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Baltzly, M.; Hendrickson, D. A. |
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The new Desert Fishes Council World Wide Web server on Internet |
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deserts-; freshwater-fish; computers-; conferences-, World-Wide-Web; internet- |
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The Desert Fishes Council has moved into the world of electronic publishing on the Internet. Dr. John Rinne (U.S. Forest Service, Flagstaff, Arizona) has allowed the first author to scan his well-known collection of fish photographs into digital format. They have been variously cropped and enhanced, and can now be viewed in different formats or downloaded by anyone in the world with Internet access. The second author is converting the Proceedings (staring with Vol. 24 [1992 meeting]) to hypertext format, so they may be browsed, searched or downloaded. All future DFC Proceedings will be published on WWW at the same time final hard copy is sent to the printer. The World Wide Web (WWW) allows anyone who has obtained free, public domain client software (readily available on Internet), primarily one called Mosaic, to browse effortlessly through multimedia files (graphics, video, sound, formatted text) that are stored on computers around the globe. Multimedia presentations can combine real-time sound, graphics and video with text. Exploration of WWW and the DFC system using Mosaic is facilitated by hypertext links, which offer the simplicity of “point and click” movement through the “cyberspace” of WWW. The Texas Memorial Museum of the University of Texas at Austin is providing storage space for these large DFC files at no charge as a pilot project for other WWW projects at UT, and can likely continue to provide this service for the forseeable future if it receives the usage and growth are predicted. All DFC members are encouraged to provide additional text, graphics and other files for inclusion in the system. Growth of the Internet has been phenomenal, and as more and more people throughout the world obtain access to it, these electronic files will allow DFC to better reach a far larger audience than was formerly possible. DFC members and others using materials provided here will be better equipped to educate the public regarding the plight of desert fishes. The system should also improve communications among ourselves and with others regarding fish conservation efforts throughout the world, and eventually should lead to reduced costs of publishing the Proceedings. |
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131 |
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Borregon, J. L.; Paredes, C.; Elorza, F. J. |
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New algorithms for the statistical modelling of geological heterogeneous media: Comparative results |
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algorithms-; statistical-analysis; heterogeneity-; radioactive-waste-disposal; geology-; simulation-; aquifers-; geochemistry-; groundwater-pollution; pollution-control; waste-disposal-sites; environmental-protection |
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The characterization of an heterogeneous geological media can be approached by means of an statistical treatment of the field data. This lets us know its spatial variability behaviour, in probability terms. The algorithms presented in this work belongs to the scope of simulation of geological heterogeneous random fields. The aim of that characterization is related with the reseach studies of nuclear waste repositories in deep geological structures. Several stochastic generation algorithms are presented, based in the geostatistical regionalized variable, fractal geometry, and spectral Fourier theories. Some of them are deeply exposed here to their understanding. As a result of the paper, some comparative schemes are showed with numerical, geostatistical and spectral analysis of the implicit autorregresive generation methods. |
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241 |
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Coppola, S. R.; Fischer, W.; Garibaldi, L.; Scialabba, N.; Carpenter, K. E. |
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Global species database for fishery purposes. User's manual |
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1994 |
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fishery-data; data-collections; fishery-resources; commercial-species; information-retrieval; manuals-; FAO-; books-, Speciesdab- |
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The SPECIESDAB manual describes the use of software created to assist in the retrieval of information relevant to species of interest to fisheries. Data on scientific and vernacular nomenclature, biology, fishing gears, and geographical distribution are included for species that belong to certain marine resource groups. This information is derived from the FAO Fisheries Department species identification and data programme publications and the software is designed to permit continual updating as new publications on other resource groups appear. To date, some 25 major resource groups are covered. Among these are shrimps, lobsters, cephalopods, sharks, marine turtles, and 20 families of bony fishes, which together form a significant component of world fisheries. The program uses a menu system to provide users easy access to the information contained in SPECIESDAB. The manual includes extensive examples of how to use the software. On-line help is also available. Extensive query and reporting capabilities are provided to access data on valid scientific names, synonyms, national and local names, official FAO trilingual names, size, habitat, behaviour, kinds of gear utilized in the fishery, and level of interest to fisheries. Geographical information may be obtained by species, by country, or by fishing area. Data may be extracted for either a single resource group or for all resource groups in combination. Furthermore, the user interested in using only the data of species occurring in a particular geographical area can create, with the Regional option, a sub-database including only the species found in the countries selected. This option can be useful for regional bodies and working groups. SPECIESDAB includes a bibliographic reference system, which may be updated by the user as well as utilities for exporting data. |
