SEA Shepherd are questioning the accuracy of bycatch data recorded by contractors checking the controversial shark nets.
Despite the state government's news the nets will come out next month and be replaced with drumlines, the conservation group said they doubts DPI's data.
Sea Shepherd skipper, Jonathan Clark, said there appears to be a discrepancy in the species recorded in the monthly DPI reports, after seeing contractors remove a species of ray from the nets, which did not appear in any of the subsequent reports.
"Whilst operating at the Lighthouse Beach net our divers discovered two rays entangled in the net, after spending time taking images of the first ray, our divers progressed further along the net and found the second ray," he said.
"The contractor subsequently arrived at the net...... we then observed the crew retrieve the dead ray and take it on board the vessel."
Mr Clark said DPI's 8 Mar - 7 Apr report showed no deaths of the species at Lighthouse beach and other discrepancies involving dead ocellated eagle rays and a mobula ray also fail to align with their observations.
"Given we've been to the nets only five times and on two occasions observed catches, finding this discrepancy it does bring to question how often errors have been made," he said.
A NSW DPI spokesman said the rays were listed under Lennox Head, not Lighthouse Beach in the report.