Dissertations / Theses on the topic 'Effect of fishing on'
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Bridson, Jessica. "The effect of fishing on the evolution of North Sea Cod." Thesis, University of Strathclyde, 2001. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=9352.
Full textNimick, Aileen Margaret. "Modelling Fishing Gear to Address "More than Minimal and Not Temporary" Fishing Effects to Essential Fish Habitat." Thesis, Alaska Pacific University, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10845718.
Full textThe Magnuson-Stevens Fishery Conservation and Management Act (MSA; Magnuson-Stevens Fishery Conservation and Management Act. 2014. (16 U.S.C. 1801–1891(d)) mandates that fisheries management councils in the United States prevent adverse, or “more than minimal and not temporary”, fishing effects to essential fish habitat (EFH) to the extent practicable. Councils were left to decide what effects qualified as “minimal” and “temporary”. The lack of explicit definition in the MSA and its accompanying Final Rule has resulted in inconsistent habitat management throughout the country. The EFH mandate was written under an implicit assumption that councils have the scientific information necessary to effectively manage EFH. Basic information is lacking, such as what type of habitat occurs where, and how fishing effects habitat features. Chapter 1 briefly reviews the history of EFH regulation, the consequences of regulatory ambiguities and information gaps, and highlights that high latitude fisheries management can be disproportionately affected by climate variability. Thus, requiring investment in baseline habitat assessment and monitoring and renewed focus on under developed areas of research e.g. Fishing effects and gear-habitat interactions.
Councils have attempting to quantitatively describe fishing effects to EFH through the use of mathematical models. The most recent of which, the Fishing Effects (FE) Model, was used in the North Pacific Fisheries Management Council 2015 EFH Review cycle. The FE Model uses discrete time steps (monthly) and spatially explicit fishing effort and sediment data to calculate an estimated habitat disturbance. The FE Model is calculated in two-dimensions and implicitly assumes that if fishing gear does not contact the seabed, then there is no gear-habitat interaction. Some features stand taller than raised gear (e.g. sea whips, Halipteris willemoesi, in the North Pacific can up to 2m tall) and may interact with fishing gear. The FE Model in two-dimensions does not account for this potential interaction and cannot effectively simulate gear modifications. Chapter 2 proposes an adapted version of the FE Model that accounts for the vertical interactions through the use of discrete height bins. To accurately estimate interactions on and above the seabed, fishing gear has to be recharacterized. To demonstrate this the Bering Sea flatfish trawl was recharacterized by calculating how much of the nominal gear width is present in each height bin. A detailed methodology is provided to allow this method to be applied to any fishing gear. The adapted FE Model can be used to simulate gear modifications, as is shown by simulating two modifications of the flatfish trawl. This chapter will inform the 2020 EFH Review cycle as the FE Model is improved.
Modig, Karl Johan. "Selective fishing gear : A review on the effects of selective fishing gear on cod in the Baltic Sea." Thesis, Linnéuniversitetet, Institutionen för biologi och miljö (BOM), 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-31302.
Full textRicks, Benjamin Riddick Maceina Michael J. "The effects of tournament fishing on dispersal, population characteristics, and mortaltiy of black bass in Lake Martin, Alabama." Auburn, Ala., 2006. http://repo.lib.auburn.edu/2006%20Spring/master's/RICKS_BENJAMIN_26.pdf.
Full textMiller, Nathan. "The Gulf of Mexico Red Snapper Individual Fishing Quota Program: The Effects on the Fishing Industry and Potential Outlook." Scholar Commons, 2010. http://scholarcommons.usf.edu/etd/3626.
Full textSøvik, Siri Lise. "Characterisation of enzymatic activities in by-products from cod species : effect of species, season and fishing ground." Doctoral thesis, Norwegian University of Science and Technology, Department of Biotechnology, 2005. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-1267.
Full textWestera, Mark B. "The effect of recreational fishing on targeted fishes and trophic structure, in a coral reef marine park." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2003. https://ro.ecu.edu.au/theses/1499.
Full textCosta, André Bento. ""Fishing on Alentejo rocky shores - intensity, yield and protection effects"." Master's thesis, Universidade de Évora, 2012. http://hdl.handle.net/10174/15861.
Full textBracewell, Philip John. "The effects of electric fishing on some freshwater cyprinid fish species." Thesis, University of Hull, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.327287.
Full textLeaf, Robert Thomas. "The Evolutionary Effects of Fishing: Implications for Stock Management and Rebuilding." Diss., Virginia Tech, 2010. http://hdl.handle.net/10919/28636.
Full textPh. D.
Coutin, Patrick C. "The effects of long term exploitation on tropical demersal fish stocks." Thesis, Coventry University, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.329574.
Full textVan, der Hoop Julie M. "Effects and added drag on cetaceans : fishing gear entanglement and external tag." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/108892.
Full textCataloged from PDF version of thesis.
Includes bibliographical references (pages 283-314).
