We would like to draw attention to our new paper, which develops and uses new methods (mixture models) for analyzing mark- recapture population data in which there is heterogeneity. The abstract is below and a pdf is available at: http://whitelab.biology.dal.ca/hw/Whitehead_Wimmer_2005.pdf Hal Whitehead and Tonya Wimmer Whitehead, H., and T. Wimmer. 2005. Heterogeneity and the mark-recapture assessment of the Scotian Shelf population of northern bottlenose whales (Hyperoodon ampullatus). Canadian Journal of Fisheries and Aquatic Sciences 63:2573-2585. A population of northern bottlenose whales (Hyperoodon ampullatus) inhabits the waters along the edge of the Scotian Shelf. The most important habitat of this population is the Gully, a large submarine canyon, where animals were photographically identified between 1988 and 2003. Open markrecapture models, including mixture models that allow for heterogeneity in identifiability and (or) mortality among individuals, were fitted to identification-history data. Models without heterogeneity in identifiability had poor fit to the data and underestimated population size. The population is estimated to contain about 163 animals (95% confidence interval 119214), with no statistically significant temporal trend. About 12% of the population has a high probability of being identified within the Gully in any year. Many of them are mature males. The remainder is less likely to be identified in the Gully during any year, spend generally shorter periods in the Gully even in years when they are found, and are more likely to be female. This and other work indicate a poorly mixed population inhabiting the canyons and other deeper waters off the Scotian Shelf. Nonparametric bootstrap methods were used to validate the estimation procedure and to estimate the efficiency of future fieldwork scenarios.