TROUT FOOD SUPPLY.

Otago Daily Times, Issue 18050, 25 September 1920, Page 6

TROUT FOOD SUPPLY.

TO THE EDITOR. Sm,—l bavo read Dγ Tillyard's letter re food supply for trout in the Botorua and Taupo districts, and his remarks that "his survey of the region quickly convinced him that tho balance of Nature had been completely upset by tho introduction of trout," which lie considered had eaton out all tho food supply. Now, Sir, is it possible for anyone to arrivo at any opinion in regard to the poor condition of the trout and the cause thereof without making regular visits of at least a weeks duration to the districts five or sis times each year, and for a number of years, instead of a flying visit such us the abovo remarks appear to suggest? He would just have to take for granted what ho was told by tJioso whose business it was to make the most of what had been done or had not been done in regard to improving tlie condition of the rainbow. Professor Prince, who has made a etudy of fish and their habile and their food supply for many years in America, has distinctly stn-ted in his report sent to tho Government that there is a superabundance of food supply in tho Rotorua and Taupo disricta. No doubt ho made the statement because ho understood, apart from tho abnormal quantities of koura, enanga, tadpoles, frogs, etc., which abound in all the lakes to-day, that the fish are cannibals and prey on each other; and that is why they so readily take the spoon and minnow, because they take these baits for a young trout. "Where there is plenty of food and wellbred fish, Nature will assert itself—i.e., tho fittest will survive. But the fish are not well-bred; they have been bred from the worst fish m the lakes for the last 15 years or more, because the Natives and others are allowed to take all the beet spawning lish during the close season. No steps have been taken by the Government to put a stop to this ruthless destruction of fish, which should fill our lakes with first-class, wellbred trout that would ba sufficient}- vigorous to chase the weaklings of either brown or rainbow trout for food; these would become an easy prey. The mere act of chasing for their food supply invigorates and strengthens the trout. As it is, at the present time, many of the fish are too badly bred and too weak to try to catch the smaller trout. * Thousands of the best breeding fish have been taken out during June, July, and August of this year, and the slaughter still goes on. Why woe a close season fixed by law and why is it ignored in these districts? How can the condition of the fish improve under these circumstances? Of course, when Rotorua Lake was teeming with inferior and diseased fish, the only thing to do was to destroy them by netting and other means, but this state of affairs would not have been brought about if tho breeding had been from the best fish instead of the worst. No netting should bo done during open season. Many more trout could be taken with the minnow and spoon trolling and at very much loss cost. There would be no harm netting at the mouth of the rivers during the close season to eliminate any fish that showed signs of disease, also any weaklings and slabs, but no spawning fish should be taken, because from them comes a large portion of the food supply of the lakes. To try and impress, on visitors the shortness of food, they have been told how the trout eat stones for want of food, but I cannot think anyone would credit such an absurdity. Trout swallow stones by mistake when they are hunting koura, etc., and the stones are the last to be ejected from the stomach. Pumice -will also '"© foxind in the fish, but this is swallowed by mistake when taking other food; often when tho Waikato River is in big flood the trout by mistake take so much floating pumice, and pumice that is rolling along the river bed cr where a river empties into a lake, that many are killed by it. Stone and other hard substances will bo sometimes found in every fish that swims, according to ihe nature of the food they feed upon. Koura is a staple food for trout, and there are as many in tho lakes to-day las there ever was, bnt the largest and best trout are reared from a mixed diet; that is why in a dry winter . and summer the trout are not in nearly such good condition as in a wet season, when there are large quantities of worms, slugs, etc., washed down the rivers. In the dry season there are none; this applies to all rivers in Now Zealand as well as the Hot Lakes district. The late Right Hon. R. J. Seddon, on my recommendation, intended to start a koura hatchery at Taupo to rear annually millions of koura for liberation in all the rivers and lakes of the district, but it is much to be regretted that he did not live long enough to bring this good work about. It can etill be dbne with benefit to the food supply. The fresh-water mussel that thrives so well in many English and Scotch waters, and which fix' themselves on to the stone an.l shingle of the river beds, affords a fine food supply for the fish and could easily be brought to New Zealand and liberated in 'the lakes and rivers of the Rotorua and Taupo district. The English water snail could easily be acclimatised, andi rna.ke good food for tho fish. I do not thing- it necessary to import flies ox moths, because these, -with the green beetle, cricket, and grasshopper, abound in" these districts at certain times of tho year and make a fine change of food for the trout. I have often found the stomach of the trout full of the green beetle, especiaJly when the foliage fringes or overhangs any part of the lakes; and on tho rivers on a windy day, when these insects are blown into tho water, they are greedily devoured by the trout to the exclusion of other food. Fish are very peculiar in their habits: if they are feeling out of sorts and the wind .is cold and in the south-east thev will not take anything, except a few of "the most vigorous and well-bred fish which are nearly always on the feed more or less. Badly-bred fash and weaklings are more subject to nonieeding moods than well-bred fish; they will only hunt food easy to obtain, and sometimes will not hunt at all. The taking of the fish during close season completely changes the habits of the fish i.very fish mates, and if its mate is caught it does not spawn till much later, and! the tollowing season it goes up late to spawn Many of tho slabs in the lakes are simply nsh that have spawned as late as November and December in each year, and these fish are not an condition till the end of May or the beginning of June. ' r,rit am i at J sfi?d " t S t if the fish are proper!v protected during the close season they will soon get back to their old condition and size because the food supply for the youn- fry ™lw e^ ormouel y leased by an unlimited J? fCed °V he tobabS hatched at the same time. Roto-Aira would be of no use for a food SSS& t C T° %j? Very situated besides, .if the trout are already if thn, tIWJ ; Can n 7 Cr taken «nt. even wk TW°- P ouade 1 w». «i the &W 3&"ti£ s s& , ! Placed m all the streams having subter strong protests from sevlnl r Ah f** J elitr^S^^^^rth 40 r « in close season to be caS ed **t^ s? w^d-f^ Auckland. Cecil A "