AFTER SALMON IN THE SOUTH.

Otago Daily Times, Issue 19198, 14 June 1924, Page 17

AFTER SALMON IN THE SOUTH.

QTJIXXAT IX CAXTEKHUHY. LI IE HISTORY OF THE FISH,

liy .Malcolm Ross.

The fact that, three varieties of salmon have now been established iu New Zealand waters is one of great interest to anglers hero 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 Amur district, where the Atlantic calmon (salmo salar) aro now known to have been acclimatised. On the. way to the Te Anan rivers an invitation from Ashburton led to a brief shay there with a view to seeing what kin'd of s)>ort was obtainable witli the quiiinat (Oncorhyncns Tschawytseha). Though the eggs of the (ininnnt were introduced into New Zealand as far back as 1875, and various shipments were received in subsequent years, it was nut 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 1905 anglers fishing for trout at the month of tho river began to eate.h qninnat. During recent years tliero have been some heavy runs of fish in the Waitaki and other Gtago and Canterbury rivers to which qninnat had spread or been introduced. Tho lish have also crossed Cook Straits from ’the Wairan in Marlborough, and have been running up rivers on both coasts of five Xorth Island to latitudes equivalent to their Southern habitat on the Xorth Pacific const of America. The qninnat lias certain characteristics which stain)) 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 lemons Columbia River salmon of the packers, known also as the King salmon, and Chinook salmon. Ho is the largest mid most important of the live species of Pacific salmons, next in order being tho Sockeyo (0. Xerka), known also as tho Rlnehack, Red Salmon and Redfish. .Many anglers in Xew Zealand came to the hasty conclusion that tho introduction of salmon would he detrimental to the trout which already inhabit our rivers. Such is not the case. Salmon do not eat trout—at all events in fresn water. On the contrary, they supply an abundance of food for the trout in the rivers. Tho eggs of the qninnat hatch out in from six to nine weeks, according to the temperature of the water. The colder the water tho longer they take to hatch. Tho beginning of the salmon is tho alevin. He 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 tho 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 iiis* stomach and several others in his mouth awaiting the process of digestion of the first-swallowed I It has been estimated that a thousand trout will destroy iblhCuO alevins in a day. If, therefore, unlike trout, salmon fed in fresh water, tho whole food supply of the rivers up which they rim would bo eaten out in less than a week by tho thousands that come from tho sea, and tho salmon would then oe unable to reproduce his own species. Hunger would drive him back to the sea as soon as he had exhausted tho river food supply. There, would be no time for spawning. Tho species would become extinct. 'Therefore, neither the trout nor the trout-fisher has anything to fear iiom the salmon. On the contrary he has much to gain. Tile qninnat fry commence their downstream migration as soon as the yolk is absorbed and they are able to swim. They drift down tail first. In four or five" months the majority of them will have reached tho 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 another river many miles away. So in Xew Zealand the qninnat 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 300 miles north, while quinnat liberated in a tributary of the Wairan in Marlborough, after reaching the sea, have crossed Cook Strait and entered North Island rivers, where, no doubt, they have spawned. Here, as on the Pacific Coast, the runs vary, and it, will probably bo found tha' there will be a big run about every fourth year. As to weights, they are gradually approximating to those on the Pacific Coast. This season a fish of 331,1 b was caught with rod and line in the Rakaia, but in the Dobson, a tributary of the Waitaki, during spawning time, fish weighing 451 b, 521 b, and 641 b have been taken. The late Cloudesley Rutter, whose wonderfully patient and detailed researches have given us an extraordinary amount of information about the life history of tho qninnat. tells us that of the hundreds of thousands of fish that run up the rivers to spawn none survive. Thus we, are. faced with an extraordinary fact in natural history—that no salmon lias ever seen its own young, and that no young salmon has ever seen its parents. It has been established that the qninnat does not 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. In salt water it is difficult to tell the males from the females, but on they have entered the rivers marked sexual changes appear. The males d< velop a hooked jaw, larjie canine teeth, a slab-sided body, and a reddish tinge. There is not so great a change in the females. 'Their small month persists, they have, no hooked jaw, and their silver goes from silver to olive. Mr L. F. Aysoii, to whose knowledge and energy we are so largely indebted i the successful acclimatisation of three kinds of salmon in Xew Zealand, tells me that he doubts Cloudsley Rutter's dictum that no qninnat ever returns to the sea .after spawning. In this 1 arn inclined to agree, because it is already proved that Atlantic; salmon return to the sea and come back a second and even a third time to spawn. When Mr Ayson was last at Rattle Creek the experts were catching, for spawn sexually mature fish of about 121 b weight. One day they got a 731 b female in the trap, and it seemed incredible that a salmon could have remained sexually immature until it had reached this great weight. The very interesting problem may eventually hr. settled by marking the fish, if not by scale reading, as has been done in the ease of the Atlantic salmon. It is possible that some of the fish that run up sm-b rivers as the Rangitata and Rakaia, and spawn as low down as the railway bridges, may drift hack to the sea before they die, that oner in the sea they may fecovei from the debilitation caused by the deadly fungus which assails them after spawning, and then return, in later years, groatK increased in size. 'There are, other interesting |«)ints, such as a. comparison with the “runs” in Xew Zealand and America, that might be dealt with did space permit. Patient research by competent observers, no doubt, will eventually give us farts. Already an extraordinary amount of interest is bein" taken in the habits and life history of salmon in New Zealand rivers. This in-

(crest is not confined In \ow Zealand. It Ims extended In Mnghind :mfi Kc<ifTam? mid to America, and (Imre tire many px]ierts in those eonnlries examinin',; (he scales of New Zealand salmon, both Atlantic and rpiinnat, niieroscnpieallv. Tlioiilcli, :i< Mr William Radeliffe asserts in his remarkahle hook, Aristotle was the first scale reader, there is still much work (o he done on scientific lines, and there is no reason why some New Zealand sic.lereader may not yet arid an interesting page to the life history of the salmon in Ids' new home at the Antipodes.