The Ministry for Primary Industries (MPI) say a new vessel monitoring system was crucial to them finding those responsible for the 6km trail of dead fish at Muriwai Beach yesterday.
The technology enabled fishery officers to check what vessel was in the area and establish where it was going to dock.
This morning, Aotearoa Fisheries admitted to being responsible for the trail, saying one of its vessels lost its load of snapper due to severe weather conditions.
In a statement, the company said its trawl vessel lost about half a tonne of fish overboard after 25-knot cross-winds and 4m swells created what the boat's skipper has called "really quite frightening" conditions, like "being in a washing machine".
MPI says information gathered with the monitoring system, which is a joint venture between the Government and the commercial fishing industry, has recorded the vessel did make an unusual deviation in its course which corresponded with information the crew has given.
However, MPI is still investigating the trail and is making sure all reporting requirements have been accounted for.
Chief executive of Aotearoa Fisheries, Carl Carrington, commended the skipper "for acting responsibly and safely".
"Coming straight back to port to ensure the safety of his crew was paramount in this situation," Mr Carrington said.
"He had recorded the loss on his Catch Landing Report as he is required to do."
After losing the fish, the skipper decided the safest thing to do was head back to port, arriving back yesterday morning.
Aotearoa Fisheries says the loss of the fish has been accounted for under the Quota Management System.