Firth of Thames

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A true color photograph of the Hauraki Gulf (center). The Firth of Thames is the large bay in the southeast. The image was captured by NASA's Terra satellite on October 23, 2002.
Remnants of the historic Burke Street Wharf in Thames overlooking the Firth of Thames
Mussel farm off Matingarahi on the west coast of the Firth of Thames
New Zealand or South Island oystercatchers on Thames Beach , January 2007

The Firth of Thames is a large bay in the north of the North Island of New Zealand .

geography

The Firth of Thames is bounded to the west by the Auckland Council and the neighboring Waikato District to the south, to the south by the Hauraki Plains and to the east by the Coromandel Peninsula . The bay is open to the north and has access to the Hauraki Gulf . With a length of around 60 km and a width between 16 and 20 km, the Firth of Thames covers an area of ​​around 650 km 2 , while its catchment area is around 3,600 km 2 . The Firth of Thames is a shallow body of water. Around a third of the bay has a water depth of less than 10 meters. Towards the north, the water depth increases continuously to around 40 meters. At low tide an area of ​​around 8,500 hectares falls dry.

The main tributaries of the Firth of Thames are the Piako River , the Waihou River, and the Kauaeranga River .

Origin of name

The captain and navigator James Cook gave the bay its name and named the Waihou River the river Thames . The Māori call the bay Tīkapa Moana as they do for the Hauraki Gulf , so they make no distinction between the waters.

Flora and fauna

At low tide, the bay with the estuaries of the rivers releases around 8500 hectares of land. This land consists of mud flats , mussel beds , wet meadows , mangrove forests , salt marshes and salt marshes .

The mussel beds between Miranda and Kaiaua in the southwest of the bay are something special and were formed by the fossilized mussels Austrovenus stutchburyi . When the water level is high, they are used by many birds as a roost.

The southern part of the bay between Thames and Miranda offers the mudflats and water birds excellent conditions for their foraging and the mangrove forests and salt marshes for sea fish to raise their offspring. Over 74 different bird species that settle in coastal areas have been counted in the catchment area of ​​the Firth of Thames . Some species of birds come from the northern hemisphere in the wintertime and hibernate in the bay in the New Zealand summer. The permanent population in the bay is assumed to be around 25,000 birds, which increases to around 40,000 in the summer months due to migratory birds.

overfishing

The consumption of mussels was part of the daily consumption of the Māori as well as of the Europeans. But the mussel population was never endangered in New Zealand's pre-European times. This should change with the arrival of the Europeans. Even William Anderson , traveling with physician and naturalist of Cook expedition, reported in 1777 by the excellent quality of the mussels on the banks of the Firth of Thames . The first mussel harvests by Europeans are documented from 1909 from Tapu on the west coast of the Coromandel Peninsula . At that time the mussels were still harvested from the rocks by hand. Large-scale fishing with mechanical aids began in 1910 and continued into the 1960s. While the yields were still at a maximum of 500 tons up to 1930, they rose to 1400 tons in 1940 and to over 2800 tons by 1961. The main buyer of mussels, fresh, smoked or canned, was the greater Auckland area . After 1961, the mussel harvests dropped dramatically to 180 tons in 1965. In 1969 no more mussels were officially harvested.

Underwater video footage from 2002 showed that the natural mussel population in the Firth of Thames has not recovered. The reasons for this are assumed to be that, in addition to the ruthless overfishing of the 1940s, 50s and 60s, the overexploitation of the forest on the Coromandel Peninsula , the draining of many wetlands - especially in the Hauraki Plains - and the supply of cyanide-containing sewage from the Gold extraction in the Firth of Thames , which has permanently damaged the living conditions for the mussels in the bay.

Mussel farms

In 1965 an attempt was made to establish artificial mussel farms. But the first marketing took place only in 1978. The center of mussel farm keeping has been the Coromandel area since the 1980s . If the yields were not documented sustainably in the first few years, the first figures were available from 2004. 12,000 tons of mussels were harvested from the farms, increasing to 21,000 tons in 2006.

Protected areas

  • With the Hauraki Gulf Marine Park Act 2000 , the waters, the shore land and the seabed of the Hauraki Gulf , which also includes the Firth of Thames , were placed under special protection.
  • A special protected area is the 8,927 hectare RAMSAR protected area established on September 21, 1990 at the southern end of the bay, which places the designated wetland under the protection of international agreements. It will u. a. claimed by the local Māori of the Hauraki region on the basis of the Treaty of Waitangi . The fertile coastal strips were traditionally used by the Māori to hunt fish and sea birds.
  • The Miranda Naturalists Trust has been looking after the bird area between Miranda and Kaiaua described above since the 1940s and operates a Shorebird Information Center , which provides information and education.

literature

  • LJ Paul : A history of the Firth of Thames dredge fishery for mussels: use and abuse of a coastal resource . In: Ministry of Agriculture and Forestry (Ed.): New Zealand Aquatic Environment and Biodiversity Report . No. 94 , 2012, ISSN  1176-9440 (English, online [PDF; 3.2 MB ; accessed on January 29, 2017]).
  • N. Broekhuizen , J. Hong, J. Oldman, S. Stephens : Verification of Firth of Thames Hydrodynamic Model . In: Auckland Council (Ed.): Technical Publication . tape 326 , May 2007, ISSN  1175-205X (English, online [PDF; 3.3 MB ; accessed on January 29, 2017]).

Individual evidence

  1. ↑ Topo250 maps - Auckland - Hamilton - Coromandel . Land Information New Zealand , accessed January 29, 2017 .
  2. ^ Paul : A history of the Firth of Thames dredge fishery for mussels: use and abuse of a coastal resource . 2012, p.  14 (English).
  3. ↑ a b c d e f Firth of Thames . Department of Conservation , accessed January 29, 2017 .
  4. ↑ Broekhuizen , Hong, Oldman, Stephens : Verification of Firth of Thames Hydrodynamic Model . 2007, p.  10 .
  5. ^ Hauraki – Coromandel Region . In: Te Ara - the Encyclopedia of New Zealand . Ministry of Culture & Heritage , accessed January 29, 2017 .
  6. ^ A b Paul : A history of the Firth of Thames dredge fishery for mussels: use and abuse of a coastal resource . 2012, p.  7 (English).
  7. ^ A b Paul : A history of the Firth of Thames dredge fishery for mussels: use and abuse of a coastal resource . 2012, p.  3 (English).
  8. ^ Paul : A history of the Firth of Thames dredge fishery for mussels: use and abuse of a coastal resource . 2012, p.  20 (English).
  9. ^ Paul : A history of the Firth of Thames dredge fishery for mussels: use and abuse of a coastal resource . 2012, p.  19 (English).
  10. ↑ Firth of Thames . The National Wetland Trust , accessed January 29, 2017 .

Coordinates: 37 ° 0 ′  S , 175 ° 25 ′  E