|Scientific Name:||Mobula tarapacana|
|Species Authority:||(Philippi, 1892)|
Cephaloptera tarapacana Philippi, 1892
|Red List Category & Criteria:||Vulnerable A2bd ver 3.1|
|Assessor(s):||Pardo, S.A., Walls, R.H.L. & Bigman, J.S.|
|Reviewer(s):||Francis, M.P., Marshall, A., Notarbartolo di Sciara, G. & Ralph, G.|
|Contributor(s):||Ender, I., O'Malley, M., Fernando, D. & Stevens, G.|
|Facilitator/Compiler(s):||Kyne, P.M., Walls, R.H.L., Lawson, J. & Dulvy, N.K.|
The Chilean Devil Ray (Mobula tarapacana) is a large ray (over 3m disc width) with a circumglobal range in temperate, subtropical, and tropical waters of the Indian, Pacific, and Atlantic Oceans. It is primarily oceanic, but is also found in coastal waters. Devil rays are sensitive to even moderate levels of fishing pressure because they have low post-release survival, combined with an extremely low reproductive rate (producing around one pup per year).
Increasing international trade in gill plates has led to the expansion of largely unregulated and unmonitored manta and devil ray (Manta and Mobula spp.) fisheries worldwide. Trade pressure has likely increased for the gill plates of devil rays (including the Chilean Devil Ray) as a result of declining availability of manta ray gill plates resulting from their recent CITES Appendix II listing. The Chilean Devil Ray is taken as bycatch of gillnet, purse seine, and longline fisheries in the Pacific, Indian, and Atlantic Oceans, and is targeted opportunistically in fisheries in Peru, western Africa, and Indonesia for both meat consumed domestically and gill plates for international trade. The lack of species-specific catch, fishing effort, and population data necessitates the use of genus-wide inferences on population reduction. Where documented, catches are decreasing yet fishing effort is stable or increasing, suggesting that populations are declining. In the last decade, significant reductions (>50%) have been either inferred or suspected in three regions: Southeast Asia, Eastern Pacific, and Indian Ocean (particularly in Indonesia and Sri Lanka, where they are heavily fished). In these three regions, these declines are equivalent to population reductions of a minimum of 80% over three generation spans. In three other regions, Chilean Devil Ray is suspected to be (a) Near Threatened in the eastern Atlantic, and Data Deficient in the (b) central Pacific and (c) western Atlantic. While the relationship between these regional declines and the global population trend is not directly known and there is considerably uncertainty surrounding trend data, wide-ranging movements and migration probably connect these regions and hence steep local declines are likely to influence global population sizes. The Chilean Devil Ray is suspected to have declined by at least 30% over the past three generations (30 years) throughout its global range, which, combined with rising international trade value and demand for devil ray gill plates, domestic demand for meat, high intrinsic sensitivity to overexploitation, and the likelihood that fishing effort will increase, leads to this species being assessed as Vulnerable.
|Previously published Red List assessments:|
With a circumglobal distribution, the Chilean Devil Ray is found in tropical, subtropical, and temperate waters of the Pacific, Atlantic, and Indian Oceans (Couturier et al. 2012). It is mostly oceanic, but is occasionally found in coastal waters (White et al. 2006a). While there is a single record of Chilean Devil Ray for Australia (C. Duffy, pers. comm. 2016), there is no information on its abundance and threats in this region.
Native:Angola (Angola); Australia; Brazil; Cape Verde; Chile; Costa Rica (Cocos I.); Côte d'Ivoire; Ecuador; Egypt; Fiji; India; Indonesia; Japan; Liberia; Malaysia; Maldives; Mexico; Pakistan; Palau; Peru; Philippines; Portugal (Azores, Madeira); Saint Lucia; Senegal; South Africa; Spain; Sri Lanka; Suriname; Taiwan, Province of China; Thailand; United States (Texas); Venezuela, Bolivarian Republic of
|FAO Marine Fishing Areas:|
Atlantic – western central; Atlantic – southwest; Atlantic – southeast; Atlantic – eastern central; Indian Ocean – eastern; Indian Ocean – western; Pacific – northwest; Pacific – eastern central; Pacific – western central; Pacific – southeast
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||There are no historical baseline population data available, and global population numbers are unknown for all devil ray species. However regional, genus-wide declines are inferred based on catch landings, trawl-survey indices, and diver sightings (Couturier et al. 2012, Ward-Paige et al. 2013, White et al. 2015, Lewis et al. 2015, Croll et al. 2015). The scale and effects of devil ray fisheries in Sri Lanka, India, Indonesia, the Philippines, and Peru suggest considerable population reduction (Heinrichs et al. 2011, Lewis et al. 2015).|
Devil rays have population sizes likely one or two orders of magnitude greater than manta rays, and have larger geographic ranges and possibly larger migratory movements. This makes devil rays more challenging to assess than manta rays. By comparison, manta rays can easily be locally depleted because they may be more restricted geographically. Most population trend data for devil rays are not species-specific. Hence, most of the decline rates in this assessment were inferred based on these generic declines. Local population trend data are available from market landings, a trawl survey index, and diver surveys.
