Conservation Benefits of a Marine Protected Area on South African Chondrichthyans

33 Pages Posted: 21 May 2022

See all articles by Paolo Cortelezzi

Paolo Cortelezzi

Independent

Timothy Guy Paulet

affiliation not provided to SSRN

Jennifer Olbers

affiliation not provided to SSRN

Jean Harris

affiliation not provided to SSRN

Anthony Bernard

affiliation not provided to SSRN

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 we used Baited Remote Underwater Stereo-Video systems (stereo-BRUVs) inside and outside a small partially protected MPA (Robberg MPA, Western Cape, South Africa) to assess the relative abundance, species richness and size of cartilaginous fishes’ assemblages in one of the world’s chondrichthyan biodiversity and endemism hotspots, 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: Marine Protected Areas, baited remote underwater video, chondrichthyans, Conservation, South Africa

Suggested Citation

Cortelezzi, Paolo and Paulet, Timothy Guy and Olbers, Jennifer and Harris, Jean and Bernard, Anthony, Conservation Benefits of a Marine Protected Area on South African Chondrichthyans. Available at SSRN: https://ssrn.com/abstract=4116009 or http://dx.doi.org/10.2139/ssrn.4116009

Timothy Guy Paulet

affiliation not provided to SSRN ( email )

No Address Available

Jennifer Olbers

affiliation not provided to SSRN ( email )

No Address Available

Jean Harris

affiliation not provided to SSRN ( email )

No Address Available

Anthony Bernard

affiliation not provided to SSRN ( email )

No Address Available

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