No description available.

The Isle of Man fishing industry is currently predominated by two lucrative and heavily exploited scallop fisheries, targeting Pecten maximus and Aequipecten opercularis. The impacts of which have previously been investigated, however without the addition of environmental information. This thesis represents a unique long-term investigation into the impacts of fishing pressure and environmental variables on the benthic invertebrate communities of fishing grounds found around the Isle of Man. A significant positive trend in seawater temperature was found, along with an inverse correlation with chlorophyll-α. Fishing pressure was found to have a small, significant negative effect on indices of diversity; however environmental variables were unable to explain the remaining patterns in diversity. The composition of each of the benthic communities was then investigated in more detail. Fishing pressure had a significant negative effect on densities of benthic invertebrates at some grounds; however this study showed that many of the heavily fished sites were composed of dredge-tolerant species. Significant relationships were found between the densities of Asterias rubens and Porania pulvillus and several environmental variables on the south-west fishing grounds, suggesting that environmental variation, rather than fishing pressure was responsible for variations in these species. Further evidence was found of the negative impact of scallop dredging from the long-term analysis of a closed area, implemented in 1989. Recovery of P. maximus has occurred within this closure, without the concurrent increase in of the predatory starfish A.rubens. Relationships between several benthic species with the closed area and environmental variables were found. However, the results of this study indicate a complex ecosystem, which is also affected by predator-prey interactions. The overall findings of this research indicate that closed area management is a relatively straightforward and effective measure in this region. Future management decisions will however, have to account for the potential effects of climate change.

The well-being of humans and their societies depends on goods and services from marine ecosystems. Management of the fish stocks off Northern Chile is based on a single species approach. However, the fish species are not independent, and there is a need to understand the species interactions within the community and with the 3climate variability and human pressures. In this thesis I studied the size-based dynamics of pelagic fish community off Northern Chile. I investigated temporal effects of climate variability on size-based indicators from the pelagic fishery. I found that catches from the pelagic community have been declining and have become composed of smaller fish. The main signals from the environment were short-term effects, but the trends found were probably combined consequences of climate variability and fishing. I developed a multispecies size-spectrum model to explore the dynamics of the pelagic community. The model examined the effect of cannibalism and intraguild predation on anchovy and sardine dynamics under different environmental conditions. I found that climate variability and predation interactions are both needed to understand the coexistence and extinction of anchovy and sardine. The effect of fishing on anchovy dynamics was also explored through the model. Preliminary results showed that fishing below maturity has lower impact on anchovy dynamics than current fishing pattern off northern Chile. In addition the approach of a balanced harvest strategy would be more beneficial for anchovy only when it follows the relative growth rate of the species. Indicators and models are key tools in implementing the ecosystem-based approach. This thesis has combined these tools with emerging ecological theory about the role of size in the structuring marine ecosystems and, in this way, has set up a basic framework to work towards the ecosystem-based fishery management off Northern Chile.

Fishing once defined many coastal community identities around the British Isles. Over recent decades, these communities have faced the decline of their fishing industry in addition to demographic, environmental, economic change and a changing policy context in coastal areas focused on marine conservation and economic growth. Using a qualitative case study of a smallscale crab fishery, in North Norfolk, famous for its iconic ‘Cromer Crab’, I investigate place identity and attachment and their implications for social resilience. Like many coastal fishing towns, Cromer has become less reliant on fishing and the future of the fishery, central to the town’s identity, appears to be in question. Although the fishing community has been reduced, the remaining Cromer crab fishermen could be considered resilient. I identify the different livelihood strategies fishermen have adopted in order to continue fishing and explore the trade-offs each strategy involves. However, given the significant entry barriers new fishermen face, the future of this fishery appears bleak regardless of the strategy selected. The conceptual approach used allows the relational dynamics of coastal communities experiencing change to be drawn out, enabling a deeper analysis of social resilience. It challenges some of the implicit ideas in the social-ecological resilience and place attachment literature on collective action. It questions the extent to which fishing communities can collectively respond to change and influence fisheries governance. While the social and cultural importance of small-scale fisheries are recognised in national and European policy, the limited participation of fishing communities in their governance continues to hinder their sustainable development and social resilience. The insights from this case study are particularly relevant given recent changes to the management and use of marine space in the UK and highlights the need to broaden debates on social resilience and sustainable development by considering the governance context and relational dynamics of coastal communities experiencing change.

