Submitted to Biological Conservation, April 21st 2017.
The 3D plot is interactive (click and drag to rotate the plot).
The 3D plot represents the densities of brown trout and cutthroat trout (z-axis; log10) in the Logan River, Utah, from 2001 to 2016 (y-axis), at 5 locations on the mainstem (x-axis; x=0 at 3rd dam; x increases in the upstream direction; x=35.4 km at Franklin Basin). Densities are maximum likelihood estimates based on 3-pass removal sampling data, which were aggregated over 1+ and older age classes. Densities were 2D-interpolated before plotting thus providing continuous values, between the most downstream (3rd dam) and the most upstream (Franklin Basin) sampling sites, and for the complete period (2001-2016).
This plot illustrates some important aspects of the status of brown trout and cutthroat trout populations in the Logan river as discussed in the paper:
1. brown trout (red) are dominant downstream, where some cutthroat trout are still present (green-blue),
2. cutthroat trout (yellow) are dominant upstream with a nearly complete absence of brown trout (blue),
3. the location of the inflection point where species dominance switches appears fairly stable from 2001-2009, although the inflection point may be moving upstream in more more recent years
4. most variation in density is of spatial nature (3D X-shape; the apparently prominent drop of cutthroat trout density at 3rd dam in 2007-2008 is due to the log-scale, the values decrease from 0.041 in 2006 to 0.01 in 2007, 0.001 in 2008, and back to 0 0.038 in 2009),
5. brown trout density at 3rd dam is the lowest in 2012, and cutthroat trout density is highest in 2012-2016; the mechanical removal took place a the 3rd dam reach in 2009-2012.