Title page for ETD etd-04122005-145005


Type of Document Dissertation
Author Scognamillo, Daniel Gustavo
URN etd-04122005-145005
Title Temporal and Spatial Harvest Patterns of River Otter in Louisiana and Its Potential Use as a Bioindicator Species of Water Quality
Degree Doctor of Philosophy (Ph.D.)
Department Renewable Natural Resources
Advisory Committee
Advisor Name Title
Michael Chamberlain Committee Chair
Andrew Nyman Committee Member
Nina Lam Committee Member
William Kelso Committee Member
Joseph Siebenaller Dean's Representative
Keywords
  • river otter
  • spatial analysis
  • harvest
  • trapping
  • time series
  • Louisiana
  • mercury
Date of Defense 2005-03-31
Availability unrestricted
Abstract
Louisiana is the leading state in number of river otters used in reintroduction programs in other states and in the production of pelts. However, habitat loss and degradation have prompted concern about the status of otter populations. This dissertation undertakes a spatial and temporal analysis of river otter harvest activity and examines environmental factors related to monitoring mercury levels in streams in Louisiana. Harvest data for 1957-2004 were analyzed to identify spatial and temporal trends in otter harvest activity. Changes have occurred in the last 20 years in the spatial dynamics of otter harvest in Louisiana, these include an increasing proportion of harvested otters coming from upland parishes in more recent years, and an increase in the proportion of trappers catching otters in that region. Spatial analysis indicated that this shift in harvesting activity has been gradual rather than abrupt. An explanation for this shift could be a greater interest of upland trappers in catching otters because of increasing otter pelt price and a decline in pelt price for other furbearer species. Analyses indicated that a management plan based on spatial control of harvest could be an option in Louisiana, with rice fields and protected areas playing an important role in the management/conservation plan. Temporal analysis suggested that the number of otters harvested 1 and 5 years ago has an impact on number of otters harvested at present time. An autoregressive model was developed to describe this association and to forecast number of otter pelts to be harvested 1 year in the future. The structure identified in the harvest data was used to develop a model to describe the dynamics of the otter populations. The simulation using 4-year and 8-year periods offered a reasonable approximation to the estimated cyclic dynamics of otter population in Louisiana. Mercury levels in otters were compared to levels in fish collected in different streams in Louisiana. Mercury levels in otters were higher than in fish. Otter samples also identified streams where mercury level in water may require further analysis. These results suggested that a mercury monitoring program based on river otters could be feasible in Louisiana.
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