Summary
The most recent assessment of stocks D and E uses a population model that allows for mixing between feeding areas (Johnston and Butterworth 2002, 2005). This model makes a number of assumptions about whale distribution in these feeding areas and the historic catch distribution across these feeding areas. We extend a preliminary investigation where we tested the sensitivity of Johnston and Butterworth’s model to these assumptions using a simulation approach. Specifically we generated data from a population model where the assumptions were relaxed in a number of plausible ways and fitted the model to the data. Using this approach we explore whale distribution over a finer spatial scale in the feeding areas and the catch distributions across this sub area scale. In almost all simulations we implemented we found that Johnston and Butterworth’s model was robust to both whale distribution on a fine scale and with catch distributed as per this scale.