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Your search keyword '"Irwin, Elise R."' showing total 29 results
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29 results on '"Irwin, Elise R."'

7. Identifying monitoring information needs that support the management of fish in large rivers

Author

Counihan, Timothy D., primary, Bouska, Kristen L., additional, Brewer, Shannon K., additional, Jacobson, Robert B., additional, Casper, Andrew F., additional, Chapman, Colin G., additional, Waite, Ian R., additional, Sheehan, Kenneth R., additional, Pyron, Mark, additional, Irwin, Elise R., additional, Riva-Murray, Karen, additional, McKerrow, Alexa J., additional, and Bayer, Jennifer M., additional

Published
2022
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9. Tuning stochastic matrix models with hydrologic data to predict the population dynamics of a riverine fish

Author

Sakaris, Peter and Irwin, Elise R.

Subjects
Coosa River, Alabama, USA, dams, fishes, flathead catfish, hydrology, lotic, matrix model, Ocmulgee River, Georgia, USA, population dynamics, Pylodictis olivaris, riverine, river regulation
Abstract

We developed stochastic matrix models to evaluate the effects of hydrologicalteration and variable mortality on the population dynamics of a lotic fish in a regulated riversystem. Models were applied to a representative lotic fish species, the flathead catfish(Pylodictis olivaris), for which two populations were examined: a native population from aregulated reach of the Coosa River (Alabama, USA) and an introduced population from anunregulated section of the Ocmulgee River (Georgia, USA). Size-classified matrix models wereconstructed for both populations, and residuals from catch-curve regressions were used asindices of year class strength ( i.e., recruitment). A multiple regression model indicated thatrecruitment of flathead catfish in the Coosa River was positively related to the frequency ofspring pulses between 283 and 566 m3/s. For the Ocmulgee River population, multipleregression models indicated that year class strength was negatively related to mean Marchdischarge and positively related to June low flow. When the Coosa population was modeled toexperience five consecutive years of favorable hydrologic conditions during a 50-yearprojection period, it exhibited a substantial spike in size and increased at an overall 0.2%annual rate. When modeled to experience five years of unfavorable hydrologic conditions, theCoosa population initially exhibited a decrease in size but later stabilized and increased at a 0.4% annual rate following the decline. When the Ocmulgee River population was modeled toexperience five years of favorable conditions, it exhibited a substantial spike in size andincreased at an overall 0.4% annual rate. After the Ocmulgee population experienced five yearsof unfavorable conditions, a sharp decline in population size was predicted. However, thepopulation quickly recovered, with population size increasing at a 0.3% annual rate followingthe decline. In general, stochastic population growth in the Ocmulgee River was more erraticand variable than population growth in the Coosa River. We encourage ecologists to developsimilar models for other lotic species, particularly in regulated river systems. Successfulmanagement of fish populations in regulated systems requires that we are able to predict howhydrology affects recruitment and will ultimately influence the population dynamics of fishes.

Published
2021
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14. Can data from disparate long-term fish monitoring programs be used to increase our understanding of regional and continental trends in large river assemblages?

Author

Counihan, Timothy D., primary, Waite, Ian R., additional, Casper, Andrew F., additional, Ward, David L., additional, Sauer, Jennifer S., additional, Irwin, Elise R., additional, Chapman, Colin G., additional, Ickes, Brian S., additional, Paukert, Craig P., additional, Kosovich, John J., additional, and Bayer, Jennifer M., additional

Published
2018
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16. Using structured decision making to manage disease risk for Montana wildlife

Author

Mitchell, Michael S., primary, Gude, Justin A., additional, Anderson, Neil J., additional, Ramsey, Jennifer M., additional, Thompson, Michael J., additional, Sullivan, Mark G., additional, Edwards, Victoria L., additional, Gower, Claire N., additional, Cochrane, Jean Fitts, additional, Irwin, Elise R., additional, and Walshe, Terry, additional

Published
2012
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28. Using structured decision making to manage disease risk for Montana wildlife

Author

Mitchell, Michael S., Gude, Justin A., Anderson, Neil J., Ramsey, Jennifer M., Thompson, Michael J., Sullivan, Mark G., Edwards, Victoria L., Gower, Claire N., Cochrane, Jean Fitts, Irwin, Elise R., and Walshe, Terry

Abstract

We used structured decision‐making to develop a 2‐part framework to assist managers in the proactive management of disease outbreaks in Montana, USA. The first part of the framework is a model to estimate the probability of disease outbreak given field observations available to managers. The second part of the framework is decision analysis that evaluates likely outcomes of management alternatives based on the estimated probability of disease outbreak, and applies managers' values for different objectives to indicate a preferred management strategy. We used pneumonia in bighorn sheep (Ovis canadensis) as a case study for our approach, applying it to 2 populations in Montana that differed in their likelihood of a pneumonia outbreak. The framework provided credible predictions of both probability of disease outbreaks, as well as biological and monetary consequences of management actions. The structured decision‐making approach to this problem was valuable for defining the challenges of disease management in a decentralized agency where decisions are generally made at the local level in cooperation with stakeholders. Our approach provides local managers with the ability to tailor management planning for disease outbreaks to local conditions. Further work is needed to refine our disease risk models and decision analysis, including robust prediction of disease outbreaks and improved assessment of management alternatives. © The Wildlife Society, 2012

Published
2013
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29. Acute Toxicity of an Acid Mine Drainage Mixing Zone to Juvenile Bluegill and Largemouth Bass.

Author

Henry, Theodore B., Irwin, Elise R., Grizzle, John M., Wildhaber, Mark L., and Brumbaugh, William G.

Abstract

The toxicity of an acid mixing zone produced at the confluence of a stream that was contaminated by acid mine drainage (AMD) and a pH-neutral stream was investigated in toxicity tests with juvenile bluegill Lepomis macrochirus and largemouth bass Micropterus salmoides. Fish mortalities in instream cages located in the mixing zone, below the mixing zone, and upstream in both tributaries were compared to determine relative toxicity at each site. In all tests and for both species, significantly higher mortality was observed in the mixing zone than at any other location, including the acid stream, which had lower pH (2.9-4.3). The mixing zone was defined chemically by rapid precipitation of dissolved aluminum and iron, which arrived from the low-pH stream, and by the presence of white precipitates, which were attached to the substratum and which extended below the confluence. Possible seasonal changes in mixing zone toxicity were investigated by conducting field tests with bluegill in June, July, and August 1996 and in January 1997 and by conducting field tests with largemouth bass in April and May 1997. Toxicity was not significantly different at the extremes of temperature, pH, and metal concentration that occurred in June and July, as compared with January. Toxicity was significantly lower in August; however, elevated stream discharge during the August test may have disturbed mixing zone characteristics. High toxicity in AMD mixing zones may lower the survival of fishes in streams, reduce available habitat, and impede movements of migratory fish. [ABSTRACT FROM AUTHOR]

Published
1999
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