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Transparency and Temperature Effects on Benthic Trawl Efficiency in Large River Habitats

Transparency and Temperature Effects on Benthic Trawl Efficiency in Large River Habitats. Sean Reese Marshall University Thesis proposal Spring 2008. What is benthic trawling. http://oceanexplorer.noaa.gov. Alternative Sampling Method Electro Fishing Gill Net Seine Net.

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Transparency and Temperature Effects on Benthic Trawl Efficiency in Large River Habitats

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  1. Transparency and Temperature Effects on Benthic Trawl Efficiency in Large River Habitats Sean Reese Marshall University Thesis proposal Spring 2008

  2. What is benthic trawling http://oceanexplorer.noaa.gov • Alternative Sampling Method • Electro Fishing • Gill Net • Seine Net

  3. Why benthic trawling? Tom Jones 2007 • Increase Species Detection • Reduce Zero Catch • Species Specific • Modifications • Bio-Indicators

  4. Electro fishing efficiency 500 m reach at river mile 160.2 Bathyometric map of 500 m reach at river mile 160.2 S. Reese/C. Swecker

  5. Trawl protocol Dr. Tom Jones 2006

  6. S.Reese

  7. Transparency • Photic Zone • How far light is visible through the water column. • Photosynthesis • Temperature • Dissolved Oxygen • Organisms

  8. Null Hypotheses Transparency has no effect on catch rates. Transparency has no effect on number of species collected. Temperature has no effect on catch rates. Temperature has no effect on number of species collected.

  9. Previous studies (A.L. Sheils 2005) (Whiteside and McNatt 1972). Temperature directly effects termination of spawning Abiotic factors such as temperature are an important influence in habitat Ongoing studies

  10. Materials and methods • Trawl Net • 8 ft Missouri type trawl Net • 3.8 inch mesh • 25 m rope • Hydro Lab • Secchi Disc • River Surveyor

  11. Hydrolab http://www.fws.gov/midwest/ashland/mtan/mtan51/images/Mar05-(2).jpg Recorded Temperature Individual probes Single Reading

  12. Secci Disc Measures Transparency of Water Recorded at lowest point visible Subjective www.uwosh.edu

  13. River Surveyor

  14. Preliminary data

  15. Preliminary data cont.

  16. Temperature vs. catch rate 2006

  17. Temperature vs. catch rate 2007

  18. Pike Island data without outliers

  19. Pike Island secci data

  20. Future Plans of Study • Compare Summer River Run Trawl Data with ORSANCO Trawling Data. • Trawl Lower Susquehanna River Using Same Protocols and Sampling Equipment • Study Other Factors Effecting Trawl Outcome ( Velocity, Dissolved Oxygen, Boat Speed Etc.)

  21. Future Plans of Study Bathymetric and substrate maps using copper pole technique

  22. Acknowledgments Dr. Tom Jones and lab ORSANCO Faculty and Students of BSC 662

  23. Questions??

  24. Questions???

  25. Conclusion temperature and or secci depth show a pattern with number of specimens and darters per trawl lower transparency shows a tendency for better trawl efficiency in benthic habitats

  26. Temperature / catch rate 2007

  27. Secci depth /catch rates 2007

  28. Sampling Sites 2006 ORSANCO trawling contract – 4 Specific pools - Montgomery - Willow Island - Greenup - Cannelton

  29. Sampling Sites 2007 River Run 2007 – entire Ohio River ORSANCO trawling contract – 3 Specific pools - Pike Island - Meldahl - Newburgh

  30. 2007 temperature /darters per trawl

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