Snapper fishers will need to lengthen their rulers and return more fish to the sea from Tuesday as measures to restore the country's most popular fishery take effect.

This is the last weekend when recreational fishers can legally take home as many as nine snapper with a minimum size of 27cm in the Snapper 1 fishery, which covers the east coast of Northland, the Hauraki Gulf and the Bay of Plenty.

From April 1, the bag limit drops to seven and the legal minimum size goes up to 30cm.

The changes were signalled last year by Primary Industries Minister Nathan Guy, but recreational lobbyists remain angry that the restrictions will bite them while commercial fishers remain free to land snapper as small as 25cm.


"It's ironic that it will be illegal for us to catch fish that the commercial guys can keep," Legasea spokesman Richard Baker told the Weekend Herald. He predicts shore-based and harbour fishers who land smaller fish will struggle to take home a feed.

There's concern that the measures will do little to enhance the fishery, particularly as many fish thrown back do not survive, Mr Baker says.

Mr Guy left the commercial take and size limits unchanged after a review last year, despite suspicions that high juvenile mortality in trawl nets and illegal practices were to blame for growing scientific alarm about the health of the fishery.

But a raft of changes to better monitor commercial activity and obtain a more accurate picture of the fishery's health are being worked on. The first scientific tagging survey in the fishery since 1993 is due to begin on October 1. The industry has introduced a "move on" rule when a high proportion of the catch is juvenile. Use of on-board cameras and requirements for commercial fishers to report quantities of fish caught below the legal minimum are also expected to improve knowledge of the fishery — though the ministry is employing no extra staff to monitor the information.