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Animals have occupied a prominent position in geographical research for some time (Philo and Wilbert 2000, Wolch and Emel, 1998) and the importance of animals in personal narratives of identity, place and space is widely accepted (see for example Matless et al., 2005). However, such research is predominantly focussed on understandings of mammals. This thesis contests this dominance by critically investigating the significance of fish in shaping understandings of animals. The work also connects with the burgeoning geographical interest with water (see for example, Gandy, 2002; Swyngedouw, 2004; Gandy, 2004, Kaika, 2005; and Braun 2005) but through an approach which steps away from understandings of water as just a resource to recognise that it is a resource that connects different issues, scales and approaches and has a materiality that shapes, and influences understandings of people and places. It also contributes to debates surrounding nature/society as it examines the interactions between humans and non-mammalian animals to interrogate issues relating to escape, wildness, nostalgia and connects large scale ‘landscape’ approaches to close-up encounters with the more-than-human world. These connections flow from the connectivity generated through water as it connects ‘diffuse’ issues into particular organisms. This connectivity has been exploited as fish are used as indicator species for public policy. Alongside this use as indicator species, fisheries management is usually science driven. Therefore running through the thesis is a critique of the role of the natural sciences and economics in shaping understandings fish as the political ecology of which fish, in which locations, are made to count. All this was achieved through a methodology that encouraged anglers to address the complexities, inconsistencies and tensions within their angling experience.

Oceanographic features such as currents, fronts and upwelling cells have been recognised as possible factors driving population differentiation within species. The Benguela Current is one of the oldest upwelling systems in the world, located off the west coast of Southern Africa, and represents a biogeographical boundary between the Atlantic and Indo-Pacific Oceans. Previous studies have reported the influence of this system in isolating several marine taxa between the two oceans. However, few have been conducted within the Benguela Current boundaries, in order to understand its role in shaping population genetic structure of fish species at a regional level. The present study documents the influence of the Benguela Current oceanographic features on the genetic differentiation, population connectivity and evolutionary history of five coastal fish species (Diplodus capensis, Argyrosomus inodorus, Argyrosomus coronus, Atractoscion aequidens and Lichia amia), and one oceanic pelagic fish species (Thunnus albacares). Results for both mitochondrial and nuclear marker variation in all coastal species revealed a similar geographical pattern of population genetic structuring despite distinct differences in life history features. The oceanic species exhibited shallow population differentiation between Atlantic and Indian Oceans. For coastal species, different depths of differentiation were observed, ranging from speciation events (A. aequidens, A. coronus and A. japonicus) to shallow structuring (A. inodorus and T. albacares). Furthermore, in these cases, population structures were coincident with the Benguela Current oceanographic features, suggesting that the system may represent a vicariant barrier to dispersal of coastal fish species. Congruence between mitochondrial and nuclear markers suggests that population isolation was not a single historical event, but has persisted over large timescales and is still active. The existence of cryptic speciation events, and the high levels of genetic diversity and differentiation documented make the Benguela Current a natural laboratory to study evolutionary mechanisms shaping biodiversity and genetic population structure of marine fish species.

