Green turtle at Poor Knights Island marine reserve
Image: Laurent Bernard ©

Introduction

Although turtles breed in the tropics and subtropics, there are five species of turtle that are seen in New Zealand waters. Green and Leatherback turtles are the most common.

Leatherback turtle

Leatherback turtles (Dermochelys coriacea) are widely spread around New Zealand, and have been recorded as far south as Fiordland. Satellite tracking studies indicate that the waters around North Cape and the eastern coast of Northland are favoured foraging grounds.

Green turtle at Poor Knights Island marine reserve. Image: Luke Howe.
Green turtle at Poor Knights Island marine reserve

They prefer deep, open water and unlike the other turtle species, they can sustain the colder temperatures of the polar and subpolar regions (they have been recorded in the Arctic).

Leatherbacks only come inshore to breed; those of the Pacific breed in Australia and the Solomon Islands. They appear to return swiftly to feeding grounds in cooler waters, such as New Zealand.

They reach maturity at 3-5 years and their maximum age is unknown.

Leatherback turtles are listed as critically endangered by International Union for Conservation of Nature (IUCN).

Estimates suggest a 70% reduction in the global population of females within the last generation. Much of this is due to development and degradation of their nesting beaches.

In New Zealand and elsewhere, Leatherbacks are bycatch in the pelagic longline fisheries.

Green turtle

Green turtles (chelonia mydas) are the only herbivorous turtle, feeding mostly on seagrasses, algae and mangroves. They also eat fish and their eggs, jellyfish, sponges and various shellfish.

In turn they are preyed upon by many animals throughout their life cycle, including humans. They are called Green turtles because of the colour of their meat when made into soup.

Some Green turtles spend a part of their life cycle around the northern North Island, with individuals regularly seen at Rangaunu Harbour (Far North) and Poor Knights Islands.

These turtles are thought to come from the Indo/Western Pacific population, though some have been discovered from the Eastern Pacific population. Eastern Pacific Green turtles can be recognised by their distinctive tent-shaped carapace (particularly the females).

Green turtles are IUCN listed as Endangered (population decreasing). Coastal development and overharvesting by humans are thought to be the main causes of their decline. Some also die by ingesting plastic bags, as rubbish collects easily in the shallow harbours where they feed.

Loggerhead turtle

Records of Loggerhead turtles (Caretta caretta) in New Zealand are concentrated around the upper North Island, though they have washed up on beaches as far south as Stewart Island.

They appear to be only occasional visitors to mainland New Zealand, however they can live in relatively cold waters (10?c). Some may even hibernate in waters below 15?c; they do this by resting on the seafloor and surfacing as little as every ten hours to breathe.

It's estimated that they live 47 to 67 years.

Hawksbill turtle

Because they are the most tropical species, Hawksbill turtles (Eretmochelys imbricata) are relatively rare visitors to mainland New Zealand.

They are mostly seen in the upper North Island though they have been recorded as far south as Cook Strait.

They generally live in the clear, shallow waters of continental and island shelves and are distributed widely through the tropical band of the central Atlantic and Indo-Pacific regions.

Olive ridley turtle

Only five specimens of the Olive ridley turtle (Lepidochelys olivacea) have been reported stranded around the New Zealand mainland, and there have never been regular sightings. It is most likely that these specimens were stragglers, possibly sick, drifting on ocean currents.

The turtle is not named after a person called Olive Ridley. Rather the 'olive' refers to its colour, and the 'ridley' may refer to the fact that 19th Century fishermen around Florida and the Bahamas (where it is common) often confused it with Loggerhead or Green turtles. It was therefore considered to be 'riddly' (a riddle).

Turtles in the Kermadecs

The Kermadec Islands are a string of volcanic islands and islets in the subtropical zone between New Zealand and Tonga. Hawksbill, Green, and Leatherback turtles have been found in the Kermadecs, which are New Zealand territory.

Green turtles are commonly seen in the Kermadecs, but records are sparse because the region is so remote. The first records (made by W.B. Oliver in 1911) note that turtles were seen in the summer months, and that they did not breed in the Kermadecs but went north to the tropics.

Green and Hawksbill turtles were spotted inshore. All this is consistent with our current understanding of the habitat and behaviour of these turtles.

There are just four sightings of Leatherback turtles in the Kermadecs, all caught as bycatch in the New Zealand pelagic longline fishery. Again this is consistent with our understanding of Leatherbacks as turtles who prefer a deeper, offshore environment.

Green turtle Release at Rangiputa in February, 2012. Image: Dan Godoy.
Green turtle Release at Rangiputa in February, 2012

DOC's work with turtles

DOC staff attend beached or entangled sea turtles.

Those that are alive when found may be sent to a specialist facility such as an aquarium for rehabilitation. Dead specimens may be given to museums and scientists for research and educational purposes.

Data from beached turtles and live sightings are recorded in the New Zealand Amphibian and Reptile Distribution Scheme.

DOC monitors the bycatch of turtles and other protected species in commercial fisheries through its Conservation Services Programme .

All reptiles, including sea turtles, are protected under the Wildlife Act 1953. This means it is illegal to kill or harass any species of sea turtle within New Zealand's Territorial Sea or Exclusive Economic Zone.

It is also illegal to possess a sea turtle, or any part of a sea turtle without a permit issued under the Wildlife Act, or evidence that it was legally imported into New Zealand or was in your possession prior to commencement of the Wildlife Act (1 April 1954).

Convention on International Trade in Endangered Species

DOC is also involved in monitoring and regulating international trade in endangered species under the Convention on International Trade in Endangered Species (CITES).

DOC CITES officers work closely with officers from other government agencies, particularly Customs and the Ministry for Primary Industries biosecurity team, to detect illegal trade in endangered species.

All species of sea turtle are listed on Appendix 1 of CITES. This prohibits all international trade in specimens and products derived from sea turtles, except for exceptional non-commercial purposes such as scientific research.

CITES export permits

No sea turtle products can be carried or shipped out of New Zealand without a  CITES export permit – this includes personal items such as specimens and curios that may have been in your possession prior to protection under the Wildlife Act (1 April 1954).

It also applies to items shipped through New Zealand. Without a CITES export or re-export permit issued by DOC, these items are likely to be confiscated by customs officers upon arrival in any country that is a party to CITES.

Similarly, any sea turtle material imported into New Zealand without an export permit from the country of origin is likely to be confiscated at the border.

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