A new hypothesis for South African sardine stock structure

A new hypothesis for South African sardine stock structure is conceptualised following newly available genomic and transcriptomic research, which adds to the body of evidence already available regarding spatial structure within the South African sardine population. The hypothesis consists of two primary components: (i) some fish of Atlantic Ocean origin actively move eastward to take part in the Sardine Run on the East Coast; and (ii) some spawning products of Indian Ocean origin sardine are passively transported to the West Coast for a period of time before returning to the South Coast as adults.

Quantitative assessment and management of the South African sardine resource has adapted over time as new information about stock structure has become available (e.g. de Moor and Butterworth 2015, van der Lingen et al., 2015; de Moor et al., 2017). In recent years, a two component stock structure hypothesis as described by Butterworth et al. (2016) has been assumed. In the light of newly available genomic and transcriptomic research (Teske et al. 2021), this document provides an updated two‐component stock structure hypothesis for South African sardine.