The Chesapeake Bay spawning stock of striped bass, Morone saxatilis, is considered one of the largest sources of juvenile production along the Atlantic coast and exhibits a high degree of interannual recruitment variability. Year class strength is judged by near-shore seine surveys that cover major tributaries of Chesapeake Bay and survey results are incorporated into annual stock assessments. In these surveys, the contribution of the Rappahannock River (Virginia) to total production is significant. In this system, abundance of juveniles is highest at a single seine site, suggesting that juvenile production may be related to habitat heterogeneity and food availability. To evaluate this possibility, we describe daily variability in prey consumption, prey composition, and prey selection of juvenile striped bass at the productive site (RK 89) and habitat-specific patterns in feeding along an estuarine gradient that included the productive site. I examined diets of juvenile striped bass collected in five 24-h seine surveys at RK 89 in 1983 and conducted seine hauls at four stations (RK 89, RK 81, RK 71 and RK 60) in 2004. During 24-hr sampling, more fish were caught at 1800 hours and 2100 hours than at other times. In 2004, significantly more fish were caught at RK 89 than at RK 60. Fish were significantly less full at 0300, 0600 and 0000 hours than at all other times. Prey with the highest Index of Relative Importance values were dipteran larvae, calanoid copepods and polychaetes, ranking 1-3 respectively in both years. Peak mean density of Bosmina, other cladocerans, calanoid copepods, and dipteran larvae occurred at RK 89. However, fish were fuller at RK 60 than at RK 89. YOY striped bass showed some indications of selective feeding. As young striped bass grow in the Rappahannock River, they gradually disperse from natal areas into heterogeneous nursery habitats downriver. This ontogeny is reflected in diets as smaller fishes upriver fed on many individuals of smaller plankton prey (especially calanoid copepods) and were less full than cohorts downriver that consumed fewer individuals of larger benthic prey (especially polychaetes).

No description available.

The Longnose Lancetfish, Alepisaurus ferox, is a pelagic marine fish that has a heterodont dentition, including large fangs on both the upper and lower jaws. Their diet is well documented and includes salps, hyperiid amphipods, pelagic polychaete worms, mesopelagic fishes, and cephalopods. However, the function of the heterodont dentition, the structure of the teeth, and replacement mode is largely unknown. We studied a series of A. ferox to describe their dentition and tooth replacement. All teeth are replaced extraosseously. Palatine and dentary fangs develop horizontally in the oral epithelium on the lingual surface of dentigerous bones. Developing fangs rotate into place and attach to the bone through a pedicel that forms at the base of each tooth on the lingual side of the dentigerous bone. We compare extraosseous horizontal tooth replacement and rotation of large fangs in A. ferox to examples of other teleosts rotation of fangs. Atlantic Cutlassfish, Trichiurus lepturus, have large, barbed premaxillary and dentary fangs and sharp, dagger-shaped teeth in their oral jaws. We used dry skeletons, histology, SEM, and micro-CT scanning to study T. lepturus to describe its dentition and tooth replacement. We identified and described three modes of intraosseous tooth replacement in T. lepturus depending on the location of the tooth in the jaw. Such distinct modes of tooth replacement in a teleostean species are unknown. We compared modes of replacement in T. lepturus to 20 species of scombroids to explore the phylogenetic distribution of these three replacement modes. Our study highlights the complexity and variability of intraosseous tooth replacement and that developmentally different tooth replacement processes can yield remarkably similar dentitions. We review literature on the comparative anatomy of Ocean Sunfishes (Molidae) and presents new findings based on our studies. We document similarities and differences among the three living genera, Ranzania, Masturus, and Mola using an organ system approach to examine: general body form and external anatomy; skeleton; integument; brain and sense organs; digestive organs; heart and circulation; respiratory system; excretory system; and endocrine organs. Molids have many anatomical specializations such as the formation of the clavus from dorsal- and anal-fin elements, enlarged gills with unusual skeletal supports, a heart with thick walls and more valves than other teleosts, ontogenetic loss of the swimbladder, enlarged kidneys and a well-developed urinary bladder, reduced otoliths, and a spinal cord contained completely within the braincase. Tagging studies on locomotion and diving behavior demonstrate that molids move efficiently over horizontal and vertical distances in the water column, and this new information helps to interpret the many unusual features of molid anatomy.

No description available.

