A Bayesian stock assessment of the eastern Pacific gray whale using abundance and harvest data from 1967-1996

Abundance and harvest data since 1966/67 were used to assess the eastern Pacific stock of gray whales. A Bayesian statistical method was estimate probability distributions for parameters both a simple an age sex structured population dynamics model, as well output quantities interest. Model comparisons using Bayes Factor provided conclusive evidence that additional parameter should be account unexplained variation in abundance time series. Incorporating variance decreased precision estimates other parameters. Point carrying capacity ranged from 24,640-31,840 different models, but posterior selected models very broad excluded few values. The current depletion level (population size fraction capacity) estimated about 0.75, with lower 2.5th percentile 0.36. still below one-half its 0.21, corresponding 0.28 maximum sustainable yield level. Quantities which catch limits could potentially calculated estimated, including replacement yield, quantity Q1 (described Wade Givens, 1997).