Given the patchy nature of data occurrence, the distribution of Chilean Devil Ray has been divided into six regions: Southeast Asia, central Pacific, eastern Pacific, western Atlantic, eastern Atlantic, and Western Indian Ocean. Next, the status of this species in each of these regions was considered, before drawing these together into a global estimate of population reduction.
In Indonesia, catches of the Chilean Devil Ray were recorded in the country’s three largest devil ray landing sites (Tanjung Luar, Lombok; Lamakera, Solor; Cilacap, West Java). Landed catch was estimated to have declined by 77-99% over the past 10-15 years in these three landing sites and there is evidence of increased directed fishing effort in Tanjung Luar and Lamakera (Lewis et al. 2015). Local population depletions can be inferred from an increase in the number of operating fishing vessels concurrent with these landed catch declines. The number of vessels catching devil rays from Tanjung Luar has increased since 2014 but any longer-term trend is unquantifiable owing to a lack of effort data. From Lamakera however, the number of vessels fishing devil rays has approximately doubled since 2001 (S. Lewis, unpublished data). Anecdotal evidence from artisanal harpoon fisheries also suggest that historical declines of the Chilean Devil Ray have occurred (Lewis et al. 2015). There appears to have been a recent expansion and collapse of devil ray fisheries due to population depletion in Bohol, Philippines. Historically, from the 1900s to 1960s the devil ray fishing grounds were inshore (within five km of shore), but subsequently expanded to offshore waters extending over the jurisdiction of municipal waters (15 km from the coastline) following fleet modernization in the 1970s. By 2014, the devil ray fishing grounds had contracted to a smaller area in the northeast of the Bohol Sea, suggesting a decrease in devil ray fishing effort led by several factors including a possible depletion of fishing grounds and decrease in financial viability of the fishery, compared to historical records (A. Ponzo, unpublished data). Interviews with fishermen in the Philippines indicate villages take as many as 1,000 devil rays per year, and the number of villages and fishermen participating in the fishery expanded at least through 2002. This is concurrent with declines in catch rates, therefore local population declines can be inferred but not quantified (Alava et al. 2002).
Population reductions can be suspected or inferred from three forms of data: (i) diver sightings from Cocos Island, (ii) bycatch rates in tuna purse seine fleet, and (iii) fisheries landings in Peru.
Over the past 21 years a 78% decline in devil ray sighting probability at Cocos Island, Costa Rica has been reported based on diver surveys (White et al. 2015). Over this time period, devil rays were generally rare and seen on only 7% of dives. While species-level identifications were not available in this study, area dive operators report the Chilean Devil Ray as the species generally sighted (E. Herreño, pers. comm. 2012). The degree to which this index reflects wider population sizes is unknown, however, Cocos Island is one of the world’s oldest Marine Protected Areas, and lies within the area of activity of the Eastern Tropical Pacific purse seine tuna fisheries which takes large numbers of devil rays as incidental catch (Croll et al. 2015, White et al. 2015). Fishing effort and species-specific data from this region are currently unavailable for quantification of declines.
The Inter-American Tropical Tuna Commission (IATTC) catch and bycatch data for devil rays from purse seine fisheries in the eastern Pacific between 1998 and 2009 show a significant increase from <1t in 1998 to >80t in 2006, and a subsequent decline over three years until 2009, when the reported catch was 40t (Hall and Roman 2013). While population trends cannot be directly taken from grouped species bycatch data such as these, this pattern may be indicative of overall devil ray population declines following overexploitation in the region, depending on the corresponding trajectory of fishing effort.