Animal movement is motivated in part by energetic constraints, where fitness is maximized by minimizing energy consumption. The energetic cost of movement depends on the resistive forces acting on an animal; changes in this force balance can occur naturally or unnaturally. Fishing gear that entangles large whales adds drag, often altering energy balance to the point of terminal emaciation. An analog to this is drag from tags attached to cetaceans for research and monitoring. This thesis quantifies the effects of drag loading from these two scenarios on fine-scale movements, behaviors and energy consumption. I measured drag forces on fishing gear that entangled endangered North Atlantic right whales and combined these measurements with theoretical estimates of drag on whales' bodies. Entanglement in fishing gear increased drag forces by up to 3 fold. Bio-logging tags deployed on two entangled right whales recorded changes in the diving and fine-scale movement patterns of these whales in response to relative changes in drag and buoyancy from fishing gear and through disentanglement: some swimming patterns were consistently modulated in response. Disentanglement significantly altered dive behavior, and can affect thrust production. Changes in the force balance and swimming behaviors have implications for the survival of chronically entangled whales. I developed two bioenergetics approaches to estimate that chronic, lethal entanglements cost approximately the same amount as the cost of pregnancy and supporting a calf to near-weaning. I then developed a method to estimate drag, energy burden and survival of an entangled whale at detection. This application is essential for disentanglement response and protected species management. Experiments with tagged bottlenose dolphins suggest similar responses to added drag: I determined that instrumented animals slow down to avoid additional energetic costs associated with drag from small bio-logging tags, and incrementally decrease swim speed as drag increases. Metabolic impacts are measurable when speed is constrained. I measured the drag forces on these tags and developed guidelines depending on the relative size of instruments to study-species. Together, these studies quantify the magnitude of added drag in complementary systems, and demonstrate how animals alter their movement to navigate changes in their energy landscape associated with increased drag.
by Julie M. van der Hoop.
Ph. D.
Stanovick, John Stuart. "Sampling characteristics of the bus route survey technique in the James River, Virginia." Diss., Virginia Tech, 1993. http://hdl.handle.net/10919/38651.
Full textPilling, Graham Michael. "The effects of fishing on the growth and assessment of snappers and emperors." Thesis, Imperial College London, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.314276.
Full textMaluleke, Vutlhari Absalom. "The effects of boat mooring systems on squid egg beds during squid fishing." Thesis, Cape Peninsula University of Technology, 2017. http://hdl.handle.net/20.500.11838/2528.
Full textIn South Africa, squid fishing vessels need to find and then anchor above benthic squid egg beds to effect viable catches. However, waves acting on the vessel produce a dynamic response on the anchor line. These oscillatory motions produce impact forces of the chain striking the seabed. It is hypothesised that this causes damage to the squid egg bed beneath the vessels. Different mooring systems may cause more or less damage and this is what is investigated in this research. The effect of vessel mooring lines impact on the seabed during squid fishing is investigated using a specialised hydrodynamic tool commercial package ANSYS AQWA models. This study analysed the single-point versus the two-point mooring system’s impact on the seabed. The ANSYS AQWA models were developed for both mooring systems under the influence of the wave and current loads using the 14 and 22 m vessels anchored with various chain sizes. The effect of various wave conditions was investigated as well as the analysis of three mooring line configurations. The mooring chain contact pressure on the seabed is investigated beyond what is output from ANSYS AQWA using ABAQUS finite element analysis. The real-world velocity of the mooring chain underwater was obtained using video analysis. The ABAQUS model was built by varying chain sizes at different impact velocities. The impact pressure and force due to this velocity was related to mooring line impact velocity on the seabed in ANSYS AQWA. Results show the maximum impact pressure of 191 MPa when the 20 mm diameter chain impacts the seabed at the velocity of 8 m/s from video analysis. It was found that the mooring chain impact pressure on the seabed increased with an increase in the velocity of impact and chain size. The ANSYS AQWA impact pressure on the seabed was found to be 170.86 MPa at the impact velocity of 6.4 m/s. The two-point mooring system was found to double the seabed mooring chain contact length compared to the single-point mooring system. Both mooring systems showed that the 14 m vessel mooring line causes the least seabed footprint compared to the 22 m vessel.
Tonello, Junior Antonio José <1976>. "Effects pinger use on dolphins' behavior and fish capture in artisanal fishing activities." Doctoral thesis, Università Ca' Foscari Venezia, 2008. http://hdl.handle.net/10579/778.
Full textMorrell, Thomas J. "Analysis of "Observer Effect" in Logbook Reporting Accuracy for U.S. Pelagic Longline Fishing Vessels in the Atlantic and Gulf of Mexico." Thesis, NSUWorks, 2019. https://nsuworks.nova.edu/occ_stuetd/511.
Full textFitwi, Biniam Samuel. "Determination of salinity tolerance limits of tilapia, Oreochromis mossambicus, for use in tuna line fishery." Thesis, Stellenbosch : Stellenbosch University, 2003. http://hdl.handle.net/10019.1/53355.
