Use the capture-mark-release-recapture method to estimate the population size of crayfish.

• Initial number of crayfish caught and marked ($M$) = 50
• Total number of crayfish caught in the second sample ($C$) = 50
• Number of marked crayfish in the second sample ($R$) = 3

The estimated population size ($N$) is given by the formula:

Since we cannot have a fraction of an organism, we round to the nearest whole number.

The estimated number of crayfish in the pond is $\text{833}$.