Comparative analysis of data-poor methods for non-aged stocks

Assessment models are available that do not require age information (e.g. AIM, ASPIC, and SCALE in the NOAA Fisheries Toolbox). These models, often utilized when production aging is not conducted for a stock, can be applied even when aging data are available. Simulations were used to evaluate whether similar results from simple and complex methods are sufficient to “validate” results from age-based methods, and whether lack of concordance might indicate that non-aged methods “miss the mark” because of reduced biological realism. Bias and precision were similar in the two types of models when all data were generated according to the assumed dynamics. Non-symmetric aging error introduced bias in the complex models that was not evident in the simple non-aged based models. Both simple and complex models exhibited bias when time-varying processes were assumed stationary. These results suggest that using simple models is useful even when richer data are available.