Consequences of error in natural mortality and its estimation in stock assessment models

Natural mortality (M) is often considered to be one of the most important parameters in a fish stock assessment and affects productivity estimates for population. However, it also among difficult estimate using commonly available data. The magnitude error (both bias variance) when estimating this parameter can substantial affected by ignoring its variation over time, space, age, length. In study we explore implications errors M on estimation management performance simulations illustrative examples. reference points such as F35% FMSY related directly associated with M. Estimates biomass are expected positively biased over-estimated vice versa. Use feedback strategies reduces impact M, but meeting objectives compromised error. Estimating was found perform better than pre-specifying closed-loop simulations. Also, that consequences setting an incorrect value were reduced if stock-recruitment steepness estimated. Based our review work, advocate within assessment, ideally prior tailored concerned.