Natural mortality and life history stage duration of Pacific sardine (Sardinops caeruleus) based on gnomonic time divisions

The gnomonic-interval natural-mortality method (GIM) that provides an indicative vector of natural mortality (M) of short-lived species was used for species with longevity greater than an annual life cycle. The GIM was solved for the Pacific sardine (Sardinops caeruleus) from the Gulf of California, Mexico. New features added to the original GIM were (a) the use of estimates of the mean annual fecundity, (b) the ability to incorporate observed data for specific interval of durations for developmental stages to calibrate calculations of M vectors, and (c) uncertainty because of fecundity variation. When this approach was used for the Pacific sardine, we did not find statistical differences (P > 0.05) between the GIM estimates and independent estimates based on the literature. The GIM showed that it provides reasonable estimations for the duration of life history stages. Variability in egg-stage duration was also explored for M vectors. We observed daily survival increases as the duration of early stages decrease.