Spatial and temporal distribution of shallow-water hake Merluccius capensis off the south coast of South Africa

Abstract

This study investigated the spatial and temporal distribution of shallow-water hake Merluccius capensis off the south coast of South Africa, using 1 807 females collected by bottom trawling during industry and research surveys between 2014 and 2016. Mean body size increased significantly with bottom depth (p < 0.05), although the relationship was weak (r ² = 0.22). The vertical adjustment of the position in the water column between the immature and regressing stages of maturity appeared minor; however, hake in the regenerating stage were found significantly deeper, typically at ∼225 m compared with at 160–200 m for the other maturity stages. Because M. capensis is a serial spawner, females tended to move upwards by ∼25 m to release egg batches, doing so in April–May and in September, as evidenced by a higher incidence of actively spawning females. A latitudinal distribution pattern was also apparent as females generally moved northwards before spawning (to 35.4°–35.3° S), followed by spawning (centred at 34.9° S), and subsequently returning southwards (to 35.2°–35.4° S). These latitudinal movements were coupled with longitudinal relocations eastwards during pre-spawning (21.7°–21.8° E) and farther eastwards when spawning (22.8° E), and then returning to the west after spawning (21.2° E). Thus, the various phases of the spawning cycle of this species are characterised by specific spatio-temporal dynamics.