Download AEBR 351 Marine heatwaves and fisheries in Aotearoa New Zealand: observed and projected temperature anomalies and potential impacts by fisheries management area

Behrens, E.; Dunn M.R.; Holmes, S.J.; Cummings, V.J. (2025). Marine heatwaves and fisheries in Aotearoa New Zealand: observed and projected temperature anomalies and potential impacts by fisheries management area. New Zealand Aquatic Environment and Biodiversity Report No. 351. 58 p.

The ocean around Aotearoa New Zealand has been warming, and marine heatwaves have become more prevalent and more intense.
This project examines patterns in warming (the slow warming trend over time) and heatwaves (shorter periods that are exceptionally warm) around Aotearoa New Zealand.

Maps of past and future projected coastal and ocean temperatures are reported for “shallow” (0–200 m) and “deep” (200–1500 m) waters in the ten Aotearoa New Zealand Fisheries Management Areas.

Most coastal waters show a sea surface warming trend between 0.2–0.3°C per decade.

Coastal bottom temperatures are warming by about 0.1°C per decade.

Marine heatwaves are projected to get hottest around the North Island, and more frequent around the South Island.

The fish stocks more likely to be impacted by future temperature changes include: green-lipped mussels on the west coast of the North Island; pelagic mackerels and tunas around the North Island and the west coast of the South Island; pāua around the Chatham Islands; snapper and John dory around the North Island and the west coast of the South Island; and arrow squid off Southland and northern parts of the Sub-Antarctic.

We recommend these regions and fisheries would benefit from further and more detailed study to better understand the potential scale and implications of these impacts.

We have the most knowledge of how temperature influences some shellfish, but relatively little for most New Zealand finfish species. The threats from marine heatwaves to most species remain poorly known and speculative, simply because we don’t know much about the impacts of temperature on these species.