Global review of shark and ray entanglement in anthropogenic marine debris

Parton KJ, Galloway TS, Godley BJ (2019) Global review of shark and ray entanglement in anthropogenic marine debris. Endangered Species Research 39:173–190.

Numerous marine taxa become entangled in anthropogenic marine debris, including cartilaginous fishes (class: Chondrichthyes, e.g. elasmobranchs [sharks, skates and rays], holocephalans [chimaeras]). Here we review research that has been conducted on the susceptibility of these taxa to entanglement in marine debris by conducting a systematic literature review complemented by novel data collection from the social media site Twitter. Our literature review yielded 47 published elasmobranch entanglement events (N = 557 animals) in 26 scientific papers, with 16 different families and 34 species in all 3 major ocean basins affected. The most common entangling objects were ghost fishing gear (74% of animals) followed by polypropylene strapping bands (11% of animals), with other entangling materials such as circular plastic debris, polythene bags and rubber tyres comprising 1% of total entangled animals. Most cases were from the Pacific and Atlantic oceans (49 and 46%, respectively), with a bias towards the USA (44% of animals), the UK (30% of animals) and South Africa (10% of animals). While investigating Twitter, we found 74 cases of elasmobranch entanglement, representing 14 families and 26 species. On Twitter, ghost fishing gear was again the most common entangling material (94.9% of animals), with the majority of entanglement records originating from the Atlantic Ocean (89.4% of total entangled animals). Entanglement in marine debris is symptomatic of a degraded marine environment and is a clear animal welfare issue. Our evidence suggests, however, that this issue is likely a far lesser threat to this taxon than direct or indirect take in marine fisheries. We highlight a relative paucity of scientific data on this subject and recommend a standardisation of reporting in an attempt to accurately quantify elasmobranch entanglement risks and locate interaction hotspots.