Mobulid rays, including the Shorthorned Pygmy Devil Ray, are targeted and caught incidentally in industrial and artisanal fisheries (Couturier et al. 2012, Croll et al. 2016). These rays are captured in a wide range of gear types including harpoons, drift nets, purse seine nets, gillnets, traps, trawls, and longlines. Their tendency to aggregate makes mobulid rays particularly susceptible to bycatch in purse seine fisheries and longline fisheries, targeted capture in artisanal fisheries, and incidental entanglement (Croll et al. 2016, Duffy and Griffiths 2017). Devil rays are often easy to target because of their large size, slow swimming speed, tendency to aggregate or predictably use specific habitats, and their general lack of human avoidance (Couturier et al. 2012). The species’ preference for coastal waters places it within the range of inshore fisheries, which are known to be intensive in many parts of its range, including Pakistan, India, Sri Lanka, and elsewhere (de Young 2006, Flewelling and Hosch 2006).
Some of the largest documented targeted artisanal fisheries for mobulids, including the Shorthorned Pygmy Devil Ray, have been in India, Indonesia, Mozambique, the Philippines, Sri Lanka, and Taiwan (Courturier et al. 2012, Ward-Paige et al. 2013, Croll et al. 2016). In some regions, directed artisanal fisheries can land hundreds of Shorthorned Pygmy Devil Rays per annum (that may include the Longhorned Pygmy Devil Ray, M. eregoodoo) (Alava et al. 2002, Dewar 2002, Fernando and Stevens 2011, Lewis et al. 2015, Acebes and Tull 2016, Rambahiniarison et al. 2018). While many artisanal fisheries have grown into trade fisheries, some still target these rays mainly for food and local products (White et al. 2006a, Fernando and Stevens 2011). Mobulids, including the Shorthorned Pygmy Devil Ray, are caught incidentally as bycatch throughout their ranges in small- and large-scale fisheries (Croll et al. 2016). Despite being unintentionally caught, mobulid rays are typically kept because of their high trade value and even when discarded alive they are often injured and have high post-release mortality (Tremblay-Boyer and Brouwer 2016, Francis and Jones 2017).
Even after Appendix listings on the Convention for the Conservation of Migratory Species of Wild Animals (CMS) and the Convention on International Trade in Endangered Species of Wild Flora and Fauna (CITES), and dozens of national fishing bans, many fisheries remain open and active. Robust, quantitative assessments are challenging because multiple mobulid species are caught and landed simultaneously, and species identification continues to be a source of error in this group (Croll et al. 2016).
Global landings of mobulid species, including the Shorthorned Pygmy Devil Ray, have been increasing steadily due in large part to the recent rise (from the 1990s onwards) in demand for gill plates (O’Malley et al. 2017). Many former bycatch fisheries have become directed commercial export fisheries (Dewar 2002, White et al. 2006b, Heinrichs et al. 2011, Fernando and Stevens 2011, Acebes and Tull 2016). Between 2000 and 2007, total reported landings of ‘Mantas, devil rays nei’ ('nei' refers to 'not elsewhere included') increased from 900 tonnes to over 3,300 tonnes, and from 2008 to 2014 had average landings of 4,462 t per annum, according to the FAO Fishstat Capture Production database (Lack and Sant 2009, Oakes and Sant 2019); reported landings are likely to represent only a fraction of total fishing-related mortality (Ward-Paige et al. 2013).
Almost all (99%) of mobulid gill plates are destined for the markets of Guangzhou, China, with these products sourced from over 20 countries and regions (O’Malley et al. 2017). The source locations for the largest product volumes are Indonesia, Sri Lanka, India, China, and Viet Nam (O’Malley et al. 2017). Demand has driven up the price of these products in recent decades, as well as the volume of product being traded. Between 2011 and 2013, there was an increase from 60 to 120 t of mobulid gill plates moved through shops in Guangzhou (O’Malley et al. 2017).
In the Indian Ocean, specifically India, intensive gillnet fisheries take mobulid species, including the Shorthorned Pygmy Devil Ray, along the eastern and western coasts (Nair et al. 2013, Kizhakudan et al. 2015, Nair et al. 2015). Devil rays in this region are also taken as bycatch in pelagic gillnet and longline fisheries targeting swordfish (Coelho et al. 2011), and in the tuna purse seine fishery (Lezama-Ochoa et al. 2015), but effort trends for these fisheries are unknown. In Pakistan, Shorthorned Pygmy Devil Ray represented 27% of the mobulids landed by number in tuna gillnet fisheries (Nawaz and Khan 2015). In the Saudi Red Sea, only one specimen of this species was recorded during extensive landing site surveys (Spaet and Berumen 2015). In Oman and United Arab Emirates, devil rays, likely including Shorthorned Pygmy Devil Ray, are often caught incidentally using beach seines (FAO 2008, R.W. Jabado unpubl. data).
In Indonesia, catches of the Shorthorned Pygmy Devil Ray have been recorded in the country’s two largest devil ray landing sites (Tanjung Luar, Lombok and Cilacap, West Java) (Lewis et al. 2015). In the Bohol Sea, Philippines, mobulid rays have been targeted for over a hundred years, however fleet modernization and the introduction of nets have allowed fishers to hunt these rays further afield and target a wider range of species (Alava et al. 2002, Acebes and Tull 2016). Interviews with fishers indicate villages historically took as many as 1,000 devil rays per year (Alava et al. 2002, Acebes and Tull 2016).
In the Western and Central Pacific from 2010 to 2015, observed bycatch of mobulids (excluding Oceanic Manta Ray, Mobula birostris) in purse seine fisheries was 4,324 individuals, and in longline fisheries was 410 individuals. Shorthorned Pygmy Devil Ray is likely among these catches, and although none were reported, the majority of catches were reported as Mobula spp., hence many were not identified to species level (Tremblay-Boyer and Brouwer 2016).
Indirect and sublethal sources of mortality include habitat destruction and degradation, climate change, ocean acidification, oil spills, and other pollution and contaminants (e.g. heavy metals) (Essumang 2010, Ooi et al. 2015, Stewart et al. 2018). Furthermore, shallow water lagoon systems have been identified as important nursery habitats of other mobulids. The effects of habitat destruction and degradation and pollution in these systems may negatively impact the survival of juvenile Shorthorned Pygmy Devil Rays (Stewart et al. 2018).