In Tumbes, Peru, there is a significant decline from an apparent peak of 1,188t in 1999 (Llanos et al. 2010), to 135t in 2013 (IMARPE 2014), however reported devil ray landings fluctuate considerably from year to year. Llanos et al. (2010) describe all the devil rays landed as the Bentfin Devil Ray (M. thurstoni), but this information is likely inaccurate and are likely to also include the Chilean Devil Ray. This is likely as a more recent fishery survey recorded mobulid landings in Tumbes between 2013 and 2014 to consist mainly of the Spinetail Devil Ray (M. japanica, 93% of individuals), followed by the Smoothtail Devil Ray (M. munkiana, 5%). The Bentfin Devil Ray and Chilean Devil Ray were also caught, but each species only accounting for 1% of the total number of devil rays landed (SOSF 2014). The short duration of this survey, however, means that these data cannot be used to determine species-specific catch or effort trends over time. Fishing effort in this area for mobulids is unknown, but given the ongoing international demand for mobulid gill plates this decline in landings may be indicative of overall devil ray population declines in the region.
In Sri Lanka, population reductions are suspected because fishermen reported declines in devil ray catches over the past five to ten years as targeted fishing pressure has increased, and it is estimated that the Chilean Devil Ray composes 12% of the total catch of devil rays (Fernando and Stevens 2011).
In India, population reductions are suspected based on declines in devil ray catches, while effort has increased in several regions, including: Kerala, along the Chennai and Tuticorin coasts, and Mumbai (Mohanraj et al. 2009, Couturier et al. 2012). Catch per unit effort (CPUE) analyses from trawlers in Mumbai waters revealed maximum landings of 6.3 tonnes (t) for “M. diabolus” (an invalid name, possibly referring to the Chilean Devil Ray and/or the Spinetail Devil Ray) in 1993-95 surveys, declining to 4.8t in 1996-98, and then to 3.1t in 1999-2001 and 2002-2004 (Raje and Zacharia 2009). This represents a 51% decline in landings over approximately 10 years during which fishing effort almost doubled, from which local population declines can be inferred. Such declines are unquantifiable to species level given the potential grouping of several species under one synonym. We caution that trawling indices may not provide accurate trend estimates for mid-water species such as devil rays, and that the reported catches were very small, but the change in index is consistent with a decline in some combination of abundance or spatial extent or catchability, which are indicators of population reduction.
Population reduction and three-generation decline rates
Overall, the rate of population reduction appears to be high in three regions, with suspected declines of at least 80% over the last three generations (approximately 30 years). Regional, genus-wide reductions over this period calculated from landings, catch data, and diver surveys, are as follows. At Cocos Island, a 78% decline was estimated from diver surveys over 21 years (White et al. 2015), this is equivalent to an estimated decline of 86.1% (95% CI: 81-90.8%) decline over a 3-generation span. In Sri Lanka, the overall decline in catch landings or devil rays was 51% over three years (Raje et al. 2007). While it is unlikely that this decline rate would remain constant over a three-generation period, if it was the case it would be equivalent to an inferred population decline of 99% over a three generation span in this region. In Indonesia, the overall decline in catch landings for the Chilean Devil Ray was between 77 and 99% over 10-15 years (Lewis et al. 2015), and assuming that declines rates stayed constant over a larger period, this is equivalent to an inferred population decline of 88-99% over a three-generation span.
The ocean regions used as a reference to assess the status of the Chilean Devil Ray are listed below. The likely threat categories are only tentative rather than actual regional assessments:
The information available suggests population reductions are occurring in multiple regions, however these data are highly uncertain as they might not accurately reflect true abundance and many of these trends are suspected from genus-wide measurements rather than species-specific data. In addition, we have no data from certain regions where they are also being heavily fished. While wide-ranging movements and migration possibly connect these regions (Thorrold et al. 2014) and steep local declines may reflect a global population reduction, we cannot extrapolate the magnitude of suspected regional declines (~80% over three generations) to the global population. Nonetheless, it is suspected that the Chilean Devil Ray has declined globally at rates equivalent to 30% over a three generation span at the very least, thus warranting a Vulnerable status. Furthermore, the causes of these declines are likely to be maintained as demand for gill plates will continue, thus future declines at similar rates can be suspected.
|Current Population Trend:||Decreasing|
|Habitat and Ecology:||The Chilean Devil Ray is found in temperate and tropical waters of the Indian, Pacific, and Atlantic Oceans. It is primarily oceanic, but is also found in coastal waters, and it appears to be a seasonal visitor along productive coastlines with regular upwelling in oceanic island groups, and near offshore pinnacles and seamounts (White et al. 2006a, Mendonça 2011). Within its broad geographic range, the population is patchily distributed.|
This species undertakes long migrations (Couturier et al. 2012) of up to 3,800 km over seven months, crossing through oligotrophic tropical and subtropical waters and diving to depths of 1,896 m (Thorrold et al. 2014). It is known to make seasonal migrations into the Gulf of California during the summer and autumn months while sightings are rare in winter months (Notarbartolo di Sciara 1988). The Chilean Devil Ray has been observed travelling both in schools and in solitude (Notarbartolo di Sciara and Hillyer 1989, Sobral and Afonso 2014, G. Stevens, pers. comm. 2016).
