Productive Capacity of North American Lakes as Related to the Quantity and the Trophic Level of Fish, the Lake Dimensions, and the Water Chemistry

Abstract

The Productivity Index, which is derived (using appropriate factors) from the angling catch, commercial catch, or standing crop of fish, is given by the regression log PI = -−.236 + 1.47 · 10−4x1 − 0.517x2 + 0.287x3 where x1 = √105/area in square kilometers, x2 = log depth in meters, and x3 = log methyl orange alkalinity in p.p.m. The equation accounts for 67 percent of the variability in Productivity Index, of which 20 percent is due to the area function, 29 percent to depth, and 18 percent to alkalinity.