ESTIMATED POPULATION-SIZE OF THE CALIFORNIA GRAY WHALE

The 1987-1988 counts of gray whales passing Monterey are reanalyzed to provide a revised population size estimate. The double count data are modeled using iterative logistic regression to allow for the effects of various covariates on probability of detection, and a correction fa ctor is introduced for night rate of travel. The revised absolute popu lation size estimate is 20,869 animals, with CV = 4.37% and 95% confid ence interval (19,200, 22,700). In addition the series of relative pop ulation size estimates from 1967-1968 to 1987-1988 is scaled to pass t hrough this estimate and modeled to provide variance estimates from in terannual variation in population size estimates. This method yields a n alternative population size estimate for 1987-1988 of 21,296 animals , with CV = 6.05% and 95% confidence interval (18,900, 24,000). The av erage annual rate of increase between 1967-1968 and 1987-1988 was esti mated to be 3.29% with standard error 0.44%.