Reaching the objective of fur-seal research and management, maximum sustained productivity from the Pribilof, seal herd, is now complicated by acute fluctuations in the size of year classes. When the experimental approach to the calculated point of maximum yield began in 1956, year-class fluctuations were moderate, as they apparently had been since commercial sealing resumed after the Convention of 1911. These sharp fluctuations stimulated renewed emphasis on ways to forecast year-class success and, consequently, the probable size of the kill. Island seal-pup mortality, number of 2-year-old seals taken, and early season kins. of 3-year-old seals have shown some promise as indicators for making kill-size predictions. Measurements of condition or growth may be supplementary information indicative of the relative success of a year class. Recent studies suggest an inverse relationship between the return of bachelors and year-class size.