SALMON IN N.Z.

Evening Post, Volume CVII, Issue 140, 14 June 1924, Page 13

SALMON IN N.Z.

QUINNAT IN CANTERBURY

LIFE HISTORY OF THE FISH

PROSPECTS OP SPORT.

(By Malcolm Ross.) (Written for "The Post,")

The fact, that three varieties of sal-. mon have now been established in New Zealand waters is one of great interest to anglers here, and, indeed, to anglers in other countries far distant from these shores. The main object of an expedition made by the writer to the South Island .this year was' to ascertain what prospects, of sport were obtainable' in the Te Anau district, where the Atlantic salmon (salmo salar) are now known to have been. acclimatised. On the way to the Te Anau rivers an invitation from Ashburton led to a brief stay there with a view to seeking what kind of sport was-obtainable with the Qumnafc (Oncorhyncus. Tschawytsha). _ Though the-.eggs of the Quinnat were introduced.into New Zealand as far back as 1875, and various shipments were received in subsequent years, it was not till 1900 that intensive stocking of one river was taken in hand by the Government. The result was that acclimatisation was successfully accomplished in the Waitaki River and its tributaries: In ISOS anglers fishing for trout at the mouth, of the. river began to catch Quinnat. During recent years there have-been some heavy runs of fish in the Waitaki and other Otago and "Canterbury rivers to which Quinnat had spread or been introduced. The fish have also crossed Cook Strait from the Wairau in Marlborough, and have been running up rivers on both coasts of the North Island to latitudes equivalent to their southern . habitat on the North Pacific coast of America. DIFFERENT FROM ATLANTIC SALMON. The Quinnat has certain'characteristics which stamp him as quite different from the Atlantic variety of salmon, and his life history so far as it is known, is particularly interesting. He is the famous Columbia River salmon of the packers, known also as the King salmon and Chinook salmon. He is the largest and most important of the five species of Pacific salmon's, next in order being the Sockeye' (0. Nerka), known, also as the Blueback, Red Salmon, and Redfish. Many anglers in New Zealand came to the hasty conclusion that the introduc- . tion of salmon would be detrimental to 1 the trout which already inhabit our rivers. Such is not the case. .■ Salmon do not eat trout—at all events, in fresh water. On the contrary, they supply an abundance of food for the trout in the rivers.

The eggs of the Quinnat hatch out in from six to nine weeks, according to the temperature of the water. The colder the water the longer they take to hatch. The beginning of the salmon, is the aleviu. Be has the yolk-sac still attached to him, and, at the bottom-of a. pool,' ■with this bulgy, yellow excrescence, his wriggling tail, and pectoral fins, he is, unfortunately, a very conspicuous fellow— a■> prey, to -all the predatory fishes and birds that feed in rivers, The alevin is indeed such a tasty morsel that even a six-inch trout will "gorge himself on the delicacy thus provided. Such a trout has often been found to have ten alevins in his stomach and several others in his. mouth awaiting the process of digestion of the first-swallowed! It has been estimated that' a thousand troutwill destroy 150,000 alevins in a day. If therefore, uiflike trout, salmon fed in fresh water, the whole food supply of the rivers up- which they run -would be eaten out in less than a week by the thousands that come from the sea, and the salmon would then be unable to reproduce his own species. Hunger would drive him back to the sea as soon as he ha-d exhausted the river food supply. There would be no time for spawning. The species' would become extinct. Therefore,- neither the trout nor the trout-fisher has anything to fear from the salmon. On the contrary, he has much to gain. " '

The Quinnat fry commence their down-stream migration as soon as the yolk is absorbed, and they are able to swim. They drift down tail first. In fonr or five months the majority of them ■will have reached the sea. There the change from a fresh-water diet of insects, both in the larval and the adult stage, to the .magnificent marine banquet that is spread before them causes a rapid increase in size". They stay in the sea from two to four years. It was once believed that they all returned to their parent rivers, but this has now been disproved, both in regard to the Pacific and the Atlantic varieties. Fish marked in Scotland have been caught in Norway, and fish marked in one river on the Pacific coast have been found in •V other river many miles away. ' So, in i\ew Zealand, the .Quinnat have spread from one river to another, and even from the South to the North Island. They have spread from the Waitaki to the Clutha, a hundred miles south, and to rivers .three' hundred miles north, while Quinnat liberated in a tributary of the. Wairau in Marlborough, after reaching the sea, have crossed Cook Strait and entered North Island rivers, where, no doubt, they have spawned.

VARYING WEIGHTS.

Herej as on the Pacific coast, the runs vary, and it will probably be found that there will be • a big run about every fcurth year. As to weights, they are gradually approximating to those on the Pacific coast. This season a fish of 33^1b was caught with rod and line in the Rakaia, but in the Dpbson, a trilmtary of the AVaitaki, during spawning t:me, fish weighing 45/ 52, and 641b ■have been taken. The late Cloudsley llutter, whose wonderfully patient and detaile! researches have given us an extraordinary amount of information p,bout the life history of the quinnat, fells i s that of the hundreds of thousands or fish that run up the rivers to •spawn none survive. Thus we are faced with an extraordinary fact in natural history—that no salmon has' ever seen its own young,, and that no young salrr.on has ever seen its parents. It has l-een established that the quinnat does r.ot eat after leaving the sea. Its stomach shrivels up to one-tenth of its normal size, and in their migration up 'stream the fish lose, from 10 to 15 per cent, of their weight, and, in spawning, a similar percentage. Tn the salt water it is difficult to'tell the nuiles from the females, but-once they have entered the livers marked sexual changes appear. .The males develop a hoolrad' jaw," Jnrsrc canine teeth, a slab-sided body, and'a reddish tinge. There is uofc "so great a change in the. females. Then- snv-'.H mouth persists, they have no hooked jaw, and their colour goes from silver to olive.

Mr. L.'TV Ayson. to whose knowledge ami energy we are so largely indebted for the successful acclimatisation of three kinds of salmon in New Zealand, tells me that ho doubts Cloudsley Butter's dictum that no qulnuat ever re-

turns to the sea after spawning. In this [ am inclined to agree, because it is al-. ready proved that Atlantic salmon return to the sea and come hack a second and even a third time to spawn. When Mr. Ayson was last at liattle Creek the experts were catching for spawn sexually maturo fish of about twelve pounds weight. One day they got a 731b female in the trap, and it seemed incredible to him that a salmon could have remained sexually immature until it had reached this great weight. The very interesting problem may eventually be settled by marking the* fish, if not by scale reading, as has been clone in the case o£ the Atlantic salmon. I think H is possible that some of the fish that run up such rivers as the Rangitata and Rakaia, and spawn as low down as the railway bridges, may drift back to the sea before they die, that once in the !sea they may recover from the debilitation caused by tho deadly fungus which assails them after spawning, and then return in later years greatly increased in size. There are other interesting points, such as a comparison with the " runs " i.i New eZaland and Aemrica, that might be dealt with did space permit. Patient research by competent observers, no doubt, will eventually give us facts. Already an extraordinary amount el interest is being taken in the habits and life history of salmon in New Zeamnd rivers. This interest is not confined to Aew Zealand. It has extended to England and Scotland and to America, and there are many experts in those countries examining the scales of New Zealand salmon, both Atlantic and quinnat, microscopically. Though, as Mr. William Radcliffe asserts in his remarkable book, Aristotle was the first scale reader, there is still much work to be done on scientific lines, and there is no reason why some New Zealand scale reader may not yet add an interesting page to the life history of the salmon in his new home at the Antipodes.