Full textENGLISH ABSTRACT: Many species of tilapia such as Oreochromis mossambicus are euryhaline, able to adapt to different salinity waters. Their ability to withstand high salinity levels has given rise to the possibility of using tilapia as baitfish for tuna line fishery. The purpose of the study was to determine the survival rate of tilapia O. mossambicus during direct transfer from freshwater to the salinity levels of 0, 15, 20, 22.5, 25, 27.5, 30, 32.5, and 35 ppt. The data was analysed through means of univariate ANOVAand regression analysis. O. mossambicus showed no mortality to all salinity regimes up to 25 ppt. Mortality was observed at 27.5 ppt, with 100% mortality at 35 ppt. LC 50 and LC 90 were found to be 30.5 and 34.2 ppt, respectively. The results indicate that tilapia (0. mossambicus) will survive a direct transfer to salinities up to 25 ppt. acclimation will be required in the event of transfer to salinity levels above 25 ppt, in order to prevent significant levels of mortalities.
AFRIKAANSE OPSOMMING: Meeste van die tilapia spesies soos Oreochremis mossambicus het die vermoë om by water van verskillende soutgehaltes aantepas. Dit is hierdie vermoë om hoë sout vlakke te weerstaan wat die moontlikheid vir gebruik as lewende aas in die tuna langlyn visvangbedryf moontlik maak. Die doel van hierdie studie was om die oorlewingsvlak van tilapia, O. mossambicus te bepaal by die oorplasing van varswater direk na soutwater by vlakke van 0, 15, 20, 22.5, 25, 27.5, 30, 32.5, en 35 dele per duisend. Die data is verwerk deur gebruik te maak van eenvariant ANOVAen regressie analises. O. mossambicus het geen mortaliteite tot gevolg gehad by al die oorplasings van vlakke tot en met 25 dele per duisend sout nie. Mortaliteite is wel gevind vanaf 27.5 dele per duisend, met 100 % mortaliteite by 35 dele per duisend. LC 50 en LC90 was gewees 30.5 en 34.2 dele per duisend onderskeidelik. Die resultate toon aan dat tilapia (0. mossambicus) sal oorleef by direkte oorplasing na soutwater by vlakke van tot en met 25 dele per duisend. Tilapia wat na hoër vlakke as 25 dele per duisend oorgeplaas wil word, sal eers geleidelik moet akklimatiseer om mortaliteite te beperk.
O'Leary, Jennifer K. "Effects of fishing and trophic interactions on tropical reef builders : coralline, algae, and corals /." Diss., Digital Dissertations Database. Restricted to UC campuses, 2009. http://uclibs.org/PID/11984.
Full textHlavacs, Lauri A. "Mapping the Effects of Blast and Chemical Fishing in the Sabalana Archipelago, South Sulawesi, Indonesia, 1991-2006." Ohio University / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1219347860.
Full textFernandez, John. "Analysis of increases in fishing power in the western rock lobster (Panulirus cygnus) fishery." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 1999. https://ro.ecu.edu.au/theses/1227.
Full textWilliamson, Craig W. "Tournament-associated mortality and the effects of culling in Wisconsin black bass (Micropterus spp.) tournaments /." Link to full text, 2007. http://epapers.uwsp.edu/thesis/2007/williamson.pdf.
Full textSubmitted in partial fulfillment of the requirements of the degree Master of Science in Natural Resources, College of Natural Resources. Includes bibliographical references (leaves 75-81).
Bellinger, Nathan H. 1982. "Globalization and neoliberalism in Ecuador: The expansion and effects of the commercial tuna fishing industry." Thesis, University of Oregon, 2011. http://hdl.handle.net/1794/11268.
Full textBetween the 1980s and early 2000s, Ecuador's commercial tuna fishing industry evolved from an insignificant player in the global marketplace to the third largest tuna fishery in the world. The reasons behind this dramatic expansion are integrally linked to economic globalization and more specifically, the proliferation of neoliberal economic policies throughout Latin America and Ecuador. In this thesis, I link neoliberal reforms, such as increased capital mobility, free trade agreements, and export-led development, to the rapid growth of Ecuador's tuna fishery, centrally located in Manta. I then explore the place-based effects of these reforms by elucidating the social and environmental impacts of the tuna industry. I argue that while there have been some benefits, such as economic growth and job creation, expansion of Manta's tuna fishery has exacerbated local inequalities, created serious environmental problems, and led to new workplace challenges for employees in the industry.
Committee in charge: Dr. Derrick Hindery, Chairperson; Dr. Lise Nelson, Member
Viegas, Vera Lúcia Coelho. "Pesca comercial na costa alentejana: rendimento, esforço de pesca, rejeições e efeitos da proteção." Master's thesis, Universidade de Évora, 2013. http://hdl.handle.net/10174/13081.
Full textSamaranayaka, Ari, and n/a. "Environmental stochasticity and density dependence in animal population models." University of Otago. Department of Mathematics & Statistics, 2006. http://adt.otago.ac.nz./public/adt-NZDU20060907.114616.
Full textHsieh, Chih-hao. "Separating environmental effects from fishing impacts on the dynamics of fish populations of the Southern California region." Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2006. http://wwwlib.umi.com/cr/ucsd/fullcit?p3210008.
