Life Sciences Commons^™

Extensions And Applications Of Mean Length Mortality Estimators For Assessment Of Data-Limited Fisheries, Quang C. Huynh

Dissertations, Theses, and Masters Projects

For data-limited fisheries, length-based mortality estimators are attractive as alternatives to age-structured models due to the simpler data requirements and ease of use of the former. This dissertation develops new extensions of mean length-based mortality estimators and applies them to federally-managed stocks in the southeastern U.S. and U.S. Caribbean.

Chapter 1 presents a review of length-based methods from the literature. Common themes regarding the methodology, assumptions, and diagnostics in these length-based methods are discussed. In Chapter 2, a simulation study evaluates the performance of the length-converted catch curve (LCCC), Beverton-Holt equation (BHE), and Length Based-Spawner Potential Ratio (LB-SPR) over a …

Spatiotemporal Abundance Patterns And Ecological Drivers Of A Nearshore U.S. Atlantic Fish And Invertebrate Assemblage, Mark A. Stratton

Dissertations, Theses, and Masters Projects

Taking an ecosystem approach to fisheries requires the consideration of relevant ecological processes within research and assessment frameworks. Processes affecting ecosystem productivity can be categorized as biophysical (climate variability, primary production), exploitative (fishing), or trophodynamic (food web interactions). This dissertation incorporates these three governing processes to characterize spatiotemporal diversity and population abundance trends for multiple demersal fish and invertebrate species that inhabit the nearshore zone (15-30 ft. depth) along portions of the U.S. Atlantic east coast.

Two large marine ecosystems (LMEs) encompass the U.S. East coast – the Southeast and Northeast U.S. Continental Shelf LMEs. The level of connectivity within …

Age, Growth And Reproduction Of Western North Atlantic Butterfly Rays (Myliobatiformes: Gymnuridae), With The Description Of Two New Species, Kristene Teal Parsons

Dissertations, Theses, and Masters Projects

Batoid fishes are among the most threatened and least understood chondrichthyan species worldwide due to their large body size, conservative life-history characteristics, and predominantly coastal distributions where fishing and habitat degradation threaten the stability of populations. A lack of empirical life history data is widespread across batoid taxa — nearly half of all species are considered data deficient, thus hindering species assessments and the development of effective management strategies. Furthermore, many batoid taxa are in need of taxonomic re-examination. Increasing our understanding of life history traits that determine population productivity, such as age and size at maturity, growth rate, and …

Juvenile Blue Crab (Callinectes Sapidus) Response To Altered Nursery Habitat, Megan Wood

Dissertations, Theses, and Masters Projects

Habitats of Chesapeake Bay have been altered due to anthropogenic impacts and climate change. Due to these human disturbances, seagrasses have been extirpated from many areas in lower Chesapeake Bay and persisting beds face future losses as water temperatures continue to rise. Further loss of seagrass habitat will negatively impact juvenile blue crabs (Callinectes sapidus) that use seagrass beds as nursery grounds. Habitat degradation allows for more successful introductions of exotic species, and the communities formed from the mixing of native and exotic species are known as emerging ecosystems. Gracilaria vermiculophylla, an exotic macroalga, may be an emerging nursery habitat …

Ecosystem Services Of Restored Oyster Reefs In A Chesapeake Bay Tributary: Abundance And Foraging Of Estuarine Fishes, Bruce William Pfirrmann

Dissertations, Theses, and Masters Projects

Oyster reef restoration may enhance the production of ecologically or economically important fish species, an ecosystem service, by providing refuge and foraging habitat. Predicting the effects of oyster habitat restoration on fisheries production in Chesapeake Bay requires a better understanding of fish habitat use, trophic dynamics, and the processes leading to production on a habitat-scale. The objective of this thesis was to evaluate the influence of restored subtidal oyster reefs on the abundance and foraging patterns of mobile estuarine fishes. Specifically, I compared the 1) abundance, 2) stomach fullness, 3) diet composition, and 4) daily consumption rate of fishes collected …

Juvenile Blue Crab Survival In Nursery Habitats: Predator Identification And Predation Impacts In Chesapeake Bay, Amanda Marie Bromilow

Dissertations, Theses, and Masters Projects

Predator populations can have significant impacts on prey recruitment success and prey population dynamics through consumption. Young, inexperienced prey are often most vulnerable to predation due to their small size and limited evasion capabilities. to reduce the risk of predation, new recruits and young juveniles typically settle in structured nursery habitats, such as seagrass beds, which promote higher survival by acting as refuges from predators. Thus, successful recruitment to the adult portion of the population is often dependent on the availability of suitable nursery habitat. In this thesis, I used field tethering experiments and gut content analyses to assess the …

Impact Of The Parasitic Nematode Anguillicoloides Crassus On American Eels (Anguilla Rostrata) In Chesapeake Bay, Zoemma Taudel Warshafsky

Dissertations, Theses, and Masters Projects

American eels are infected by the introduced parasitic nematode, Anguillicoloides crassus, which can cause significant damage to their swimbladders. Despite the high prevalence and severe damage caused by A. crassus, the population level effects on American eels are not well understood. The prevalence and swimbladder damage in young glass eels and elvers are relatively unstudied, despite the potential for this parasite to cause tissue damage. Additionally, the effects of environmental, temporal, and spatial variables have been debated in previous studies without consensus. Also, the potential for eels to recover from infection and tissue damage has been speculated but not definitively …