Several properties within Tennessee were managed under a quality deer management (QDM) philosophy from 1998 to 2006. Harvest characteristics of three private properties and three Wildlife Management Areas (WMAs) were compared to determine effects on buck harvest rates and the age structure and sex ratio of the harvest. Average annual buck harvest decreased at most areas following antler restrictions and ranged from 55 to 68% of pre-QDM levels because younger bucks were protected. Although the raw numbers showed an increase in older-aged bucks harvested following antler restrictions, when calculated on a per hunter or per permit issued basis, statistical increases were not observed at all study areas. Regardless, hunters at each area felt QDM restrictions were working toward their goal and planned to apply to hunt that area the following season. Most hunters regarded themselves “somewhat knowledgeable” with QDM and considered it a sensible management philosophy. The majority of club hunters (55.5%) and plurality of sportsman license holders (36.9%) and WMA hunters (34.7%) favored a statewide limit of two bucks, and the majority of all hunters favored including does in the harvest and protecting young bucks from harvest. The production and nutritional quality of twenty forages used in food plots and the effects of prescribed burning and understory fertilization on browse production in closed-canopy hardwoods one growing season after treatment were also evaluated. Crimson clover and a cool-season grain (wheat or oats) are recommended to address the mid-late winter stress period, and can be planted with arrowleaf clover to further extend forage availability in the spring. Warm-season annual forages (cowpeas, lablab, and soybeans) supplied forage during the late summer stress period when natural forage quality is low. Ladino clover and chicory supplement production gaps of annual forages. Because of variable results among two sites and because the cost per pound of forage produced following fertilization exceeded $26 per pound, understory fertilization and prescribed fire in closed-canopy hardwood stands are not recommended for increased deer browse. Treatments providing increased sunlight through a reduction in percent canopy cover are much more effective and efficient in providing increased browse.

Variation, or modulation, of suction feeding performance across two prey location treatments, as measured by peak subambient pressure generation, was studied in the Florida largemouth bass, Micropterus salmoides floridanus. Previous studies of suction feeding in centrarchids have excluded possible sources of performance variation to minimize the modulatory response. Florida bass are known to modulate their feeding kinematics when exposed to prey at different levels of elusiveness, and were in turn predicted to vary suction pressure generation when exposed to these conditions. Eight bass fed Palaemonetes sp. shrimp in an open water (elusive) setting and in a vegetated (non-elusive) setting were found to generate significantly different amounts of suction during prey capture (Fli48=5.676, p=0.021). Principal component analysis of variables derived from high speed digital video footage found that the suite of behaviors associated with the feeding strike also differed across prey location treatments. Bass feeding on open water prey approached at higher velocity, exhibited faster cranial kinematics, and generated larger values of suction force, while bass feeding on vegetated prey approached more slowly, had slower cranial kinematics, and generated smaller values of suction. Florida bass clearly modulate their repertoire of feeding activities in response to differing prey capture conditions.

