In case you have not heard, plastic is killing marine life in vast numbers. The latest study has demonstrated that hundreds of sharks and rays are dying after getting tangled in drifting “ghost nets” and plastic waste–and scientists warn that figure is likely a serious underestimation. The pain and suffering endured (and death) from entanglements of our plastic castoffs raise the alarm as a serious animal welfare issue.
The review of academic papers found reports of 557 sharks and rays entangled in plastic, spanning 34 species in oceans including the Atlantic, Pacific and Indian. Almost 60 per cent of these animals were either lesser spotted dogfish, spotted ratfish or spiny dogfish.
Additionally, monitoring reports of marine life entanglements on Twitter, the researchers found 74 entanglement reports involving 559 individual sharks and rays from 26 species including whale sharks, great whites, tiger sharks and basking sharks.
Both data sources suggested “ghost” fishing gear (nets, lines and other equipment lost or abandoned) were by far the most common entangling objects. Other items included strapping bands used in packaging, polythene bags and rubber tires.
The study identified factors which appear to put certain species more at risk:
Habitat – sharks and rays in the open ocean appear more likely to get entangled, as do those living on the sea floor, where materials such as nets loaded with dead fish sink and attract predators, which in turn get stuck.
Migration – species that cover long distances appear at more at risk of encountering plastic waste.
Body shape – sharks seem to be at greater risk than rays. Species with unusual features – such as manta rays, basking sharks and sawfish – are also at more risk.
The study says more research is needed, and the researchers have worked with the Shark Trust to create an online report form to gather data on entanglements.
Journal Reference: KJ Parton, TS Galloway, BJ Godley. A global review of shark and ray entanglement in anthropogenic marine debris. Endangered Species Research, 2019; DOI: 10.3354/esr00964