Updating the model for the variability of egg and larval transport of Antarctic toothfish under the extreme SAM event in the East Antarctic region (Divisions 58.4.1 and 58.4.2)

This paper examined egg and larval transport under different SAM phases in the continental shelf-slope regions of East Antarctica using particle tracking models following the study by Mori et al. (2021). While ocean data outputs used for simulations were the same as in the last study (i.e., “COCO”), temporal and spatial resolutions of data increased in this experiment. Particles were mainly passively advected by ocean current using three different transport scenarios: (i) passive advection at the surface layer, (ii) passive advection + DVM between the surface layer and the mid layer, and (iii) passive advection at the mid layer. Results showed that the overall successful transport level was higher in scenarios1 & 2 (>80%) than them in scenario 3 through all simulations. Under different SAM phases, the decrease in the successful transport percentage with the increase in the values of SAM index was observed in east side sources, especially in northern shelf-slope regions. This paper suggests identifying the density of potential spawners over the east side shelf-slope region by continuous sampling and tagging research are important to develop the knowledge about egg and larval transport mechanisms under different SAM phases in the East Antarctic region.