Scientists predict major snapper boom this summer

New Zealand can expect a golden summer for recreational fishing, with a long-term boom for snapper numbers if warm seas continue.

NIWA principal scientist Dr Malcolm Francis says the rise in New Zealand's sea temperatures - up to 6dgC in some areas - means we can expect an influx of gamefish. As well as this, fish that spawn in warmer waters - like snapper - can expect a "big boost" if this continues.

Snapper spawning starts in the Hauraki Gulf when water temperature reaches about 16degC, and is likely to start earlier in warm years.

"The number of snapper larvae that survive and settle to the seabed as juveniles is positively related to water temperature - in warm years we get more recruits, leading to what are known as strong 'year classes'," Dr Francis told Newshub.

"The last three summers have produced higher than normal temperatures, so we predict that the number of young snapper in the Hauraki Gulf will be greater than normal in future years.

"If summer 2018 is another warm one, then there should be a big boost to snapper numbers in the Gulf as a result of several consecutive years of good recruitment."

It might take a few more years for the snapper to reach the minimum legal size, so in the meantime it might be time to bait up the hook and target larger species.

Every summer and autumn, we get an influx of subtropical and tropical fishes coming down from the north into northern NZ waters, like skipjack tuna, yellowfin tuna, albacore tuna, and striped marlin - check here to see what you should and shouldn't be catching.

We would expect to see more of these fish immigrating into our waters and staying longer than before.

"Some species migrate southward through NZ waters as the water temperature increases," Dr Francis told Newshub.

"Albacore tuna are caught by trolling off the west coast of both main islands, with the fishery starting west of Auckland and Northland usually in December-January and then progressing southward to Westport and Greymouth by Feb-March.

"In warmer summers, the fish may move south earlier than normally."

There's good news for the South Island too. North Island fish are likely to move down the country and stay longer down south.

"Kingfish and kahawai occur mainly around North Island for much of the year but they extend their range down to South Island waters in late summer-autumn," Dr Francis says.

"Snapper migrate from Tasman and Golden Bays down the west coast of South Island. These movements may intensify and last longer in warm years."

Newshub.