Does James Meager’s rush to take over Fish and Game stem from the Coalition Government’s realisation that irrigation and healthy salmonid fisheries are incompatible?
Is this why the Minister’s new bill will give him the power to block Fish &Game’s ability to take legal action in the defence of fish habitat?
Hydroelectricity and irrigation destroy salmon rivers
A seminal paper for studying the history of the loss of our salmon and sea-trout is WATER AND CHOICE IN CANTERBURY (K. L. Leathers et al. 1983. Research Report No. 135 Agricultural Economics Research unit, Lincoln College NZ.) This study is so accurate at predicting all we would lose it takes your breath away. It predicted the loss of salmon, native species, and clean drinking water:
“The Rakaia River is the last of the great South Island East Coast rivers to exist in a virtually unmodified state.
“If the LRIS (Lower Raikaia or Barrhill Chertsey Irrigation Scheme) and CPIS (Central Plains Water Enhancement Irrigation Scheme) go ahead as planned, there exists some doubt about the future of the quinnat salmon run, the wrybill plover, and the vegetation reserve on the river islands.
It is now beyond doubt that the quinnat salmon run, the wrybill plover, and the vegetation reserve on the river islands no longer have a future
In the following forty-two years after this comprehensive report was published
• The Rakaia River National Water Conservation Order (1988) was gazetted.
• The National Party amended the RWCO in 2013. This amendment occurred after the Key government passed the ECan Act under urgency, enabling the government to take over the Environment Canterbury (ECan). ECan in turn managed the hearing to amend the RWCO. One of the stipulations was no stakeholder in this process had recourse to the Environment Court. This is a recurrent theme in the current National-ACT-NZ First regime, as they too eliminated appeals to the Environment Court on Fast-track projects.
• In 2014 Trustpower wrote to the council of how Trustpower chose to unilaterally amend water storage in Lake Coleridge. This has yet to be challenged.
• The quinnat salmon run has crashed to an all-time low of 720 salmon in the 2024-2025 season.
• The wrybill population is on a path to extinction, and the vegetation reserves on the lower river islands have been either totally defoliated with herbicide or converted to dairy pasture. The exception is a narrow ribbon of ancient Kanuka forest at the western tip of Great Rakaia Island.
The economists failed to recognise the existence of the outstanding sea-trout fishery in the lower Rakaia River. The entire anadromous fishery’s food chain as well as its bird population depend on the Stokell’s Smelt. The smelt comprised the largest fishery by mass and underpinned the whole lower Rakaia River (hapua) ecology. Both these fisheries no longer exist in appreciable numbers. The collapse occurred as the Central Plains Water Irrigation scheme was implement from 2015 to around 2019.
The Rakaia River’s recreational value, in 1982, at NZ12millionwhichconvertsto12millionwhichconvertsto
51.36 million in 2025. Much of this value has been irreversibly wiped out by irrigation without any compensation or mitigation for anglers.
The 1983 economists’ report recognised mitigation would be difficult if not impossible to achieve.
The ECan Act 2010 and Canterbury Water Management Strategy (CWMS) ensured the only mitigation has been in the form of the non-achieved environmental targets of the CWMS.
A case of economic growth first: the environment has no place in decision making.
“The present recreational uses of the Rakaia account for much of its current economic worth to the local community. Salmon and trout angling alone are estimated to contribute up to nine million dollars annually to the regional economy. Other river-based recreation, and the value of the river to those who wish to see it preserved in its present state could raise the annual value to an amount in excess of $12 million. ‘The relevant question, however, is the degree to which the river’s amenity value will be degraded by abstracting water for irrigation purposes, and the answer is not readily apparent. Presumably, with careful planning the incremental loss in amenity value can be kept to a minimum” (Leathers et al., 1983).
A Litany of Loss – the Quinnat Salmon Rivers of the South Island
(Editor’s note: these overviews are based on river conditions from the early 1980s. From The Salmon Angler Vol. 8, No. 1 October 1981 pp 10 – 21)
1. Waiau River
The salmon run in the Waiau varies considerably in size but is normally of the order of a few hundred fish. Angling pressure is low because of the small run and because of the distance from Christchurch. The Waiau Plains Irrigation Scheme is the principal water abstraction on the river, with future schemes now being planned. During the 1980/81 season the river mouth closed, apparently for the first time (Hughey, 1982).
2. Hurunui River
Variable sized runs occur in this river. Because of the distance from Christchurch it has low to moderate fishing pressure. Low flows during the summer spawning migration often lead to physiological stress in the salmon (Docherty et.al., 1978). The Balmoral Irrigation Scheme exacerbated this problem due to the unnatural flow conditions, especially in summer. A proposed local hydro dam on the North branch may lead to further detrimental effects. Bryant summarised these impacts (1979) as being associated with increases in water temperature and reductions in dissolved oxygen levels; reduction in rearing habitat; diversion of fish in to irrigation races; salinity increase; and barriers to migration.
3. Ashley River
There is a variable run of salmon in this river which generally depends on the flow conditions prevailing during the season in question. Water abstractions have resulted in the annual drying of large sections of the river bed. This stops salmon migration to stable spawning grounds and forces adult fish to spawn in the flood-prone gravels, thus greatly increasing juvenile mortality. Fishing pressure is generally low to moderate.
