Table1. Mark-recapture Largemouth bass data from the Des Plaines River.

Using these data, estimate the density (number/hectare) of each size class plus the overall density. [Note: 1 hectare = 10,000 m².]

Sample calculation
For < 10 cm size class,
N = [73 x (64 + 22)] / 22
N = 285
The sample was taken from a 1,000 m x 5 m stretch of river which equals 5,000 m².
One hectare is 10,000 m², so we need to double our density estimate.             285 x 2 = 570 fish in the < 10 cm size class.

Bluntnose minnow

Complete the following table

Table 2. Mark-recapture Bluntnose minnow data from the Des Plaines River.

1. Which species was more numerous is the Des Plaines River?  How much more abundant?
2. Based on the data, which species grows to a larger size?
3. Which species do you think is the prey and which is the predator? Why?