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316 |
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Fotland, A.; Mehl, S.; Sunnanaa, K. |
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Methods of index calculation and presentation of fish abundance data using standard computer programs |
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1995 |
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fishery-management; fishery-statistics; stock-assessment |
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Standard 0-group indices and distribution maps are now produced based on hand-drawn maps using AutoCad with some additional procedures. This paper briefly describes the method. The paper further describes ways of importing coastlines and survey data directly into standard computer programs such as AutoCad and SAS. Standard methods are used for gridding data, producing isolines and further calculation of abundance indices and presentation of distributions. Interactive editing of distribution maps are made, which makes corresponding automatic updating of indices possible. |
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435 |
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He, X. |
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Effects of predation on a fish community: A whole lake experiment |
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1990 |
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predation-; interspecific-relationships; freshwater-fish; population-dynamics; Esox-lucius; Phoninus-eos; Lepomis-; Semotilus-atromaculatus; freshwater-ecology |
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Studies of predator-prey interactions have been limited to laboratories or relatively small scale field experiments because of logistic difficulties in large scale field experiments. Much evidence has suggested that predictions based on small scale experiments on predator-prey interactions may not be simply extended to large scales, e.g. whole system. This study was designed to examine predation effects on a prey fish assemblage at the whole lake scale. After a year of premanipulation study, northern pike (Esox lucius) were introduced into a small piscivore-free lake inhabited by 14 species of fishes. In the third and fourth years, the lake was divided by a large mesh fence and northern pike were introduced into one half of the lake. Predation effects on individual prey population were estimated for both direct effects (i.e., consumption of prey species) and indirect effects, including habitat changes associated with predator avoidance behavior, increase of emigration rates and changes of population size structure. The relative importance of direct versus indirect effects was examined using randomized intervention analysis along with a model that quantifies the indirect effects. Decreases of prey fish biomass due to increased emigration was at least as great as that due to the direct effect of consumption when prey biomass was high (>40 kg/ha) but not when prey biomass was low (<30 kg/ha). Significant indirect effects included dramatically decreased abundance of the dominant species (northern redbelly dace, Phoxinus eos), increase of some rare species (sunfish, Lepomis spp. and creek chub, Semotilus atromaculatus), and decreased mean sizes of redbelly dace. Indirect effects occurred rapidly and were most apparent immediately following the introduction of northern pike. Community responses to northern pike predation included changes of species composition, species diversity and community stabilities. The fish communities were significantly different among the pre-pike period, pike period and post-pike period. The greatest variance was related to abundances of redbelly dace and sunfish. However, predation effects on the prey fish community depended on the observational scales used to determine community structure. (DBO) |
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628 |
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Kaiser, M. S. |
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Statistical models for limiting factors in ecology |
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1991 |
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biological-production; energy-transfer; trophic-levels; aquatic-environment; statistical-analysis; limiting-factors; ecosystems-; ecology- |
