Between 1970 and 1975, the AOSERP study area contained up to 131 registered trapping areas (traplines). Traplines averaged 165.8 km2 (64 mi 2) in area. For the four trapping seasons 1971-72 to 1974-75, affidavits reporting trapper harvests were available for an average of 75 percent of the traplines. An average of five percent of the traplines reported nil catches each year. The mean annual value of wild fur reported produced per trapline was calculated at $1,252.61, with beaver, lynx, and muskrat having the greatest economic importance. Fur value produced per square kilometre averaged $7.58 ($19.64/mi2) but ranged more than 500-fold, with much variation seeming attributable to trapper effort. Cash value per unit area was negatively correlated with trapline size; this relationship appeared to stem primarily from decreasing trapping intensity with increasing size of traplines. It is suggested that trapping areas could in all likelihood have produced, on a sustained yield basis, several times more fur than they had.