salmon, so diminishing salmon stocks are potentially a new stress on them; and 4) these killer whales have adapted to vessel traffic and noise for several decades in relation to vessel-based salmon fishing operations, and that this influence has recently been replaced by record levels of whale watching traffic, which potentially poses more severe impacts than fishing vessels because the boats follow the whales, rather than their prey.
This historical assessment facilitates the application of “adaptive management” strategies for these whales by providing the basis for predicting the current “resiliency” of this population to adapt to environmental conditions.Graduate
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Kriete, Birgit. "Bioenergetics in the killer whale, orcinus orca." Thesis, 1994. http://hdl.handle.net/2429/7258.
Full textAbstract:
A series of three papers is presented, each one related to the bioenergetics of killer whales,
Orcinus orca. The first chapter describes how standard and realized metabolic rates were
determined in captive killer whales by collecting respirations at different apneas and different
activity states by training the animals to exhale into a funnel onto which a meteorological
balloon was attached. These exhalations were analyzed for tidal volumes and respiratory
gases; estimates of realized metabolic rates were based on activity budgets observed in the
individual animals. Tidal volumes at rest were 2.7 to 4.2 times higher than those predicted by
allometric equations, while estimated vital capacities are estimated to lie between 68% and
94% of the values predicted by allometric equations. Standard metabolic rates for the adult
animals were similar to Kleiber’s estimates (1.2 to 1.3 times Kleiber). Realized metabolic
rates were between 2.7 and 2.9 times those of the whales’ SMR, which are values similar to
those of terrestrial mammals.
In the second chapter, food consumption and the influence of other factors such as
pregnancy, lactation and water temperature on the food intake of captive killer whales, were
examined. Food data were collected from the aquaria at which the animals were held and
analyzed for caloric values on a daily basis. While food intake increased with age, differences
in water temperature ranging between 7 and 23 °C had little or no effect on food intake.
Pregnancy caused an increase in food consumption of 25% only during the last month of
gestation, but food intake increased up to 100% with lactation. The best fit for feeding rate
as a function of body weight was determined as: food intake (kg/d) = 0.277 M⁰⁶⁶³, where
M = body mass in kg. A mean net assimilation efficiency of 0.73 was calculated by
comparing food intake to energy expenditure measured by respiration analysis.
In the third chapter, realized metabolic rates were estimated in free-ranging killer whales
along the Pacific West Coast of British Columbia and Washington. Swimming velocities and
respiration rates were determined by tracking movements of whales using a theodolite and a
loran. The relationship between swimming velocities and respiration rates showed an increase
in respiration rate with increasing swimming speed for different age and sex classes of killer
whales. These data were combined with metabolic rates determined by respiration analysis in
captive killer whales during different activity states to estimate metabolic rates of wild killer
whales during swimming (males: metabolic rate (kcal/kg/d) = 29.32 + 1.11V²⁵ females:
metabolic rate (kcal/kg/d) = 32.29 + 1.26V²⁵). The minimum cost of transport for male and
female killer whales occurred at 3.1 rn/sec which corresponded to 0.18 and 0.20 kcal/kg/km.
The drag that killer whales experience at different swimming velocities was calculated based
on theoretical assumptions and suggests that drag is mainly laminar (males: 88% of the flow
was laminar and 12% were turbulent; females: 89% of the flow was laminar and 11%
turbulent).
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Harms, Elvira. "Association patterns and pod cohesion in northern resident killer whales (Orcinus orca)." Thesis, 1997. http://hdl.handle.net/2429/5951.
Full textAbstract:
Understanding the social structure of a killer whale community may give insight
into the short-term factors that determine pod-cohesion and pod-splitting. Social
patterns within British Columbia's northern resident killer whale community were
analyzed using a 20-year long photographic database. Females were found to associate
primarily with their mothers when young, and with their own offspring later in life. They
showed a surprising lack of contact with other females in their pod, and were
photographed more often with females of other pods. Males seemed to be the preferred
associates of all pod members, especially other males. Upon reaching age 21, males
showed an explosion in social contacts of all sorts, especially with their extended kin.
