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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
61

Mining the behavioural reality of fish-fisher interactions to understand vulnerability to hook-and-line fishing

Monk, Christopher 27 February 2019 (has links)
Angelerfolg hängt vom Fischverhalten ab und selektiver Fang aufgrund vererbbarer Verhaltensmerkmale kann sich auf Fischpopulationen auswirken. Die anglerische Vulnerabilität ergibt sich aus einer Kombination aus dem Zustand des Fisches, dem Zusammentreffen mit dem Fanggerät und den Eigenschaften desselben. Höhere Aktivität sollte die Begegnungswahrscheinlichkeit mit dem Fanggerät und dadurch die Vulnerabilität steigern. Ziel dieser Arbeit war es zu verstehen, wie Bewegungsmuster die Vulnerabilität durch die Angelfischerei beeinflussen. Dazu habe ich das Verhalten von vier Arten (Karpfen, Cyprinuscarpio, Schleie, Tinca tinca, Barsch, Perca fluviatilis, und Hecht, Esox lucius) in einem See mittels akustischer Telemetrie gemessen. Zudem habe ich verhaltensselektives Angeln auf Benthivore (Karpfen und Schleie) von festen Plätzen mit dem mobilen Angeln auf einen aktiven Raubfisch (Barsch) und einen Lauerjäger (Hecht) verglichen. Barsche wurden gezielt von freiwilligen, unterschiedlich versierten Anglern in GPS-überwachten Booten beangelt, um zu verstehen, wie Anglerfähigkeiten verhaltensbasierte Selektion beeinflussen. Für die individuell wiederholbare Aktivität von Karpfen, Schleie und Barsch lag keine Angelselektivität vor, da das Zusammentreffen mit Fanggeräten in keinem Zusammenhang mit der Vulnerabilität stand. Beim Barsch hingegen hing die Vulnerabilität mit der Habitatwahl zusammen. Die Geschicklichkeit der Angler verstärkte die Selektion durch höhere Mortalität. Für große Hechte mit großem Aktionsradius kann ein auf Begegnungen basierender Mechanismus nicht ausgeschlossen werden. Zusammenfassend lässt sich sagen, dass die wichtigsten Verhaltensweisen, die die Vulnerabilität durch die Angelfischerei ausmachen und nach denen eine Selektion erwartet wird, häufig erst nach dem Zusammentreffen von Fisch und Fischer stattfinden. Jedoch kann die Bedeutung dieser Fisch-Fischer Begegnungen für die Vulnerabilität art- und fischereispezifisch sein. / Capturing fish by angling depends on fish behaviour. Selective capture based on heritable behaviours may have ramifications for fish populations and fishing communities, but the behavioural components of angling vulnerability are unclear. Conceptually, vulnerability derives from a combination of a fish’s internal state, gear encounter rate and gear quality. Accordingly, greater activity or space use is expected to increase vulnerability via elevated encounter rates with fishing gear. However, behaviourally selective angling may also interact with angler behaviour (e.g. skill). My aim was to understand the role of fish movement and space use in driving angling vulnerability. I measured the behaviour and angling vulnerability of four species (viz. carp, Cyprinus carpio, tench, Tinca tinca, perch, Perca fluviatilis, and northern pike, Esox lucius) using whole-lake high resolution acoustic telemetry. Perch were targeted by variably skilled anglers in GPS tracked boats to understand how skill affects selection. I have therefore contrasted behaviourally selective angling of benthivores (carp and tench) targeted from fixed angling sites, an active top predator (perch) targeted by searching anglers and an ambush predator (northern pike) targeted by searching anglers. Angling was unselective for repeatable carp, tench or perch activity and movement as encounter was unrelated to vulnerability. Vulnerability related to perch habitat choice as shown by a latitudinal division of captured and uncaptured perch and high skilled anglers only strengthened selection via greater enacted mortality. Finally, large pike with greater space use were most vulnerable to angling and an encounter based mechanism cannot be ruled out. In conclusion, the key behaviours distinguishing angling vulnerability, upon which selection should be expected, frequently operate after a fish-fisher encounter, but the importance of fish-fisher encounters for vulnerability may be species and fishery specific.
62

Recreation in the Greenstone and Caples Valleys: for whom and how?

