- / -

- / -

- / -

Pre-Pleistocene freshwater fish assemblages in the eastern United States are exceedingly rare, limited to only a handful of localities. The Gray Fossil Site, an early Pliocene sinkhole fill in northeast Tennessee, has yielded an abundance of vertebrate remains, including fish. Comparison with extant and fossil fish taxa reveals a depauperate ichthyofauna consisting of only two centrarchid genera: Micropterus cf. M. salmoides (black bass) and Lepomis sp. (sunfish). This material includes hundreds of specimens and represents the oldest centrarchid material from the eastern United States; it has potential to inform our understanding of centrarchid evolution and diversification. Fishes of the genus Micropterus are opportunistic predators that feed increasingly on fish and even terrestrial vertebrates as they increase in size. Lepomis, smaller Micropterus, and terrestrial vertebrates such as frogs and salamanders likely formed a major food source for Gray Fossil Site Micropterus. Extant fishes in the genus Lepomis are generally predators of aquatic insect larvae, small crustaceans, zooplankton, and other aquatic invertebrates and prey occasionally on small fish. Lepomis from the Gray Fossil Site were likely non-specialized predators of aquatic invertebrates – they are “short-jawed,” indicating low levels of piscivory and lack the robust pharyngeal jaws associated with extensive feeding on mollusks. Extant species of Micropterus and Lepomis occupy a wide variety of freshwater habitats but typically only spawn in shallow, open water with soft substrate overlying gravels. This suggests these conditions were present in the sinkhole pond. The absence of other fish species that are ubiquitous in streams and rivers in the southeastern United States today suggests that the sinkhole pond was not connected to surrounding waterways by surface hydrology. In addition to large numbers of isolated bones, several articulated and partially articulated fish specimens have also been recovered and show minimal evidence of postmortem disarticulation or scavenging. This suggests a cold and/or anoxic hypolimnion within the sinkhole pond as well as an absence of scavengers such as crayfish, which have not been documented from the site. Osteological thin sectioning of fish atlantes suggests slow growth rates in Gray Fossil Site fishes and small overall size for their age, possibly due to high competition or limited surface area of the pond they inhabited.

Thesis (doctoral)--Rijks-Universiteit te Utrecht, 1931. / Summary in English. Includes bibliographical references and indexes.

The purpose of this creative research project was to develop and evaluate three units of study for the Ichthyology course (Zoology 444/544) offered at Ball State University. Three audio-visual tape/ slide modules were developed entitled: Fish Topography and Measurement, Perch Dissection, and The Lampreys. These instructional modules were presented via Caramate 35mm rear-screen projectors to members of the Ball State University Ichthyology classes in the 1978 and 1979 winter quarters. There were two main goals of these presentations: 1) testing of modules to improve the software through revision of the content, slides, and test questions, and 2) collection of pre- and post-test data for statistical evaluation of module effectiveness toward student short-term learning. After revisions were made to programed content, slides, and test questions, additional pre- and post-test data were collected by presenting the modules to 12 Ecology class students at Huntington College during the 1979 spring semester. A correlated, paired, one-tailed, t-test was computed to compare student means for pre- and post-test scores. Percent gains between pre- and post-test scores were also computed, and test reliability was evaluated using the Kuder-Richardson "20" formula. In addition, four members of the 1979 winter quarter Ichthyology class at Ball State University and 12 members of the Ecology class at Huntington College participated in a student evaluation questionnaire dealing with learning effectiveness, program quality, and testing.A total of six tested null hypotheses (0.05 level) stated that there would be no significant differences between the mean scores of each module's pre- and post-test scores for both the study groups. The t-test data revealed significant differences beyond the 0.0005 level for the three modules in both groups. Since there were significant increases in short-term learning for the three modules, all six null hypotheses were rejected.Mean percent gains comparing pre- and post-test scores were acceptable beyond the 60% level for all three modules of both study groups.The three modules had unacceptable post-test reliability coefficient levels (below 0.70) prior to revisions. After revisions, however, the three module post-tests showed acceptable reliability coefficients beyond the 0.70 level.A majority of students completing the evaluation questionnaire rated items either excellent or good.Items pertaining to learning effectiveness and testing were rated excellent or good by 88% of the students. Software quality was rated excellent or good by 61% of the students. Average module study time ranged from 50 minutes (Module II), to 80 minutes (Module III), with 50 minutes as the highest rated module study time. Students commented that 60 minutes would be an appropriate module study time.