Climate change and fisheries have affected marine environments worldwide leading to impacts on ecosystem structure and functioning. However there is clear evidence of spatial variability in the response of these impacts both within and among marine ecosystems. Although several studies have tried to explain the effect of these impacts on marine food webs, it is unclear how they interact, and how they may affect marine ecosystems remains an important unanswered question. This suggests the urgent need for multiple-trophic level and ecosystem-based management approaches to account for both fisheries and climate change impacts at ocean basins across the globe. Marine apex predators, such as seabirds, are vulnerable to the effects of both climate and fishing impacts, and can be used as reliable and sensitive bio-indicators of the status of the marine ecosystem. The Celtic Sea ecosystem is a productive shelf region in the Northeast Atlantic. It is characterized by high fish and invertebrate biodiversity. In addition, internationally important numbers of seabirds, such as Northern gannet Morus bassanus (L.), Manx shearwater Puffinus puffinus (B.), Common guillemot Uria aalge (P.) and Black-legged kittiwake Rissa tridactyla (L.), breed along the Celtic Sea coasts. In recent years, fisheries from across Europe have intensively exploited the Celtic Sea, leading to changes in stock structure. Moreover, the increase in annual average Sea Surface Temperature by 0.67 oC over the past two decades has altered the composition of plankton communities. These impacts, independently and in tandem, are likely to have had dramatic effects upon the Celtic Sea food web emphasizing the need to enhance our understanding of this important marine ecosystem. In this thesis the effects of climate change and fisheries on the Celtic Sea pelagic food web are evaluated, in particular focussing on the response of seabird populations. This is in part because of recent declines in the breeding success of many seabird colonies in the northeast Atlantic, particularly around the North Sea. Long-term data across four trophic levels (phytoplankton, zooplankton, mid-trophic level fish and seabirds) and different modelling approaches are used to determine factors influencing seabird productivity at different geographical scales. First, I review the direct and indirect effects of climate change and fisheries upon marine ecosystems, as well as their impacts upon marine birds. Second, I use data collected during 1986-2007 from a single seabird colony, across four trophic levels, to investigate long-term direct and indirect climate effects. The results suggest only a weak climate signal in the Celtic Sea, and this is only evident between mid-trophic level fish and certain species of seabird. Third, a similar multi-trophic level approach across three nearby regions in the southwest UK (Irish Sea, Celtic Sea, and English Channel) reveal no evidence of a bottom-up signal during the period 1991-2007. These findings are in contrast with the nearby North Sea region, where a strong bottom-up effect was found to affect seabird populations, highlighting the importance of regional-based studies across multiple trophic levels. Finally, to provide a more complete picture of the Celtic Sea, and how it might respond to changes in fisheries management and climatic variation, I use the complex tropho-dynamic ecosystem model Ecopath with Ecosim. The main focus is on how seabird biomass changes in response to the application of different fisheries regimes likely to be implemented under forthcoming reforms to the Common Fisheries Policy (e.g. the application of quotas and discard bans), as well as future climate change scenarios, in order to provide guideline support for resource management and seabird conservation in the Celtic Sea. The results suggest that some seabird guilds (gulls and some other scavengers) may be negatively affected by a reduction in discards, while other species (offshore divers) will benefit from a decrease in the fishing of pelagic fish species. Climate change is likely to have a negative impact across all trophic levels with a strong negative impact upon seabird populations. Therefore seabirds are likely to show species-specific responses to both climate variation (bottom-up effect) and changes in fishing practices, in particular our findings suggest that for some species climate may outweigh the fisheries impacts even when fisheries pressure is reduced by 50%. In summary, this study suggests that despite the generally negative impact of climate described for some regions in the Northeast Atlantic, the Celtic Sea ecosystem seems to be more resilient. However, both climate and fisheries and the interactions between these factors should be taken into account in the formulation of future management plans for the Celtic Sea ecosystem. The use of multiple-trophic level and ecosystem-based approaches over multiple spatial and temporal scales has helped to elucidate possible trophic mechanisms that are the response to future fishing and climate impacts in the Celtic Sea. The results of this study could have implications for both management plans and conservation policy.

The maximum number (Nmax) of fish was recorded using baited underwater camera (BUC) techniques to study spatio-temporal changes of the fish community in localize areas. In the central North Sea (~100m depth) abundance models revealed that for both, whiting and flatfish, the Nmax was influenced by light level at the time of deployment. Nmax of hagfish was strongly related to current speed in a non-linear way with a predicted upper threshold (~11 cm.s-1) above which Nmax declined. Current speed and inter-annual variation had an important effect on haddock Nmax. Large predators that prompt avoidance mechanisms (e.g. large conger eel, marine mammals and fishing vessels) and bottom current speed >25 cm.s-1 can modify demersal fish behaviour depending on size and species and therefore have important effects on BUC-derived data. The BUC was applied for the first time to the monitoring of the Buzzard platform, a new oil and gas development in the central North Sea that host 12 demersal and benthic fish species. The benthic taxa, flatfish and hagfish, showed higher numbers closer to the platform whilst the most mobile species showed constant numbers (haddock) or highest numbers outside of the 500m of Exclusion Area (whiting). No significant changes in fish diversity were found between the areas surveyed before the platform construction. After the construction, the species richness and diversity were higher outside the 500m Exclusion Area surrounding the platform. Offshore sand banks, like oil platforms, can modify the composition of the local fish abundance. BUC and commercial trawl observations on the Jones Bank (75-150m depth, Celtic Sea) recorded 23 species, the highest richness, on top of the bank and 18 species on the slope and off-bank areas. Conger eel and Nephrops were both absent from the top of the bank site whereas haddock was only observed in the bank area.