Full textTitle from first page of PDF file (viewed June 5, 2006). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references.
Armstrong, Bryan. "Oceanographic Effects on the Behavior of Shallow-Set Pelagic Longline Fishing Gear in the Western North Atlantic." NSUWorks, 2009. http://nsuworks.nova.edu/occ_stuetd/246.
Full textGhebrehiwet, Dawit Yemane. "Assessing the effects of fishing on fish communities using South African case studies : empirical and theoretical approaches." Doctoral thesis, University of Cape Town, 2007. http://hdl.handle.net/11427/8919.
Full textCurrently heavy fishing is recognized as one of the major threats to the structural and functional organization of marine ecosystems in many coastal nations. The threat is mainly the result of the inherent nature of the various fishing activities: size selectivity, habitat destruction, biomass removal, and uncertainty in resource status and management of the resource. Thus this thesis investigates structural changes that result from fishing. This thesis aims to answer whether there were changes in the structure of fish communities off the of South Africa using two case studies, to explore the response of fish communities to the proposed creation of Marine Protected Areas and to investigate the alternate application of spatially uniform and heterogeneous fishing mortalities. The research questions of the thesis are answered through empirical analysis of landing data for the line fishery and analysis of demersal trawl survey data from the south coast of South Africa, and analysis of output of the Individual Based Model OSMOSE applied to the southern Benguela. Structural changes in the landings from the line fishery and south coast survey data are assessed using a variety of ecosystem indicators believed to capture such changes: size-based indicators {mean size, slope and height of the size spectra, mean Lmax7, proportion of size classes), species-based indicators (ordination by multidimensional scaling, and dendrograms, various diversity indices, dominance curves). Inferences are based on the reference directions of the indicators, according to the expected response of indicators to heavy fishing. Structural changes in the fish communities are observed, over the spatial and temporal bounds of the two case studies, to be the most likely cause of the observed changes is heavy fishing, although the influence of environmental factors cannot he ruled out. investigation of alternative implementation fishing mortality using the simulation model OSMOSE showed that the system and species biomass do differ between the two implementations, but the variability in the system remains the same. The modelled response of fish communities to the introduction of Marine Protected Areas is an overall increase in relative biomass of large predatory fishes and a decline in the biomass of prey and competitor species.
Brown, Rachel L. "Untangling the effects of fishing effort and environmental variables on benthic communities of commercially fished scallop grounds." Thesis, University of York, 2013. http://etheses.whiterose.ac.uk/4657/.
Full textTULONE, Antonio. "ITALIAN COASTAL COMMUNITIES’ WILLINGNESS TO PAY FOR THE MITIGATION OF CLIMATE CHANGE EFFECTS ON THE FISHING INDUSTRY." Doctoral thesis, Università degli Studi di Palermo, 2020. http://hdl.handle.net/10447/395414.
Full textTelfer, Carli. "The Western Australian charter boat industry: Working towards long-term sustainability." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2010. https://ro.ecu.edu.au/theses/154.
Full textMaufroy, Alexandra. "Drifting Fish Aggregating Devices of the Atlantic and Indian Oceans : modalities of use, fishing efficiency and potential management." Thesis, Montpellier, 2016. http://www.theses.fr/2016MONTT150/document.
Full textSince the mid 1990s, the use of drifting Fish Aggregating Devices (dFADs) by purse seiners, artificial objects specifically designed to aggregate fish, has become an important mean of catching tropical tunas. In recent years, the massive deployments of dFADs, as well as the massive use of tracking devices on dFADs and natural floating objects, such as GPS buoys, have raised serious concerns for tropical tuna stocks, bycatch species and pelagic ecosystem functioning. Despite these concerns, relatively little is known about the modalities of GPS buoy tracked objects use, making it difficult to assess and manage of the impacts of this fishing practice. To fill these knowledge gaps, we have analyzed GPS buoy tracks provided by the three French fishing companies operating in the Atlantic and the Indian Oceans, representing a large proportion of the floating objects monitored by the French fleet. These data were combined with multiple sources of information: logbook data, Vessel Monitoring System (VMS) tracks of French purse seiners, information on support vessels and Local Ecological Knowledge (LEK) of purse seine skippers to describe GPS buoy deployment strategies, estimate the total number of GPS buoy equipped dFADs used in the Atlantic and Indian Oceans, measure the contribution of strategies with FOBs and support vessels to the fishing efficiency of tropical tuna purse seiners, identify potential damages caused by lost dFADs and finally to propose management options for tropical tuna purse seine FOB fisheries. Results indicate clear seasonal patterns of GPS buoy deployment in the two oceans, a rapid expansion in the use of dFADs over the last 7 years with an increase of 4.2 times in the Indian Ocean and 7.0 times in the Atlantic Ocean, possible damages to fragile coastal ecosystems with 10% of GPS buoy tracks ending with a beaching event and an increased efficiency of tropical tuna purse seine fleets from 3.9% to 18.8% in the Atlantic Ocean over 2003-2014 and from 10.7% to 26.3% in the Indian Ocean. Interviews with purse seine skippers underlined the need for a more efficient management of the fishery, including the implementation of catch quotas, a limitation of the capacity of purse seine fleets and a regulation of the use of support vessels. These results represent a first step towards better assessment and management of purse seine FOB fisheries
Nenadovic, Mateja. "The Effects of Bottom-Tending Mobile Fishing Gear and Fiber-Optic Cable Burial on Soft-Sediment Benthic Community Structure." Fogler Library, University of Maine, 2009. http://www.library.umaine.edu/theses/pdf/NenadovicM2009a.pdf.