Cessford, Gordon R. January 1987 (has links)
This study investigates issues of changing recreation use and management in the Greenstone and Caples Valleys. Its underlying research themes are the differing characteristics and activities of four distinct user-groups, how such differences could contribute to conflict in recreation use and management, and the implications of such for management. The conceptual framework used to deal with these issues is the Recreation Opportunity Spectrum (ROS), which is based upon the assumption that quality in recreation experiences and management is best achieved through provision of a range of recreation opportunities. This recognises that objective research input into recreation management cannot substitute for the ultimate subjectivity required in decision-making. Management has two roles here. First, to maintain and/or enhance the range of recreation opportunities availible. Second, to provide users with appropriate signals regarding the availibility of opportunities, and the acceptable norms of use and behaviour. Thus user choice of area and activities undertaken within becomes more a consequence of management action. This differs from most recreation management to date, which has tended to be in response to changing conditions (eg'demand-driven'). The absence of an equitable management approach results in selective reduction of opportunities for certain experiences, as evident from research into effects of conflict/crowding perceptions. In contrast, approaches such as the ROS emphasise management for such opportunities. On this basis and from research results, this study found that maintenance of experiences associated with angling and hunting opportunities in the study area, should be the basis for its management. These opportunities were exploited by relatively more experienced participants. For anglers in particular this was reflected by their characteristics of high activity specialisation. Greater experience and specialisation involved more specific resource requirements and norms of appropriate behaviour. Thus opportunities for hunting and angling in the study area were more susceptible to negative impacts from other uses and users. These impacts would be greatest for angling experiences. This would be more a consequence of perceived inappropriate behaviour by less specialised anglers than a consequence of physical crowding. For hunters these impacts would be primarily a result of concern about the increased presence of others on hunting management, rather than their actual presence. Experiences from the tramping and commercial guided walking opportunities availible are also important, but their participants were relatively less experienced and their recreation opportunities less unique in the region. In the context of an equitable regional ROS approach, there is greater flexibility for their provision elsewhere than there is for experiences from hunting and fishing opportunities. For maintenance of a spectrum of opportunities in the regional ROS, these hunting and angling opportunities should be emphasised in management decision-making. Within the study area itself, management for a regional ROS requires that the Greenstone and Caples Valleys be managed differently. It was clear that the Caples was perceived as providing more 'back-country'-type experience opportunities. In the regional ROS context, management should emphasise maintenance of such opportunities there. Along with this should be noted the greater preference for the CapIes by hunters, and for the Greenstone by anglers.
63

Metodikstudie av trollingfisket i Vänern : Jämförelse av fångstrapportering mellan intervjuer och enkäter gjorda på trollingfiskare samt vädrets påverkan på ansträngning / A methodological study of angler surveys for the sport fishery in Lake Vänern: comparison between interviews and mail-in surveys for reporting catch

