Description of the growth, reproductive biology and feeding habits of the False Jacopever (Sebastes capensis)

Mohamed, Taahir

Description of the growth, reproductive biology and feeding habits of the False Jacopever (Sebastes capensis)

Thesis / Dissertation

2026

Publisher

University of Cape Town

Department

Department of Biological Sciences

Faculty

Faculty of Science

Abstract

The genus Sebastes (rockfishes) is a group of viviparous marine scorpionfish represented by at least 110 species worldwide, of which Sebastes capensis (the false jacopever) is the only South African species. Historically, S. capensis has been confused with Helicolenus dactylopterus (the jacopever) and Sebastes oculatus (the Patagonian redfish), which has contributed to lack of reliable information on the species. To describe the life-history of this important reef fish on South Africa's west coast, biological data were extracted from 269 specimens collected by hook and line and used to describe the morphology, growth, reproduction, and feeding habits of the species. The length-weight models indicated hyper-allometric growth for female fish (W = 5.08 × 10–6 TL3.23), while that of males and combined sexes was determined to be isometric (W = 1.39 × 10–5 TL3.04 and W = 1.57 × 10–5 TL3.02, respectively). Fish ranged from 205 to 372 mm in length and 3 to 23 years old. The best-fit von Bertalanffy growth model for females was TL = 358.1 × (1 – e−0.105 (t + 5.70)), and that for males was TL = 355.4 × (1 – e−0.138 (t + 3.21)). Males dominated the sex ratio, outnumbering females by 2.68:1. Length at 50% maturity for female and male fish were estimated to be 251.2 mm (6 years) and 216.3 mm (4 years), respectively. Seasonal trends in the gonadosomatic index and the frequency of reproductively active fish point towards a parturition season extending from the start of winter into early spring. Copulation occurs mainly during late autumn. Evidence of sperm storage were found in the ovaries of females during the reproductive period. The presence of both eyed-larvae and unfertilised eggs inside the ovaries of pregnant fish points towards a multiple brooding reproductive strategy, with brood fecundity estimated to be between 40 000 and 100 000 embryos. Sebastes capensis is an opportunistic and generalist predator with a close association to the benthos, a characterization supported by its morphology and bright colouration. Sebastes capensis is a slow-growing and late-maturing rockfish, making the species potentially vulnerable to overfishing, particularly given its prevalence in catches of recreational and commercial boat fishers along South Africa's west coast.

Keywords

Sebastes capensis

life history

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