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For several decades, aquatic ecologists have debated differing viewpoints on the factors that control ecosystem productivity. Much of the controversy centers on the interpretation of empirical relationships between factors that limit the amount of energy transferred among trophic levels in aquatic ecosystems. The primary statistical tool used has been regression analysis, but such models often fail to explain a substantial portion of the variability observed. The suggestion has been made in the literature of aquatic ecology that regression models may be inappropriate, and that limiting factors may be better related to the maximum rather than mean response. Statistical models that account for the large variability in relationships between limiting factors and response variables at higher trophic levels and shift the focus from description of expected values to description of upper boundaries have not been developed. The goal of this project was to develop statistical models for the relationships between limiting factors and the maximum output of biological processes. A number of models may be formulated, one of the primary being Y sub(i) – gamma x sub(i)U sub(i) + sigma epsilon sub(i), where gamma > 0, U sub(i) similar to iid Beta ( alpha , beta ), the x's are considered fixed values on the real line, and the error terms, epsilon sub(i), are centered iid random variables. This model describes a triangular array of points lying between zero and a straight line with positive slope, a data pattern seen numerous times in the ecological literature. The response variable Y is an identifiable mixture of the random variable U, with the model representing a situation in which Y is observed but U is unobserved. Maximum likelihood estimates for the parameters ( alpha , beta , gamma , sigma ) may be computed using the EM algorithm. Estimation is based on maximization of the expected full-data likelihood where the expectation is taken with respect to the conditional density of U given Y. A portion of the dissertation is devoted to the confirmation of asymptotic properties as the response variable, Y sub(i)'s, are not identically distributed. A set of conditions depending on the identically distributed error terms is given for consistency and asymptotic normality of MLE's. The model specific conditions are met by a number of error densities. (DBO) |
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772 |
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Leshkevich, G. A. |
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Great Lakes CoastWatch program update |
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1995 |
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North-America,-Great-Lakes; monitoring-; decision-making; satellite-technology; coastal-waters; ecosystems-; data-transmission; environmental-monitoring; satellite-sensing |
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As the CoastWatch regional node for the Great Lakes, the Great Lakes Environmental Research Laboratory (GLERL) is working to obtain and/or develop and deliver environmental data and products for near real-time monitoring of the Great Lakes to support environmental science and decision making. In support of this goal, GLERL is providing access to near real-time and retrospective satellite observations and in-situ data for the Great Lakes to Federal, state, and local agencies and academic institutions. There are currently nearly 40 regional CoastWatch users. The goals and objectives of the Great Lakes CoastWatch Program directly support agency statutory responsibilities in estuarine and marine science, living marine resource protection, and ecosystem monitoring and management. GLERL is currently receiving an enhanced digital image product suite of 26 images including satellite derived surface-temperature, visible and near-infrared reflectance, brightness temperatures, satellite and solar zenith angle data, and cloud masks from the NOAA-12 satellite. These products are downloaded from the NOAA Ocean Products Center (OPC) via INTERNET on a daily basis and archived at GLERL. Over 32,000 image products have been received and archived since becoming the Great Lakes CoastWatch Node in 1990. GOES-8 data is also currently being received. |
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1005 |
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Ragen, T. J. |
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The estimation of theoretical population levels for natural populations |
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1991 |
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environmental-conditions; biological-production; marine-mammals; marine-fish; population-dynamics; size-distribution; computer-programs; simulations-; frequency-analysis; migratory-species; Callorhinus-ursinus; Atractoscion-nobilis; Seriola-lalandei; Stereolepis-gigas; INE,-USA,-California; ISW,-USA,-Alaska,-St.-Paul-Island, carrying-capacity |
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The focus of this dissertation was the estimation of theoretical reference levels such as K, the environmental carrying capacity, and MNPL, the maximum net productivity level, for three fishes off Southern California and for the northern fur seal (Callorhinus ursinus) population of St. Paul Island, Alaska. The estimation techniques were based on computer modeling of historical population trends. The assessment of these theoretical reference levels for nature populations is fundamentally important to the development and testing of concepts in theoretical ecology and population dynamics. In the first study, maximum-likelihood estimates of pre-exploitation biomass were made for the white seabass (Atractoscion nobilis) and the yellowtail (Seriola lalandei) by assuming that development of corresponding commercial fisheries led to a shift in size distributions of these fishes, as indicated by records of the Avalon Tuna Club, Santa Catalina Island, California. Pre-exploitation biomass for Southern California populations of both these fishes was estimated to be about 20,000 tons. The pre-exploitation biomass of the giant sea bass (Stereolepis gigas) was estimated to be 1300 tons. Due to insufficient natural history information, this estimate was based on commercial catch records only. In the second study, estimates of theoretical reference levels for the northern fur seal population of St. Paul Island were based on computer simulations of pup production from 1912 to 1970, repetitive simulations were used to construct frequency distributions of estimates for MNPL, K, the number of pups born at MNPL and K, and the ratio MNPL/K. These distributions serve as a measure of the confidence that can be placed in single estimates of reference levels, and thereby provide a general context within which these reference levels can be evaluated. The final study of this dissertation investigated the pelagic migration of northern fur seal pups. Results indicated that initial migration paths for these pups are more widely dispersed than previously assumed. This information contributes to the understanding of northern fur seal life histories. A fuller understanding of life history information will eventually facilitate more accurate modeling of northern fur seal population dynamics. (DBO) |
