In 1996, 623 humpback whitefish Coregonus pidschian 360mm FL and 529 least cisco C. sardinella 290mm FL were sampled from a 30 km section of the Chatanika River during August and September. The August sampling period corresponded to the timing of 1992-1994 assessments, while the September sampling corresponded to the time when the sport spear fishery was open to exploitation (prior to 1994). Ages 4, 5 and 6 predominated in humpback whitefish indicating strong pre-recruit classes; ages 4, 5 and 6 also dominated in least cisco, however the younger age classes (ages 2 and 3), normally vulnerable to sampling gear, were low in abundance. Significantly fewer age 4 humpback whitefish were sampled in September than in August (2 = 25.38, df = 11, P=0.008). There was no significant difference among the August and September age samples for least cisco. In 1997, we conducted a mark-recapture experiment in a 53 km (33 mi) section of the Chatanika River from August 20-28 to estimate abundance and stock composition of both species. The investigation was timed to correspond to the upstream spawning migration of both species, and to provide in-season estimates of abundance prior to the timing of a recreational spear fishery. An estimated 16,107 (SE = 1,260) humpback whitefish ( 360 mm FL) were present in the study area. The assessed stock was characterized by a high proportion of humpback whitefish between 390 and 430 mm FL with ages 5, 6, and 7 predominating. An estimated 22,811 (SE = 4,496) least cisco ( 290 mm FL) were present in the study area. The assessed least cisco stock was predominated by age 5 and 6 fish, and primarily comprised of fish greater than 340 mm FL. Poor recruitment within the least cisco stock was indicated by the age composition, and estimated recruitment levels of age 3 fish were the lowest in 11 years of stock assessment.