Дисертації з теми "Demersal specie"
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O'Sullivan, Martha. "Population structure of demersal fish species in the north eastern Atlantic." Thesis, Available from the University of Aberdeen Library and Historic Collections Digital Resources. Restricted: no access until Dec. 31, 2010. Online version available for University members only until June 2, 2011, 2009. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?application=DIGITOOL-3&owner=resourcediscovery&custom_att_2=simple_viewer&pid=26063.
Повний текст джерелаKuta, Kevin G. "The Effect of Demersal Reef Fish on Two Species of Gorgonian Coral." NSUWorks, 1992. http://nsuworks.nova.edu/occ_stuetd/356.
Повний текст джерелаIsidro, Eduardo Jose Louca Florencio. "Biology and population dynamics of selected demersal fish species of the Azores Archipelago." Thesis, University of Liverpool, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.307638.
Повний текст джерелаMoore, Cordelia Holly. "Defining and predicting species-environment relationships : understanding the spatial ecology of demersal fish communities." University of Western Australia. Faculty of Natural and Agricultural Sciences, 2009. http://theses.library.uwa.edu.au/adt-WU2010.0002.
Повний текст джерелаSampson, Mark Robert. "Modelling the distribution and abundance of several demersal fish species on the Agulhas Bank, South Africa." Thesis, Rhodes University, 2002. http://hdl.handle.net/10962/d1006207.
Повний текст джерелаChatfield, Brenton Sean. "How to find the one that got away : predicting the distribution of temperate demersal fish from environmental variables." University of Western Australia. School of Earth and Geographical Sciences, 2008. http://theses.library.uwa.edu.au/adt-WU2009.0009.
Повний текст джерелаGuerra, Alessandro. "Estimates of length-at-50% maturity of two South African demersal species: Monkfish, Lophius vomerinus, and Kingklip, Genypterus capensis." Master's thesis, Faculty of Science, 2019. http://hdl.handle.net/11427/31570.
Повний текст джерелаLelli, Stefano. "Contribution to a better knowledge of biology, distribution and diversity of demersal species along the Lebanese coast, eastern Mediterranean : a focus on Lessepsian fish species." Thesis, Perpignan, 2017. http://www.theses.fr/2017PERP0051.
Повний текст джерелаThe aim of this study was to contribute to a better knowledge of demersal species in the Lebanese coastal waters, Eastern Mediterranean. Various aspect related to the distribution, diversity and biology of these species were studied. The data were collected from a three-year experimental survey in the framework of the ‘CIHEAM-PESCA Libano project’. A highly diversified mix of fish species (teleosteans and selaceans), cephalopods and crustaceans were sampled. Spatio-temporal distribution and diversity was evaluated respectively using the ‘Catch Per Unit Effort’ which was considered as an approximation of an abundance index and the total number of species caught in the surveys
Lundy, Caroline. "Genetic structure of demersal fish populations in oceanic environments : implications for management of European hake (Merluccius merluccius), a commercially important species." Thesis, University of East Anglia, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.323388.
Повний текст джерелаMafunda, Patrick Siyambulela. "Aspects of the reproduction of male and female African penguins (Spheniscus demersus) with special reference to sperm biology and cryopreservation." University of the Western Cape, 2018. http://hdl.handle.net/11394/6551.
Повний текст джерелаIn the marine environment, penguins have been described as curators and serve a critical role in ecological balance. The African penguin (Spheniscus demersus) has undergone a rapid population decline, mainly due to disturbances in their natural habitat. The African penguin was up-listed from vulnerable to endangered on the IUCN Red List for Threatened Species in 2010 and thus urgent conservation action is required. Integral to long-term conservation action of any species is a basic knowledge of its reproductive biology, which is currently lacking for African penguins. The main aim of this investigation was to evaluate techniques for the collection of semen in African penguin and to determine sperm quality in order to cryopreserve sperm for in vitro fertilization (IVF) purposes of captive and wild populations. Semen was collected once a week during two breeding seasons from two captive African penguins. Ejaculates (n=51) were obtained over two breeding seasons (Jan-Feb and Jun-Oct) and evaluated for semen volume, sperm concentration, sperm vitality, sperm motility and sperm morphology. In addition twelve (six females and six males, n=4 were breeding pairs) captive African penguins were monitored for hormone (estradiol, testosterone, progesterone) levels prior to and after the egg-laying period.
