No specific measures are in place. In Indonesia in 1980, trawls were banned, however, large numbers of mini or baby trawls (Lampara) are still used throughout the country (Chong et al. 1987). In 2015, an additional ban on seine nets (Cantrang) was to be fully implemented in February 2020 (Ambari 2019). There are currently plans in place to lift both these bans in the near future, where the Ministry of Marine Affairs and Fisheries (MMAF) plan will allow the operation of the fishing gear with restrictions on the area of fishing pressure (Dharmadi unpubl. data 2020). Throughout Indonesia there are 196 marine protected areas (MPAs) making up 239,428 km2 that may provide some refuge to this species (CTI 2020). However, most MPAs in the region are not well enforced and unlikely to provide any tangible relief from fishing pressure. In Thailand, all commercial fishing vessels greater than 10 gross tonnage are prohibited within three nautical miles from the shore (DoF 2015).
To conserve the population and to permit recovery, a suite of measures will be required which may include species protection, spatial management, bycatch mitigation, and harvest and trade management measures (including international trade measures). Effective enforcement of measures will require ongoing training and capacity-building (including in the area of species identification). Catch monitoring is needed to help understand population trends and inform management.
The Starrynose Cowtail Ray has a restricted distribution in the Western Central Pacific off southwest Kalimantan, Indonesia and possibly in the Gulf of Thailand; it may have a wider distribution within the Indo-Malay archipelago (Last et al. 2016, Krajangdara 2019).
There is no population trend estimate for this species. Despite the lack of species-specific trend data, landings data from 1950 to 2014 are available on combined whipray species from fisheries within the Indonesian Exclusive Economic Zone (EEZ) (Zeller and Pauly 2016). Although landings data are not a direct measure of abundance, these can be used to infer population reduction where landings have decreased while fishing effort has remained stable or increased. There are two lines of evidence throughout its range in Indonesia that can be used to infer population trends, a catch reconstruction for central Indonesia and a research survey. In central Indonesia, whipray catch increased by 550% throughout the early-1970s to 2000, from 30 t to >200 t per year (Zeller and Pauly 2016). Catch then decreased by 45% since the early 2000s (Zeller and Pauly 2016). Fishing effort has been increasing during this period and this represents a 92% population reduction when scaled to three generation lengths (36 years) of the Starrynose Cowtail Ray. Secondly, research surveys from 1976 to 1997 reveal more than a 90% decline in ray catch-per-unit effort throughout the Java Sea in 20 years (Blaber et al. 2009). Considering these catch and effort trends, the suspected population reduction of Starrynose Cowtail Rays in Indonesia is >80% over the past three generation lengths (36 years).
There are no species-specific ray landings data in Thailand, however, data are available on combined ray landings from the Exclusive Economic Zone from 1998 to 2018 (Krajangdara 2019). The landings data showed an 89% reduction over 16 years from 2003 to 2018. Catches rose steadily from 1998 to a peak catch of 18,131 t in 2003 followed by a steady decline in catches to ~2000 t in 2018 (Krajangdara 2019). It is difficult to infer a population trend as the decline in catches from 2003 to 2018 coincided with a decline in fishing effort.
Actual levels of exploitation are high across the range of this species and the dramatic declines in whiprays and rays can be considered representative of population reduction of the Starrynose Cowtail Ray. Overall, it is suspected that the Starrynose Cowtail Ray has undergone a >80% population reduction over the last three generation lengths (36 years).
The species is subject to fishing pressure across its range. It is taken as target and bycatch in industrial and artisanal fisheries with multiple fishing gears including trawl and gillnet. In Indonesia, the Starry Cowtail Ray is uncommonly caught by mini-trawls and only a single individual was recorded from market surveys in 2019 (Fahmi unpubl. data 2020). Small-scale fisheries comprise most (~90%) of fisheries production in Indonesia (Tull 2014). In some regions, effort by these small-scale fisheries has tripled when taking population growth into account (Ramenzoni 2017). Sharks and rays are an important resource in Indonesia and are the main livelihood for some communities (Sadili et al. 2015). Fishing pressure in Indonesia is intense with the largest chondrichthyan fishery globally and the country has been among the top shark fishing nations for over 20 years (Oakes and Sant 2019). The catch of rays is rising as shark fisheries collapse; in 2003, rays comprised over 50% of chondrichthyan landings, up from 32% in 1981 (White et al. 2006). Stingrays contribute the most (>95%) to elasmobranch catch by danish seines (cantrang) operating in the Java Sea (Fahmi et al. 2008). Additionally, this species is subject to intensive trawl and gillnetting throughout the Malacca Strait and Danish seines operating throughout Kalimantan and the Java Sea (Fahmi unpubl. data 2020). Thus, the actual level of exploitation of this species could be extremely high throughout the Indonesian portion of its range.
In Thailand, the gulf coast is considered one of the most overfished regions of the world due to the rapid industrialization of their fishing fleet (Sylwester 2014). The number of Thai trawlers peaked in 1989 at ~13,100 boats (Poonnachit-Korsieporn 2000), which was reflected in the catch-per-unit-effort (CPUE) which declined from >300 kg/hour in 1963 to 20–30 kg/hour in the 1990s (Poonnachit-Korsieporn 2000). Fisheries in Thailand have been moving to deeper water for decades due to the overexploitation of the coastal region (Sylwester 2014).
There is a large amount of illegal, unregulated, and unreported fishing (IUU) in the Indo-Pacific region with reported catch estimated to represent only 0.9–19.4% of the true catch (Tull 2014). In some areas, including near marine protected areas (MPAs), IUU catch of sharks was estimated to equal 77% of the reported catch, indicating much higher levels of depletion (Varkey et al. 2010). This species’ preference for inshore coastal waters means it is also threatened by extensive habitat degradation, including pollution and clearing, and destructive fishing practices. Large coastal areas, in particular mangroves, have been lost in Indonesia and Malaysia through land conversion for urban development, shrimp farms and agriculture. Across Indonesia and Malaysia from 1980 to 2005, the area of mangroves was reduced by >30% (FAO 2007, Polidoro et al. 2010).