Riley A. Pollom

Seattle Aquarium · Conservation Programs and Partnerships

Understanding the details of local and regional extinctions allows for more efficient allocation of conservation activities and resources. This involves identifying where populations persist, where populations may still be present, and where populations may be locally extinct. Three threatened angel sharks occur in the Eastern Atlantic and Mediterr...

Overfishing is the primary cause of marine defaunation, yet declines in and increasing extinction risks of individual species are difficult to measure, particularly for the largest predators found in the high seas. Here we calculate two well-established indicators to track progress towards Aichi Biodiversity Targets and Sustainable Development Goal...

Few marine taxa have been comprehensively assessed for their conservation status, despite heavy pressures from fishing, habitat degradation and climate change. Here we report on the first global assessment of extinction risk for 300 species of syngnathiform fishes known as of 2017, using the IUCN Red List criteria. This order of bony teleosts is do...

The scale and drivers of marine biodiversity loss are being revealed by the International Union for Conservation of Nature (IUCN) Red List assessment process. We present the first global reassessment of 1,199 species in Class Chondrichthyes—sharks, rays, and chimeras. The first global assessment (in 2014) concluded that one-quarter (24%) of species...

Overfishing is the most significant threat facing sharks and rays. Given the growth in consumption of seafood, combined with the compounding effects of habitat loss, climate change, and pollution, there is a need to identify recovery paths, particularly in poorly managed and poorly monitored fisheries. Here, we document conservation through fisheri...

The true state of ocean biodiversity is difficult to assess, and there are few global indicators to track the primary threat of overfishing. We calculated a 50-year Red List Index of extinction risk and ecological function for 1199 sharks and rays and found that since 1970, overfishing has halved their populations and their Red List Index has worse...

Here, we summarise the extinction risk of the sharks and rays endemic to coastal, shelf, and slope waters of the southwest Indian Ocean and adjacent waters (SWIO+, Namibia to Kenya, including SWIO islands). This region is a hotspot of endemic and evolutionarily distinct sharks and rays. Nearly one-fifth (n = 13 of 70, 18.6%) of endemic sharks and r...

The Bowmouth Guitarfish (Rhina ancylostomus) is an Indo-Pacific shark-like ray that inhabits coastal waters of East Africa and the Red Sea, the northern Indian Ocean rim to Southeast Asia, north to Japan, south to Australia across the north of the continent, and east to the Solomon Islands, and New Caledonia. The genetic structure of regional popul...

The deep ocean is the last natural biodiversity refuge from the reach of human activities. Deepwater sharks and rays are among the most sensitive marine vertebrates to overexploitation. One-third of threatened deepwater sharks are targeted, and half the species targeted for the international liver-oil trade are threatened with extinction. Steep pop...

Biodiversity loss is a major global challenge and minimizing extinction rates is the goal of several multilateral environmental agreements. Policy decisions require comprehensive, spatially explicit information on species’ distributions and threats. We present an analysis of the conservation status of 14,669 European terrestrial, freshwater and mar...

Sharks and rays are key functional components of coral reef ecosystems, yet many populations of a few species exhibit signs of depletion and local extinctions. The question is whether these declines forewarn of a global extinction crisis. We use IUCN Red List to quantify the status, trajectory, and threats to all coral reef sharks and rays worldwid...

Chondrichthyan fishes are among the most threatened vertebrates on the planet because many species have slow life histories that are outpaced by intense fishing. The Western Central Atlantic Ocean, which includes the Greater Caribbean, is a hotspot of chondrichthyan biodiversity and abundance, but has been characterized by extensive shark and ray f...

The southwest Indian Ocean (SWIO) is a hotspot of endemic and evolutionarily distinct sharks and rays. We summarise the extinction risk of the sharks and rays endemic to coastal, shelf, and slope waters of the SWIO and adjacent waters (Namibia to Kenya, including SWIO islands). Thirteen of 70 species (19%) are threatened: one is Critically Endanger...

Chondrichthyan fishes are among the most threatened vertebrates on the planet because many species have slow life histories that are outpaced by intense fishing. The Western Central Atlantic Ocean, which includes the greater Caribbean, is a hotspot of chondrichthyan biodiversity and abundance, but is historically characterized by extensive shark an...

The scale and drivers of marine biodiversity loss are being revealed by the International Union for Conservation of Nature (IUCN) Red List assessment process. We present the first global reassessment of 1,199 species in Class Chondrichthyes—sharks, rays, and chimeras. The first global assessment (in 2014) concluded that one-quarter (24%) of species...

The southwest Indian Ocean (SWIO) is a hotspot of endemic and evolutionarily distinct sharks and rays. We summarise the extinction risk of the sharks and rays endemic to coastal, shelf, and slope waters of the SWIO and adjacent waters (Namibia to Kenya, including SWIO islands). Thirteen of 70 species (19%) are threatened: one is Critically Endanger...

