Answer
$\sigma^{2}$ and $\sigma.$
Work Step by Step
If there were no other turtles involved but these $76$, they would make up the $\text{population}$ of turtles, and the data collected would be population data (not sample data).
In this case, the variance is population variance, annotated with $\sigma^{2},$
and the standard deviation is the population standard deviation, annotated with $\sigma.$
