Conservationists have decried NSW’s shark nets after it was revealed they caught a number of protected species.

Figures from a trial of shark nets on northern NSW beaches have revealed they snared turtles, rays, and a critically-endangered grey nurse shark (which was released alive).

The nets did manage to catch a single bull shark (which they are aimed at), but no tiger or white sharks - two species they are intended to capture.

The trial is the second of its kind run by the state government at five beaches at Ballina and Evans Head.

In the first trial, 9 of the 275 animals caught were targeted sharks.

The second trial saw nets with a different design placed at different heights in an effort to reduce bycatch.

The data shows a slight reduction in the overall number of animals caught than in the first trial.

The shark net project is only possible because of legal exemptions granted by the federal environment minister, Josh Frydenberg.

Humane Society International marine scientist Jessica Morris says both trials have been “a complete disaster”, and called for the removal of the exemption.

“The federal environment minister needs to rethink his decision to allow shark nets and focus on his real job which is to ensure our endangered species are protected,” she said.

“Shark attacks are not the norm – they are traumatic but they are rare, and we need to realise that nets are doing more harm than good.”

Mr Frydenberg says the nets protect beach-goers, and public safety is of “paramount importance”.

“NSW’s shark net trials are being undertaken in accordance with national environmental law,” he told Guardian Australia.

NSW minister for primary industries, Niall Blair, said the new data is an “important part of testing the north coast net trial”.

“The second trial is one part of an overall shark management strategy being implemented by the NSW government, including Smart drumlines, helicopter surveillance, shark tracking and VR4G listening stations,” Mr Blair said. 

“The NSW government is committed to trialling and testing the best technology in the world to address shark attacks in NSW and will continue to work closely with local communities and all affected stakeholders.”

Nets are used regularly off 51 beaches between Wollongong and Newcastle.