The results suggest that it is male social bonds that give cohesion to killer whale
pods, binding two or more related female-offspring units. Female associations are mainly
between mothers and their offspring, and their associations with females of other pods
may give some cohesion to the community as a whole. These patterns lead to the
prediction that without an adult male and the possibility of male-male bonds between
mother-offspring units, a pod is likely to split after the death of the common mother.
This prediction is consistent with observed cases of pod-splitting.
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Deeke, Volker Bernt. "Stability and change of killer whale (Orcinus orca) dialects." Thesis, 1998. http://hdl.handle.net/2429/8392.
Full textAbstract:
Vocal dialects have been described in many species, but most studies so far have
focused on territorial species such as songbirds and humans. This study investigates
patterns of structural variation in the stereotyped calls of 9 matrilineal units of killer whales
(Orcinusorca) with congruent home ranges.
In Chapter I, I describe an index of acoustic similarity based on neural network analysis of
frequency contours. I test this index on simulated signals, and compare it to similarity
ratings from three human subjects. The index could discriminate along global differences
in contour frequency, as well as localized differences in frequency and shape. It rated
similarity comparably to humans, since differences between ratings among subjects
exceeded differences between subject ratings and the neural network index.
In the second Chapter, I analyse 2 call types used by 2 groups over a 12 year period to
identify mechanisms of vocal differentiation. A test for structural modification detected
significant changes in one call type in both groups, but not in the other. The rate of
differentiation between both groups was significantly lower for the modified call type than
the rate of modification in one group showing that modifications are transmitted between
groups. Results of an analysis of structural parameters are consistent with a theory of
structural drift.
In Chapter III, I quantify patterns of structural variation for 4 call types shared by 9
matrilineal units. Patterns are consistent across some call types, and similarity ratings for
two call types are correlated with the frequency of association among groups. This
presents additional evidence for the role of cultural transmission in maintaining structural
similarity of shared calls.
This study shows that discrete calls of killer whales are modifiable behavioural traits and
transmitted through learning. Since multiple vocal traditions persist in spite of frequent acoustic contact between their members, this study presents evidence for selective
copying in resident killer whales. If association patterns reflect kinship among matrilineal
units as they do among individuals and among communities, similarity of shared call types
indicates the degree of maternal relatedness, and may function in kin recognition or mate
choice.
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Vester, Heike Iris. "Vocal repertoires of two matrilineal social whale species Long-finned Pilot whales (Globicephala melas) & Killer whales (Orcinus orca) in northern Norway." Doctoral thesis, 2017. http://hdl.handle.net/11858/00-1735-0000-0023-3E3F-5.
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Barrett-Lennard, Lance Godfrey. "Population structure and mating patterns of Killer Whales (Orcinus orca) as revealed by DNA analysis." Thesis, 2000. http://hdl.handle.net/2429/12856.
Full textAbstract:
This thesis reports a genetic investigation of population segregation, social organization, and mating patterns in killer whales (Orcinus orca) of the northeastern Pacific Ocean. Previous studies identified two sympatric, non-associating populations, fish-eating residents and mammal-eating transients, and described many aspects of their demography, ecology, and social behaviour. Less is known about a third offshore population. Here, I focused on two aspects of killer whale social organization that are unusual among wellstudied mammals: maintenance of complete segregation between residents and transients in sympatry, and lack of dispersal in individual residents of either sex. I began by developing and testing lightweight pressure-propelled biopsy darts. They were an efficient way of acquiring skin samples from free-ranging whales and caused only minor behavioural responses in sampled animals. Using these darts and sampling stranded carcasses, colleagues and I collected biopsies from 269 individually-identified killer whales in British Columbia and Alaska. I used DNA from the biopsies to sequence the mitochondrial D-loop of 111 matrilines, and genotyped all individuals at 11 polymorphic microsatellite loci. I found that residents and transients are strongly differentiated genetically and that there is little or no gene flow between them. Both are divided into three genetically-differentiated regional subpopulations. Each resident subpopulation is more closely related to other resident subpopulations than to any transient subpopulation and vice versa, implying that the differences between residents and transients stem from a single divergence. The offshore population is not closely related to either of the other populations. The propensity of killer whales to live in fixed groups of a few hundred individuals apparently allows sympatric or parapatric populations to diverge genetically and could eventually result in speciation. I examined mating patterns in residents by conducting paternity tests and analysing fixation indices based on microsatellite genotypes. I found that residents rarely mate within their pods. Further, in the most thoroughly-sampled resident subpopulation, most matings were between rather than within acoustic clans (groups of pods with similar acoustic repertoires). Because pods within clans proved to be closely related, inter-clan mating appears to be an inbreeding avoidance mechanism. Most matings were between individuals from the same subpopulation. This pattern of population segregation coupled with inbreeding avoidance closely resembles marriage patterns in many human societies.