Heterodontus mexicanus

Rhizoprionodon lalandii. The IUCN Red List of Threatened Species 2020

Red list assessment of Dasyatis chrysonata

The Multispine Skate (Bathyraja multispinis) is a medium-sized (to 126 cm total length) skate that occurs in the Southeast Pacific Ocean from Coquimbo, Chile to Cape Horn and in the Southwest Atlantic Ocean from Santa Catarina, Brazil to Tierra del Fuego and the Falkland Islands (Malvinas) and is demersal on the continental and insular shelves and...

The Broadnose Skate (Bathyraja brachyurops) is a medium-sized (to 125 cm total length) skate that occurs in the Southeast Pacific and Southwest Atlantic Oceans from Biobío, Chile, south around Cape Horn and north to Rio Grande do Sul, Brazil, including the Falkland Islands (Malvinas). It is demersal on the inner continental shelf and upper slope at...

The Whitedotted Skate (Bathryraja albomaculata) is a large (to 150 cm total length) skate that occurs in the Southeast Pacific and Southwest Atlantic Oceans from Coquimbo, Chile south around Cape Horn and north to Uruguay, including the Falkland Islands (Malvinas) and the Burdwood Bank, and is demersal on the inshore continental shelf and upper slo...

The Greytail Skate (Bathyraja griseocauda) is a large (to 157 cm total length) skate that occurs in the Southeast Pacific and Southwest Atlantic Oceans from Coquimbo, Chile south around Cape Horn and north to Uruguay, including the Falkland Islands (Malvinas), and is demersal on the mid-continental shelf and upper slope at depths of 30–1,010 m. It...

The Patagonian Skate (Bathyraja macloviana) is a small (to 71 cm total length) skate that occurs in the Southeast Pacific Ocean off Magallanes, Chile and in the Southwest Atlantic Ocean from Uruguay to Tierra del Fuego, Argentina and the Falkland Islands (Malvinas) and is demersal on the inner continental shelf and upper slope at depths of 50–515 m...

The Southern Thorny Skate (Amblyraja doellojuradoi) is a small (to 69 cm total length) deepwater skate that occurs in the Southeast Atlantic Ocean from Uruguay to Southern Argentina and the Burdwood Bank, including the Falkland Islands (Malvinas). It is demersal on the mid- and outer continental shelf and upper slope at depths of 50–1,000 m. This s...

The Darkbelly Skate (Bathyraja meridionalis) is a large (to 158 cm total length) that occurs in the Southeast Pacific Ocean off Magallanes Province, Chile, in the Southwest Atlantic Ocean from Buenos Aires to Tierra del Fuego, Argentina and westward to the Falkland Islands (Malvinas), and in the Antarctic Atlantic Ocean around the Shag Rocks and So...

The Magellan Skate (Bathyraja magellanica) is a medium-sized (to 105 cm total length) skate that occurs in the Southeast Pacific Ocean from Puerto Montt, Chile to Cape Horn and in the Southwest Atlantic Ocean from San Matías Gulf to Tierra del Fuego, Argentina, off the Falkland Islands (Malvinas), and on the Burdwood Bank. It is demersal on the con...

Hypanus dipterurs red list assessment

Sharks are a taxon of significant conservation concern and associated public interest. The scientific community largely supports management policies focusing on sustainable fisheries exploitation of sharks, but many concerned members of the public and some environmental advocates believe that sustainable shark fisheries cannot and do not exist and...

The Thintail Skate (Dipturus leptocaudus) is a medium-sized (to 88 cm total length) skate that occurs in the Southwest Atlantic from Santa Catarina, Brazil to Uruguay (and possibly Argentina). It inhabits the continental shelf and upper slope at depths of 10–550 m. It is captured in commercial deep-water trawl, longline, and gillnet fisheries, whic...

The Lesser Numbfish (Narcine brasiliensis) is a small (to 45 cm total length) ray that occurs in the Southwest Atlantic from southern Brazil to Buenos Aires Province, Argentina. It is benthic on soft substrates of the continental shelf at depths of 6–60 m. It is captured in intense and largely unmanaged commercial and artisanal trawl and beach sein...

The Wingfin Stingray (Fontitrygon geijskesi) is a medium-sized (to 150 cm disc width) ray that occurs in the Western Central and Southwest Atlantic from eastern Venezuela and Trinidad and Tobago to western Ceará, Brazil. It is demersal on the continental shelf inhabiting shallow coastal waters and estuaries, from inshore to 80 m depth. This stingra...

The Southern Eagle Ray (Myliobatis goodei) is a medium-sized (to at least 115 cm DW) coastal eagle ray that occurs in the Western Central and Southwest Atlantic Oceans from South Carolina and Florida, USA and Quintana Roo, Mexico to San Jorge Gulf, Santa Cruz, Argentina. It inhabits continental shelves from inshore to depths of 181 m. It is capture...

