"Do we want a fishing-based tourism economy in Northland or do we want to save our native fish and aquatic environment of Kai Iwi Lake Reserve?"
That's the big question circling between trout fishing enthusiasts and guardians of Northland's Kai Iwi Lakes.
Reporter Avina Vidyadharan looks at both sides of the debate.
The decision to stop putting trout into Northland's Kai Iwi Lakes has got fishers riled, but the guardians of the lakes say returning them to their natural state, and protecting native species, is the ultimate aim.
Kaipara District Council (KDC) released the Kai Iwi Lakes (Taharoa Domain) Reserve Management Plan 2016 which states they want to ban trout fishing and noted: "Exotic fish releases cease in all lakes by 2018. Monitor changes in other species as the trout population decreases."
The plan identified trout as a pest fish in Northland dune lakes. However, it stated it would consider re-releasing trout if native species were seen to decline in their absence.
"Consider using Lake Kai Iwi as a 'control' lake to aid research," the report said.
The Taharoa Domain Governance Committee (TDGC) had established a dedicated Department of Conservation-led working group to monitor and advise on the management of native species in the Lakes and to better understand the ecology of species.
DoC freshwater science adviser Dr Dave West said the decision to stop the release of trout was part of community discussion when the TDGC developed its management plan which went through a very formal process to develop in 1999 and again at its review and update in 2015/16, which had public support.
"Trout is a large efficient predatory fish which are not native to Aotearoa's fresh waters. They eat the young and adults of native freshwater species and compete with native species for food and habitat.
"There is debate on the impact of different trout species on different native fish species in different places.
"New Zealand science journals contain many articles documenting the impact of trout on native freshwater species, but I am not aware of any that show trout benefit or have no effect on native freshwater species.
"Trout and native fish can co-exist, but native fish are unlikely to thrive. Additional factors can impact native fish more than exotic fish, such as poor water quality and habitat so native fish that might have been able to coexist with trout under good conditions may become extinct at that location.
"Basic fish biology suggests that when a fish does not have to compete with another fish for food or habitat it will have better growth. Removal of trout from a lake in Zealandia sanctuary in Wellington benefited the resident native banded kokopu."
Speaking about the effect of trout on mosquito fish, West said he was not sure if the presence of gambusia was factored into TDGC's decision.
"There is a risk that when trout are no longer present in the lakes gambusia numbers will increase and they will impact native freshwater species such as Dune Lakes Galaxias.
"Few gambusia have been found in trout guts sampled from the lakes which suggest trout are not currently playing a large part in controlling gambusia numbers so lower risk that numbers will explode once trout are no longer present in the lake.
"We have obtained a cheap mass-producible gambusia trap that catches large numbers of gambusia and plan to get support to set large numbers in lakes to monitor and remove gambusia."
As trout cannot reproduce in the Taharoa lakes, stopping releases would mean trout will not be in lakes after the last released trout are caught or die after 3-5 years, said West.
"The same is not true for gambusia, the only confirmed pest fish in the lakes which breed prolifically in the margins of the lakes and would be impossible to eradicate without impacting native freshwater species.
"DoC and Northland Regional Council undertake pest fish (eg, koi carp) eradication and control in other Northland lakes."
KDC customer experience general manager Darlene Lang said the plan gave TDGC the confidence to proceed in accordance with the direction set and cease the release of exotic species.
"The committee's intention, as reflected in the Reserve Management Plan, remains to restore the Taharoa Domain to the as near natural state as possible, including phasing out exotic forestry after harvest, restorative planting with native species, pest control, weed control and ceasing releases of exotic fish [trout]."
Since implementing the plan in 2018, this year was the third consecutive year that saw the ban of the release of trout into Kai Iwi Lakes, which raised concern from trout fishing enthusiasts because there would not be any trout left in the "put and take" lakes.
Northland Fish & Game Council manager Rudi Hoetjes said trout fishing was a major tourist attraction in Northland and the ban would affect the council economically.
"We are going to have fewer people who want to go trout fishing and it will affect our income. This will in turn affect the management we do towards freshwater fishing and freshwater resources in our region. We are a use-to-pay group and are not funded by any government groups.
"It is the best fishery north of Hamilton and it will cease to exist in a fairly short period of time."
Hoetjes asserted the KDC did not undertake the economic evaluation while making these rules.
"This will have an impact not just on the fishing licence house, but also the local retailers. People won't be going to the local coffee houses or restaurants.
"People coming here with the sole purpose of fishing are not just international tourists, it's also people coming from Auckland just to spend a couple of days. They won't be looking for accommodation here or buying petrol for their boats or cars and so on and so forth."
Trout fishery had co-existed with native fish since 1968 and trout fishing alone had not caused the decline of native fish in New Zealand, said Hoetjes.
"There is a whole lot of reasons and the main reasons primarily are water quality, habitat loss and lack of water. The native fishery is also declining because there is over-harvesting of some species for whitebaiting in some catchments. It is a combination of factors and it is not just one on its own.
"Trout eat other fish. The argument that they are endangering the native fish is not proven and currently.
"There is gambusia in the lake which were introduced illegally in the lake years ago. They predate on native fish as well. They feed on the eggs, juveniles and they also feed on zoo planting which the native fish feed on. It is a whole food web problem, not just the trout.
"Some of the management decisions made by the Kaipara District Council have been made without knowing all the science that goes with the decision."
