The San Granit is a $25 million ship that joined Sanford's Timaru-based fishing fleet in 2016.
"We are sad to advise the tragic death of one of our crew members on our deepwater factory vessel, the San Granit," a Sanford spokesperson said yesterday.
"Our thoughts are with the family, friends and workmates of our team member as they are dealing with this terrible incident.
"As of now, we are unable to provide more detail about this situation, as the facts are still being established and we need to allow the relevant authorities to do their work.
"The family has been advised and we are offering every support that we can."
Police said their thoughts go out to the family of Stewart at this sad time.
They continue to work with TAIC and the matter will be referred to the Coroner.
The Commission opens an inquiry when it believes the circumstances of an accident or incident have - or are likely to have - significant implications for transport safety, or when the inquiry may allow the Commission to make findings or recommendations to improve transport safety.