Full textSchroeder, Robert E. "The ecology of patch reef fishes in a subtropical Pacific atoll: recruitment variability, community structure and effects of fishing predators." Thesis, University of Hawaii at Manoa, 1989. http://hdl.handle.net/10125/18158.
Full textxvi, 321 leaves, bound : ill. ; 29 cm.
Castro, Kreder Natasja. "In vitro studies on radiation effects and radiosensitization: HDR vs LDR and cytotoxic agents FISHing for, breaking and rejoining radiosensitivity /." [S.l. : Amsterdam : s.n.] ; Universiteit van Amsterdam [Host], 2004. http://dare.uva.nl/document/88010.
Full textHarding, Craig Thomas. "Tracking African penguins (Spheniscus demersus) outside of the breeding season: Regional effects and fishing pressure during the pre-moult period." Master's thesis, University of Cape Town, 2014. http://hdl.handle.net/11427/6565.
Full textNogueira, Barbara Galindo. "Aplicação do conhecimento de pescadores artesanais para entender a captura incidental de tartarugas marinhas no sul do Brasil." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2016. http://hdl.handle.net/10183/142044.
Full textWithin the context of global fishing crisis that affects both industrial and artisanal fisheries, this survey aims to describe and analyze the artisanal gillnet fishery in southern Brazil and study the interaction between this fishing and sea turtles. The chapter 1 consists in social, economic and operational characterization of artisanal fisheries, assessing the fishing effort of different kinds of fisheries. The analysis of data provided by fishermen revealed the differentiation in catch and effort between two vessel’s groups: boats up to 12.5 meters long and boats over 12.5 meters. The interviews also show the spatial overlap of areas of operation of fishers. In this chapter we proposed measures for the management of small-scale gillnet fishing that consider the income of fishermen and preserve fish stocks. In chapter 2 we analyzed social and operational fishing factors related to bycatch of sea turtles. Interviews (n=92) and landings (n=320) recorded in fishing grounds inside and outside of Marine Protected Areas in Rio Grande do Sul and Santa Catarina assessed the influence of the spatial management on bycatch. It analyzed also the local ecological knowledge (LEK) of fishers about sea turtles. The creation of exclusive zones for artisanal fishing and to increase inspections of fishing nets are presented to reduce incidental catches by artisanal gillnet fishing in southern Brazil, such as the involvement of fishermen in research and co-management of resources.
Warlimont, Petra. "Application of the Tracking and Analysis Framework (TAF) to Assess the Effects of Acidic Deposition on Recreational Fishing in Maine Lakes." Fogler Library, University of Maine, 2002. http://www.library.umaine.edu/theses/pdf/WarlimontP2002.pdf.
Full textChi, Danielle K. "The Effects of Salmon Availability, Social Dynamics, and People on Black Bear (Ursus Americanus) Fishing Behavior on an Alaskan Salmon Stream." DigitalCommons@USU, 1999. https://digitalcommons.usu.edu/etd/4242.
Full textSmedley, Marie A. "Nutritional and environmental effects on triploid Atlantic salmon skeletal deformity, growth and smoltification." Thesis, University of Stirling, 2016. http://hdl.handle.net/1893/23342.
Full textMorrison, Jean. "Bajau gender : a study of the effects of socio-economic change on gender relations in a fishing community of Sabah, East Malaysia." Thesis, University of Hull, 1993. http://hydra.hull.ac.uk/resources/hull:3711.
Full textMarzuki, Marza Ihsan. "VMS data analyses and modeling for the monitoring and surveillance of Indonesian fisheries." Thesis, Ecole nationale supérieure Mines-Télécom Atlantique Bretagne Pays de la Loire, 2017. http://www.theses.fr/2017IMTA0012/document.
