Of the country's 63 largest fishing boats, it's possible only one of them meets modern safety standards.
The findings are in a Transport Accident Investigation Commission (TAIC) report into a fire on the 48-year-old Dong Won 701 in Timaru last year, which says the vessel's age contributed to how quickly the fire spread.
The year the Dong Won 701 first entered service in 1971, the Vietnam War was raging, Richard Nixon was still safe in the White House and Jim Morrison from The Doors was found dead in a Paris bathtub.
The TAIC report noted the boat's wooden interior, common for the time, led to the fire spreading in a matter of minutes.
TAIC manager Martin Harper said it was fortunate it was not at sea at the time, where the consequences for its 44 crew members would have been much more severe.
"There was very, very little left from the actual source of ignition where the fire started", he said.
The Dong Won 701 was registered in New Zealand before stricter safety standards were introduced in 2004.
It was one of 50 vessels working New Zealand's waters that did not meet modern standards and which had been given special dispensation to continue operating, known as grandparenting.
TAIC said it knew of another 12 vessels that may not comply with the 2004 standard either.
That suggests all but one of New Zealand's large fishing vessels - those measuring 24m or more - are not meeting modern safety standards.
TAIC said the crew on these vessels were at greater risk from threats such as fires because they lacked features such as doors that closed automatically or fire-resistant materials.
Harper said among the commission's recommendations was a law change to ensure non-compliant grandparented vessels not be allowed to continue sailing indefinitely.
"Clearly we have to look at modern day standards and how at some points those vessels either meet new modern day standards or are slowly taken off the register. Otherwise, you can see the standards would slowly deteriorate."
Maritime New Zealand's Kenny Crawford compared the safety checks required for fishing boats to those in place for cars.
He said just like an older car, an older boat registered in New Zealand before 2004 would still receive a pass as long as it complied with the safety standards in place at the time it was built.
"Vessels are built for 25, 30-year, sometimes 40-year lifespans. It's not appropriate to spend millions of dollars on a vessel and then two years later a rule amendment comes and makes it illegal. So that's why there's a grandparenting system in place."
Crawford said the current rules were confusing for everybody to follow, including Maritime NZ's surveyors who are in charge of safety checks.
Maritime New Zealand is consulting with fishing boat operators and builders on making the rules easier to understand.
Crawford said it may also impose stricter rules on the 50 grandparented vessels identified by TAIC.
"It may be that some of those are allowed to operate as they are, and some of them may have to do some amendments and some of them it may be that they have to do some significant changes. But this has not been worked through yet."
Sanford, which contracted the Dong Won 701 to catch fish for it, said its own vessels were regularly checked to ensure they complied with Maritime New Zealand standards.
It said it was in the process of adding three new scampi boats to its fleet which it described as "state of the art."
Seafood New Zealand said all fishing vessels were subject to regular safety audits and the industry took the safety of its crew very seriously.
In the TAIC report, Dong Won Fisheries which continues to operate two vessels in New Zealand waters said it had brought in changes around staff training to handle fires and was making fire safety improvements to its boats.
If passed by parliament, the new rules being worked on by Maritime New Zealand would come in to force in 2023.