Oceanic and coastal water temperatures are the highest since records began more than 40 years ago.

According to new data from Stats NZ, the waters around New Zealand reached their warmest annual temperatures between 2022 and 2023.

Stats NZ says sea-surface temperatures increased on average by 0.16 to 0.26°C per decade (equivalent to 0.63 to 1.05°C during the recorded period).

This is the temperature of the uppermost layers of the ocean. Stats NZ says this is typically between about 10 and 300 metres in depth.

Since 1982, the Tasman Sea was recorded as having the highest average rate of sea-surface warming.

"Measuring sea-surface temperature tells us how rapidly the ocean's uppermost productive layers are warming," says Stats NZ environment and agricultural statistics senior manager Stuart Jones.

Coastal regions warmed on average by between 0.19 to 0.34°C per decade (equivalent to 0.74 to 1.35°C during the recorded period), with East Coast South Island having the highest average rate.

Changes in sea-surface temperatures can impact marine processes, environments, species, and nature's contribution to people, says Stats NZ.

This can include some species, including some sharks, dolphins, and whales, changing location to maintain their temperature or the possibility they will not survive if they cannot move.

And changes to growth and reproduction of fishes like snapper, as well as an increase in invasive species occurring, it said.

The data used came from the National Institute of Water and Atmospheric Research (NIWA); National Oceanic and Atmospheric Administration (NOAA); National Aeronautics and Space Administration (NASA).

-RNZ.