On April 20th, 2010, a fire broke out on the Deepwater Horizon (DWH) offshore oil drilling rig on the Macondo prospect located off the coast of the Gulf of Mexico (GOM). This fire and resulting explosions resulted in the sinking of the Deepwater Horizon rig and the largest marine oil spill in history. An estimated 4.9 million (+/- 10%) barrels were released into the Gulf of Mexico over the ensuing 87 days. Many economically important fish species spawn in northern Gulf of Mexico waters; the spawning seasons and pelagic larval phase of many of these species occur within the temporal extent of the DWH oil spill (April through July). Fish eggs and larvae in waters exposed to Macondo oil likely experienced lethal and sublethal physiological effects, leading to potential losses in year class strength depending on the proportion of a population’s larval production encountering oil. Differing spatial distributions of larvae due to different spawning locations and seasons could predict that some species were disproportionately affected by the DWH oil spill. This study aims at quantifying the impact of the spill across numerous taxa, by estimating the proportion of species-, genus-, or family-specific fish larval abundances located within the spatial/temporal domain of the DWH spill until the Macondo well was capped. Estimates and related uncertainties were based on empirical ichthyoplankton data collected over 27 years and on observed and modeled distribution of surface oil slicks and concentrations. In addition, two hypothetical oil spills were simulated on the Western Florida Slope and on the Western interior of the Gulf of Mexico to assess the impact of oil spills to the ichthyoplankton from different offshore locations that would have occurred during the DWH spill period. Ichthyoplankton data collected during annual plankton surveys (and other resource surveys) as part of the Southeast Area Monitoring and Assessment Program – Gulf of Mexico (SEAMAP) during years 1982-2009 were used to describe the composition and distribution of ichthyoplankton in the northern Gulf of Mexico. The SEAMAP larval fish data along with oil surface distributions (both actual and simulated) were used to estimate the proportions of larvae of 115 selected fish taxa that were potentially exposed to DWH oil. Bootstrapping methods were applied to the SEAMAP data to quantify the variability. Proportions of larval fish potentially exposed to oil were calculated for four oil spill scenarios: (1) the DWH spill, (2) an September-December oil spill with the same spatial footprint as the DWH spill but occurring later in the year, (3) a west Florida Slope spill occurring during the months of April-July and centered at 27˚N, 85˚W, and (4) a western GOM spill occurring during the spring and centered at 27˚N, 93.5˚W. Spill scenarios (3) and (4) were modeled using the Connectivity Modeling System (CMS). The CMS is a Lagrangian model which predicts oil droplet distribution and degradation based on oil properties and ocean currents. Significant differences in the proportion of larvae potentially exposed were found in the DWH spill and the three simulations. The proportion of fish larvae exposed to the DWH spill varied between 0% (many species) and 26.8% (Cynoscion nebulosus). The proportion of fish larvae exposed to simulated spills varied between 0% and 78.9% (Bonapartia pedaliota in Western GOM spill). Both the west Florida Slope oil spill and the western GOM spills had a disproportionally greater impact on a larger number of taxa than the DWH spill, even after correcting for their larger spatial extent. For the DWH spill (Scenario 1), the potentially most impacted taxa were Cynoscion nebulosus, Engraulidae, Rachycentron canadum, and Etropus spp. If the DWH spill had occurred in the fall (Scenario 2), the most potentially impacted taxa would have been Leiostomus xanthurus, Elopidae, and Pomatomus saltatrix. For a west Florida slope exposure (Scenario 3), the potentially most impacted taxa would be Holocentridae, Acanthocybium solandri, Coryphaena spp., and Pomacanthidae. For a western GOM spill (Scenario 4), the most potentially impacted taxa would be Bonapartia pedaliota, Thunnus thynnus, Caranx spp., and Holocentridae.. The historical SEAMAP data set combined with the CMS modeling tool provides a powerful planning tool to understand the potential impacts of oil spills in the northern GOM and the relative sensitivity of locations in the Northern GOM to oil spill effects.

Aspects of oxygen consumption and bioenergetics of the Atlantic halibut (Hippoglossus hippoglossus L. ) were studied under laboratory conditions. Resting oxygen consumption rate was monitored over 36 hour periods in Atlantic halibut while held individually in open system respirometers. Routine oxygen consumption rate was determined in small populations of tank held Atlantic halibut over 24 hour periods, through modification of tank systems as open system respirometers. Values for resting and routine oxygen consumption in this species were quantified and models Produced enabling the prediction of the energetic cost of homeostasis and spontaneousa ctivity for a range of fish size from 53g to 5861g, at temperatures of 6, 10 and 14°C. These results were ftirther used to form the basis of an energy budget equation for this species. PhotoPeriod influences on the periodicity of respiratory rhythm in both resting and routine oxygen consumption trials were determined through analysis of data recorded throughout the 24 hour daily period. The results indicated a cyclic respiratory rhythm, with peak oxygen consumption often observed nocturnally. The relevance of these results to culture of this organism are discussed. Post-prandial oxygen consumption and ammonia excretion were measured in small populations of tank held Atlantic halibut, these results contributing further information to the partitioning of energy within the metabolic and excretory components of the energy budget equation. Values for resting, routine and postprandial oxygen consumption in the Atlantic halibut were found to be low in comparison to roundfish species, but corresponded closely with literature data produced for other species of temperate marine flatfish. Activity patterns in small populations of Atlantic halibut were monitored over 24 hour periods in a specially constructed film unit. The results of this work showed dualistic patterns of activity over the diurnal cycle. Further elucidation of the energy budget was achieved through the determination of the metabolic costs of activity in the tank environment. Atlantic halibut were observed to remain at rest for periods of between 76% and 94% of any 24 hour period, with the time at rest dependent on fish size and stocking density. One 28 day trial was undertaken in which the components of the energy budget were measured simultaneously, and the balance of the budget investigated. Oxygen consumption, ammonia excretion, growth, feed consumption and faecal production were monitored within a purpose built experimental unit, and these values finther applied to the construction of an energy budget model. Finally, the oxygen consumption data of this study was ftirther applied to produce a model quantifying the water requirements of this species in a single-pass tank system, for the intensive culture of this species in the tank environment. Further development of these figures allowed the quantification of the pumping costs in an Atlantic halibut ongrowing tank system, and these figures were incorporated into a simple economic model. The results present some of the first bioenergetic data produced for this species, and this is an important step towards the development of an Atlantic halibut farming industry.