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Reis, Miguel Neves dos. "Temporal change in the calling behaviour of an isolated killer whale (Orcinus orca)." Dissertação, 2014. https://repositorio-aberto.up.pt/handle/10216/81417.
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Reis, Miguel Neves dos. "Temporal change in the calling behaviour of an isolated killer whale (Orcinus orca)." Master's thesis, 2014. https://repositorio-aberto.up.pt/handle/10216/81417.
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Belonovich, Olga Andreevna. "Northern Fur Seals (Callorhinus ursinus) of the Commander Islands: Summer Feeding Trips, Winter Migrations and Interactions with Killer Whales (Orcinus orca)." Thesis, 2011. http://hdl.handle.net/1969.1/ETD-TAMU-2011-08-9320.
Full textAbstract:
The northern fur seal (NFS) population on the Pribilof Islands (PI) is currently declining while the population on the Commander Islands (CI which includes Bering and Medny Islands) is stable. The reasons for the different population trajectories remain unknown. Comparing differences in behavioral ecology and predation pressure between these two populations could provide an explanation. This study examined lactating NFS female behavior to determine: 1) summer foraging patterns (trip duration, trip direction, dive depth) of animals from two nearby rookeries on Bering Island, 2) winter migration from Medny and Bering Islands relative to patterns of ocean productivity, and 3) the potential impact of killer whale predation on population dynamics. Data were collected from 2003 to 2010 using visual observations and telemetry. Twenty-one satellite transmitters, 29 time-depth recorders and 17 geolocation recorders were deployed. Shore-based observations of killer whale predation and photo-identification were conducted near the CI rookeries in 19992010. During lactation, both mean foraging trip duration and mean maximum diving depth (3.4 plus/minus 1.3 days and 17.7 plus/minus 6.8 m, respectively) for NFS adult females (n = 28) did not significantly change among years. Although foraging areas of NFS from the two rookeries on Bering Island overlapped, the mean direction of travel from Severo-Zapadnoe rookery was significantly (p<0.01) different compared with Severnoe rookery. The foraging patterns suggested that these females had a reliable food source that did not change despite potential environmental changes or the effects of fisheries. During their winter migration, NFS females from the CI traveled to the Transition Zone Chlorophyll Front (32° N-42° N) in the North Pacific Ocean. Their winter migration routes and the location of overwinter foraging areas were positively correlated with high ocean productivity (near surface chlorophyll a concentration). Over 82 percent (n=17) of these females spent 38 months near the eastern coast of Hokkaido, Japan and followed the coastal high productivity areas on their way back to the CI.
Transient killer whales in groups of 2-12 individuals were repeatedly observed preying mostly on NFS males during the summer. The simulation model showed little impact on population dynamics as long as male fur seals were the primary prey. However, if the number of killer whales increased or they changed their diet to include females and pups, then the NFS population on the CI could decline.
The winter migration of NFS from CI and PI are similar. Lactating NFS from the PI exhibit greater summer foraging effort (longer average trip duration and bout duration; greater number of deep dives) compared with females from the CI.
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Stredulinsky, Eva Helene. "Determinants of group splitting: an examination of environmental, demographic, genealogical and state-dependent factors of matrilineal fission in a threatened population of fish-eating killer whales (Orcinus orca)." Thesis, 2016. http://hdl.handle.net/1828/7603.