Northland Fish & Game Council's total revenue in 2019 was $181,716 (fish licences $37,446; game licences $144,270) and $171,325 in 2020 (fish licences $39,763; game licence $131,562).
KDC customer experience general manager Lang said they had not kept any economic information about the impacts of fishing-based tourism at the Lakes.
"There are a number of other places in Kaipara where fishing is possible."
The decision to ban trout release also saddened many trout fishing enthusiasts, including retired couple Christine and John Laue of Omapere who had been going to Kai Iwi Lakes for more than 20 years.
Laue said many annual trout fishing competitions had been held at the lakes under the auspices of Fish & Game, which have had, as the main aim, the nurturing of a love for trout fishing alongside environmental awareness among junior anglers which becomes life-long.
"Trout fishermen are ardent enthusiasts in practical nature conservation and advocate for the value of protecting all water resources.
"Alas, the annual trout fishing competitions seem about to come to an end with the Kaipara Council unable to renew permission for Fish & Game to restock the lakes in 2021. In my opinion, it will be a sad loss of the trout fishing aspect of this wonderful angling resource to the public if the trout are to no longer be part of the Kai Iwi Lakes' appeal."
The Reserve Management Plan outlined the objective to honour the intent of Paramount Chief Parore Te Awha in 1876 that the lakes be open and enjoyed by all and to restore natural, indigenous biota, ecological systems and restore traditional kai, among other objectives.
Historically, an extensive tract of land known as the Maunganui Block was sold to the Crown in 1876 by the Chiefs Tiopira Kinaki and Parore Te Awha. Subsequently, a small 250-acre portion of that area which was centred on Lake Kaiiwi was cut out of the wider area that had been purchased and granted back to Parore Te Awha, which became known as the Taharoa Native Reserve and was to become the subject of a Treaty of Waitangi claim after it was sold to the Crown in 1950 without the involvement of Parore's descendants.
Around 10,000 rainbow trout fingerlings were released into Lake Taharoa in 1968, Lake Waikare the following year and trout fishing at Kai Iwi Lakes commenced.
Amongst the goals of the plan was to significantly enhance the qualities of Kai Iwi Lakes while addressing use pressures.
A close, long-standing relationship with the lakes and surrounding land lead to Māori regarding them as taonga (treasure) and an important food source. They had fished, lived in the area around the lakes and buried their dead there. Two urupa (burial grounds) were known to exist and a pa site overlooked Lake Kaiiwi from just outside the legal boundaries of the reserve.
The Taharoa Native Reserve was defined in an effort to conserve iwi access to the Lakes when broader land holdings were sold by local Māori.
The plan noted: "When Parore sold the Kai Iwi Lakes land, he sought and was granted back 250 acres as part of the transaction as an inalienable Native Reserve. This area includes Lake Kai Iwi and the land adjoining this lake to Lake Taharoa, including the channel where eels use to cross.
"Since the 1876 sale, neither the Crown nor local authorities have honoured the intent of the sale. The Crown did not establish the inalienable Native Reserve that it was supposed to, the eels' fishery has largely been destroyed, and exotic species have significantly changed the whole ecosystem."
TDGC chair Ric Parore said the lakes were a heritage, beautiful water and lovely place to go to.
"It's been part of the whanau for many hundreds of years and we can go back many generations, probably 11 or more. In the 2016 Plan, it was noted that we would return the lakes to their original form.
"In its natural state, we used to get eels to come up to lake from the ocean, but the Hobson county council [now Kaipara District Council] interrupted the flow and they altered the access way for eels to go from one lake to another.
"Apparently, there are eels still in the lake but we would like to restore it back to its natural native form."
TDGC is a four-member committee and they had a vote on the question of releasing trout in the lake.
"Three voted against the release, while one abstained from voting," said Parore.
Te Roroa Group science adviser Taoho Patuawa was also the science adviser on the TDGC. He said their focus was to promote indigenous species so they could thrive in their natural environments.
"We can't speak for all of Te Taitokerau, but within the rohe of Te Roroa it is important to have our values and mana reflected in decision making when it comes to all activities which could potentially have an impact on native biodiversity within our culturally significant indigenous ecosystems, such as ngahere (forests), awa (rivers), moana (coastal areas), and in this case roto (lakes).
"Trout is a voracious, efficient predator which is not native to the waterways of Aotearoa.
"Within the context of the Kai Iwi lakes, native fish and invertebrates, for example, native bullies and kewai (freshwater crayfish), would make up a significant proportion of the diet of trout as that is all that is there, and there is very little evidence to indicate that trout predate on gambusia, the only other pest fish known to occur in those lakes.
"Trout are added on purpose by humans for one single purpose, a purpose that is not supported and does not take into account the cultural values and mana of hapu and iwi.
"Te Roroa does not support a recreational trout fishery in Te Taitokerau, especially within our taonga lakes.
"Te Roroa and Te Kuihi are actively involved in several activities to protect the outstanding indigenous landscape of Taharoa including monitoring of the lake beds to ensure they remain free of unwanted aquatic weeds, regional response to invasive fish incursions, removal of wildling pine trees and other noxious plant species within the reserve management area, pest control including possum, stoat and rat removal from the reserve management area.
"Most of these activities are achieved with the support of and in collaboration with our partners NRC, DoC, NorthTec, and KDC. If there is a positive financial return from trout tourism, it certainly is not reinvested into the natural landscape of Taharoa Domain."