Höök, David January 2014 (has links)
There are five endemic populations of migratory Atlantic salmon (Salmo salar, Salmonidae) and brown trout (Salmo trutta, Salmonidae) remaining in Lake Vänern, whereof two are salmon and three are trout. There is one population of each species in Klarälven, also one of each in Gullspångsälven and there is a population of trout still remaining in Tidan River. Since the beginning of the 20th century endemic populations of salmon and trout have either vanished or declined dramatically due to the construction of hydropower in the rivers around the lake, and still today the future of the remaining populations remains uncertain. To manage salmonid fishes effectively more knowledge of their ecology throughout their different life-stages is needed. A large part of the Lake Vänern salmonoids lives are spent in the lake, where a mayor mortality factor is recreational fishing, especially angling. Estimation of fishing effort and catch is important in order to remain a sustainable fishery. In Lake Vänern commercial fishers are bound to report their catch, but anglers are not, -even though they are now thought to be responsible for the largest proportion of the catch. Angler interviews and access point surveys are the best ways to get accurate information in order to assess sport fish effort and catch. There are drawbacks of this method though that includes large costs, logistical problems and biased results due to the higher chance of interviewing the most avid anglers. To hand out mail-surveys is a kind of off-site survey that is less costly compare to interviews, but the drawbacks are bigger in getting correct information due to biased results from non-respondence. A study was conducted to compare an interview-survey with a mail-in survey, in which the interviews were conducted in Lillängshamnen, a port on the northern coast of Lake Vänern, and the mail-in surveys were distributed in different ports around the lake, though not in Lillängshamnen. This study shows a significant difference in catch per boat day between the interviews and mail-in survey. To find out more about how to develop the interview-survey there was also an analysis done on the correlation between weather and the number of interviews that were collected. One could find a negative correlation between numbers of interviews collected and the wind ratio, where very few interviews were collected once the wind speed measured more than 5-8 meters per second. There are improvements to be made both for the conduction of interviews and mail-in surveys, including more staff for conducting interviews at different ports and follow-ups on the non-respondents for the mail-in survey. / Av atlantlax (Salmo salar, Salmonidae) och öring (Salmo trutta, Salmonidae) finns idag fem endemiska populationer kvar i Vänern varav två är av lax och tre av öring. Det finns en klarälvsvariant av båda arterna, likaså finns det en gullspångsvariant av varje och sen finns även en öringpopulation kvar i Tidan. Sen början av 1900-talet har populationer av lax och öring utrotats eller minskat kraftigt till följd av vattenkraftens utbyggnad i vattendragen runt Vänern, och än idag är de resterande populationernas framtid oviss. För att kunna förvalta laxfiskarna på ett bra sätt krävs kunskaper om deras ekologi i dess olika livsstadier. En stor del av laxfiskarna runt Vänerns liv tillbringas i Vänern, där en mortalitetsfaktor består av fritidsfisket, då främst trolling. Uppskattning av ansträngning och fångst är viktigt för att hålla fisket i sjön på en hållbar nivå. Yrkesfisket måste rapportera all sin fångst men detta krävs inte av trollingfisket som idag tros stå för den största proportionen lax- och öringsfångst i Vänern. Genomförandet av intervjuer är en typ av plats- och åtkomstpunktsundersökning och är den bästa metoden att samla in korrekt information för att uppskatta sportfiskets ansträngning och fångst. Det finns dock nackdelar i form av stora kostnader, svår logistik och vinklade resultat då de mest entusiastiska fiskarna löper större chans att bli intervjuade. Att dela ut enkäter är en form av distansundersökning och även brevundersökning som kostar betydligt mindre än att genomföra intervjuer men brister vad gäller svarsfrekvens som i sin tur leder till vinklade resultat. En studie gjordes för att jämföra intervjuer med enkäter, där intervjuer genomfördes i Lillängshamnen på Vänerns norra kust och enkäter delades ut i olika hamnar runt hela Vänern, dock ej i Lillängshamnen. Denna undersökning visade att enkäter har en signifikant större fångst per båt än intervjuer. För att ta reda på mer om hur genomförandet av intervjuer skulle kunna förbättras undersöktes hur vädret påverkade antalet intervjuer som genomfördes. Man fick en negativ korrelation mellan antalet genomförda intervjuer och vindhastighet där ytterst få intervjuer genomfördes i vindhastigheter över 5-8 meter per sekund. Det finns förbättringspotential vad gäller både genomförandet av intervjuer och enkätundersökningar, bland annat mer personal till att kunna intervjua fler folk i olika hamnar och uppföljning på de enkäter som inte svarats på.
64