The Chilean Devil Ray aggregates around the seamounts at the Princess Alice Bank in the Azores during the summer months of June-September (Sobral and Afonso 2014). Similar aggregations of this species are also reported from the St. Peter and St. Paul's Archipelago in Brazil (Mendonça 2011) and around Cocos Island off Costa Rica (E. Herreño, pers. comm. 2012).
Reported maximum sizes for females are 305.2 cm disc width (DW) from the Gulf of California (Notarbartolo di Sciara 1988), 310 cm DW from Sri Lanka (Fernando et al. in prep), and 328 cm DW from Indonesia (White et al. 2006b). Maximum sizes on record for males are 249.4 cm DW from the Gulf of California (Notarbartolo di Sciara 1988), 314 cm DW from Sri Lanka (Fernando et al. in prep), and 304 cm DW from Indonesia (White et al. 2006b). A reported maximum size of 370 cm DW by Compagno and Last (1999) cannot be confirmed.
Size at maturity is 270-280 cm DW for females and 240-250 cm DW for males in the Gulf of California (Notarbartolo di Sciara 1988), and 240-250 cm DW for males in Indonesia (White et al. 2006b). Size at birth is at least 105 cm DW (Compagno and Last 1999), but it is likely to range between 117 and 132 cm DW (Fernando et al. in prep).
This devil ray is an aplacental, live-bearing matrotroph (i.e., the neonate receives nourishment from uterine milk secretion; Wourms 1977). Only the left ovary is functional and litter size is one pup (Wourms 1977, Notarbartolo di Sciara 1988).
Cuevas-Zimbrón et al. (2013) estimated age at maturity of 5-6 years and minimum lifespan of 14 years for the Spinetail Devil Ray. While an accurate generation length is unknown for the Chilean Devil Ray, based on life history information on other devil rays it can be inferred as approximately 10 years.
|Generation Length (years):||10|
|Movement patterns:||Full Migrant|
|Use and Trade:||
The dried branchial filter plates (gill plates or pre-branchial appendages) from devil rays are used in an Asian health tonic purported to treat a wide variety of conditions (Heinrichs et al. 2011, Couturier et al. 2012). Recent surveys suggest an escalation in demand for devil ray gill plates in China (O’Malley et al. in press), with the estimated number of devil rays represented in Guangzhou, China gill plate markets more than doubling from early 2011 to late 2013. The Chilean Devil Ray was identified in the Guangzhou gill plate markets, making up approximately 13% of the estimated number of devil rays traded annually, and is reported to sell for up to US$359 per kg (O’Malley et al. in press). Gill plates are known to be traded to China from Indonesia (Dewar 2002, Lewis et al. 2015), the Philippines (Alava et al. 2002), Sri Lanka (Fernando and Stevens 2011), India (Fernando 2012), Vietnam, Thailand, Myanmar, Japan, Africa, South America, and the Middle East (O’Malley et al. in press). While no specific data are available to quantify declines, 64% of sellers of devil ray gill plates at Guanzhou, China claimed that supply of the product had decreased in 2014, with two interviewees claiming the market for this product “has no future” (O’Malley et al. in press). This may indicate dwindling supply, consistent with declining catches (and catch per unit effort) in nearby Indonesian and Sri Lanka target fisheries (Population Section). Moreover, reports from fishermen and traders of devil ray gill plates indicate that devil ray gills are becoming harder to source, with prices escalating as the supply continues to decline (O’Malley et al. in press).
