Conservation benefits of a marine protected area on South African chondrichthyans

Paolo Cortelezzi; Timothy G Paulet; Jennifer M Olbers; Jean M Harris; Anthony T F Bernard

doi:10.1016/j.jenvman.2022.115691

Conservation benefits of a marine protected area on South African chondrichthyans

J Environ Manage. 2022 Oct 1:319:115691. doi: 10.1016/j.jenvman.2022.115691. Epub 2022 Jul 12.

Authors

Paolo Cortelezzi¹, Timothy G Paulet², Jennifer M Olbers³, Jean M Harris⁴, Anthony T F Bernard⁵

Affiliations

¹ Earth and Environmental Science Department, University of Milano Bicocca, Piazza Della Scienza 1, 20126, Milano, Italy; South African Shark Conservancy (SASC), Hermanus, 7200, Western Cape, South Africa. Electronic address: p.cortelezzi@campus.unimib.it.
² South African Shark Conservancy (SASC), Hermanus, 7200, Western Cape, South Africa.
³ Wildlands Conservation Trust, 460 Townbush Road, Pietermaritzburg, 3201, South Africa.
⁴ Wildlands Conservation Trust, 460 Townbush Road, Pietermaritzburg, 3201, South Africa; Institute for Coastal and Marine Research (CMR), Nelson Mandela University, Gomeroy Avenue, Summerstrand, Port Elizabeth 6031, South Africa.
⁵ South African Institute for Aquatic Biodiversity, Somerset Street, Makhanda, 6139, South Africa; Rhodes University, Department of Zoology and Entomology, Makhanda, 6139, South Africa.

PMID: 35839646
DOI: 10.1016/j.jenvman.2022.115691

Abstract

Chondrichthyans are threatened worldwide due to their life-history traits combined with a plethora of anthropogenic impacts that are causing populations to collapse. Marine Protected Areas (MPAs) are a conservation option, but their efficacy for chondrichthyans is still unclear. Conservation efforts might be challenging especially in developing countries, due to a lack of resources and monitoring and limited data and stakeholder support. Here Baited Remote Underwater Stereo-Video systems (stereo-BRUVs) were deployed inside and outside a small partially protected MPA (Robberg MPA, Western Cape, South Africa) to assess the status of cartilaginous fishes' assemblages and to investigate the potential benefits derived from the presence of a marine reserve. Overall, 19 chondrichthyan species in 11 different families were observed. Chondrichthyans were observed in 78.5% of the sites and, of these, 89.7% of the MPA sites showed at least one chondrichthyan, while only in the 67.5% of surrounding exploited sites a cartilaginous fish was sighted. The presence of the MPA had a significant effect on the relative abundance of batoids, threatened species and local endemics, with more observations inside the MPA than outside, indicating the potential benefit of marine reserves on species that are more vulnerable to fishing pressure. Relative abundance was generally higher inside the bay than in the exposed area, and both relative abundance and species richness decreased significantly with depth. The analysis of the body length showed that the 35.5% of species had an average body length below maturity length, indicating that the area might be used as nursery ground for different species. This study provides evidence that MPAs, even though small and partially protected, can provide benefits for chondrichthyans, specifically to threatened species, endemic species and lesser-known species. Importantly, different environmental parameters must be considered to maximize the benefits an MPA can provide.

Keywords: Baited remote underwater video; Chondrichthyans; Conservation; Marine protected areas; South Africa.

MeSH terms

Animals
Conservation of Natural Resources*
Ecosystem
Endangered Species*
Fisheries
Fishes
South Africa