This investigation examined the adequacy of the forage base to meet current demand of piscivores in Smith Mountain Lake, Virginia. Surplus production, or the maximum sustainable supply, of alewife (Alosa pseudoharengus) and gizzard shad (Dorosoma cepedianum) were determined using data on the biomass, growth, and mortality of each species. Mean hydroacoustic alewife biomass from 1993-1998 was 37 kg/ha and mean gizzard shad cove rotenone biomass from 1990-1997 was 112 kg/ha. Mean annual alewife surplus production was determined to be 73 kg/ha and mean annual gizzard shad surplus production totaled 146 kg/ha. Bioenergetics modeling and population density estimates were utilized to derive the annual food consumption (realized demand) of the two most popular sport fish in the system, striped bass (Morone saxatilis) and largemouth bass (Micropterus salmoides). The striped bass population consumed 46 kg/ha of alewife and 27 kg/ha of gizzard shad annually. Largemouth bass ate 9 kg/ha of alewife and 15 kg/ha of gizzard shad annually. Annual consumption by ancillary predators was estimated to be 13 kg/ha of alewife and 35 kg/ha of gizzard shad. Prey supply to predators is limited by morphology, behavior, and distribution. The cumulative effect on prey availability of these three factors, in addition to consumption by other predators, was quantified. For largemouth bass, available supply of alewife and gizzard shad exceeded demand by 20% and 53% respectively. For striped bass, available supply of gizzard shad surpassed demand by 30% but available alewife supply was only 4% greater than demand. Annual demand of all predators was 94% of total available clupeid supply. Striped bass stockings were increased by 50% in 1998 and will remain at this level in the near future. A predator-prey simulation model of alewife and striped bass populations was developed to explore the consequences of increased predator demand. This model incorporated dependencies between alewife abundance and mortality and the mortality, abundance, and growth of striped bass. Model output showed that a 50% stocking increase has a near-zero probability of increasing the mean annual number of legal and citation striped bass in Smith Mountain Lake. / Ph. D.

Les paramètres de croissance de poissons pélagiques et démersaux ont été étudiés durant la période de 1990 à 2015 dans le but d’examiner l’impact de facteurs biotiques comme la densité-dépendance, le recrutement, la mortalité totale et de facteurs abiotiques tels que l’intensité d’upwelling, la température et la concentration en chlorophylle a. Les paramètres d’histoire de vie des espèces peuvent varier selon les espèces, d’une région à l’autre, et dans le temps au sein d’une même région en raison de leur plasticité et de la pression de la pêche. Une comparaison inter-espèces et inter-régions a été réalisée. Le modèle non linéaire à effets mixtes a été utilisé pour différentes populations de l’Océan Atlantique afin d’établir les paramètres de croissance aux niveaux individuel et de la population. Les variations des paramètres de croissance d’une sélection d’espèces ont été mises en corrélation avec des facteurs biotiques et abiotiquesLes espèces (Sardinella aurita, sardinelle ronde, Atherinella brasiliensis, tinicalo, Merlangius merlangus, merlan, Melanogrammus aeglefinus, églefin et Solea solea, sole) montrent des réponses différentes aux facteurs biotiques et abiotiques. Au niveau spatial pour le merlan et l’églefin, la croissance est affectée par la latitude et la température, tandis qu’au niveau temporel la croissance du merlan est affectée par la température et la densité. Il y avait un intérêt pour savoir si les variables morphométriques et le diamètre de l’otolithe de tinicalo étaient de bons indicateurs de la croissance : c’est la longueur standard qui a présenté / The impact of biotic factors such as density-dependent processes, recruitment, total mortality, and abiotic factors such as upwelling intensity, temperature and chlorophyll a concentration on the variation of growth parameters of pelagic and demersal fish were studied during the periods 1990 - 2008 (pelagic) and 1971 - 2015 (demersal). Life history parameters vary according to the species and from one region to another and over time within a given area because of their plasticity and the high fishing pressure. Interspecies and inter-regional comparison were carried out. Non-linear mixed effects models were used on different fish species of the Atlantic Ocean in order to estimate the growth parameters at the individual and population levels. Variations in growth parameters of selected species were correlated with biotic and abiotic factors.Selected species (Sardinella aurita, round sardinella, Xenomelaniris brasiliensis, tinicalo, Merlangus merlangus, whiting, Melanogrammus aeglefinus, haddock and Solea solea, sole) showed different responses to biotic and abiotic factors. Regardind the spatial component for whiting and haddock, the variation of growth parameters was affected by latitude and temperature. Concerning the temporal component, whiting was affected by temperature and density-dependent processes. There was also an interest to know if the morphometric variables and the diameter of the otolith of Atherinella brasilensis were good growth indicators. Among the morphometric parameters examined, the standard length-Age relationship showed the best fit (r2 = 0.90), foll