College of Agriculture & Natural Resources
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The collections in this community comprise faculty research works, as well as graduate theses and dissertations.
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Item Advancing Ecosystem Based Fisheries Management: Biological Reference Points for Nutritional Status of Striped Bass (Morone saxatilis)(2014) Haus, William; Harrell, Reginal M; Environmental Science and Technology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Nutritional condition is a valuable metric in ecosystem-based fisheries management. However, the need for lethal sampling for the most accurate indicators ethically and logistically limits sample sizes. Percent moisture has been recommended for management of striped bass Morone saxatilis and a management threshold has been suggested. Past researchers have used bioelectrical impedance analysis (BIA) to non-lethally estimate percent dry weight, the inverse of percent moisture. We sought to develop species-specific BIA models for striped bass in a controlled, laboratory setting and later validate those models with independent, field-collected data. BIA models were developed for five size classes and sampled across three temperatures. Results in the lab suggest BIA is an accurate and robust method for estimating percent dry weight in striped bass. However, when implemented in field surveys results are less conclusive. Possible differences between wild and hatchery-reared striped bass that effect BIA need further exploration. Additionally, the effects of salinity and stress response on BIA warrant further work.Item Toward the Development of Integrated Oyster-Algae Aquaculture in the Chesapeake Bay(2014) Ray, Nicholas; Kangas, Patrick C; Environmental Science and Technology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Oyster aquaculture is a rapidly expanding industry in the Chesapeake Bay. Experiments were conducted to investigate the biogeochemical impact of a commercial oyster aquaculture facility on downstream waters at a facility on Maryland's Eastern Shore. An algal production system (ATS) was installed at the facility to assess the potential for bioremediation and algal production in an integrated multi-trophic aquaculture system (IMTA). Results of the experiments showed an increase in available ammonia downstream of the aquaculture facility, coupled with decreases in dissolved oxygen and total phytoplankton. The algal production system demonstrated an average productivity rate of 82.8 g/m2*day-1, a nitrogen (N) removal rate of 9.6 gN/m2*day-1, a phosphorus (P) removal rate of 0.20 gP/m2*day-1, and harvests consisted of an average of 7.8% organic content. Productivity and N and P removal rates from this study are higher than other systems tested in the Chesapeake Bay region at sites without an aquaculture facility.Item The Effects of Water Quality Improvements on a Commercial Fishery: Evidence from the Maryland Blue Crab Fishery(2014) Ball, Sarah; Lipton, Douglas; Agricultural and Resource Economics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Developing and implementing total maximum daily loads (TMDLs) is a costly and controversial process. However, there are many potential benefits, such as improvements to commercial fisheries. A two-stage model is developed to estimate the benefits of the Chesapeake Bay TMDL on the Maryland blue crab fishery. In the first stage, a bio-economic model links water quality to stock and harvest and various hypotheses on this link are tested. In the second stage, a model of fisherman behavior links the effects of changes in water quality on stock and harvest to fisherman behavior, such as fishing, location, and effort decisions. A number of simulations are then run to predict the effects of the TMDL on the Maryland blue crab fishery. The simulations predict that the TMDL is likely to have a small, if not insignificant, effect on the fishery. This result is in part explained by the fact that the current level of water quality in the Chesapeake Bay is suitable for the blue crabs.Item The effect of freezing rate on striped bass (Morone saxatilis) spermatozoa(2013) Frankel, Tyler Edward; Woods, Lewis C; Animal Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Several studies have attempted to determine the optimal freezing rate for the cryopreservation of striped bass spermatozoa. In this study, the effects of freezing rate (-10, -15, -20 and -40oC/min) on sperm quality was examined utilizing Sybr-14/Propidium Iodide staining to confirm membrane integrity, a luciferin-luciferase assay to estimate ATP concentration and a Hamilton-Thorne CEROSTM system to characterize sperm motion. Males (n=12) were sampled once a week for five weeks. Samples were extended, cryo-protected using a 7.5% (v/v) dimethyl sulfoxide solution, and frozen using a controlled-rate freezer. Samples were stored in liquid nitrogen for 49 days and re-evaluated post-thaw. Sperm cryopreserved at -40oC per minute resulted in: total motility (10.06%), progressive motility (7.14%), ATP concentration (0.86 pmol/million cells), and sperm viability (56.5%); which were greater (P < 0.05) than the slower rates. Results demonstrate that -40oC/minute was the optimal freezing rate among those tested for the cryopreservation of striped bass spermatozoa.