London, Jul 5 (IANS): Hundreds of sharks and rays are tangled in plastic waste in oceans across the world, researchers said.

According to the study published in the journal Endangered Species Research, scientists from the University of Exeter scoured existing published studies and Twitter for posts on shark and ray entanglements and found reports of more than 1,000 entangled individuals.

The true number is likely to be far higher as few studies have focussed on plastic entanglement among shark and rays, said the researchers.

"Due to threats of direct over-fishing of sharks and rays and 'bycatch' (accidental catching while fishing for other species), the issue of entanglement has perhaps gone a little under the radar," said Brendan Godley, Professor at the University of Exeter.

The research says such entanglement - mostly involving lost or discarded fishing gear - is a "far lesser threat" to sharks and rays than commercial fishing, but the suffering it causes is a major animal welfare concern.

In the study, researchers 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.

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 tyres.

The study also identified factors such as habitat, migration and body shape that appear to put certain species more at risk.