I made a panel figure that compares histograms of the frequency of oyster shell heights between harvested and non-harvested regions, but one histogram (the smaller one) fall behind the larger histogram in one panel and kind of obscures it. I was hoping there was a way I could change just this one panel (Matanzas River) and keep the rest the same so I do not have to change my color scheme.

Here is the picture:

and here is my code I used to make this:

  ggplot(aes(x=Shell, fill=Harvest, color = Harvest)) +
  geom_histogram(alpha=0.5, position = 'identity') + 
  scale_fill_manual(values = harvest_colors) + 
  scale_color_manual(values = harvest_colors) +
  labs(x = "Shell Height (mm)", y = "Frequency") + facet_wrap(~Region) +
  theme(panel.background = element_blank(), axis.line=element_line(size=1), 
        plot.title = element_text(hjust = 0.5)) +
  geom_vline(xintercept = 75, linetype = "dashed") + 
  ggtitle("Oyster Measurement Frequency by Region")

harvest_colors = c("Yes" = 'black', "No" = 'gray49')
  

The data can be found on my github: https://github.com/hprev30/oysterharvest titled “Sh.csv”