A comprehensive understanding of migration dynamics, within-estuary behaviors and physiological tolerances of fish is needed to assess and predict future responses of fish to environmental disturbance and to protect habitat necessary for growth and survival. This study adds to current knowledge of summer flounder (Paralichthys dentatus) responses to environmental conditions by (1) examining migration and within-estuarine behaviors of adult summer flounder and (2) establishing summer flounder metabolic requirements and cardiorespiratory responses to variations in hypoxia and temperature. To elucidate use of a southern mid-Atlantic Bight estuary by adult summer flounder, the movements of 45 fish were monitored using acoustic telemetry within a seaside lagoon along Virginia‟s Eastern Shore. Mean residence time in this region was 1.5 times greater than previously reported for this species. The majority of fish remained within the estuary until mid-October, although some fish dispersed from the system earlier, and some temporarily exited and re-entered the system before final dispersal. Migration into or out of the system most closely followed seasonal changes in mean water temperature, but photoperiod and other factors may also play a role. Fish resided primarily in the deeper regions of the lagoon system, where strong currents preclude the development of suboptimal conditions such as hypoxia. Summer flounder also generally exhibited low levels of large-scale activity (e.g., 100s of meters). Variations in the migratory and within-estuary behaviors indicate that individual fish use different strategies to maximize food and habitat resources. Additional research is necessary to identify preferences and behaviors of summer flounder within estuaries and along the inner continental shelf and to relate these to prey distribution. To provide a metabolic framework for understanding how summer flounder respond to hypoxia, stopflow respirometry was used to measure changes in resting metabolic rate, oxygen extraction, gill ventilation and heart rate during progressive hypoxia at an acclimation temperature (22°C) and after an acute increase to 30°C. Summer flounder experience a 6-fold increase in gill ventilation while maintaining oxygen extraction above 50%. However, the critical oxygen saturation increased significantly from 27% at 22°C to 39% at 30°C, suggesting a lower tolerance to hypoxia after exposure to an acute increase in temperature. In addition, fish subjected to 30°C were unable to increase gill ventilation to as great an extent as at 22°C. At both temperatures, significant bradycardia was only observed when oxygen levels decreased to levels below critical oxygen saturation. Due to their ability to maintain aerobic metabolism in low oxygen conditions, summer flounder are not likely to avoid hypoxic conditions to maintain aerobic metabolism in the wild. However, exposure to hypoxia can decrease aerobic scope and consequently affect somatic and gonadal growth rates. Additional studies specifically examining the effects of hypoxia and temperature on aerobic scope are necessary to fully understand the effects of variable environmental conditions on growth and reproduction in this species.

Since the square-foot bottom sampler was described by Surber it has been the principle instrument used for quantitative studies of the bottom fauna in riffle areas of streams. However, little has been written concerning the actual number of square-foot samples necessary to describe stream bottom fauna in terms of the number or volume of organisms.

The Chesapeake Bay region values oysters for the ecosystem services, lucrative fishery, and historical significance that the species embodies; however, over the last half century, oyster abundances have been reduced to historical lows. Two protozoan parasites, Perkinsus marinus and Haplosporidium nelsoni, have been major influences on oyster populations, especially in high-salinity regions. Today, the population is recovering; catches have increased and oysters have expanded spatially. to investigate the cause of the recovery, three measurements were made on slides of oysters from a histological archive collected during summer at Wreck Shoal in the James River from 1988–2017: oocyte diameter, oocyte density, and gonad area fraction. Gametogenic investment served as a proxy for the fitness of oysters; it was hypothesized that an outbreak of P. marinus in the 2000s led to a tolerance response that can be detected as an increase in reproduction. Oocyte diameter has remained variable yet steady overall, except for a decrease in 2001 and 2002. Oocyte density and gonad area fraction increased sharply around 2003. Mean oocyte densities increased by a factor of 2.05 and gonad area fraction by a factor of 2.04. Oocyte density has been maintained at these higher counts in recent years. The increase in gonadal area ratio is presently decreasing slowly yet significantly (p=0.00429). The cause of the increase is still not well understood, as a variety of environmental variables were significant predictors of reproduction as well as the hypothesized cause, P. marinus weighted prevalence. Regardless of the cause, changes in reproductive patterns signify a positive change on the part of the oyster. The ability of the wild oyster population to adapt supports management strategies that protect old oysters, like sanctuaries and slot fisheries. These strategies allow fit oysters to grow to old age and pass on their beneficial traits to future generations. in the face of doubts about the efficacy of restoration, conservation emerges as a path forward.

