A decade of surf-zone linefish monitoring in the Dwesa-Cwebe Marine Protected Area, with a preliminary assessment of the effects of rezoning and resource use

Abstract

An 11-year assessment of surf-zone linefish (marine fish captured on hook and line) was carried out in the Dwesa-Cwebe Marine Protected Area (MPA) in the Eastern Cape, South Africa, by research fishing to determine species and size composition, movement and relative abundance using catch per unit effort (CPUE). Comparisons were made between the Cwebe and Dwesa sections of the MPA on either side of the Mbhashe Estuary, as well as between two partially protected areas (PPAs) and two no-take zones in the Dwesa section, which came into effect in January 2016. A total of 7 241 fish representing 43 species were recorded, where 39.5% of the species are endemic, 29.5% are considered threatened by the IUCN, and 27.3% are either overexploited, collapsed or in decline. Of 3 963 tagged fish, 128 (3.2%) recaptures were recorded, of which most (62%) exhibited no movement. Localised differences in species diversity, size frequency and CPUE were detected between the Dwesa and Cwebe sections, and lower average length and CPUE of some species were recorded in the Dwesa PPAs compared with in the Dwesa no-take zones. These differences were more prominent in slow-growing, long-lived species with small home ranges, indicating the negative impacts of fishing pressure on vulnerable species found in this MPA and a reduction in benefits that would otherwise be associated with no-take zonation. These findings highlight the need to revisit the rezoning of the MPA with regard to the size of the no-take zones and emphasise the need for effective law enforcement to ensure adherence to existing regulations.

Keywords:

• CPUE
• Eastern Cape coast
• fish diversity
• fish population recovery
• marine partially protected areas
• mark-recapture
• monitoring
• MPA zonation