Title
Chondrichthyans of the Western Indian Ocean: threats, research and management
Author(s)
Rhett Bennett; Dave van Beuningen
Published
2022
Abstract
Forty percent (89) of the 224 chondrichthyan species in the Western Indian Ocean (WIO) are threatened, due mainly to overfishing. This is worse than the global situation (33%). The WIO contributed 12% (±90,000 mt annually) of chondrichthyan catches globally over the past decade, as reported to FAO, yet these figures are gross underestimates. Poorly-monitored artisanal fisheries dominate, contributing up to 90% of total marine fish catch in some WIO countries. Actual chondrichthyan mortality is therefore many times higher than reported. WIO states contribute 1.2% (±1,250 mt annually) of reported global chondrichthyan trade. Yet importing states report nearly double the export volumes reported overall by WIO states. These major reporting discrepancies render reported trade volumes highly unreliable. WIO countries harbour many threatened chondrichthyan species, including national and regional endemics; yet few chondrichthyans are protected. WIO states are also party to numerous multilateral environmental agreements, yet none fully implements the measures of these agreements. Domestic policy and legislation are inadequate for effective chondrichthyan management. Movement behaviour, population connectivity, ecologically important areas and reproductive aspects remain unknown for at least 75% of WIO chondrichthyan species, while aspects of age and growth remain unknown for approximately 25% of species. Ecological and biological information are inadequate for management. WIO chondrichthyans need strengthened management and conservation measures, strengthened policy and legislation, improved compliance and enforcement, improved information (ecological, biological, fishery and trade), strengthened capacity for management and improved awareness of the issues chondrichthyans face, if there is any hope of improving their dire conservation status.
Keywords
conservation; fisheries management; research priorities

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