Diets of large marine predators have been extensively studied to assess interactions with fisheries, monitor links between diet and reproductive success, and understand trophic interactions in marine ecosystems. Since marine species can rarely be observed foraging directly, most studies rely on the identification of prey remains in stomach contents or faeces to determine the prey items being consumed. While this approach has provided a wealth of information, it has several limitations resulting primarily from difficulties identifying digested prey and from biased recovery of remains due to differential digestion. My thesis explores the use of molecular genetic methods in dietary studies of large marine predators. DNA-based identification techniques have been used in several diet studies, but the methods and applications are still in the early stages of development. Through a number of studies, I investigated the ability to recover genetic data from various dietary samples using a range of genetic techniques. A) Genetic screening for prey in the gut contents from a giant squid - I assessed the use of polymerase chain reaction (PCR)-based methods for isolation of prey DNA from an Architeuthis gut content sample. A taxonomically informative molecular marker was selected and a screening method developed using denaturing gradient gel electrophoresis. The methodology was used to identify prey from otherwise unidentifiable hard-part remains and the amorphous slurry component of the squid gut sample. The techniques developed here provided a framework for later chapters. B) Analysis of prey DNA in faeces of captive sea lions Part I: DNA detection, distribution and signal persistence - A feeding trial with captive Steller sea lions (Eumetopias jubatus) was carried out to investigate the use of genetic faecal analysis as a tool to study diet. I used group-specific PCR detection to determine: (i) the reliability of prey DNA recovery, (ii) the distribution of prey DNA within faeces and (iii) the persistence of the genetic signal after a prey item was removed from the diet. The proportions of prey DNA in several samples were also determined using a clone library approach to determine if DNA quantification could provide semi-quantitative diet composition data. Results show that the prey DNA could be reliably detected in sea lion faeces and the genetic signal could persist in samples up to 48 hours after ingestion. Proportions of prey DNA isolated from faeces were roughly proportional to the mass of the prey items consumed. Part II: DNA quantification - Quantitative real-time PCR was used to further investigate if quantitative diet composition data could be obtained through quantification of the DNA present in faeces. I quantified the relative amounts of DNA in three fish species being fed to captive sea lions, then determined the amount of DNA recovered from these prey items in the sea lions - faeces. The results indicate that diet composition estimates based on the relative amounts of DNA in faeces can be biased due to the differential survival of DNA from different fish species; however, these biases may be less than those commonly observed in the conventional analysis of prey hard remains. C) Quantification of damage in DNA recovered from faecal samples - I developed a general method to quantify the frequency of DNA damage present in specific gene regions. The technique was applied to assess the amount of DNA damage in predator and prey DNA recovered from sea lion faeces. The estimated frequency of DNA damage was always higher for the prey DNA than for the predator DNA within a faecal sample. The findings have implications for marker development and comparison of results obtained in future DNA-based diet studies. D) Studying seabird diet through genetic analysis of faeces - I investigated the diet of macaroni penguins (Eudyptes chrysolophus) through conventional analysis of stomach contents and through the analysis of prey DNA extracted from faeces. Genetic data was obtained from faecal samples using PCR tests to determine the presence or absence of DNA from potential diet items and also using a clone library approach. Approximately half of the faecal samples tested positive for one or more of the prey groups targeted with PCR tests. Euphausiid DNA was most commonly detected in early stages of chick rearing and DNA from a myctophid fish was prevalent in faeces collected later; this trend mirrored the data obtained from the stomach contents. Analysis of prey sequences in 'universal'clone libraries revealed a highly biased recovery of sequences from fish prey; this bias is most likely caused by the use of degenerate primers with a higher binding affinity for fish DNA template compared to DNA from other prey groups. Results obtained from the genetic and traditional approaches are compared, and potential future applications of the genetic techniques to studying seabird diet are discussed. This series of studies has contributed significantly to our understanding of the strengths and the limitations of DNA-based diet analysis. The work identifies situations where genetic methods can be successfully applied to study the diet of marine predators and provides guidance for future studies in this emerging field.

The currently most accepted population theory for reef fish was developed on tropical reefs and suggests that populations of most reef fish species are limited primarily by recruitment, with little post-recruitment resource limitation. I tested the validity of this theory for temperate reef fishes by examining growth rates in six common species from a number of isolated populations for evidence of resource limitation. If resources are limiting, spatial and temporal variation in recruitment and mortality should lead to isolated populations experiencing differing levels of resource availability, particularly food availability, which will be reflected in growth rates. I worked with six of the most common reef fishes found in Tasmanian waters so that any findings would form the basis of a broadly applicable model. These were Notolabrus tetricus, Notolabrus fucicola, Pictilabrus laticlavius, Pseudolabrus psittaculus, Penicipelta vittiger, and Meuschenia australis. Before examining growth rates it was first necessary to define the scale at which populations could be considered to be isolated. The short and long-term movement patterns of each species were studied using visual observations to interpret short-term patterns, and recaptures of tagged fish to interpret the long-term patterns. Methods of ageing each species were developed and validated, with growth rates of tagged fish being used to validate the use of otoliths for ageing. General growth curves are presented. For most of the species, there was some uncertainty in current texts about the sexual system used and the relationship between sex and dichromatism and dimorphism. To clarify this situation the reproductive biology of each species was examined. The relationship between sex and growth rate was also examined. For two species (N. tetricus and N. fucicola) annual growth data from tagged fish were obtained over a 3-4 year period, allowing inter-annual growth variability to be examined. As well as providing an insight into the variability of growth with time, these results also aid in the interpretation of growth curves determined from otolith ageing. In all species investigated, no significant differences in growth rates were detected between populations occupying similar habitats and subject to similar environmental conditions. These results suggest that post-recruitment resource limitation in the form of food limitation may not be an important factor influencing the post recruitment growth and survival of many temperate reef fishes with pelagic larval stages. This agrees with the assumptions made, but rarely tested, in current theories concerning the regulation of populations of reef fish, particularly those on temperate reefs.