The relatively low-value meat is most often used locally for human consumption, shark bait, fishmeal, or animal feed (Couturier et al. 2012, Croll et al. 2015). Fishers in Senegal have reported exporting dried devil ray meat for human consumption to neighbouring African countries such as Ghana, Togo, and Mali (Ender and Fernando 2014). In Guinea, devil ray meat is exported as smoke-dried meat to the Ivory Coast, Sierra Leone, and Liberia, and as salt-dried meat to Nigeria, Ghana, and Togo (F. Doumbouya, pers. comm. 2015). Devil rays are also used for cartilage, which is exported as filler for shark fin soup; for skin, which is exported for leather production (Croll et al. 2015); and to make chondroitin sulfate supplements for export to Japan and Britain (Heinrichs et al. 2011).
Threats to the Chilean Devil Ray include targeted and incidental catch in both artisanal and large-scale fisheries. Directed fisheries and retention in bycatch fisheries are increasingly driven by the international trade demand for gill plates (Rajapackiam et al. 2007, Heinrichs et al. 2011, Couturier et al. 2012, Kizhakudan et al. 2015). This species’ epipelagic tropical distribution in regions of high productivity, which overlaps with that of tuna and other highly valued target teleost species, means it is exposed to multiple fisheries (White et al. 2006b, Couturier et al. 2012, Croll et al. 2012, Thorrold et al. 2014, Croll et al. 2015). Collectively, it is estimated that over 94,000 devil rays are landed annually worldwide (Heinrichs et al. 2011).
While devil ray meat is generally not highly valued (Couturier et al. 2012), artisanal fisheries also target the Chilean Devil Ray for food and local products using a variety of gear types including harpooning, longlining, handline, netting, and trawling (White et al. 2006a, Ayala 2008, Fernando and Stevens 2011, Heinrichs et al. 2011, Acebes 2012). In Sri Lanka, where certain local communities consume devil ray meat, the Chilean Devil Ray is preferred over other devil ray species (Fernando and Stevens 2011).
There are 13 known fisheries (mostly artisanal) in 12 countries that specifically target devil rays, and 30 fisheries in 23 countries that incidentally catch them (Croll et al. 2015). Devil rays are reported as bycatch in nine large-scale fisheries in 11 countries using driftnets, trawls, and purse seines, and in 21 small-scale fisheries in 15 countries using driftnets, gillnets, traps, trawls, and longlines (Croll et al. 2015). Between 1998 and 2009, global landings of mobulids reported to the Food and Agriculture Organization (FAO) increased by more than an order of magnitude, from 200 to 5,000 metric tons (Ward-Paige et al. 2013).
The global tuna purse-seine fishery is a particularly important source of devil ray bycatch, reporting them in five tuna fisheries from eight countries (Croll et al. 2015). Furthermore, devil rays are usually not identified to species in bycatch reports (Hall and Roman 2013). Most mobulids (including the Chilean Devil Ray) have been reported as bycatch in purse seines (Hall and Roman 2013). The frequency of mobulid captures and number of individuals captured per net set is generally relatively small (averaging less than 0.45 individuals per set, see below), but global distribution of purse seine fisheries and the large number of sets presents concern for mobulid conservation (Croll et al. 2015).
The Chilean Devil Ray is caught in targeted fisheries and as bycatch from artisanal and industrial fisheries throughout the Indonesian archipelago with the largest landings reported off East and West Nusa Tenggara and Central Java provinces (Dewar 2002, White et al. 2006b, Lewis et al. 2015). While previously mainly taken in Indonesia as bycatch of the inshore pelagic tuna gillnet fisheries and purse seine fisheries, devil rays are increasingly being targeted in response to Asian demand for devil ray gill plates (Dewar 2002, White et al. 2006b, Heinrichs et al. 2011, Lewis et al. 2015). Gillnet fisheries target devil rays, including the Chilean Devil Ray, in Indonesia, the Philippines, Mexico, India, the eastern and western coasts of Africa (Couturier et al. 2012), and Sri Lanka (Fernando and Stevens 2011).
Targeted mobulid harpoon fisheries have been documented across Indonesia including Lombok, Lamakera, Lamalera, and villages in the Alor region (Dewar 2002, White et al. 2006a, Croll et al. 2015). In Tanjung Luar (Lombok), a number of fishers reported a shift in focus to devil rays as a primary target since 2010 (Lewis et al. 2015). In the traditional whaling village Lamakera (Indonesia), the primary focus of fisheries has shifted from whales to manta and devil rays, with the Chilean Devil Ray the most commonly caught devil ray (Lewis et al. 2015). These fisheries have increased effort in terms of power and number of boats in recent years, resulting in an increase in local fishing pressure equivalent to an order of magnitude (Dewar 2002). Targeted fisheries are reported from the Philippines, with the Chilean Devil Ray comprising 2% of the devil ray fishery in 2002 (Department of Agriculture Bureau of Fisheries and Aquatic Resources 2009). In Sabah, Malaysia, the Chilean Devil Ray is targeted using baited handlines (A. Hochstetter, pers. comm. 2012).