L'aménagement et la recherche s'inscrivent dans un contexte de banalisation de la participation des acteurs, en particulier dans le domaine de l’environnement. Cette tendance forme l'élément fondateur de cette recherche en géographie. Parmi les démarches d'accompagnement de la démocratie environnementale, la géoprospective se définit comme une modalité de scénarisation à long terme, collective et spatialisée qui repose largement sur l'utilisation de modèles spatio-temporels. Cette thèse avance que la géoprospective peut également constituer un outil heuristique de la contribution de l'espace et du temps à la démocratie environnementale, à plusieurs niveaux, et notamment celui de l’ancrage dans l’espace et le temps de la participation, celui des objets spatio-temporels produits par la participation ainsi que celui de la portée socio-politique de la référence à l’espace et au temps de la participation. Afin de tester ces hypothèses, une série de motivations conduisent à appliquer une démarche géoprospective aux pêches maritimes du golfe de Gascogne, caractérisées par exemple par la singularité de leurs dimensions spatio-temporelles, par la centralité du pouvoir de gestion et par la hiérarchisation des types de savoirs environnementaux. Le dispositif développé pour explorer les hypothèses de recherche combine plusieurs méthodes participatives, d’une part d’enquête par entretiens et d’autre part de modélisation (selon une définition étendue de la notion de modèle). L’analyse des matériaux narratifs collectés permet d’abord d’affiner la connaissance sur les dimensions spatio-temporelles des pêches maritimes et sur la variabilité de leur perception selon les acteurs. La recherche menée met ensuite en évidence les charges affectives et symboliques contenues dans les modèles qualitatifs destinés à un usage participatif. Enfin, un travail de réflexivité sur l’exercice mis en œuvre permet de discuter la capacité de la participation à modifier, reconduire ou reproduire le pouvoir et le savoir des acteurs. / Participation is normalizing in management and research practices, especially in environmental management and research. This trend founded this research in geography. Geoprospective is a way to collectively create spatial and long-term scenarios thanks to a large use of simulation tools. Moreover, it is considered as a mean to enhance environmental democracy. In this thesis, geoprospective is also considered as a mean to explore the contribution of space and time to the environmental democracy, in terms of power, knowledge, interactions between actors and models and social and political impacts of scenarios process. In order to test this hypothesis and for several other reasons (originality of spatial and temporal dimensions, centrality of power, hierarchy of knowledge), a geoprospective exercise has been applied to the fisheries of the Bay of Biscay.This exercise was based on a combination of participatory interviews and modeling. The materials and reflexivity analysis have shown that spatial and temporal dimensions of environmental democracy are multiwfaced. First, space and time lie in the transmission of knowledge. Then, space and time lie in the appropriation of models. In the end, space and time lie in actors narratives, play and imaginaries.

No description available.

Senegalese fishermen have significantly expanded their mobility into the eastern Atlantic Ocean since the early 1980s. Fishermen have been crossing international maritime borders and organising long sea journeys, in part as a response to the decrease in fishing resources in Senegalese waters. From the early 2000s, they began carrying West African migrants on the maritime routes from Senegal to Spain, diversifying into irregular maritime migration or ‘people smuggling’. Fishermen’s fishing techniques and the migration flows they have facilitated are well documented. We have a good understanding, too, of the push-and-pull factors shaping these maritime migration patterns. Thus far, the social and political meanings of fishermen’s maritime mobility and cross-border movements have been comparatively neglected. This thesis argues that these mobility patterns are connected, revealing links between regional fisheries and mobilities and international migration flows that create distinctive maritime geographies. Drawing on participant observations and narratives collected in 69 in-depth interviews, my analysis explores the ways in which power and knowledge shape the at-sea experiences of Senegalese fishermen. For them, mobility is more than a response to the decrease in fish resources. By deploying their mobility, fishermen seek to recover control over their maritime and social environments. To map the maritime geographies this mobility co-creates, I examine three spaces. First, I chart the social and political mechanisms of fishermen’s mobility in Senegal, examining the gendered and local meanings of their movements. Second, I examine these mechanisms at the regional level – at the Senegal–Mauritania border and in the waters off Guinea and Guinea-Bissau. Finally, I track fishermen’s routes to the Canary Islands. By attending to fishermen’s accounts, I demonstrate the many ways in which they appropriate the ocean space, shape the geographies of maritime borderlands and rationalise their navigation. I reveal how their maritime mobility opens up multiple opportunities for fishermen to negotiate with – and reshape – the power relations that structure their social, political and natural environments.