Research into small-scale fisheries is often insufficient, resulting in limited data, because this type of fishery is inevitably constrained by financial considerations. This creates a challenge to provide adequate information to support sustainable management, particularly given the shift from single species management to more integrated spatial and multi-species management and, ultimately, to ecosystem based fisheries management (EBFM). Striped trumpeter (Latris lineata) is widely distributed around the temperate latitudes of the southern hemisphere. The species is iconic to Tasmania where it supports a small commercial fishery, and it is increasingly targeted by recreational fishers. This fish is common on most rocky reefs between 50 – 250 m around Tasmania. However, the historical data for striped trumpeter from Tasmania is patchy in time and space, reflecting opportunistic sampling over many years. Using striped trumpeter as an example of a small-scale data-limited fishery, this study applies a variety of techniques to describe key biological and ecological processes required for sustainable fisheries management. The study was divided into three themes. First, standard and novel analytical techniques were applied to evaluate data to provide key biological parameters required for single-species assessment. Second, stock structure was investigated on both local and global scales using molecular techniques and otolith morphometrics. Finally, recruitment processes were investigated based on otolith microchemistry and modelling of larval dispersal. Seasonal growth variability was observed over the first five years, with growth rates peaking approximately one month after the observed peak in sea surface temperature. The oldest fish in this study was 43 years. Lifetime growth was modelled using a modified twophase von Bertalanffy growth function, with the transition between growth phases linked to changes in physiological and life history traits, including offshore movement as fish approach maturity. Total mortality was estimated using catch curve analysis based on the standard and two-phase von Bertalanffy growth functions, and estimates of natural mortality were calculated using two empirical models, one based on longevity and the other based on the parameters L1 and k from both growth functions. The spawning season around Tasmania occurs in the austral spring, with peak spawning activity in September and October. Size at 50% maturity was estimated at 543 mm fork length (FL) for females (estimated age = 6.8 years) and 529 mm FL for males (estimated age = 6.2 years). Striped trumpeter is a multiple spawner with batch fecundity estimates ranging from 205,054 for a 2 kg fish (540 mm FL) to 2,351,029 for a 9.5 kg fish (800 mm FL). At the current minimum legal size limit of 450 mm total length (equivalent to approximately 425 mm FL), yield-per-recruit was estimated to be close to maximum, and spawning biomass-per-recruit (SPR) ranged from 35 – 52% of virgin stock, depending on the mortality estimates used. Otolith morphometrics, in particular elliptical Fourier analysis of otolith shape, indicated little to no connectivity between the striped trumpeter population of Tasmania and the St. Paul/ Amsterdam Island populations. A molecular assessment of mtDNA confirmed this finding. In addition, the DNA sequence analysis indicated that the New Zealand striped trumpeter population was genetically distinct from the Tasmanian and St. Paul/ Amsterdam Island populations. DNA sequence analysis also indicated that the population around Tasmania is a single population. The affinity of juvenile striped trumpeter to inshore reefs has been suggested from anecdotal fishing observations. Using otolith microchemistry the comparative contribution of juvenile striped trumpeter from shallow inshore habitats to the adult population was estimated. Juvenile striped trumpeter from a strong recruitment pulse (1993 cohort) were collected at age two from inshore reefs and as adults at age six from deeper offshore reefs around the coast of Tasmania. Natural variations were identified in the concentrations of lithium and strontium within the incremental structure of the observed otoliths. Discriminant analysis suggested that 70% of adults sampled originated from an inshore juvenile habitat, 13% were from deeper reefs and 17% could not be statistically allocated with confidence. An integrated bio-physical larval dispersal model was developed in an attempt to explain the high degree of inter-annual recruitment variability displayed by this species. The model utilised information developed through the course of this study on reproductive biology, ontogenic habitat preferences and stock structuring as well as additional information on striped trumpeter larval biology from aquaculture trials to generate realistic scenarios. While the model was unable to accurately predict observed interannual recruitment variability, it did provide insights to important source and settlement regions as well as the importance of the addition of biological components, such as: timing of spawning, growth and mortality. Through efficient data-mining, novel methods and technological advancements this study has provided robust scientific advice to support the management of the striped trumpeter fishery. Information has been collated to support traditional single-species management and also for developing spatial fisheries measures, leading to a more ecosystem based approach to fisheries management. Otoliths proved to be valuable in several areas, and small-scale fisheries would be advised to initiate otolith collections even though analysis may not be planned for some time. This study demonstrates how targeted research could be used in other small-scale data limited fisheries in a cost effective manner to provide information for sustainable management.

Thesis (doctoral)--Rijks-Universiteit te Utrecht, 1931. / Summary in English. Includes bibliographical references and indexes.