Biology Theses and Dissertations
Permanent URI for this collectionhttp://hdl.handle.net/1903/2749
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Item The influence of episodic river flow events on striped bass (Morone saxatilis) spawning in Chesapeake Bay, USA(2010) Jahn, Ginger Lee; North, Elizabeth W.; Marine-Estuarine-Environmental Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The upper Chesapeake Bay is an important and dynamic nursery habitat for striped bass (Morone saxatilis) eggs and larvae. The hypothesis that pulses in flow cause temperature changes that cue striped bass spawning was evaluated with field surveys and historical data analyses. Water temperatures in April and May were negatively correlated with river flow (1956-2002), suggesting that water temperatures decrease during flow events and then increase as flow diminishes, potentially providing a cue for spawning. Survey data from the upper bay in 2007 and 2008 were analyzed in conjunction with historical data on striped bass eggs in tributaries of Chesapeake Bay. Results suggest that increasing water temperatures are the dominant cue for striped bass spawning. Temperature increases after pulsed flow events may cue striped bass spawning and may result in more favorable prey abundances and better larval survival compared to years when spawning is cued by water temperature increases alone.Item Evaluation of Off-Season Spawning Techniques and Larval Diet Supplementation of Yellow Perch (Perca flavescens)(2004-08-13) Rath, Mark Allen; Lazur, Andrew M; Marine-Estuarine-Environmental Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)400 yellow perch (Perca flavescens) were divided into four groups, each targeted to spawn in a different season. The photo-thermal conditions of each group were manipulated to mimic seasonal changes that initiate reproductive activity. Spawning occurred in all groups. Using photo-thermal manipulation it is possible to spawn yellow perch at different times of year providing multiple crops of fingerlings. Eggs and larvae of yellow perch were analyzed for fatty acid content. A feeding trial was conducted comparing experimental diets high in eicosapentaenoic (EPA) and docosahexaenoic acid (DHA) to the traditional larval diet used by perch producers. Enriching live foods with EPA and DHA improved survival. Although it was high in both EPA and DHA, the emulsified diet used resulted in lower survival than the control diet because the larvae did not accept it. However, yellow perch larvae may be able to be weaned onto manufactured diets, further improving survival.