No description available.

The redevelopment of existing riverine barriers with modern hydropower turbines is becoming increasingly prevalent on main stem rivers with valuable stocks of migratory salmonids. This is a concern because these fish rely on longitudinal connectivity to complete their lifecycles, and modifications for hydropower could jeopardize that connectivity by obstructing or injuring migrating fish. In order to exploit very low head hydropower potential, novel turbine types are emerging. The Archimedean screw hydropower turbine is one such technology which is becoming increasingly popular for low-head applications. However the impact of these turbines on fish movements remains largely untested. This thesis aims to provide much needed evidence on the effects that these turbines and schemes may have on migrating salmonids. Fixed radio and passive integrated transponder receivers were used to track the downstream movements of wild migrating juvenile salmonids through a low-head Archimedean screw hydropower scheme. Atlantic salmon smolts were found to pass through the alternative routes of the turbine and main river channel in proportion to flow through these channels. Passage times were generally fast through both routes (median = 17.6, range = 5.1-905.6 minutes over the 350m scheme extent, for radio tagged fish), and longer passage times were associated with daytime presence in both routes. The majority of PIT tagged Atlantic salmon and sea trout smolts that passed through the 100 m long turbine channel, did so in under 27 minutes (median = 6.8 minutes), whilst a few fish had much longer passage times, associated with daytime presence. There were no differences in onward survival (measured as distance survived downstream) between turbine passed and non-turbine passed migrants. Atlantic salmon smolts were passed through an Archimedean screw turbine to test for harmful effects from the turbine, with comparison to equivalently handled non-turbine passed smolts. There was no evidence of visible damage aside from low to moderate scale loss, which was not significantly associated with turbine passage. Blood chemistry parameters were used to test for subtle turbine-induced damage. This novel application of these techniques did not yield conclusive results, but serves as a useful precedent for future studies. Radio and PIT telemetry equipment were used to investigate the movements of upstream migrating adult salmonids at three separate low-head hydropower schemes which may act as obstacles to migration. These schemes each had distinct configurations and flow management regimes. Movements within, and progression beyond these schemes varied substantially between sites, and in some cases were related to flow management parameters. Whilst not conclusive, the results suggest that scheme configuration and the management of flows influence the time that fish spend at such schemes, and the proportion of fish that ascend beyond them. With the global shift towards renewable energy generation, the exploitation of running water for hydropower is likely to become increasingly pervasive. The results of these studies provide valuable information for the informed and ecologically sustainable development of low-head hydropower schemes.

Longline fishing is the most common elasmobranch capture method in the world, both for commercial fishing, and to a lesser extent for scientific surveys. The capture of an animal on a longline initiates a series of physiological responses designed to promote survivorship in the short term, but if unchecked, can cause reduced individual fitness and/or mortality in the long term. Given widespread declines in shark populations, an improved understanding of the physiological costs of longline capture is needed. The aim of this thesis was to investigate the physiological response of sharks to capture and restraint, to assess novel, non-invasive alternatives to scientific longline surveys, and to generate scientific insight into poorly understood elasmobranch populations in The Bahamas. The results presented herein suggest that some species of shark are able to recover from the physiological stress of capture despite the presence of persistent negative stimuli. Tonic immobility was assessed as a means of generating baseline blood chemistry data, but was found to be inappropriate given that it increases the magnitude of physiological perturbation in the short term. To avoid the stress of capture altogether, Baited Remote Underwater Video Surveys (BRUVS) were considered as a non-invasive alternative to capture based surveys, however, it was concluded that they lack the resolution necessary to answer fine scale demographic questions. For the Caribbean reef shark, longline surveys yielded high resolution data allowing the identification of fine scale spatiotemporal shifts in demographic population structure with minimal cost (mortality). Nevertheless, the ethics of using capture based surveys on sensitive species are questionable when alternative techniques are available. Deep water sharks caught on longline surveys exhibited high mortality rates, however, for these very poorly understood species moribund specimens have great scientific value which in some cases can offset the high ecological costs of the surveys. The results presented in this thesis highlight the on-going need for improved biological and ecological research into the majority of elasmobranch populations, particularly with regards to anthropogenic interactions such as capture. Given the tenuous conservation status of many species, the acquisition of applied, management focused data should remain the priority of elasmobranch scientists.