Giliberto, Irene. "Implementazione di un sistema per la classificazione di banchi di pesce da dati di acustica." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2014. http://amslaurea.unibo.it/6484/.
Повний текст джерелаKing, Nicola Jane. "Deep-sea demersal ichthyofauna of contrasting localities - Mid-Atlantic Ridge, Nazaré Canyon (North Atlantic Ocean) and Crozet Plateau (Southern Indian Ocean) - with special references to the abyssal grenadier, Coryphaenoides (Nematonurus) armatus (Hector, 1875)." Thesis, University of Aberdeen, 2006. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU602325.
Повний текст джерелаGuijarro, González Beatriz. "Population dynamics and assessment of exploited deep water decapods of Balearic Islands (western Mediterranean): from single to multi-species approach." Doctoral thesis, Universitat de les Illes Balears, 2012. http://hdl.handle.net/10803/97300.
Повний текст джерелаMorfin, Marie. "Dynamiques spatio-temporelles d'espèces démersales clés du golfe du Lion : bénéfices potentiels d’aires marines protégées." Thesis, Montpellier 2, 2013. http://www.theses.fr/2013MON20158.
Повний текст джерелаDemersal species represent 50% of French fisheries catches in theGulf of Lions, most of which are fully exploited, or overfished for decades. This thesis evaluates the relevance of marine protected areas (MPAs) as a tool for conservation and management of these populations. So far these areas have been implemented only along the coast to protect the very few mobile species. The problem is more complex for deep sea species because their habitat is broader and more diffuse. To do this, the spatial distribution of 12 key demersal species exploited were studied from 1994 to 2010, with scientific observations and ad hoc statistical tools. A geostatistical approach allowed to detect spatial autocorrelation structures for all species, and produce maps of annual distributions of each species. These distributions appeared very stable over 17 years, apart from a phenomenon of expansion/ contraction with the level of total abundance in the region. In addition, a generalized linear model approach revealed significant associations of these species to a temporally stable habitat. These results are consistent with MacCall basin theory, according which habitat suitability is a density-dependent thus the increase of individuals in an area make them colonize sub-optimal habitats. An optimal habitat under protection could thus be "source" habitat, if the area is carefully chosen. Indeed reporting the fishing effort outside the MPA can instead make this measure ineffective or deleterious. The adult population were generally in more concentrated areas and included in the spatial range of juveniles. These common areas of essential habitat (breeding and nursery) may be potentially interesting to protect a single species . However, the heterogeneity of distributions of a species to another involves the introduction of very sparse areas, making the management difficult. However an area of reasonable size has been identified, covering 20% of the population of each species and representative of the diversity of bottom habitats in the region
Kide, Saïkou Oumar. "Analyse de la diversité et de la structuration spatio-temporelle des assemblages démersaux dans la zone économique exclusive mauritanienne." Thesis, Aix-Marseille, 2018. http://www.theses.fr/2018AIXM0085/document.
Повний текст джерелаThe Mauritanian exclusive economic zone is the seat of an upwelling phenomenon and constitutes a transition zone where species of temperate and tropical affinities coexist. To understand the spatio-temporal behavior of demersal assemblages from the point of view of their composition, structure, distribution of probability and diversity faced to ecological concerns. Abiotic factors contribute in the structuring of persistent groundfish assemblages over time. The fishing effects were relatively low, although significant in some years and in some specific geographic areas. Temporal trajectories between groundfish assemblages and environmental conditions have been highlighted for some years and in some specific areas. In each type habitats, two species groups were identified: a minority group of species very aggregative well fitted by Fisher’s log-series distribution and another majority of species little or not aggregative well fitted by the truncated negative binomial distribution. Diversity indices analyzed reveal that this set can be split into two distinct and complementary groups: a group associated with the species richness and another group associated with evenness. One component of diversity may not represent the diversity of the groundfish in the study area. GLMs of complementary indices showed essentially a temporal effect and Bathymetric strata-Year interaction. No effect of fishing effort was observed on the species richness and neither was the concentration of chlorophyll a on the evenness. This work could provide managers and scientists to further knowledge on the spatio-temporal dynamics of groundfish species assemblages exploited in upwelling ecosystems
CRISCOLI, ALESSANDRO. "Distribuzione spaziale di giovanili di specie ittiche di interesse commerciale." Doctoral thesis, 2008. http://hdl.handle.net/11573/392174.
