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The Hauraki Gulf (Māori: Tīkapa Moana) is a coastal feature of the North Island of New Zealand. It has an area of 4000 km2,[1] Zeldisl, J. R. et al. (1995) Salp grazing: effects on phytoplankton abundance, vertical distribution and taxonomic composition in a coastal habitat. Marine Ecology Progress Series, Vol. 126, p 267-283 and lies between, in anticlockwise order, the Auckland Region, the Hauraki Plains, the Coromandel Peninsula, and Great Barrier Island. Most of the gulf is part of the Hauraki Gulf Marine Park.
Hauraki is Māori for north wind. Hauraki Gulf (from 'Te Ara', the Encyclopedia of New Zealand') In 2014, the gulf was officially named Hauraki Gulf / Tīkapa Moana. The New Zealand Ministry for Culture and Heritage gives a translation of "the mournful sea" for Tīkapa Moana. In traditional legend, the Hauraki Gulf is protected by a taniwha named Ureia, who takes the form of a whale.
Three large channels join the gulf to the Pacific. Colville Channel lies between the Coromandel Peninsula and Great Barrier, Cradock Channel lies between the two islands, and Jellicoe Channel lies between Little Barrier and the Northland Peninsula. To the north of Auckland several peninsulas jut into the gulf, notably the Whangaparāoa Peninsula. Tiritiri Matangi Island is near the end of this peninsula. Further north, Kawau Island nestles under the Tāwharanui Peninsula.
Numerous beaches dot the shores of the gulf, many of them well known for swimming and surfing.
During the last glaciation period the gulf was dry land, with the sea level being around 100–110 m (300 ft) lower than at present. The gulf was submerged when the sea reached its current level around 7200 years ago. During this period, the area was home to two river systems. The first of these was a river formed by two tributaries, the Mahurangi River and Waitematā Harbour (then a river). This river flowed north-east between modern day Little Barrier Island and Great Barrier Island, and emptied into the Pacific Ocean north of Great Barrier Island. The second was a stream formed by the major Hauraki Plains rivers: the Waihou River, Piako River and Waitakaruru River. Prior to the Oruanui eruption 27,000 years ago, the Waikato River also flowed into the Hauraki Gulf at the Firth of Thames. The Hauraki Plains rivers were met by two tributaries, the Wairoa River to the west from modern-day Clevedon and the Umangawha Stream to the east, at Colville, Coromandel Peninsula. This river flowed north, along the plains, turning east and exiting towards the Pacific Ocean along the modern-day Colville Channel between the Coromandel Peninsula and Great Barrier Island.
Other islands in the gulf include Browns Island, Motuihe Island, Pakihi Island, Pakatoa Island, Rākino Island, and Rotoroa Island in the inner gulf, around Waiheke and Rangitoto; Tarahiki Island just east of Waiheke; Motukawao Islands and Whanganui Island in the lee of the Coromandel Peninsula; and Channel Island in the outer gulf.
In March 2020, a small excavation was carried out in a large coastal midden on Ōtata Island. In January 2018, huge swells in the Hauraki Gulf caused widespread damage to its coastal areas and in only a few hours, the coastline of Ōtata had been reduced by up to 5 meters, exposing the midden. The aim of the excavation was to record this information before it is lost to erosion and was carried out in partnership with Ngāi Tai ki Tāmaki, the landowners. An understanding the changing marine environment around the island will also form part of the work.
An early visitor to the coast near the Thames was the 150-ton brig Fancy, under the command of Captain Thomas Dell, in December 1795. After three months in the area, the vessel returned to Sydney on 15 March 1795 with a cargo of flax and 200 spars. (1977). 9780909434151, Roebuck. ISBN 9780909434151
Many of the islands are official or unofficial bird sanctuaries, holding important or critically endangered species like kiwi, takahē, brown teal and grey-faced petrel. Centred on the main conservation island of Tiritiri Matangi and Little Barrier Island, numerous bird species that were locally extinct have been reintroduced in the last decades, while there have also been some naturally occurring bird "re-colonisations", especially after introduced pests were removed from breeding and nesting grounds.
Particularly damaging were the introduction of Fishing industry, with for example Lutjanidae fishing peaking in the 1970s at more than 10,000 tonnes a year (though even in the 2000s, private fishing of this species is also a considerable factor, weighing in at 400–800 tonnes a year). This severe overfishing, which unbalanced the marine environment by the removal of a main predator in the food chain, led to further degradation, such as a widespread disappearance of kelp beds as they were overtaken by kina barrens. Trawler fishing in general is seen as severely damaging the gulf, and lobster stock are also reported as not rebuilding. It is estimated that today's fish stocks are around 25% of pre-European levels.
Also particularly damaging are the results of nitrogen carried into the gulf from surrounding agricultural land, with almost 90% coming from the dairy-farming runoff into the Firth of Thames.
Other exploitation such as the dredging of the mussel beds of the Firth of Thames, reaching its height in 1961 with an estimated 15 million mussels taken (shortly before collapse of the industry) have led to damage which has not been recovered from forty years later, possibly due to the dredging having destroyed the seafloor, and sediment drainage from the agriculture in the Firth of Thames affecting the mussel's viability.
Numerous beaches dot the shores of the gulf, many of them well known for swimming and surfing. Although environmental problems exist around urban areas, with 14 out of 52 beaches in the Auckland Region at least occasionally showing unsafe pollution levels (mostly because of untreated sewage) for bathing, environmental groups are working to clean the beaches and restore their vitality.
Marine Park
The Hauraki Gulf was declared a marine park in 2000 by legislative statute. This was accompanied by the formation of the Hauraki Gulf Forum, whose membership includes representatives of local iwi and local authorities in the area surrounding the Hauraki Gulf. The park is distinctly different from other conservation areas of New Zealand not only by being a marine environment, but because it is home to more than one million people along its shores and on its islands. It also contains a number of (above-water) wildlife sanctuaries.
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