Fish assemblages in European lakes

Emmrich, Matthias 28 February 2013 (has links)
Fischgemeinschaften in Seen sind zunehmenden Umweltveränderungen unterworfen. Die Analyse des Einflusses abiotischer und biotischer Faktoren auf die Größenstruktur von Fischgemeinschaften ist entscheidend, um die Entwicklung von Seeökosystemen im Zuge von Umweltveränderungen vorhersagen zu können. Es ist jedoch schwierig Fische in Seen zu beproben, da Fanggeräte selektiv sind. Die Qualität und Vergleichbarkeit von Fischfängen durch Angler, Kiemennetze, Schleppnetze und Hydroakustik wurden untersucht. Anglerfänge eignen sich begrenzt für vergleichende Fischbestandsuntersuchungen. Vertikale Hydroakustik eignet sich für die Fischbiomassequantifizierung in geschichteten Seen. Der Beprobungsaufwand von Kiemennetzen kann reduziert werden, wenn zeitnah hydroakustische Untersuchungen statt finden. Schleppnetze eignen sich für die Beprobung von pelagischen Fischen in tiefen Seen. Die Größenstruktur von Fischgemeinschaften unterschied sich auf regionaler und überregionaler Ebene entlang abiotischer und biotischer Gradienten. Die regionale Studie zeigte, dass tiefe nährstoffarme Seen mit hohen Raubfischabundanzen durch mehr große Fische gekennzeichnet waren. Nährstoffreiche Flachseen mit wenigen Raubfischen zeigten höhere Anteile von mittleren Fischgrößen. Im überregionalen Vergleich führten Temperaturpräferenzen der Fischarten zu zwei Fischgemeinschaften, die sich in ihrer Größenzusammensetzung unterschieden. Ein hoher Anteil großer Salmoniden war typisch für hochgelegene Kaltwasserseen im Norden und Süden Europas. Flachlandseen mit Kühl- und Warmwasserfischen zeichneten sich durch eine Dominanz von kleinen Fischen aus. Das lässt vermuten, dass Fischgemeinschaften in Flachlandseen relativ robust gegenüber Umweltveränderungen reagieren. Kaltwasserfischgemeinschaften könnten im Zuge der Klimaerwärmung starken Änderungen unterliegen, da eine Veränderung in der Artenzusammensetzung von einer Verschiebung in der Größenstruktur hin zu mehr kleinen Fischen begleitet sein wird. / Lake fish assemblages are increasingly exposed to environmental change in their habitats. The investigation of abiotic and biotic factors and their effects on the size structure of lake fish is essential for predicting the response of fish assemblages to environmental change. However, sampling of lake fish is challenging because sampling gears are selective. The quality and correspondence of fish catches from angling, gillnetting, trawling and hydroacoustics were analysed. Non-standardised catch data from recreational angling were of limited quality for a comparison of fish stocks. Vertical hydroacoustics is an efficient method to quantify fish biomass in stratified lakes. Sampling effort of multi-mesh gillnets can be reduced when fish abundance estimates are derived from contemporarily operating hydroacoustics. Trawling is useful to sample pelagic fish assemblages in deep lakes. The size structures of fish assemblages differed on a small and a large geographical scale along gradients of abiotic and biotic lake descriptors and differences in fish assemblage composition. At a small geographical scale assemblages in deep and less nutrient-rich lakes with high predator abundances were characterised by a higher proportion of large fish. Shallow nutrient-rich lakes with few predators were characterised by more medium-sized fish. At a large geographical scale thermal optima of fish generated two types of assemblages with different size structures. A high proportion of large salmonids was observed in coldwater lakes at high elevation sites in northern and southern Europe. Lowland lakes with cool- and warmwater fish were dominated by small-sized individuals. The results suggest that lowland lake fish assemblages are relatively robust against environmental change. Coldwater fish assemblages instead may suffer dramatic consequences from global warming as expected species shifts are likely to be accompanied by shifts in the size structure towards smaller individuals.
65

Land-Based Food Initiatives in Two Rural and Remote Indigenous Communities

Leibovitch Randazzo, Michael January 2017 (has links)
The purpose of this thesis is to describe the harvesting and dietary practices of two rural and remote Indigenous communities. The ethnographic methods of participant observations and semi-structured interviews availed an abundance of rich and detailed data that allowed for a clear understanding of the barriers these two communities face when accessing food. This is an articled-based thesis containing three parts. Part one is composed of a literature review that describes the barriers that have contributed to food insecurity problems in Indigenous communities. It finishes with a chapter dedicated to defining the postcolonial theoretical perspective and describing how and why it was employed during this research process. The postcolonial perspective was chosen to best understand the historical forces that caused food insecurity in Indigenous communities and justify my position as a non-indigenous researcher in the field of Indigenous health. The second part of the thesis is made up of two articles. Article one will describe the current situation of food access challenges and responses in Canada, more specifically in two rural and remote First Nations communities. The article illustrates how both First Nations are experiencing challenges obtaining healthy food from the market and from the land. The article describes what is involved in acquiring food in both communities, and the responses each community is taking to increase food access. The article concludes by pointing out how these initiatives are building more than just food capacity and why they deserve greater external support. The second article is focused solely in the community of Wapekeka, and is entitled The Cost of Local Food Procurement in One Northern Rural and Remote Indigenous Community. The purpose of the article is to provide a specific example of building local food capacity as strategy to address food insecurity. It documents the costs associated with traditional food procurement and compares these costs against the price of food available in the store. The final component of the thesis is the overall conclusion, highlighting the belief that the findings presented in this thesis will promote and emphasize the importance of land-based food initiatives as a way to foster positive health outcomes for all Indigenous peoples.
66