Повний текст джерелаParra, Hugo Alexandre Esteves. "Habitat predictive modelling of demersal fish species in the Azores." Master's thesis, 2013. http://hdl.handle.net/10400.3/3092.
Повний текст джерелаSpecies distribution modelling of the marine environment has been extensively used to assess species–environment relationships to predict fish spatial distributions accurately. In this study we explored the application of two distinct modelling techniques, maximum entropy model (MaxEnt) and generalized linear models (GLMs) for predicting the potential distribution in the Azores economic exclusive zone (EEZ) of four economically important demersal fish species: blackbelly rosefish, Helicolenus dactylopterus dactylopterus, forkbeard, Phycis phycis, wreckfish, Polyprion americanus and offshore rockfish, Pontinus kuhlii. Models were constructed based on 13 years of fish presence/absence data derived from bottom longline surveys performed in the study area combined with high resolution (300 m) topographic and biogeochemical habitat seafloor variables. The most important predictors were depth and slope followed by sediment type, oxygen saturation and salinity, with relative contributions being similar among species. GLMs provided ‘outstanding’ model predictions (AUC>0.9) for two of the four fish species while MaxEnt provided ‘excellent’ model predictions (AUC=0.8–0.9) for three of four species. The level of agreement between observed and predicted presence/absence sites for both modelling techniques was ‘moderate’ (K=0.4–0.6) for three of the four species with P. americanus models presenting the lowest level of agreement (K<0.1). For the scope of this study, both modelling approaches presented here were determined to produce viable presence/absence maps which represent a snap–shot of the potential distributions of the investigated species. This information provides a better description of demersal fish spatial ecology and can be of a great deal of interest for future fisheries management and conservation planning.
Novaglio, C. "Evaluating baseline conditions and resulting changes in demersal fish communities of South East Australia." Thesis, 2016. https://eprints.utas.edu.au/23119/1/Novaglio_whole_thesis.pdf.
Повний текст джерелаCanha, Ângela Maria Lourenço. "Caracterização das rejeições na pescaria de demersais nos Açores." Master's thesis, 2014. http://hdl.handle.net/10400.3/3102.
Повний текст джерелаDesde 2004 que o Departamento de Oceanografia e Pescas da Universidade dos Açores é a instituição responsável pela implementação na Região Autónoma dos Açores de um programa de observação das rejeições da pesca comercial nas pescarias de palangre de fundo. Foram amostradas as rejeições de todas as espécies demersais de acordo com um esquema de amostragem aleatório estratificado baseado na arte de pesca e segmento de frota. O objectivo deste trabalho é caracterizar as rejeições em termos de composição específica, quantificar em número e em peso as taxas de rejeição observadas e estimar a rejeição para o total da frota de pesca de demersais com palangre de fundo. As rejeições observadas foram ampliadas por viagem para cada segmento de frota e para cada ano através de dois métodos diferentes: pela teoria da amostragem e considerando que o volume de rejeições é proporcional a uma variável auxiliar. No total, 275 viagens e 993 lances foram amostrados totalizando 1209 dias de mar. A amostra representa entre 0,5% em 2006 e 1,3% em 2007 de cobertura das viagens. Foram rejeitados em média, 117 ± 8.8 kg de pescado por viagem enquanto por lance foram rejeitados em média 32.4 ± 1.3 kg de pescado. Neste estudo foram identificadas 107 espécies diferentes das quais 94 espécies rejeitadas. As espécies que mais contribuíram para as rejeições em número foram o Helicolenus dactylopterus, Etmopterus spinax e o Beryx splendens. A variável auxiliar viagens estimou rejeições anuais que variaram entre 363 t em 2006 (CV = 38.3%) e 665 t em 2010 (CV = 21.8%). A utilização das descargas nas estimativas produziu valores de rejeição que oscilaram entre as 163 t em 2009 (CV = 40.7%) e 249 t em 2007 (CV = 26.7%). Se a variável auxiliar for o esforço (número de anzóis), os resultados variaram entre as 750 t em 2009 (CV = 7.1%) e as 1345 t em 2011 (CV = 3.8%) de pescado rejeitado. Este trabalho contribui com as primeiras estimativas de rejeições para a pescaria de demersais com palangre de fundo.
