For the first time, catch limits are being introduced for recreational fishers targeting southern bluefin tuna.

Photo: Supplied/WWF

The recreational catch for the tuna has typically been low, but Fisheries New Zealand said it had increased substantially in the last five years.

In 2016, recreational fishers were catching just over a tonne, but that had gone up to more than 24 tonnes by 2017.

The increase in the recreational catch was put down to social media posts, good catch rates and favourable weather, which had resulted in anglers increasingly targeting the species, particularly in Bay of Plenty, a fisheries report said.

But the increased catch threatened New Zealand's ability to meet international obligations to ensure the sustainability of southern bluefin tuna stocks.

As a result, from 1 June, only one fish can be caught per person.

Acting director of fisheries management Steve Halley said the limit reflects the need to carefully manage and rebuild the fishery.

"Following consultation and having received responses from tangata whenua and submissions from stakeholders, Fisheries New Zealand advised the Minister of Fisheries to introduce a daily limit for the recreational fishery," he said.

"Introducing a bag limit will ensure that New Zealand continues to meet its international obligations under the Commission for the Conservation of Southern Bluefin Tuna."

The species is "highly valuable", but current stock estimates show breeding-age bluefin tuna numbers have dropped to about 13 percent of what they were before fishing began.

"Which is below the level able to produce the maximum sustainable yield," the report said.

For the 2017/2018 fishing year the Minister of Fisheries increased the recreational catch allowance of bluefin tuna nationally from 12 tonnes to 20 tonnes, and the Annual Catch Entitlement for commercial fishers was increased by 76 tonnes.

Fisheries New Zealand said it was also working on longer-term measures to manage the fishery.