Full textMonitoring, control and surveillance (MCS) of marine fisheries are critical issues for the sustainable management of marine fisheries. In this thesis we investigate the space-based monitoring of fishing vessel activities using Vessel Monitoring System (VMS) trajectory data in the context of INDESO project (2013-2017). Our general objective is to develop a processing chain of VMS data in order to: i) perform a follow-up of the fishing effort of the Indonesian longline fleets, ii) detect illegal fishing activities and assess their importance. The proposed approach relies on classical latent class models, namely Gaussian Mixture Models (GMM) and Hidden Markov Models (HMM), with a view to identifying elementary fishing vessel behaviors, such as travelling, searching and fishing activities, in a unsupervised framework. Following state-of-the-art approaches, we consider different parameterizations of these models with a specific focus on Indonesian longliners, for which we can benefit from at-sea observers¿ data to proceed to a quantitative evaluation. We then exploit these statistical models for two different objectives: a) the discrimination of different fishing fleets from fishing vessel trajectories and the application to the detection and assessment of illegal fishing activities, b) the assessment of a spatialized fishing effort from VMS data. We report good recognition rate (about 97%) for the former task and our experiments support the potential for an operational exploration of the proposed approach. Due to limited at-sea observers¿ data, only preliminary analyses could be carried out for the proposed VMS-derived fishing effort. Beyond potential methodological developments, this thesis emphasizes the importance of high-quality and representative at-sea observer data for further developing the exploitation of VMS data both for research and operational issues
Bealey, Roy Steven John. "Short-term changes to the life history of shad, Pomatomus saltatrix (Perciformes: Pomatomidae), in Southern Angola." Thesis, Rhodes University, 2015. http://hdl.handle.net/10962/d1017211.
Full textStäbler, Moritz [Verfasser], and Axel [Akademischer Betreuer] Temming. "Effects of and on the food-web when fishing for maximum sustainable yields in the southern North Sea / Moritz Stäbler ; Betreuer: Axel Temming." Hamburg : Staats- und Universitätsbibliothek Hamburg, 2017. http://d-nb.info/114386865X/34.
Full textSantos, Paulo Roberto Santos dos. "A pesca artesanal da Miragaia (Pogonias cromis, Scieanidae) e consequências da sobreexplotação, no estuário da Lagoa dos Patos." reponame:Repositório Institucional da FURG, 2015. http://repositorio.furg.br/handle/1/6060.
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O aumento na abundância de peixes não residentes da zona estuarina, atraem o interesse da frota pesqueira, que atua sobre os estoques de forma intensa, muitas vezes levando a sobreexplotação. No estuário da Lagoa dos Patos, a Miragaia (Pogonias cromis), é um peixe estuarino dependente que por muitos anos foi um importante recurso pesqueiro, e hoje encontra-se sobreexplotado e ameaçado de extinção. As capturas que atingiram 1400 t em 1976, decaíram posteriormente e foram inexistentes nos anos de 2004, 2005, 2008, 2009 e 2010. Mas recentemente, se observa o aumento dos desembarques na região. A partir disso, a presente dissertação tem por objetivo descrever a pesca artesanal da Miragaia no estuário da Lagoa dos Patos e analisar o efeito da sobreexplotação no ciclo reprodutivo da população remanescente na região. No primeiro capítulo intitulado "A pesca artesanal da Miragaia (Pogonias cromis, Scieanidae) no estuário da Lagoa dos Patos", é discutida a hipótese de que os maiores valores de esforço e CPUE são encontrados no mesmo período de maior abundância da espécie no estuário, e verifica-se a influência do esforço de pesca nas variações da CPUE. De forma complementar, se confirma a distinta composição dos desembarques entre o período de desova e o resto do ano, a predominância de adultos no período de desova evidencia o aumento da abundância. No segundo capítulo intitulado "O efeito da sobreexplotação no ciclo reprodutivo da Miragaia (Pogonias cromis, Scieanidae)" é discutido a redução da idade e tamanho de primeira maturação sexual e consequentemente fecundidade dos exemplares, como consequência da sobrepesca sofrida pela espécie em anos anteriores. Os resultados encontrados mostram a situação preocupante da população de Miragaias no estuário da Lagoa dos Patos, onde a manutenção da intensidade pesqueira pode levar ao colapso da atividade e posterior extinção local da espécie.
The increase in the abundance of non-resident fish estuarine zone attract the interest of the fishing fleet, which operates on the intensely stocks, often leading to overexploitation. In the estuary of Patos Lagoon, the Black drum (Pogonias cromis) is an estuarine-dependent fish who for many years was an important fishing resource, and today is overexploited and threatened with extinction. Catches reached 1400 t in 1976, declined later and were negligible in the years 2004, 2005, 2008, 2009 and 2010. But recently observed increased landings in the region. Thus, this thesis aims to describe artisanal fishing of Black drum in the estuary of Patos Lagoon and analyze the effect of v overexploitation in the reproductive cycle of the remaining population in the region. In the first chapter entitled "The artisanal fishery Black drum (Pogonias cromis, Scieanidae) in the estuary of Patos Lagoon," discusses the hypothesis that higher values of effort and CPUE are found in the same period of greatest abundance of the species in the estuary, and there is the influence of fishing effort in changes in CPUE in a complementary way confirms the different composition of landings spawning periods for the rest of the year, the prevalence of adults in spawning highlights the increasing abundance. In the second chapter entitled "The effect of overexploitation in the reproductive cycle of Black drum (Pogonias cromis, Scieanidae)" is discussed reducing the age and size at first sexual maturity and consequently fertility of copies as a result of overfishing suffered by the species in previous years. The results show the worrying situation of the population of Black drum in the estuary of Patos Lagoon, where the maintenance of fishing intensity can lead to the collapse of activity and subsequent local extinction of the species.