ABSTRACT: Since 2004, the Department of Oceanography and Fisheries from the University of the Azores began to implement a fisheries observer monitoring program for discards in set longline. Discards from all demersal species were analysed using a stratified sampling scheme based on fishing gear and fleet segmentation. The main goal of this study is to characterize the species composition of discards, quantify in number and weight discards rates and estimate discards for the all set logline fleet. Monitored discards were raised by trip for each fleet segment and year using two methods: sample mean ratio and ratio estimator through two different auxiliary variables. Overall, 275 fishing trips and 993 sets were sampled totaling 1209 days at sea. Sampling coverage represented between 0.5% in 2006 and 1.3% in 2007 of fishing trips. On average 117 ± 8.8 kg of fish by trip were discarded while 32.4 ± 1.3 kg of fish were discarded by set. In this study, 107 species were identified of which 94 were discarded. Helicolenus dactylopterus, Etmopterus spinax and Beryx splendens were the species that contributed the most to discards. Estimates of annual discards based on trips ranged from 363 t in 2006 (CV = 38.3%) and 665 t in 2010 (CV = 21.8%), while estimates based on landings varied from 163 t in 2009 (CV = 40.7%) and 249 t in 2007 (CV = 26.7%). Estimates of discards based on effort (number of hooks) ranged between 750 t in 2009 (CV = 7.1%) and 1345 t in 2011 (CV = 3.8%). This work contributed with the first estimates of discards for the demersal set longline fishery in Azores.
Chen, Yu-Sheng, and 陳育生. "The diversity and assemblage of demersal fish, and reproductive, condition and feeding cycles of the dominant species in surrounding waters of theThree Northern Isles, Taiwan." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/f7nm6t.
Повний текст джерела國立臺灣海洋大學
海洋事務與資源管理研究所
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The diversity and assemblage of demersal fish, as well as spawning, condition and feeding cycles of the dominant fish species were examined using bi-weekly or monthly samplings and daily catch records from small bottom trawlers operate in surroundings waters of the Three Northern Isles, Taiwan between Nov. 2012 and Dec. 2015. Results indicated that bycatch (both in number and weight) from these vessels was on average, about 50% of the total. These bycatches included ~20-30% (in number), and more than 50% (in weight) of economical important fish species. The species richness, evenness and diversity were higher both for economically important and bycatch species from end of summer to fall or early winter period (i.e., Sept.-Dec or Sept.-Jan.), while they were lower between end of spring to summer period. The percentage of juvenile bycatch also was higher between end of summer to winter, and lower during the spring, which was opposite with that seen in adult fish. Two fish assemblages been identified were roughly corresponding to cooler (i.e., Sept.-Mar.), and warmer (i.e., Jun.-Aug.) seasons for both economic and bycatch species, and these assemblages were not structured by habitat types or water depths. The spawning season of most fish species occurred in the spring and summer. Most fishes also showed high feeding activity during summer-fall period, and reached highest condition factor in the fall, with a second in summer. The optimum exploitation and management strategies including implementation of close season during the spring and summer to protect spawner, and explore the resources with additional mesh size limitations during the fall when most fishes were plump, and juvenile fishes were abundant, are then suggested accordingly to ensure the sustainable use of the demersal fishery resources of the region.