The Zebra Shark (Stegostoma tigrinum) is usually found within a narrow band of shallow coral reef habitat and soft bottom that is heavily fished throughout all of its range except Australia. It is taken in inshore fisheries (demersal trawls, floating and fixed bottom gillnets and baited hooks) and regularly seen in fish markets in Indonesia, Thailand, Philippines, Pakistan, India, Taiwan, and elsewhere. There are limited data on population declines in these areas, with the exception of the Gulf of Thailand, but the species is susceptible to capture in a wide range of fisheries, has a narrow habitat range with potential limited dispersal, shows strong site fidelity and forms aggregations which facilitate the rapid removal of individuals.
Population genetic analysis supports two subpopulations of the Zebra Shark: Indian Ocean-Southeast Asian and Eastern Indonesian-Oceania. The greatest levels of exploitation and ongoing threats for this species occurs in Southeast Asia, particularly Thailand through to Indonesia. Given little or no genetic exchange from unexploited areas it is suspected that this subpopulation has declined by at least 50% over the last three generations (51 years) and these threats are suspected to continue at these levels into the future. Therefore the Indian Ocean-Southeast Asian subpopulation is considered Endangered. The Eastern Indonesian-Oceania subpopulation is composed of regions with minimal exploitation to this species as well as regions of greater fishing pressure and habitat threats. In particular, the Zebra Shark in Australian waters is considered Least Concern due to minimal impacts from fishing, non-consumptive exploitation and habitat loss. However, population genetic and tracking studies suggest there is likely to be exchange between Australian waters and the Arafura Sea in Eastern Indonesian waters where extensive trawl fishing occurs and has been increasing in intensity over the last 30 years. Based on the ongoing fishing and habitat threats posed by these trawl fisheries in the Arafura Sea and the potential impacts on Zebra Sharks migrating from adjacent regions, reductions of at least 20% of its population size within three generations (51 years) are suspected and the Eastern Indonesian-Oceania subpopulation is assessed as Near Threatened.
By combining the subpopulation assessments according to relative area (the Indian Ocean-Southeast Asian subpopulation has approximately 70% of the available habitat; the Eastern Indonesian-Oceania subpopulation has approximately 30% of the available coastal habitat), and given the ongoing threats from fishing and habitat loss across much of its range and suspected reductions of over 50% of its population size within three generations, this species is assessed globally as Endangered.