Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 37 for “"length frequency"”.
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The impact of bias in length frequency data on an age structured fisheries stock assessment model
… on the part of data collectors. Alternatively, length frequency distributions within the annual catch are relatively simple and inexpensive to acquire, and can be employed to extrapolate age structure given that some information regarding age length relationships in the population is known. This …
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Reproductive biology, growth and mortality of tylochromis Bangwelensis (Regan, 1920) in Bangweulu lakes and swamps complex fishery.
… seven months from March 2019 to September 2019. Length measurements were taken from each fish specimen using a fish measuring board. Weight was measured using an electronic balance to the nearest one gramme. The reproductive biology were investigated by examining fish sex and maturity stages of …
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Age, Growth, Mortality, and the Effects of Trawling on Mortality of the Longspine Porgy, <i>Stenotomus caprinus</i>
… Gulf of Mexico (GOM). Biological data of length, weight, and abundance have been collected since 1972 on the Southeast Area Monitoring and Assessment Program (SEAMAP) surveys with a variety of GOM species, including Longspine Porgy, using trawl nets during groundfish surveys. In 2010-2011 …
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Effects of Habitat on Population Density of Centrarchid Species in the James River, Missouri
… test was used to test for differences in length-frequency distributions and χ2 test was used to test for differences in fish species abundance. The CPUE for centrarchid species varied among species and among sites with longear sunfish Lepomis megalotis having the highest CPUE. The PCA …
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Spatiotemporal variability in Antarctic krill (Euphausia superba) around South Georgia from Antarctic fur seal (Arctocephalus gazella) diets at two long term monitoring sites
… the two sites forage in distinct regions. Krill length-frequency distributions generally followed a synchronous pattern across both sites with summer increases in length associated with growth, and winter decreases associated with ongoing senescence, mortality and possibly krill shrinkage, …
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Aspects of the biology, ecology and fishery of the beaked clam Eumarcia paupercula (Holten, 1802), in Maputo Bay
… FiSAT II, using mark-recapture experiments and length-frequency data. Monthly reproduction analysis was based on the fluctuation of body weight and gonad smear analysis. Furthermore, interviews were used to ascertain the importance of the resources for collectors and estimate landings of E. …
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Growth and otolith zone formation of Namibian hake, merluccius capensis
… relation to their environment. A time series of length-frequency distributions (LFDs) from otoliths collected from fur seal scat samples was used to identify cohorts and calculate the approximate hatchdates and growth rates of young M. capensis from 1994 to 2009. Monthly otolith samples of five …
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Population Dynamics and Productivity of the Prosobranch Snail Goniobasis Potosiensis
… a progressive wave from upstream down. Mean lengths ranged from 0.7 mm to 13.7 mm with the maximum sized snail being 19.27 mm long. The sex ratio for all three stations was 1.2, with a significant excess of males. No sexual dimorphism in length was found. Growth was interrupted by winter in …
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Age, Growth, Reproduction and Population Structure of the Striped Shiner (Luxilus Chrysocephalus) and Duskystripe Shiner (Luxilus Pilsbryi) in the James River, Missouri
… pilsbryi) using asterisci otoliths, scales, and length-frequency data. Monthly samples of both species were obtained from the headwater reaches of the James River in southwest Missouri from February 1998 to January 1999. Total samples were 242 L. chrysocephalus and 322 L. pilsbryi. Otolith ages …
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Hatchdate distributions and growth rates of anchovy (Engraulis encrasicolus) in the Southern Benguela ecosystem
… Sub-samples were chosen proportional to the length-frequency distributions at each stratum or station at each survey. Otoliths of 193 specimens (14-70 mm standard length, SL) from the March survey and 80 specimens (52-114 mm SL) from the May survey were successfully prepared for light …
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Seasonal infection of invasive Brook Stickleback (Culea inconstans) by the nematode Contracaecum multipapillatum at Turnbull National Wildlife Refuge, Washington
… individual host (intensity). Fish were aged with length frequency histograms identifying two distinct cohorts, adults and young-ofthe- year (YOY). Aquatic invertebrates were identified and seasonal species composition by pond was recorded. Our study found prevalence of C. multipapillatum infection …
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Comparison of Creel Survey Data to Traditional Sampling Techniques in Pit-Lake Fisheries of Muhlenberg County, Kentucky
… In two of the pit-lakes, the sampling-generated length frequency data was not significantly different from the creel survey data (Pump G<sub>adj[1]</sub>=0.03, P=0.8629, Goose G<sub>adj[1]</sub>=0.76, P=0.3850). There were significant differences between creel and sampling data for the other …
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The Aging of Two Madtom Catfish Species From a Southwest Missouri Stream
… to otolith age estimates for each individual. Length versus age regressions and age-frequency distributions were compared between the two species. Marginal increment analysis data suggested that annuli formed concurrently in the otoliths of both species between the months of August and …
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Vibrations of and sound radiation from some periodic structures under convected loadings
… obtained by analysing this field into a wave length frequency spectrum and then numerically integrating the response due to each wave length component. The low wave numbers in the spectrum are important for sound power radiated by the structure especially at subsonic convection velocities of …
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Dynamics and distribution of Fishes Occupying a South Dakota Power Plant Cooling Reservoir
… grew well, reaching a weighted mean total length of 271 mm at formation of annulus I. Survival of walleye was poor, with population estimates of 41 and 43 fish in 1984 and 1985, respectively. Low sample size precluded analysis of distribution, but no consistent preference for an area of the …
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The impact of cormorants (Phalacrocorax carbo carbo and Phalacrocorax carbo sinensis) on inland fisheries in the UK
… analysed for fish population dynamics, including length frequency of species, year class strength, natural mortality rate and growth indices; and for angling performance, including catch per unit effort and the relative importance of species. Combining site-specific data for the fish species …
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Ecological impacts of shrimp trawling on juveniles of selected benthic fish species in the southwestern Gulf of Maine
… structure of H. platessoides analyzed with length frequency analysis and scale-age determination revealed four age classes, Age 0+, 1+, 2+ and 3+, to be present in the study area. The diet of H. platessoides was also analyzed to understand potential impacts of trawling on its trophic …
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Life history traits that predispose South African linefishes to overexploitation
… of resilience to exploitation. For this purpose, length frequency data from 1988-1990 and 2008-2010 and biological parameters sourced from literature were used to conduct per-recruit analysis to estimate spawner biomass depletion (SBD) for both time periods. The majority of the 26 species …
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Coal waste deposition and the distribution of freshwater mussels in the Powell River, Virginia
… a decline in abundance and diversity upstream. Length frequency distributions of the muckets Actinonaias pectorosa and A. ligamentina indicated an absence of smaller mussels at most sites. Sediment samples, collected in riffles at 10 sites to determine particle size distributions and the amount …
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