Despite national protection in Mexico, illegal targeted catch and substantial mortality from artisanal and large-scale fisheries still occurs (Croll et al. 2012). In ports around Tumbes, Peru, around 45% of fishing trips in which devil rays were caught were actively targeting these species (SOSF 2014).
There are artisanal fisheries in multiple West African countries that target devil rays for human consumption both locally and for exporting to other markets (Couturier et al. 2012, Ender and Fernando 2014). However, little is known about the extent of these fisheries at present.
Targeted fisheries are reported in Sri Lanka (Fernando and Stevens 2011) and India (Rajapackiam et al. 2007).
In Sri Lanka, traditionally, mobulids were not fished due to the poor quality of their meat, but recently, demand for the gill plate export has fuelled targeted takes, with an estimated 6,700 Chilean Devil Rays landed annually (Fernando and Stevens 2011, Heinrichs et al. 2011).
In India, targeted devil ray fisheries are reported along the coast of Chennai, Tuticorin, Mumbai, and Veraval, within the Union Territory of Lakshadweep, and in the Andhra Pradesh and Kerala regions (Couturier et al. 2012). Following the high demand for devil ray products, a new ﬁshery formed along the Chennai coast using mechanized gillnets (Rajapackiam et al. 2007). The Chilean Devil Ray is fished on the west and east coast of India in marine, pelagic-oceanic, and benthopelagic/reef associated environments, primarily through use of gill nets and is commonly caught in the fishery (Kizhakudan et al. 2015). In recent years, trade in devil and manta ray gill plates has increased in Chennai (Kizhakudan et al. 2015), and this trade appears to be linked to a sudden increase in devil ray landings (Nair et al. 2013). There is also a seasonal harpoon fishery for devil rays in Andhra Pradesh, northeast India, and in Lakshadweep, north of the Maldives (Pillai 1998). No catch or effort data are available from this fishery at present to determine the extent to which it might affect the Chilean Devil Ray.
The Chilean Devil Ray is taken as bycatch (retained or discarded) in industrial and artisanal fisheries targeting other species throughout the Atlantic, Pacific, and Indian Oceans, most frequently in purse seines and gillnets (Couturier et al. 2012, Croll et al. 2015) but also in long-lines. Gillnet fisheries take large numbers of devil rays, including the Chilean Devil Ray, as incidental catch in Indonesia, the Philippines, Mexico, India, the eastern and western coasts of Africa (Couturier et al. 2012), and Sri Lanka (Fernando and Stevens 2011). The Chilean Devil Ray is also caught incidentally in Peru (SOSF 2014), Costa Rica (Dapp et al. 2013), Malaysia (A. Hochstetter, pers. comm. 2012), and the Gulf of Aden (Bonfil and Abdallah 2004).
Croll et al. (2015) estimate global mobulid bycatch in purse seine fisheries at ~14,000 devil rays per year. There is evidence for moderate to high post-release mortality of the Spinetail Devil Ray after incidental capture in purse seines (Francis and Jones, in press). In the purse-seine fishery, individuals undergo a process of encirclement, sacking up, and brailing on board; while many rays are alive when released, the release methods used in many cases are harmful (Croll et al. 2015), suggesting that even low levels of incidental capture can have a considerable negative effect on populations. Coelho et al. (2011, 2012) found very low at-haulback mortality of manta and devil rays from pelagic longline fisheries in the Atlantic and Indian Oceans, although these studies only considered the short term mortality from actual capture and did not monitor post-release survival. Given the results from Francis and Jones (in press), it is possible that internal trauma and stress resulted in slightly delayed mortality of these individuals, therefore these studies should not be used as an indicator of post-release mortality for these sensitive species.
Devil rays are caught as bycatch (and retained) in drift gillnet skipjack tuna fisheries in Indonesia, where the Chilean Devil Ray is the second most abundant mobulid, accounting for 23.5% of all mobulids caught (White et al. 2006b). An estimated 966 Chilean Devil Rays are landed annually in four landing sites in Indonesia (White et al. 2006b). No effort data are currently available from this region.