4. Waimakariri River
Christchurch residents extensively fish this river, particularly in the middle to low reaches. It has a major salmon run. Trout fishermen, jet boaters, canoeists and other recreationalists also value its amenity. For now there are no major water abstractions. But agricultural pollution is a serious problem in the lower reaches. During summer natural river flows can drop to a very low level. Development interests have proposed hydroelectric and irrigation projects for the river, with the latter seeming the most probable in the near future under fast-track development legislation.
5. Rakaia River
The Rakaia is the most important recreational salmon river remaining in New Zealand. Anglers from Christchurch, Ashburton and Timaru once fished this river extensively, with regular visitors from the North Island and overseas. For the 1978-1979 period Unwin (1980) calculated that about 8,000 anglers used the river annually. This figure is certain to underestimate the actual total because of the limited size of the population sampled. Thus, it is estimated that the total number of anglers using the river is over 10,000 per year. Historically, fishing pressure has been greatest at the mouth. Now it is spread more evenly over the entire river to a point 40 km above the Gorge bridge. The river is unpolluted and at present there are only minor abstractions for irrigation purposes. However, due to the diversion of the Wilberforce
River into Lake Coleridge impedes access to spawning habitat.
6. Ashburton River
The Ashburton was once an excellent salmon river (Hughey, 1982). Now, irrigation abstractions have reduced salmon stocks significantly. During the 1980/81 season the river mouth was closed for a period
of 10 weeks. Angling pressure is almost exclusively concentrated at the mouth.
7. Rangitata River
Although the Rangitata is considered a good salmon river, it was formerly regarded as being excellent. This degradation in status is directly attributable to major water abstractions, particularly the Rangitata Diversion Race. There is moderate to heavy fishing pressure from the mouth to the Gorge. Further irrigation plus a hydro dam in the Gorge are possible in the future.
8. Opihi River
Like the Ashburton this was once an excellent salmon river, but it too has been greatly degraded by water abstraction for irrigation. The river closes virtually all summer and is opened by manpower to let some salmon in to the river each year. Fishing pressure is moderate. The middle reaches of the river are characterised by extreme low flow problems.
9. Waitaki River:
Prior to development this was New Zealand’s greatest salmon river. However, the construction of the Waitaki dam prevented access for migrating adult salmon to key up-river spawning areas. Pre-development runs have been estimated to exceed 100,000 fish. Now they are reduced to less than 10,000. Fishing pressure is relatively heavy from the mouth to Kurow. The major hydro scheme now planned for the lower reaches of the Waitaki could result in the demise of the salmon fishery in this river if appropriate mitigating measures are not taken.
10. Clutha River:
The construction of the Clutha dam has virtually eliminated this historically important salmon river. Access is prevented to practically all spawning grounds. In a good year, the salmon run numbered 50,000 fish.
Discussion
The relative status and angling importance of New Zealand rivers has changed markedly due to water abstraction and diffuse pollution. Every salmon river has been affected to some extent. These impacts
have led to major reductions in the productivity of rivers such as the Clutha, Waitaki, Opihi, Ashburton and Ashley Rivers. Irrigation projects up to the early 1980s the Rangitata, Hurunui and Waiau have impacted these rivers only a little.
As of 1983, this left only the Rakaia and Waimakariri Rivers as substantially unmodified.
It is also important to note that Fast-track legislation will enable further development for those four rivers having “major” salmon runs. For the Waitaki this might mean that future anglers will fish in an artificial “recreational channel” bearing little resemblance to a braided river and its natural spate fluctuations. In fact, hydroelectric manipulated rivers often experience “reverse seasonality,” meaning the river’s natural high and low water periods are reversed, due to abstraction in low water.
In the Rangitata recent modifications to the intake of the major diversion race have resulted in the fortnightly desilting of the settling ponds.
As this occurs on a Thursday, it is a dirty river every second weekend.
Developers plan to irrigate large areas north of the Waimakariri for the future. This river already suffers from low flows. The Rakaia is seldom characterised by natural low-flow problems, but this would become more likely with major abstraction for irrigation.
Comment
I was staggered to find this old record with its assessment of our salmon rivers at that time and the ominous predictions it contained.
I happened to return to Ashburton in 1983 to work for the Ashburton Veterinary Club and brought part of my parents flood irrigated farm following six years working in overseas equine vet practices including a spell as a racing veterinarian in Asia.
Unaware of the above, I enjoyed good salmon fishing in the upper Rangitata River and on most reaches of the Rakaia River, even managing the odd “bonus” salmon on route to vet calls in the upper Rakaia Gorge.
Little did I know how things would change.
Two seismic shifts were in play; first the Labour government abruptly removed all farm subsidies such as the Supplementary Minimum Price (SMP) and secondly Canterbury’s dairy boom had just begun.
It was a tragic time for many established Ashburton County family farms which suddenly became unprofitable due to the collapse in both sheep and arable returns.
Surviving farming families and corporates moved in to scoop up “abandoned” farms at fire sale prices, and changed the farming culture forever with their lawyers, their hard-nosed attitudes and values.
The established contracts for farms supplied from the Rangitata Diversion Race were brushed aside as the demand for water from the new industrial dairy farms far exceeded the supply the original irrigation schemes were designed for.
The “White Gold Rush” had begun and dairying’s demand for land, cows, and water has become insatiable.
2024/25 Salmon returns;
Waimakariri River 327 Rakaia River 720 Rangitata River 79
In future articles I’ll discuss the reasons why water abstraction has been so disastrous for salmon. I’ll also explain how dairy, irrigation and power interests appropriated and polluted Canterbury’s water.
Dr Peter Trolove
Executive member NZSAA, NZFFA