Only One Percent of Important Shark and Ray Areas in the Western Indian Ocean Are Fully Protected From Fishing Pressure

TL;DR

Most critical shark and ray habitats in the Western Indian Ocean are not fully protected from fishing, despite efforts to identify and expand these areas using diverse research methods.

Contribution

The study enhanced ISRA delineation by incorporating unpublished data, revealing significant gaps in marine protection for chondrichthyans.

Findings

125 ISRAs covering over 2.8 million km² were identified in the WIO, home to 104 chondrichthyan species.

Only 1.2% of ISRAs are in fully protected no-take marine areas, with the highest coverage in the Seychelles and Chagos Archipelago.

Unpublished data expanded ISRA coverage but still favored large-bodied and shallow-dwelling species.

Abstract

The Western Indian Ocean (WIO) is known for its high diversity of chondrichthyans (sharks, rays, and chimaeras). However, intense fishing pressure has led to severe population declines and local extinctions of several species. The Important Shark and Ray Area (ISRA) process is a collaborative, evidence‐based approach used to identify critical habitat for chondrichthyans. We analysed ISRAs across the WIO to quantify the diversity of research methods used to identify them, evaluate spatial overlap with designated marine protected areas (MPAs), model the influence of several species‐ and jurisdiction‐specific variables on ISRA delineation, and explore the importance of incorporating unpublished data into the delineation process. In total, 125 ISRAs (covering > 2.8 million km2; ~10% of total regional surface area) were identified within the WIO from surface waters to ~2000 m depth. These ISRAs contain over one‐third (n = 104, 39%) of the 270 chondrichthyan species reported from the region, with 76% being threatened with extinction according to the IUCN Red List of Threatened Species. The underlying evidence supporting ISRA identification was primarily drawn from relatively inexpensive research methods, such as visual census (25%) or fish‐market/landing site surveys (22.6%), as well as citizen science (9.5%). Incorporating unpublished records substantially increased the frequency of ISRA delineation, leading to expanded taxonomic and geographic coverage. Still, the full dataset was influenced by the same biases as the published record, tending to favour large‐bodied, wide‐ranging, and shallow‐dwelling species. Only 7.1% of ISRAs are within designated MPAs, with just 1.2% in fully protected no‐take areas. The highest no‐take overlap occurs in the Seychelles and Chagos Archipelago. These findings highlight the shortfalls in spatial protection of chondrichthyan habitats, but also present a strategic opportunity for policy‐makers and resource managers to improve current MPA coverage and meet their commitments under international agreements, such as the Global Biodiversity Framework.

Delineation of Important Shark and Ray Areas (ISRAs) In the Western Indian Ocean was enhanced by the verification and incorporation of unpublished records. Even with this expanded dataset, ~99% of ISRA coverage fell outside of fully protected, no‐take MPAs.

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