Στην παρούσα εργασία μελετήθηκε η δυνατότητα ανάπτυξης δραστηριοτήτων που σχετίζονται με τον αλιευτικό τουρισμό από τους αλιείς των Κυκλάδων. Στόχος είναι η συγκράτηση των υπαρχόντων αλιέων στο επάγγελμα αλλά και η προσέλκυση νέων, η διατήρηση της αλιευτικής πίεσης σε αποδεκτά επίπεδα και η προστασία των θαλάσσιων οικοσυστημάτων στα πλαίσια μιας ολοκληρωμένης παρέμβασης, η διατήρηση της πολιτιστικής κληρονομιάς και παράδοσης καθώς και η βελτίωση του επιπέδου ζωής των αλιέων. Ο αλιευτικός τουρισμός είναι μια εναλλακτική μορφή τουρισμού η οποία αναπτύσσεται από επαγγελματίες αλιείς, κατά την οποία επιβιβάζουν στα επαγγελματικά αλιευτικά τους σκάφη τουρίστες-επισκέπτες για την ανάπτυξη της παραδοσιακής αλιευτικής δραστηριότητας για ψυχαγωγικούς και εκπαιδευτικούς λόγους. Η δραστηριότητα αυτή πραγματοποιείται ήδη σε αρκετές χώρες με εμφανή θετικά αποτελέσματα στους ευαίσθητους τομείς της αλιείας, της οικολογίας και του τουρισμού. Στα πλαίσια της έρευνας αυτής έγινε καταγραφή του ενδιαφέροντος των επαγγελματιών αλιέων και των ιδιοκτητών σκαφών για τέτοιου είδους δραστηριότητες καθώς και η ανάπτυξη μιας τυπολογίας της υφιστάμενης κατάστασης της μικρής παράκτιας αλιείας στην συγκεκριμένη περιοχή. Τα στοιχεία που χρησιμοποιήθηκαν στην έρευνα συγκεντρώθηκαν από προσωπικές συνεντεύξεις που πραγματοποιήθηκαν με 111 κατόχους επαγγελματικής άδειας αλιείας σε 9 επιλεγμένα νησιά των Κυκλάδων σε συνεργασία με τοπικούς αρμόδιους φορείς. Η έρευνα ολοκληρώθηκε σε δύο ταξίδια, κατά τους μήνες Απρίλιο και Ιούλιο του έτους 2006 αντίστοιχα. Στόχος είναι η διάγνωση των κατηγοριών αλιέων που δείχνουν ενδιαφέρον για την ανάπτυξη της δραστηριότητας καθώς και η καταγραφή των τεχνικών σημείων που φαίνεται να παίζουν σημαντικό ρόλο στην προσπάθεια αυτή. Παράλληλα έγινε εκτίμηση του ενδιαφέροντος από την μεριά των επισκεπτών για δραστηριότητες που σχετίζονται με τον αλιευτικό τουρισμό με την βοήθεια ερωτηματολογίου και ενημερωτικού τρίπτυχου φυλλαδίου που διανεμήθηκε σε διάφορες ξενοδοχειακές μονάδες των Κυκλάδων. Επιπλέον στα πλαίσια της ανάλυσης έγινε σύγκριση με παλαιότερες έρευνες που πραγματοποιήθηκαν στην περιοχή με σκοπό την αναγνώριση της υφιστάμενης κατάστασης της μικρής παράκτιας αλιείας. / -