Looks like a simple linear model with increasing numbers of recruits for a corresponding increase in escapement would fit those data as well or better then the ricker curve. One could just as reasonably interpret the data then as an indication that habitat has not been adequately seeded to establish a density dependent response as predicted by Ricker. Only way to find out for sure is to allow more escapement and see if it produces correspondingly more recruits. Instead they head the opposite direction with escapement goals, so we'll never get a chance to find out.