Standing crop is similar to density. It is the biomass per unit area and tells us how much biomass the water is supporting. With calculations of primary production, we can figure how much biomass the water is capable of supporting, and gauge if the standing crop is low or coming close meeting max production. Depending on whether the standing crop is high or low we can make management decisions for the fish populations. Species count is a measure of diversity.
Diversity can be an indicator of a healthy ecosystem.
Typically a monoculture would not be a representative of a healthy system. Total adds to 510, but there is rounding error because you cannot have a percent of a fish. The 1.2 pounds or .545 kg for our site should be close enough since we had 37 fish and the total population estimate was 38. Then average weight of fish is multiplied by the number of fish per hectare. These calculations are then repeated for each species.