Further Research Because of many uncertainties we were unable to draw conclusive results about whether Aumsville Wetlands should be used as salmon habitat. Because our tests were only taken once, we do not know what the range of variability throughout the year would be for our results. Although our research does not draw any conclusive evidence that the wetlands site could and would be used by salmon, it did not indicate any factors were present that would completely rule out Aumsville Wetlands from being viable salmon habitat either. The research that we have completed indicates that the large pond on the Northern end of the Aumsville Wetlands site to be used by salmon during the winter for rearing. It is for that reason that we recommend that further research be done to determine whether or not this site is viable salmon habitat.
Water Quality A habitat requirement that could be a limiting fact to salmon is the water temperature. The temperatures we recorded were at the high end of salmon’s optimal range. Water temperature varies throughout the year, and would probably be too warm in the summer. Because the salmon mainly use wetlands in the winter most of the time the water temperature would not be a limiting factor. Water temperature may become a problem if it increases too quickly during the spring. “Elevated water temperatures can accelerate the onset of smoltification and shorten the smolting period and may result in seaward migration of smolts at a time when conditions are unfavorable” (Wedemeyer et.al. 1980). In order to determine if this was a factor, the water temperature at the site would need to be tested throughout the year. Future monitoring of the water quality of the site would also be needed to determine if this was viable salmon habitat. Our water quality testes were only taken only one time, and may therefore be subject to errors. Also, all of the factors we tested vary seasonally, so a full range of measurements throughout the year would be recommended. Because of our limited resources, we were not able to test the full range of depths in the pond. Testing all the different variables at a full range of depths in the middle of the pond would provide a more complete picture of the water quality at the Aumsville site. It would also bring to the surface any unknown hazards that may lurk in the depths. This information could also be used to determining the suitability of Aumsville Wetlands as habitat for many other species.
Predation Another factor, which we were not able to completely examine, is predation. The site is already known to be habitat for bullfrogs (crana catesbeiana), which often prey on salmon eggs (Marion county website). It is still unknown if there are other predators that would have an effect on salmon that would use the wetlands area.
Accessibility to Site We recommend that the passageways to the site be more thoroughly examined. The number of obstructions to salmon passage and the cost of modifying them would be a severe limiting factor to the use of this site by salmon. In order for the Salmon to have access to the pond, a barrier at the north east of the pond to the stream would have to be removed. Whether this is possible and if it would have other negative effects on other types of wildlife would have to be examined before any action could be taken.
Feasibility An important consideration is if the benefit of taking the steps to make the site salmon habitat is worth the benefits. Current populations of salmon within the Mill Creak system may be so low that the wetlands site would only be used by a small number of fish. Other species may be negatively affected by changes. Lastly, the monetary cost of any changes would have to be thoroughly researched.