A patchwork of warm and cool waters this summer could bring a variety of exotic fish species to the country's shores, says a marine ecologist.

Warm water from the Western Pacific Ocean is expected to have an impact around New Zealand, as higher than normal temperatures in November are expected to continue.

NIWA marine ecologist Irene Middleton says the country could see a number of different species this summer.

"We might get more tropical species turning up in the north, but we might also get things like kingfish, which are normally more in the north of New Zealand, turning up in Fiordland.

She says storms over summer could push different species of fish into New Zealand waters.

"We've got quite a lot of fish that turn up after storm events that kind of drift with marine debris.

"The sea snakes quite often get washed ashore after large storm events as well."

Irene says the Bay of Islands has seen an example of this earlier in the year, when a Japanese tsunami fish appeared after a storm.

She says warmer waters could also attract larger pelagic fish like whale sharks to the country.

And there were other species expected to make an appearance over summer.

Department of Conservation marine technical advisor Clinton Duffy says they have seen a general increase in sea turtle sightings thanks to public documentation.

"We've seen a general increase in the number of turtle sightings that people have been reporting to the department, but also there does seem to be a genuine increase in the number of strandings that we're getting."

He says some species of marine turtles become more active as the water temperatures increase.

"Green turtles are here pretty much year round, as the water cools down over winter time they can become much less active, but as it warms up over the summer they become more active and therefore more visible,.

"Combine that with more people being at the beach, we tend to get a lot more sightings of them over this period."

Clinton says DOC appreciates any sightings of turtles from the public, asking anyone who sees leatherback or green turtles to get in contact.

If you spot marine life:

• Report sightings or accidental captures of protected species to DOC anonymously via the Protected Species Catch App or to your local DOC office.
• Report injured or stranded sea species to the DOC emergency hotline 0800 DOC HOT (0800 362 468).

-Finn Blackwell/RNZ.