Winn, Jeremy Paul. "Modeling Large Whale Entanglement Injuries: An Experimental Analysis of the Influence of Tissue Compliance, Line Tension, and Draw-Length on Epidermal Abrasion Resistance." Fogler Library, University of Maine, 2006. http://www.library.umaine.edu/theses/pdf/WinnJP2006.pdf.
Full textTorres, Edgar. "Effects of the fishing strategies developed by purse seine fleets on tropical tunas and on associated fauna in the eastern Atlantic and eastern Pacific oceans." Thesis, Montpellier 2, 2012. http://www.theses.fr/2012MON20029/document.
Full textTuna and tuna-like fisheries represent 7.9% of the global production of marine capture fisheries. Most tuna stocks are fully exploited and some overexploited, facing growing fishing pressures. Due to the extent of fishing grounds, stock assessments depend largely in commercial data, which vary over time because fishermen may invest in fishing technology, expand offshore, or start fishing in different areas. However, little attention has received the responses of fishermen facing management regulations or the effects resulting from technological investment. For these reasons the aim of this study was to investigate the effects of fishing strategies developed by purse seine fleets on tropical tunas and on associated fauna in the eastern Atlantic and eastern Pacific oceans. The continuous introduction of new fishing technology in the French fleet in the 1980s and the 1990s evidenced a direct increase in fishing power when large yellowfin in free-swimming school is targeted and likely an indirect effect by modifying the fishing grounds characterizing FAD-fishing on small size categories. The consequences of the two time-area closures on the spatio-temporal dynamics of the European Union fleet were investigated. The regulation on FADs resulted in a decrease in the days with catch and successful squares inside the restricted area, reallocating FAD-fishing outside the area while no change in free-swimming school fishing was observed. The no-take time-area increased all fishing activities outside the restricted area with apparently no gain in terms of protection of juveniles. In the eastern Pacific as a response to a closed season the Mexican fleet reduced days in port and consequently the number of sets on dolphin-associated schools increased, maintaining the catch levels observed before the regulation. The study of the effects of the EU fleet fishing strategies on bycatch over two time periods showed that the species composition of sharks caught on FADs and may be for rays caught on free-swimming schools changed over time. We also estimated the total number of species that can be potentially be caught by fishing mode
Simpson, Anne W. "An Investigation of the Cumulative Impacts of Shrimp Trawling on Mud Bottom Fishing Grounds in the Gulf of Maine: Effects on Habitat and Macrofaunal Community Structure." Fogler Library, University of Maine, 2003. http://www.library.umaine.edu/theses/pdf/SimpsonAW2003.pdf.
Full textAlarcón, Sergio Eduardo Neira. "Assessing the effects of internal (trophic structure) and external (fishing and environment) forcing factors on fisheries off central Chile : basis for an ecosystem approach to management." Doctoral thesis, University of Cape Town, 2008. http://hdl.handle.net/11427/6217.
Full textIncludes bibliographical references (p. 227-253).
Human perception of sea fisheries has evolved from an inexhaustible resource paradigm towards a generalized concern on the degraded state of fish stocks and ecosystems. Accordingly, fisheries science and management are expanding from the traditional single-species approach towards an ecosystem approach to fisheries. Marine communities are organized as webs of interactions that are affected by external natural (climate) and anthropogenic (fishing) forcing, with their relative effects poorly known, but hypothesised to strongly depend on internal food web structure (i.e., who eats and controls whom). This thesis approaches relevant ecological considerations for an ecosystem approach to fisheries in the upwelling ecosystem off central Chile (33ºS-39ºS). The main objective is to assess the effects of internal (trophic structure) and external (fishing and environment) forcing factors at the fish stock and food web level in the study area. The methodology includes i) the construction of snapshot and dynamic food web models to test hypothesis of changes in the food web in the last century, and the relative contribution of fishing, trophic controls and bottom-up environmental variability to those changes, ii) the computation and analysis of a set of ecosystem indicators to test hypotheses of changes in different aspects of the exploited community (mean trophic level, age and length at maturity, network properties and system variability), iii) the analyses of the relationships between time series of abundance of species with known trophic interactions (Chilean hake-red squat lobster and Chilean hake-small pelagic fish) to test hypothesis of top-down and bottom-up control versus alternative hypotheses of fishing and/or environmental control in the same populations, and iv) simulation experiments to test hypotheses of ecosystem change and recovery under fishing and environmental forcing. Models and indicators are constructed using data series of abundance, catches, production, consumption and diets of the main functional groups in the study area. Snapshot and dynamic food web models are constructed and analyzed using the Ecopath with Ecosim software version 5.1 and routines therein. The observed trends in indicators and model results are in accordance with what is theoretically expected in stressed ecosystems (shift towards a food web dominated by short-lived, low trophic level and high turnover rate species), and suggest that the food web could be in a state that is more susceptible to external forcing. Fishing and the environment (bottom-up anomaly in PP) may have affected the upwelling ecosystem off central Chile both at the stock and at the food web level between 1970 and 2004. The effects of these forcing factors may have been mediated by trophic controls operating in the food web. There is also evidence to support the hypothesis that trophic controls beyond fishing, e.g., trophic (internal) and environment (external) may operate in the analysed populations and this information should be considered in their assessment and management. While target objectives are set and agreed, it is proposed that the main objective for the ecosystem approach to fisheries should be to avoid fishing-induced regime shifts, since results from simulation experiments suggest that fishing can induce ecosystem changes of lower recovery than bottom-up forcing.
