WAITAKI FISH LADDER

Southland Times, Issue 22898, 25 May 1936, Page 6

WAITAKI FISH LADDER

EXPERT OPINION “MONEY COULD BE BETTER SPENT” RIVER AND COASTAL RESEARCH

(Special to The Times.) Wellington, May 23 The question whether it was worth while spending any more money on improvements to the fish ladder at the Waitaki dam was raised by the Chiet Inspector of Fisheries (Mr A. E Hefford) in a statement to The Evening Post discussing recent reports on the ladder’s failure. Mr Hefford suggested that if a large sum was needed to make the necessary improvements, the money would be better spent in river research or coastal investigations.

The plans for the salmon ladder had been sent to American and Canadian experts, who had commented favourably on them, said Mr Hefford, but he believed that the pools were too short for such big fish, and the run out of water from the ladder was not big enough to attract them. It was strange that more salmon had been observed starting up the ladder, nevertheless, than had been seen completing the journey. This season it had apparently proved no more successful than the last. The salmon seemed to become uneasy when reaching the upper pools. It did not seem that the physical capacity to get up was lacking in the salmon, as the upper pools were if anything easier than those below, but they seemed to suffer a psychological reaction when they reached a certain point. Asked whether spawning in the main stream below the dam would be likely to give as high a percentage of young fish as spawning in the natural course of events in the higher tributaries, Mr Hefford said that he did not think it would, but this could not be foretold with certainty, because much depended on the state of the river when the spawning took place. Conditions varied from one year to another, but with the river below its usual level, the fish tended to stay in the main river, and did not go into the tributaries so much. It was known that the quinnat spawned in the main stream a good deal below the first tributary, the Hakataramea. Runs Would Decrease; What he was doubtful about, in the spawning in the main stream, was not so much that the water was warmer than the upper tributaries, because nont of the water in the Waitaki was really warm, but whether the big main river was suitable for the young fish in their earlier stages. Would they get the same development as they would in the tributaries, where there were the vegetation, insect larvae, and tiny crustaceans on which they thrived? “I would be very surprised, if the dam proves to remain insurmountable, to see the runs of quinnat into the Waitaki mouth from the sea in future years continued in as great numbers as before the dam was erected,” he said. “I think the runs will go down, as there is only the Hakataramea below the dam to form a suitable spawning ground. Salmon do spawn below the Hakataramea, their redds have been seen, but whether the spawning is as fruitful there as above remains to be seen.” Mr Hefford was of the opinion that the danger from natural enemies to the young fish would be greater in the river below the dam than in the headwater tributaries, with the exception perhaps of shags, which would find the young fish easier prey in shallow water. On one point he was definite, that the number of young salmon that passed the dam going to the sea by way of the ladder from the upper reaches was only a portion, a practically infinitesimal portion, of the runs of these smolts of previous years. It appeared, however, that such young salmon, from reports from America and from other sources, could come over a very high fall without hurt, providing that they did not strike rocks or very shallow water at the bottom, and it had even been shown that young fish could go through the vanes of a turbine without injury. There were varying opinions as to the sporting qualities of land-rocked quinnat. Trout Unaffected. Brown trout did not migrate to the sea regularly, said Mr Hefford, though sometimes they went as yearlings, and the trout fishing would not be affected by the dam to any extent. The Ahuriri, a tributary of the Waitaki which came in well above the dam, had been stocked with rainbow, with the idea of developing rainbow fishing in the lake which had been formed by the building of the dam. The damming of a main river need not necessarily affect trout fishing at all. This was the case in the Waikato, where there was a dam, but plenty of tributaries above and below it for spawning. This would make for two disconnected stocks of trout, one above and one below that dam.

There was a doubt, he thought, of salmon increasing to such an extent in New Zealand seas that they would form the basis of a remunerative national industry. There were not sufficient sea foods within reach of New Zealand to maintain large numbers of salmon from the time they entered the sea until they returned to spawn. There were not the big rivers to provide them with spawning grounds, as there were in America, but the chief difficulty was that while the seas round Canada and the United States held an enormous sea life which would support the salmon. such as pilchards, which were amply fed by plankton and small crustacae, there was no such great supply of small shoal fishes in New Zealand waters, probably because the nearest supply of plankton which would feed them was in the Antarctic Circle. “There is no real financial equivalent to justify the spending of much more money on the Waitaki fish ladder,” said Mr Hefford. “It is not as though the salmon were just being acclimatized and the blocking of the present streams meant that they would eventually vanish from New Zealand waters. They are now acclimatized in many South Island rivers. By the expenditure of sufficient money no doubt the ladder at the dam could be made perfectly satisfactory, but is it worth while? Anglers are very divided as to the value of the quinnat salmon as a sporting fish. Many of them would like to see the salmon go altogether, holding that they drive the trout away when their run starts. If a large, sum were needed to make the Waitaki fish ladder satisfactory, the money could be spent to far better advantage to the country in river research, or in equipping a steamer to explore the coastal seas to ascertain the full possibilities there."

[An article describing the effect of the hydro-electric dam on the quinnat salmon in the Waitaki river was published in The Southland Times on Saturday.]