For years bluefin tuna has been the poster child for overfishing and poor management. However, recent improvements in data collection, catch monitoring and international cooperation are providing an opportunity to reverse the perception of a fishery that is doomed to collapse. Stock assessments are conducted routinely to monitor the abundance and productivity of exploited fish stocks so managers can determine how many fish can be sustainably harvested each year. Should a stock be declared overfished or under-going overfishing, the science behind stock assessments also equip managers with the knowledge necessary to make decisions about what short-term and long-term management measures should be taken to help reverse these trends. in that light, the goal of my research has been to use newly available age data to improve the quality and reliability of assessments for Atlantic bluefin tuna by reducing uncertainty about the data and methods used to infer growth and age composition. A secondary goal has been to provide managers with the knowledge necessary to implement effective stock rebuilding programs for Pacific bluefin tuna. Chapter 2 is focused on cohort slicing, a method routinely used in the Atlantic bluefin tuna assessment to estimate catch-at-age from catch-at-size information. This chapter explores how errors in cohort sliced catch-at-age data can bias estimates of total mortality rate derived from catch curve analysis. Recommendations are provided concerning the appropriate mortality estimator and plus group to use depending on the parameters characterizing the stock. Chapter 3 provides updated growth estimates for western Atlantic bluefin tuna, which were adopted in 2017 as the basis for defining growth in the assessment. Chapter 4 provides an overview of the theory behind age-length keys with particular emphasis on the assumptions that govern each method and provides notes of caution concerning their applications to real data. Chapter 5 evaluates through simulation the relative performance of different methods for estimating age composition of western Atlantic bluefin tuna catches and applies the best performing technique, the combined forward-inverse age-length key, to actual western Atlantic bluefin tuna data. Chapter 6 moves over to the Pacific and focuses on evaluating the potential impacts of different minimum size regulations on the stock of Pacific bluefin tuna and explores ways in which to minimize short-term pain to the industry while still achieving long-term yield and conservation goals. Overall, this work has contributed major improvements to the stock assessment process of Atlantic bluefin tuna and implications of this work resonate beyond the bluefin tuna world to other highly migratory species faced with similar problems.

Cobia (Rachycentron canadum) is a cosmopolitan marine fish inhabiting tropical, sub-tropical, and temperate marine and estuarine waters. Recent changes in U.S. cobia management have sparked controversy and highlighted limitations in our understanding of seasonal movement patterns and problems with estimating recreational harvests. Consecutive years (2015 and 2016) of estimated overharvests from the Atlantic Migratory Group stock triggered accountability measures to prevent overfishing by recreational anglers. My project employed pop-up satellite archival tags (PSATs) to study cobia movements, habitat utilization, and post-release survival. It was, therefore, designed to enhance knowledge of cobia biology and aid sustainable management. We deployed 36 PSATs on cobia caught in Virginia state waters using standard recreational techniques in August 2016 and August – September 2017. All fish larger than 37- inches total length were tagged, and several of these were deep-hooked. No mortalities were inferred from the 24 cobia whose PSATs reported. Only five PSATs remained attached until the 180-day programmed release date. This made it difficult to accurately describe cobia seasonal movement patterns, although it appears that areas near North Carolina's continental shelf break may be important overwintering habitat. Other overwintering areas may exist, however, as some fish made longer migrations, and one PSAT reported in Florida waters (beyond the current stock demarcation boundary). Cobia have a strong affinity for waters ≥20°C, even in the coldest months. They also display distinct seasonal differences in vertical movement patterns which make them more susceptible to capture in the summer when Virginia recreational anglers often employ sight-fishing techniques.

Spanish mackerel were purchased from commercial fisheries in the Chesapeake Bay in the period 1993-1994 and processed for biological data to describe reproductive biology. Spanish mackerel are multiple spawners with asynchronous oocyte development and indeterminate fecundity. They spawn in the Chesapeake Bay area from June through August, June being the peak spawning month. Individuals, however, vary greatly in when they begin and end spawning. The presence of Gravid and Running Ripe females indicates spawning inside the Chesapeake Bay, and the capture of small juveniles suggests the region may be used as a nursery grounds. Sex ratios vary greatly, females generally dominating at larger sizes. Length at first maturity (L50 ) was 230 mm FL in females and 232 mm FL in males; all females are mature at 330 mm FL and all males at 340 mm FL. Mean batch fecundity is 74,077 eggs, increasing with length and somatic weight. Average relative fecundity is 143 eggs/g female(± 10 SE). Spanish mackerel are .sometimes infected with a live-bearing nematode that reduces fecundity.