Andrade, Joana Isabel da Silva. "Effects of cyanide exposure on marine fish with emphasis to Amphiprion spp." Master's thesis, Universidade de Aveiro, 2015. http://hdl.handle.net/10773/14774.
Full textTropical coral reefs have a high importance on marine ecosystems due to their high productivity and biodiversity. However, these ecosystems are facing a growing number of both natural and anthropogenic threats. Cyanide fishing is a destructive technique to capture live reef fish, both for human consumption and to supply the marine aquarium industry. Clownfish and damsels ( Family Pomacentridae) are the most heavily traded group of marine aquarium fish and consequently also some of the most commonly targeted fishes by this illegal fishery. Cyanide (CN-) is considered to be a potent inhibitor of enzymatic pathways involved in respiration and other physiological functions in fish and when used in acute doses can accumulate in body tissues and fluids, negatively affecting several enzymes. In the present study, we analyzed the effects of different concentrations of CN- pulse exposures (mimicking cyanide fishing) in survival and biomarker activity in two different sizes of Amphiprion ocellaris and calculated their respective LC50. Subsequently, the same species was exposed to a sublethal concentration of CN- (25 mg L-1) under global warming scenarios predicted for 2100 (29 °C and 32 °C). Eight different species of pomacentrids were also pulse exposed to a concentration of 50 mg L-1 of CN- to investigate interspecific variability in their tolerance to CN- poisoning. Our data revealed that LC50 of small fish is nearly half of that estimated for medium sized fish (28.45 mg L-1 and 50 mg L-1 of CN-, respectively). It was also possible to demonstrate that the increase of seawater temperature, by itself, can cause mortality in clownfish, and that mortality promoted by CN- fishing will be magnified at higher temperatures. Finally, it is confirmed that vulnerability to CN- poisoning may vary interspecifically, even in species which are closely related phylogenetically. The clownfish A. ocellaris displayed the highest tolerance to CN- poisoning among all tested pomacentrids. Overall, it is mandatory to effectively ban CN- fishing from tropical coral reefs, as the damage this practice already causes in the oceans of today will be largely magnified in the oceans of tomorrow.
Os recifes de coral tropicais têm uma grande importância nos ecossistemas marinhos, devido à sua produtividade e biodiversidade. No entanto, estes ecossistemas estão a enfrentar um crescente número de ameaças naturais e antropogénicas. A pesca com cianeto é uma técnica destrutiva para capturar peixes vivos de recife, tanto para o consumo humano como para abastecer a indústria de aquários marinhos. O peixe-palhaço e as donzelas (Família Pomacentridae) são o grupo de peixes mais comercializados em aquariofilia e, consequentemente, são dos peixes mais capturados com esta pesca ilegal. O cianeto (CN-) é considerado um potente inibidor das vias enzimáticas envolvidas na respiração e outras funções fisiológicas no peixe, que quando utilizado em doses agudas pode acumular-se em tecidos e fluidos corporais, afetando negativamente várias enzimas. No presente estudo, foram analisados os efeitos das diferentes concentrações de CN- (imitando a pesca com cianeto) na sobrevivência e atividade dos biomarcadores em dois tamanhos diferentes de Amphiprion ocellaris e calculado o respetivo LC50. Posteriormente, a mesma espécie foi exposta a uma concentração sub-letal de CN- (25 mg L-1) sob o cenário de aquecimento global previsto para 2100 (29 °C e 32 °C). Oito espécies diferentes de pomacentrídeos foram expostos a uma concentração de 50 mg L-1 de CN- para investigar a variabilidade interespecífica na sua tolerância ao envenenamento por cianeto. Os nossos dados revelaram que o LC50 de peixes pequenos é quase a metade do que o estimado para os peixes de tamanho médio (28,45 mg L-1 e 50 mg L-1 de CN-, respetivamente). Também foi possível demonstrar que o aumento da temperatura da água do mar, por si só, pode causar mortalidade no peixepalhaço, e que a mortalidade promovida pela pesca com cianeto será aumentada a temperaturas mais elevadas. Finalmente, confirma-se que a vulnerabilidade ao envenenamento por cianeto pode variar interespecificamente, mesmo em espécies que estão estreitamente relacionadas filogeneticamente. O peixe-palhaço A. ocellaris apresentou a maior tolerância ao envenenamento por cianeto relativamente a todos os pomacentrídeos testados. Por isso, é obrigatório proibir eficazmente a pesca com cianeto nos recifes de coral tropicais, pois o dano que esta prática faz nos oceanos de hoje será largamente ampliado nos oceanos de amanhã.