Devil rays (labelled as manta rays) were noted as one of the common elasmobranch species identified by observers in purse seine fisheries in the Pacific Island countries and territories (Lack and Meere 2009). In the Western and Central Pacific tuna purse seine fisheries, mobulids were found in 7.4% of sets observed between 1994 and 2004 (Molony 2005).
In the eastern Pacific tuna purse-seine fishery, devil rays are most commonly taken in school sets and dolphin sets (Hall and Roman 2013). Average devil ray capture rate (individuals per set) was 0.38 per set for school sets, 0.08 per set for dolphin sets, and 0.02 per set for floating object sets (Croll et al. 2015). Although the fishery operates across the Eastern Central Pacific, devil ray captures were concentrated in regions of high productivity and prey density (particularly euphausiids; Croll et al. 2015).
The estimates of mortality for the eastern Pacific for the period 1993–2013 average almost 2,800 individuals per year, with a range of 1,100–6,500 (Croll et al. 2015). Much of the devil ray take in this fishery occurs in the Costa Rica Dome region off Central America (Croll et al. 2015), but is also occurring south to the coast of Peru (Ayala 2008, SOSF 2014). In Northern Peru, mobulids were caught as bycatch in 55% of fishing trips that reported them (SOSF 2014), while 55% of gillnet artisanal fishermen reported devil ray bycatch (Ayala 2008).
Devil rays are taken as bycatch in pelagic gillnet and longline fisheries in the Indian Ocean targeting swordfish (Coelho et al. 2011), and the tuna purse seine fishery (Lezama-Ochoa et al. 2015). Effort trends for these fisheries are unknown. Off eastern South Africa, devil rays are a bycatch of the midwater trawl fishery, with a single vessel taking the majority of the catch (da Silva et al. 2015). Most chondrichthyan catch in this fishery is discarded, although post-release survival rates are not available.
Devil rays are also caught in relatively low numbers in the bather protection nets of the Kwazulu-Natal Shark Control Programme; from 1981-1990, the average annual catch was 14.2 devil rays per year, with an average of 60% released (Dudley and Cliff 1993). Post-release survival for these fisheries and the bather protection nets is unknown.
Devil rays are taken as bycatch in pelagic longline fisheries in the South West Atlantic Ocean Uruguayan and Japanese Longline Fisheries (ULF and JLF, respectively), which operate within the Uruguayan Exclusive Economic Zone (EEZ; ULF and JLF) and adjacent international waters (ULF; Mas et al. 2015). Mas et al. (2015) estimated trends in devil ray bycatch in these fisheries from 1998-2012 for the ULF and 2009-2011 for the JLF, and found that only 201 devil rays were incidentally caught during that time, equalling a catch per unit effort (CPUE) of 0.028 individuals per 1,000 hooks, which represents only 0.5% of both fleets’ total catch combined. Catches of devil rays fluctuated over the study period, with a peak in 2006 of just under ~20 individuals caught, decreasing again until a peak in 2009 of <50 individuals caught, remaining high until catches fell again to <10 in 2012 and less than five in 2013 (Mas et al. 2015). The devil rays identified in these fisheries included the the Spinetail Devil Ray and the Bentfin Devil Ray, but as only 38% of the fisheries are covered by observers, only 14% of devil ray bycatch was identified to species level based only on photo or video identification. As the Chilean Devil Ray also inhabits these waters, it is likely that this species is incidentally caught in the ULF and JLF as well and has just been misidentified (Mas et al. 2015). Depending on corresponding fishing effort, which is currently unavailable, this may indicate regional population declines.
Industrial trawlers operating off the northwest African coast also capture devil rays, with up to 620 individuals caught per year, most likely including the Chilean Devil Ray (Zeeberg et al. 2006, Couturier et al. 2012). The Chilean Devil Ray is the most commonly caught ray in the tuna purse seine fishery operating off the African coast, with 3.9 t caught between 2003 and 2007, which accounts for half of the total rays caught by weight (Amande et al. 2010, Torres-Irineo et al. 2014).
In the context of carrying out species-specific population trend analyses, the misidentification of devil ray species in catches and landings poses a threat to the entire genus by confounding accurate determination of each species’ population status. Devil ray bycatch data, if recorded at all, are historically recorded under various broad categories such as “Other”, “Rays”, or “Batoids”, but almost never recorded to species level (Camhi et al. 2009, Lack and Sant 2009). As such, the Chilean Devil Ray has generally been overlooked in most oceanic fisheries reports, with very little effort to properly identify or accurately record the species caught (Camhi et al. 2009, Croll et al. 2015). It is possible that the larger devil ray species such as the Chilean Devil Ray are declining more rapidly than the smaller species (Dulvy and Reynolds 2002), but this cannot be determined with the available data. A lack of appropriate species-specific catch, effort and population information poses a barrier to the conservation and management of devil rays.