Full textAbstract:
Group living is a social strategy adopted by many species, where individuals can exhibit long-term social affiliation with others, strengthened through cooperative behaviour and often kinship. For highly social mammals, changes in group membership may have significant consequences for the long-term viability and functioning of a population. Detecting significant social events is essential for monitoring the social dynamics of such populations and is crucial to determining the factors underlying these events. Detecting when changes in social organization occur, especially with incomplete data, poses significant analytical challenges. To resolve this issue, I developed and assessed a straightforward, multi-stage and generalizable method with broad utility for ecologists interested in detecting and subsequently investigating causes of changes in social organization. My approach illustrates the frequency and ecological relevance of group fission and fusion events in a population of fish-eating ‘Resident’ killer whales (Orcinus orca). Group fission is a process commonly found in social mammals, yet is poorly described in many taxa, and has never been formally described in killer whales. To address this gap, I provided the first description of matrilineal fission in killer whales, from a threatened but growing Northern Resident killer whale population in which matrilineal fission has been observed for the past three decades. I also undertook the first comprehensive assessment of how killer whale intragroup cohesion is influenced by group structure, demography and resource abundance. Fission in Northern Resident killer whales occurred both along and across maternal lines, where animals dispersed in parallel with their closest maternal kin. I show that fission in this population is driven primarily by population growth and the demographic conditions of groups, particularly those dictating the nutritional requirements of the group. I posit that intragroup food competition is the most likely explanation for group fission in this population, where prey abundance also has ancillary effects. As group fission can have a direct impact on the fitness of group members and the long-term viability of a population, my findings underscore the importance of incorporating studies of sociality into the management of threatened populations of social mammals.Graduate
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Tixier, Paul. "DEPREDATION PAR LES ORQUES (ORCINUS ORCA) ET LES CACHALOTS (PHYSETER MACROCEPHALUS) SUR LES PALANGRIERS A LA LEGINE AUSTRALE DANS LA ZEE DE L'ARCHIPEL DE CROZET." Phd thesis, 2012. http://tel.archives-ouvertes.fr/tel-00910893.
Full textAbstract:
C'est dans le contexte délicat du milieu marin, marqué par l'écroulement des stocks halieutiques et la conservation urgente des espèces de prédateurs marins, que s'inscrit cette étude sur la déprédation (i.e. prélèvement des poissons capturés) par les orques et les cachalots sur la pêche à la palangre dans la ZEE de l'Archipel de Crozet. Le premier objectif a été d'évaluer les conséquences socio-économiques du phénomène. Entre 2003 et 2010 les orques ont interagi avec un total de 43,3% des palangres relevées et les cachalots avec 57,5%, les deux espèces étant présentes simultanément sur 27.8% des palangres (n =5 438). Les orques, seules ou associées aux cachalots ont été estimées prélever 926 ± 76 tonnes de légines sur l'ensemble de la période, représentant un taux de déprédation de 17,7%. Trois facteurs opérationnels ont été identifiés comme faisant varier la déprédation par les orques : i) utilisation de palangres courtes (<5 000 m) en absence d'orques, ii) déplacement du navire sur des distances supérieures à 75 km pour quitter une zone confrontée à la déprédation et changer de zone, iii) utilisation de vitesse de remontée des hameçons à bord supérieures à 50 ham.min-1. Le deuxième objectif de cette étude a été d'évaluer les conséquences démographiques de la déprédation sur la population d'orques de Crozet. Le suivi à long terme des individus a permis de mettre en évidence des réponses différentielles des unités sociales en fonction de leur degré d'interaction avec les pêcheries. En effet, les années 1990 sont d'abord marquées par une sur-mortalité des orques interagissant à des hauts niveaux avec les pêcheries, confirmant l'effet de réponses de type létales de la part des navires braconniers sur les individus. Cette tendance s'inverse à partir de 2003 avec une survie et une reproduction supérieure dans les unités à fort taux d'interaction, suggérant un effet bénéfique de la déprédation. Avec l'augmentation des cas de déprédation dans le monde, la portée de cette étude est globale, d'une part par ses résultats positifs issus d'une collaboration entre pêcheurs, gestionnaires et scientifiques, et d'autre part par la précision des priorités de conservation impliquées.