The Western Humpback Dogfish (Squalus quasimodo) is a small (to at least 85 cm total length) shark that occurs in the Southwest Atlantic off Rio Grande do Sul, Brazil, and possibly also in the Western Central Atlantic off Margarita Island, Venezuela. This shark is captured in commercial and artisanal gillnets, longlines, and trawls. Its recent taxo...

The Northeastern Brazilian Dogfish (Squalus bahiensis) is a small (to at least 69 cm total length) shark that occurs in the Southwest Atlantic and is known only from the type locality off Belmonte, Bahia, Brazil at a depth of 599 m. Its recent taxonomic resolution precludes inferences of catch rates or trends, but Squalus spp. are targeted and caug...

The Shortnose Eagle Ray (Myliobatis ridens) is a medium-sized (to 70 cm disc width) ray that occurs in the Southwest Atlantic from Santa Catarina, Brazil, to Buenos Aires Province, Argentina. It inhabits inshore bays and estuaries at depths of 5–47 m. It is captured in intense and largely unmanaged artisanal gillnet and beach seine fisheries throug...

The Bullnose Eagle Ray (Myliobatis freminvillii) is a medium-sized (to 106 cm disc width) demersal coastal eagle ray that occurs in the Northwest, Western Central, and Southwest Atlantic Oceans from Massachussetts, USA to the Texas coast of the Gulf of Mexico and from Venezuela to Buenos Aires, Argentina and inhabits continental shelves from the su...

The Brazilian Filetail Catshark (Parmaturus angelae) is a small (to at least 42.5 cm total length) deep- water shark that occurs in the Southwest Atlantic off Rio de Janeiro and Santa Catarina states, Brazil. It is demersal on the continental slope at depths of 500–600 m. It is likely captured in deep-water demersal trawl fisheries, which developed...

The Freckled Catshark (Scyliorhinus haeckelii) is a small (to 57 cm total length) shark that occurs in the Southwest Atlantic from Bahia, Brazil to northern Argentina. It inhabits the continental shelf and upper slope at depths of 37–402 m, and is often associated with deep-water reefs. This catshark is captured in artisanal and commercial trawl, g...

The Smalltail Shark (Carcharhinus porosus) is a small (<150 cm total length) coastal requiem shark that historically occurred in the Western Central and Southwest Atlantic Oceans from the central, western and southern Gulf of Mexico and along the Caribbean coast of Central and South America to the state of Paraná in southern Brazil, not including t...

Castello's Apron Numbfish (Discopyge castelloi) is a small (to at least 31 cm total length) ray that occurs in the Southwest Atlantic from Necochea, Buenos Aires, to Camarones, Chubut, Argentina. It inhabits the inner continental shelf at depths of 35–56 m. Its depth range suggests that it is exposed to commercial and artisanal demersal trawl fishe...

The Colares Stingray (Fontitrygon colarensis) is a large (to at least 165 cm disc width) ray that occurs in the Southwest Atlantic from Cayenne state, French Guiana to Maranhão, Brazil. It inhabits estuaries and shallow coastal areas around the Amazon River outflow at depths of 5–40 m. The meat is highly valued and this species has been targeted si...

IUCN Red List Assessment for Smoothback Angelshark (Squatina oculata)

IUCN Red List Assessment for Angelshark (Squatina squatina)

The International Union for Conservation of Nature's (IUCN) Red List is the global standard for quantifying extinction risk but assessing population reduction (criterion A) of wide-ranging, long-lived marine taxa remains difficult and controversial. We show how Bayesian state-space models (BSSM), coupled with expert knowledge at IUCN Red List works...

The extinction risk of sharks, rays and chimaeras is higher than that for most other vertebrates due to low intrinsic population growth rates of many species and the fishing intensity they face. The Arabian Sea and adjacent waters border some of the most important chondrichthyan fishing and trading nations globally, yet there has been no previous a...

Hippocampus patagonicus is a coastal species of seahorse that inhabits waters from northeastern Brazil to Chubut, Argentina. The major habitats occupied by the species include seagrasses, macroalgae, and sheltered areas with sessile invertabrates. The species is threatened by habitat degradation and loss from coastal development and destructive fis...

This report provides an overview of the con- servation status of chondrichthyans (sharks, rays, and chimaeras) in the Arabian Seas Region (ASR) and describes the results of a regional Red List workshop held in Abu Dhabi, United Arab Emirates, in February 2017. It identies those species that are threatened with extinction at the regional level, so t...

Europe has a long tradition of exploiting marine fishes and is promoting marine economic activity through its Blue Growth strategy. This increase in anthropogenic pressure, along with climate change, threatens the biodiversity of fishes and food security. Here, we examine the conservation status of 1,020 species of European marine fishes and identi...

Species in the family Syngnathidae were assessed for the IUCN Red List of Threatened Species at the Mediterranean regional level. Of the 13 species native to the Mediterranean Sea, two are Near Threatened, four are Least Concern, and seven are considered Data Deficient because there is not enough information about the species to assess their e...