Dispersal and survival of chub mackerel (Scomber Japonicus) larvae in the East China Sea

An early life stage individual-based model of chub mackerel (Scomber japonicus) (IBM-CM) is developed and coupled with the East China Sea (ECS) unstructured grid Finite-Volume Community Ocean Model (FVCOM). Using this coupled physical-biological model, we examined the influences of regional physical processes on the dispersion and survival of chub mackerel larvae in the ECS under climatological spring-summer temperature and circulation conditions with and without the inclusion of short-time fluctuations of a typhoon. The model results show that the seasonal variability of regional circulation, vertical stratification, and mixing play critical roles in larval dispersal and abundance distributions during the early life stages. Sensitivity experiments suggest that under the same physical environment, the larval dispersal distributions and survival rates can be significantly influenced by the location of spawning ground. The impact of a typhoon on the larval transport depends on its path, intensity, speed and timing since most typhoons swept the ECS over a time scale of a few days. The comparison of the cases with and without inclusion of Typhoon Alice indicates that cancelation of tidally-induced anti-cyclonic and typhoon-driven cyclonic currents in the ECS could limit the influence of the typhoon on the low-frequency flow and thus on larval dispersion in this region, but typhoon-enhanced vertical mixing could significantly increase larval mortality and thus decrease the abundance of surviving larvae in the nursery ground in the ECS.