The Giant Manta Ray (Manta birostris) and the Reef Manta Ray (M. alfredi) are listed on Appendix II of the Convention on International Trade in Endangered Species of Wild Fauna and Flora, yet no devil ray species have been listed. Following these protective measures there are concerns that the ongoing demand for gill plates will shift to focus on the devil rays.
Genetic research into devil ray evolution suggests that periods of global warming may have led to regional extinctions in the past (Poortvliet et al. 2015), thus current increases in global temperatures (van Nes et al. 2015) could also pose a growing threat.
All species of devil ray were added to Appendix I and II of the Convention on Conservation of Migratory Species (CMS CoP11), designating them as migratory species at high risk of extinction that would benefit from strict prohibition of take and regional cooperation to protect their critical habitats and migratory paths. In February 2016, all species of devil ray including the Chilean Devil Ray, were added to Annex I of the CMS Memorandum of Understanding on the Conservation of Migratory Sharks (CMS Sharks MOU). This non-binding agreement among 40 Signatories (as of February 2016) aims to achieve and maintain a favourable conservation status for migratory sharks based on the best available scientific information while taking into account the socio-economic value of these species. To date Australia (2015), the European Union (2015), the Maldives (Environment Protection Agency rule, 2014), Brazil (Inter-ministerial Normative Instruction No. 2 of 14/3/2013), Ecuador (Ecuador Official Policy 093, 2010), Mexico (NOM-029-PESC-2006, 2007), and Israel (2005) have passed national legislation to protect the Chilean Devil Ray through fishing and/or trade restrictions (Lawson et al. 2016). This species is also protected in three states or provinces in the United States (Florida, Guam, Commonwealth of the Mariana Islands), the Raja Ampat Regency (Indonesia) and Christmas and Cocos Keeling Islands (Australian Indian Ocean Territories).
Devil ray landings are rarely recorded to species level. Improved clarity in catch records and required, standardized reporting of devil ray catch by the Regional Fishery Management Organizations (RFMOs) would provide a basis for monitoring trends in effort and landings. Similarly, reporting of corresponding fishing effort trends is requisite for calculation of population trajectories. In 2015 the Inter-American Tropical Tuna Commission (IATTC) passed a prohibition on the transshipment, storage, landing, and sale of all devil and manta rays taken in large-scale fisheries within the IATTC convention area. The measure includes requirements for reporting devil ray catch data and ensuring safe releases, as well as provisions for technical assistance and capacity building. Developing countries were granted exceptions for devil and manta rays taken in small-scale fisheries for domestic consumption (IATTC 2015). Elasmobranch fisheries are generally unmanaged throughout Central America and Southeast Asia, and indeed elsewhere in the range of this species, and attempts to regulate fisheries in these regions would greatly improve conservation of the Chilean Devil Ray and other devil rays.
The development and implementation of management plans (national and/or regional e.g., under the FAO International Plan of Action for the Conservation and Management of Sharks: IPOA Sharks) are required to facilitate the conservation and sustainable management of all chondrichthyan species across the regions where this ray occurs. There is a lack of progress on successfully implementing shark National POAs (Davidson et al. 2015), especially with regards to devil rays.
The sensitivity of the Chilean Devil Ray, along with evidence of substantial CPUE where this species is fished, continued strong international demand for devil ray gill plates, and unmanaged, unmonitored fisheries throughout much of its range, calls for international conservation measures. These will need to focus on management of fisheries and trade, and reduction of demand for devil ray products.
The combination of i) unmanaged, unmonitored target and bycatch fisheries throughout the Chilean Devil Ray’s range; ii) evidence of substantial devil ray catch in several of these fisheries; iii) continued strong international demand for devil ray gill plates; and iv) the inherent sensitivity of the species, necessitates international conservation measures. These measures would ideally focus on management of fisheries and trade, and reduction of demand for devil ray products.
|Citation:||Pardo, S.A., Walls, R.H.L. & Bigman, J.S. 2016. Mobula tarapacana. The IUCN Red List of Threatened Species 2016: e.T60199A100016302.Downloaded on 28 October 2016.|
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