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1311 |
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Sparre, P. J. |
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The data requirements for basic fisheries bio-economics |
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1994 |
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fishery-economics; stock-assessment; economic-feasibility |
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The paper discusses the links between fish stock assessment and economics of fisheries, as perceived by a fisheries biologist. It focuses on the type and format of data required from the biological side as well as the economic side, to merge the biological and the economic methodologies into a bio-economic methodology. The biological methodology in question derives from the analytical approach, which operates with cohorts and size distributions of several stocks exploited by several fleets fishing on several fishing grounds. The economic methodology comprises costs and earnings analysis of the harvesting and the processing sectors, and computations of indicators for the economic performance of the sub-sectors. The paper is based on applications of bio-economics to tropical fisheries (targeting at shrimps). The methodology has been applied during a series of workshops and seminars organized by the Fisheries Department of FA0. The paper addresses both biologists and economists. |
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1593 |
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Whitmarsh, D.; Voit, E. O.; Balthis, W. L.; Holser, R. A. |
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A spreadsheet model of renewable resource exploitation – Hierarchical Monte Carlo modeling with S-distributions: Concepts and illustrative analysis of mercury contamination in king mackerel |
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1991 |
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Renewable-resources; Mathematical-models; Natural-resources; Economics-; Dynamic-analysis, Environmental-economics, Monte-Carlo-method; simulation-; numerical-analysis; mercury-; bioaccumulation-; fish-; quantitative-analysis; statistical-models; data-processing; pollution-effects; mathematical-models; scomberomorus-cavalla, S-distributions |
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Increasing numbers of students now study natural resource and environmental economics at undergraduate level, and this interest in the subject has been matched by a corresponding expansion in the number of textbooks and other learning material available for use. Unfortunately one very important aspect of natural resource economics which is often not adequately dealt with in the undergraduate literature concerns the question of dynamics: how rapidly will a resource become exploited, and what time path will it follow? These issues are particularly relevant to the management of renewable resources such as fish stocks whose survival depends on factors such as the rate of entry and exit by the exploiting firms, and the ability of the resource to recover from the effects of intense harvesting. The fault of most textbooks stems not from a failure to cover the question of dynamics, but rather that the treatment is often too advanced or mathematical for the majority of students. Computers can make a useful contribution to our understanding of the dynamics of natural resource exploitation, and in this example the case of marine commercial fishery exploited under 'open-access' conditions is considered. The quantitative assessment of environmental contaminants is a complex process. It involves nonlinear models and the characterization of variables, factors, and parameters that are distributed and dependent each other. Assessments based on point estimates are easy to perform, but since they are unreliable, Monte Carlo simulations have become a standard procedure. Simulations pose two challenges: They require the numerical characterization of parameter distributions and they do not account for dependencies between parameters. This paper offers strategies for dealing with both challenges. The first part discusses the characterization of data with the S-distribution. This distribution offers several advantages, which include simplicity of numerical analysis, flexibility in shape, and easy computation of quantiles. The second part outlines how the S-distribution can be used for hierarchical Monte Carlo simulations. In these simulations the selection of parameter values occurs sequentially, and each choice depends on the parameter values selected before. The method is illustrated with preliminary simulation analyses that are concerned with mercury contamination in king mackerel (Scomberomorus cavalla). It is demonstrated that the results of such hierarchical simulations are generally different from those of traditional Monte Carlo simulations. |
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