30 Dec 2021

La Niña heatwave attracting rare fish species to NZ waters

7:39 pm on 30 December 2021

Keen fishers may get some rarer catches this summer, with New Zealand's warmer water temperatures enticing tropical fish species.

Man rock fishing at base of Mount Maunganui.

Man rock fishing at base of Mount Maunganui. Photo: 123rf

The La Niña weather event has helped create a marine heatwave in the country's waters, putting sea temperatures, in some areas, four degrees higher than average.

"In the middle of December, Auckland's water temperatures were 22°C. That's what we'd expect in February," said NIWA forecaster Nava Fedaeff.

NIWA marine ecologist Darren Parsons said this is good news for fishers.

"Fish respond over the long-term, moving down south to maintain the temperature band that they like to be in," he said.

"The ranges of red snapper and pink maomao are extending further south in response to warming conditions over the last few decades and it will be no different this year."

Dr Parsons said some tropical visitors New Zealand could expect include marlin and mahi-mahi around the Poor Knights Islands, off the coast of Matapouri.

He said fishers may have an easier time of getting a catch this summer too, as warmer water can make fish hungrier.

"Water temperatures also impact a fish's metabolism. Their body temperature is the same as the water around it, so when they're warmer, their metabolism speeds up. This means they need to eat more... if the fish are hungry, they're more likely to eat your bait."

Dr Parsons also said the good fishing luck may last long-term, with La Niña helping to create large spawning events for some species.

"Snapper, for example, do their spawning migrations in spring when the water reaches about 16°C, and in the past warmer years have led to more successful spawning," he said.

"We can expect this year to be a good one and in around five years, those fertilised eggs will have grown into fish big enough for us to catch. 2026 could be another bumper year - mark it in your calendars!"

Parsons acknowledged the marine heatwave may also be attracting more sharks to the country's waters.

He said some shark species follow the warm water to feed and give birth to live young.

Though he said an increase in sightings doesn't necessarily mean an increase in shark numbers.

"If it's nice weather and the waters are pleasant, more people will be out surfing and swimming. Just by being out in the water more, we're more likely to see sharks."

Dr Parson said it is too early to say if there are more sharks than normal yet, as most head inshore during the summer season every year anyway.

"What we do know, is that they will be there."

"njoy the waters, fish responsibly, and stay safe," he said.

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