Rörelseaktivitet hos regnbågar (Oncorhynchus mykiss) med olika antal eumelaninfläckar, utsatta för stressande sportfiske / Locomotor activity of rainbow trout (Oncorhynchus mykiss) with different numbers of eumelanic skin spots, exposed to the stressor sport fishing

Gesslin, Enar January 2023 (has links)
Rainbow trout (Oncorhynchus mykiss) are introduced in large parts of the world and are commonly farmed for consumption as well as a valued sport fish. Many species of salmonids show large intraspecific variation in pigmentation, which has been shown to correlate with stress response and several other behavioral traits. In this study, the behavior and stress response of rainbow trout linked to pigmentation is investigated, depending on previous sport fishing experience. Through data from a previous study on rainbow trout in semi-natural ponds, locomotor activity was measured as a proxy of stress, under three different sport fishing treatments. From previous photos, the pigment spots of each rainbow trout are counted to test the correlation with locomotor activity. In addition, it is tested whether different previous experience of sport fishing means a higher stress response when re-exposed to fishing. No significant relationship between pigment spots and locomotor activity could be obtained for the three treatment groups. However, significant differences in locomotor activity due to angling experience between treatment groups upon re-exposure to fishing were found, with fish that were inexperienced in angling having higher locomotor activity compared to previously caught fish. Sport fishing and catch-and-release had the effect of reducing locomotor activity in rainbow trout, which can be interpreted as fishing could both stress them and trigger the fish's feeding response, depending on previous experience. Fishing is believed to create a passivation due to the negative association of being caught, while fish not previously caught were activated by sport fishing. The study's missing correlation between pigment spots and stress has been both confirmed and denied in other studies and may depend on the origin and the degree of domestication, which means that the correlation within other species of salmonids or fish with different origins would be relevant to investigate. / Regnbåge (Oncorhynchus mykiss) förekommer introducerade i stora delar av världen och är vanliga att odlas för konsumtion samt en uppskattad sportfisk. Många arter av salmonider visar stor intraspecifik variation i pigmentering, vilket visats korrelera med stressrespons och flera andra beteendemässiga karaktärsdrag. I denna studie undersöks regnbågarnas beteende och stressrespons kopplat till pigmentering, beroende på tidigare erfarenhet av sportfiske. Genom data från en tidigare studie på regnbåge i semi-naturliga dammar mäts rörelseaktivitet som indirektmått på stress, under tre olika sportfiskebehandlingar. Från tidigare foton räknas varje regnbåges pigmentfläckar för att testa korrelationen med rörelseaktivitet. Därtill testas om olika tidigare erfarenhet av sportfiske, innebär högre stressrespons vid återexponering för fiske. Inget signifikant samband mellan pigmentfläckar och rörelseaktivitet kunde erhållas för de tre behandlingsgrupperna. Signifikanta skillnader i rörelseaktivitet på grund av erfarenheten av sportfiske mellan behandlingsgrupperna vid återexponering för fiske fanns dock, där fisk som var oerfaren sportfiske hade högre rörelseaktivitet jämfört med fisk som fångats tidigare. Sportfiske och catch-and-release hade effekten att minska rörelseaktiviteten hos regnbågar, vilket kan tolkas som att fisket både kunde stressa och trigga fiskens födorespons, beroende på tidigare erfarenhet. Fisket tros skapa en passivisering på grund av den negativa associationen att bli fångad, medan fisk som inte fångats tidigare aktiverades av sportfisket. Studiens uteblivna samband mellan pigmentfläckar och stress har både bekräftats och dementerats i andra studier och kan bero på ursprung och graden av domesticering, vilket gör att sambandet inom andra arter av salmonider eller fisk med olika ursprung vore aktuellt att undersöka.

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