Browsing by Author "Maughan, O. Eugene"

Now showing 1 - 6 of 6
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    Analysis of catchable trout fisheries management by computer simulation
    Hammond, Dennis Edward (Virginia Tech, 1974-03-05)
    Although strategies to meet most management objectives are relatively clearcut in single-species catchable trout programs, strategies become much more complex when two or more species are involved. A difficult problem that must be faced in evaluating catchable trout fisheries management strategies is defining management objectives. One approach to testing alternative management strategies in complex resource systems, such as catchable trout fisheries, is systems simulation. A computer-implemented catchable trout fishery simulator (CATS) was developed to evaluate fishery response under various management strategies in a multi-species stocking program. The user of CATS can select alternative management strategies and functions which generate predictions of fishing pressure on a particular fishery. To evaluate the effect of each system component, CATS was exercised over a wide range of potential system component alterations. Predominant stocking of brook trout appreciably increased average catch per angler hour and percentage return to creel. Altering the stocking ratio to favor brown trout substantially increased the number of angler hours. Stocking predominantly rainbow trout reduced the effects caused by stocking predominantly brook or brown trout. Estimates of expected angling pressure ru1d catchability coefficients of each species stocked are of primary importance because of their considerable effect on other system components. A user must have a sound objective before deciding where, when, which species, and how many fish to plant. The primary utility of CATS is to enable the user to evaluate management strategies prior to implementation.
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    Changes in the invertebrate populations, fish populations, and water chemistry of a small stream above and below two impoundments
    Connor, Laurence Lee (Virginia Tech, 1977-06-15)
    The major impacts associated with the ponds appeared to be an alteration of energy dynamics. The alterations were seasonally dependent, and may have resulted from interception of larger particle organic matter being transported downstream and its replacement by finer organic matter. The alterations manifested themselves in changes in numbers and biomass of benthic macroinvertebrates and fish, and changes in drift patterns below the ponds. The energy dynamics alterations may have also influenced competitive interactions among benthic organisms and fish. The direct influence of physiochemical alterations appeared to be masked by energy-related alterations; however, alterations in physiochemical factors may have caused minimal changes in species composition in aquatic communities below the ponds. Material impacts in the system studied appeared to be negligible; however, Young (unpublished data) found significant impacts associated with the introduction of a floc of iron and iron bacteria below a bottom release impoundment. Material impacts may be of major importance in bottom release systems. The ponds appeared to cause a general increase in stream productivity downstream. However, increased amplitude in seasonal fluctuations of physiochemical factors combined with seasonal fluctuations in energy below the ponds appeared to produce a more fluctuating environment below the ponds leading to reduced stability in downstream communities. The impacts evidenced in this study do not appear to be as drastic as those reported in larger systems, There were no large-scale alterations in species composition or reductions in number of taxa present below the ponds. In systems containing rare species or with uniquely adapted faunas, the less stable environmental conditions, possible introduction of exotic species, and the possible disruption of competitive balance with the system may cause major impacts. These possible impacts should be dealt with in the design and planning of small pond construction.
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    Evaluation of stream improvement practices in southeastern trout streams
    Maughan, O. Eugene; Nelson, Kent L.; Ney, John J. (Virginia Water Resources Research Center, Virginia Polytechnic Institute and State University, 1978)
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    An evaluation of the removal method for estimating benthic populations and diversity
    Carle, Frank Louis (Virginia Tech, 1976-05-15)
    A Circular Depletion Sampler (the CDS) was constructed in order to collect removal data for estimating benthic sample populations and species catchability. The removal sampling method was compared to Modified Hess, Surber, and Kicknet sampling methods, and gave consistently higher and less variable estimates than other methods. Taxa showing the lowest catch abilities included the case-building Trichoptera, the Mollusca, and the Annelida. The highest catch abilities were shown by the smaller Chironomidae and the nonburrowing Ephemeroptera. Taxa with high catchability generally showed high emigrability for Surber and Kicknet methods, particularly the aquatic Insecta. The determination of species richness and evenness diversity was significantly biased by low catchabilities or emigration or both with Modified Hess, Surber, and Kicknet sampling methods. Removal samples have a higher probability of representing rare species, and as expected, pooled removal collections accumulated species at a higher rate than the pooled collections of other methods. The dominance diversity of pooled CDS collections became stable more rapidly than those of other methods, and gave higher resolution between benthic communities of different structure. DPLETE, a computer program for making removal population estimates by the method of Carle and Strub (1976) and making dominance diversity estimates based on information theory is presented, and is suitable for use in any study where removal data has been collected.
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    How to build a freshwater artificial reef, Second edition
    Prince, Eric D.; Maughan, O. Eugene; Brouha, Paul (Sea Grant, Extension Division, Virginia Polytechnic Institute and State University, 1977)
    Construction of artificial reefs in marine waters is a popular method of improving saltwater sport fishing. Steimle and Stone (1973) have compiled a voluminous bibliography on the subject, and Parker et al. (1974) of the National Marine Fisheries Service have published a guide, How to Build a Marine Artificial Reef, as an aid in planning and constructing artificial reefs in marine environments. Fishing in lakes, reservoirs, and ponds also may be improved by proper use of artificial reefs. However, the freshwater reef builder is confronted with problems somewhat different from those encountered by ocean reef builders. The purpose of this publication is to offer updated guidelines for planning and constructing artificial reefs in freshwater.
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    The role of forest debris in a southeastern stream and the effects of its removal on trout populations
    Coulston, Patrick J. (Virginia Tech, 1977-01-15)
    Measurements of substrate composition, cover characteristics, and trout populations and biomass were made at a total of ten sites on South Fork Mills River and one of its tributaries. Poplar Creek, in 1975 and 1976. Besides providing cover debris accumulations generally caused a reduction in stream velocity with accompanying deposition of smaller substrate types. Removal of debris caused a shift to larger substrates. A multiple regression treatment of the physical characteristics and trout populations indicated that regression models relating the presence of debris and large substrates (interpreted here as increasing water flow) to trout populations were the only ones significant at the .1 level and accounted for 58% of the variation in trout biomass. The presence of debris could account for none of the variations in trout numbers. Areas containing debris were found to contain populations made up of larger fish than areas without debris. The effects of debris removal were not clear cut, however, there was a trend towards reduced biomass but not necessarily reduced number of trout. This was probably due to decreases in cover, which made the areas less desirable for large trout, but increased flows which favored smaller trout.