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Antarctic silverfish (Pleuragramma antarctica) is the dominant mesopelagic fish species in the high-Antarctic zone and plays a vital role in the food web of Antarctic marine ecosystems. Despite its ecological importance, no studies have been conducted on its age and growth or early life history in the Amundsen Sea thus far. In this study, based on 266 individuals of Antarctic silverfish collected in the Amundsen Sea polynya during January 2020, growth parameters were estimated for larvae and older individuals based on the age information from otoliths. For large individuals, age classes ranged from 1 to 11 years (standard length, SL, 32-167 mm), and the von Bertalanffy growth function (VBGF) was estimated as L t = 203.97(1 − e −0.135 (t+0.66) ) . The growth performance index (P) was estimated to be 1.75 and was at the lower limit of values observed in notothenioid fishes. For larval specimens, SL ranged from 13.8 mm to 20 mm, with a daily age of 25 to 54 days. The exponential growth model indicated that the growth rate at the mean size of 17.0 mm was 0.19 mm day −1 , corresponding to a daily percentage change in size of approximately 1.14% SL. The back-calculated hatching dates showed that the hatching season lasted from December to early January. The results suggested a potential new spawning/nursery ground for Antarctic silverfish in the Amundsen Sea. In comparison with age and growth data available in the literature for Antarctic silverfish, our results from the Amundsen Sea provided more insights into the early life history characteristics of this species across the Antarctic continental shelf.

Large submarine plateaus impede the eastward flow of the deep‐reaching Antarctic Circumpolar Current (ACC), and at the southern Kerguelen Plateau (SKP), the ACC flow is steered north through the Fawn Trough and south through the Princess Elizabeth Trough. During the Kerguelen Axis study, a regional‐scale ecosystem survey, oceanographic sampling showed the ACC water properties west of the SKP to be distinct from those over the SKP. Electrona antarctica, a dominant mesopelagic fish species, is associated with Circumpolar Deep Water transported by the ACC, and modified versions that occur over and downstream from the SKP including along the Antarctic continental slope. Here, otolith chemistry from samples of E. antarctica collected during the survey were used to test a biophysical hypothesis predicting structuring and movement between populations along zonal flow in the ACC. In chemistry deposited during early life in the otolith nuclei, the relationship between MgCa−1 and SrCa−1 showed complete separation between fish collected over the SKP and within the ACC proper, indicating population differentiation. Chemistry from the otolith edges, deposited during the period leading up to capture, showed significantly higher concentrations of MgCa−1 over the SKP, likely related to differences in feeding and reproduction. Fish with nucleus chemistry characteristic of the SKP were also found in samples caught further east, suggesting they were transported along the ACC downstream, and southward toward the Antarctic continent within the Australian–Antarctic Gyre.

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