OUR ACHIEVEMENTS
with Government & Council Lakes
NZ Waterways has provided grass carp to restore a considerable number of pristine New Zealand lakes across the country. Working with Central Government, Regional & District Councils, and the likes of Biosecurity NZ to remove or eradicate potentially the worst aquatic pest weeds nationally. To date NZ Waterways has released grass carp in more than 100 man-made lakes successfully.
Some of these highlighted are as follows:
Lake Omapere
Omapere, North Island NZ
Since 2002 (restoration & maintaining)
Lake Omapere is the largest lake in Northland, being 1197 ha in area but only 2 m at it’s deepest. The surrounding catchment is mainly pasture with a few areas of native scrub and mature bush. Grass Carp and Silver Carp were released to control the pest aquatic weeds and algae there; doing so successfully immediately following their release.
The report ‘Lake water quality in New Zealand 2010 status and trends’ produced by the Ministry for the Environment found that one lake (only lake observed with grass carp) had improved significantly. Trends were analysed for 68 lakes for five years since 2005.
Verburg, P., Hamill, K., Unwin, M., & Abell, J. (2010). Lake water quality in New Zealand 2010 status and trends.. Wellington, N.Z.: Ministry for the Environment.
Lake Tauriko
Tauranga, North Island NZ
Since 2015 (restoration & maintaining)
Lake Tauriko is situated in Tauriko,Tauranga; being part of the recent 254 hectare development. It is a feature lake that is approximately 13 hectares in size. In 2015 the Tauranga City Council and NZWR agreed that grass carp would be the most appropriate, and effective aquatic control method for the lake, considering also the long term success Tauranga has had with these fish. The lake bed was covered in Egeria densa and Potamogeton crispus, and starting to reach the surface in many areas which was unacceptable due to its partial use for motorless recreation. Other aquatic weed control methods were found to be far more costly, and the likes of herbicides and the mechanical removal of weeds results in considerable loss of aquatic life; being a feature of many lakes. Not to mention that it results in the degradation of the habitat through rotting vegetation and disturbance of sediments; making it unsafe for humans or any animal to consume safely. Once introduced the grass carp reduced the weed levels, and continue to keep the weed from reaching the surface.
Lake Tutira
Hawkes Bay, North Island NZ
Since 2009 (restoration)
Alongside SH2 north of Napier, is lake Tūtira (172 ha.). This culturally significant lake is located along an ancient Maori travelling trail and were formed by a land slip at least 7200 years ago. Lake Tutira is one of our most scientifically studied lakes, and with instruction coming from Biosecurity NZ, grass carp were released by NZ Waterways to target a pest plant species known as Hydrilla. Once introduced the grass carp reduced the weed levels, and became indirectly responsible for increased native fish populations.
Lake Western Springs
Auckland, North Island NZ
Since 1996-2016 (restoration)
Lake Western Springs is a 12ha spring fed waterbody in Auckland City. A large number of juvenile Grass Carp were released to control the pest aquatic weed Egeria densa there; doing so successfully within 123 days following their release. It is one of the earliest success storys of grass carp in NZ.
Lake Swan
Northland, North Island NZ
Since 2009 (restoration & maintaining)
Lake Swan is a small dune lake of 17.4 ha. It is 5.5 m deep and situated in a pastoral dominated catchment with some areas of scrub and pines. Grass Carp were released to control the pest aquatic weeds there; doing so successfully immediately following their release
Lake Kereta
Auckland, North Island NZ
Since 2008 (restoration)
Lake Kereta is a 32ha waterbody that lies at the South Head peninsula of the Kaipara Harbour, in the Rodney District, along the west coast of the North Island of New Zealand. A large number of juvenile Grass Carp were released to control the pest aquatic weeds there; doing so successfully following their release
Lake Wainamu
Auckland, North Island NZ
Since 2009 (restoration & maintaining)
Lake Wainamu is a dune lake located in the Waitakere Ranges Regional Park and is a popular spot for swimming and walking. Grass Carp were released to control the pest aquatic weeds there; doing so successfully immediately following their release.
Lake Whitby
Porirua, North Island NZ
Since 2012 (restoration & maintaining)
Lake Whitby (lower) is an urban lake located in the Whitby township in Porirua. It is a popular spot for walking and fishing. Grass Carp were released to control the pest aquatic weeds there; doing so successfully immediately following their release.
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