Typescript. / Bibliography: leaves 267-273. / Photocopy. / Microfilm. / xi, 273 leaves, bound ill., map 29 cm

published_or_final_version / Zoology / Master / Master of Science

Sonic-tagged flannelmouth suckers made long distance and local movements; 12.5% of fish moved ≥ 98 km downstream and 40% stayed within Glen Canyon. Motivation for long distance movements could be spawning or food related. A controlled flood of 1,274 m³/sec did not displace flannelmouth suckers downstream or interrupt spawning. The majority (62%) of fish moved into the impounded mouth of the Paria River. Spawning occurred as evidenced by capture of adults over spawning areas and collection of young-of-year (YOY) in spring and summer. From May-September 1996, YOY flannel mouth suckers were captured in the impounded mouth of the Paria River. Successful rearing of YOY fish was attributed to the presence of a warm, slackwater area in the mouth. Formation of this area is dependent upon antecedent Colorado and Paria river flows and their effect on sediment deposition in the mouth of the Paria River.

Cod, haddock and whiting are among the most economically important species in the Scottish demersal fishery. Juvenile settlement, the transition from pelagic to demersal habitat, has been identified as an important milestone for these species, but there is insufficient knowledge and data about this life stage. It is believed that the period of settlement has an impact on recruitment success, as important density-dependent processes may take place, such as competition for suitable substrate, refuge or prey. Also, knowledge of settlement timing and duration is relevant to understanding population connectivity and thus to the development of successful conservation measures. Sampling was conducted between April and August 2004, June and September 2005 and June and July 2006 at an inshore site off the east coast of Scotland. Over 4000 0- group cod, haddock and whiting were collected. Comprehensive morphometric and dietary analyses of the samples were carried out, followed by statistical analysis of the data. The results suggested clear differences in the patterns of settlement between the different species. Initially juvenile haddock favoured deeper, further offshore locations, while cod occupied shallower, inshore waters. Whiting settled much later in the season and over protracted period of time. Furthermore, cod showed an affinity for structured habitat, while haddock and whiting were found only over sand. The results also showed that the transition from the pelagic to the demersal habitat was associated with clear and progressive changes in the prey composition of the juvenile fish. The results also showed temporal, spatial and dietary niche segregation of settling juveniles, which is expected to reduce competition for resources and increase the potential for settlement success.

A simulation and decision-support software product for aquaculture facility design and management planning is described (AquaFarm, Oregon State University��), including comprehensive documentation and applications to practical problems. AquaFarm provides (1) simulation of physical, chemical, and biological unit processes, (2) simulation of facility and fish culture management, (3) compilation of facility resource and enterprise budgets, and (4) a graphical user interface and data management capabilities. These analytical tools are combined into an interactive, decision support system, for the analysis and development of facility design specifications and management strategies. Intended user groups include aquaculture research, engineering, education, and production. As guided by the user, aquaculture facilities can be of any type, configuration, and management objectives, for purposes of broodfish maturation, egg incubation, and/or growout of finfish or crustaceans in cage, single pass, serial reuse, water recirculation, or solar-algae pond systems. User-accessible specifications include (1) site climate and water supplies, (2) components and configurations offish culture systems, (3) fish and facility management strategies, (4) unit costs for budget items, (5) production objectives (species, time schedules, and fish numbers and weights), and (6) parameters of unit-process and fish performance models. Based on these specifications, aquaculture facilities are simulated, resource requirements are compiled, and operation schedules are determined so that production objectives are achieved. Facility performance is reported to the user as management schedules, summary reports, resource and graphical compilations of time-series data for unit process, fish, and water quality variables. If unsatisfactory resource requirements or unattainable production objectives are found, procedures of iterative design and management refinement are supported. To provide this analytical capacity, a wide range of existing and newly developed, quantitative methods and models are assembled and synthesized into an integrated analytical framework, including aquatic chemistry, aquatic biology, fish biology, aquacultural engineering, and simulation techniques. Unit-process and system-level validation exercises are demonstrated for a wide range of aquaculture facilities, in which (1) facilities are constructed according to reported studies, (2) simulation trials are accomplished, and (3) good agreement between predicted performance and empirical observations is demonstrated, given that sufficient specification of site-specific variables is provided. / Graduation date: 2000

Thesis (M.Sc.)--Memorial University of Newfoundland, 2005. / Bibliography: leaves 201-209.