TROUT & FOOD SUPPLY

New Zealand Times, Volume XLVI, Issue 10689, 8 September 1920, Page 7

TROUT & FOOD SUPPLY

DR. TILLYARD'S LETTER LAMENTABLE SLAUGHTER OF BEST BUD FISH. SOME REMEDIES SUGGESTED. (Bv Mr Cecil A. Whitney.) I have read Dr. Tillyard's letter ro food supply for trout in the Botorua and Taupo districts, and his remarks that "his survey of the region convinced him that the balance of Nature had been completely-upset, by the introduction of trout," which lie cooadored had eaten out all the food enpPb \ "A FLYING VISIT." Now, sir. is it possible for anyone to arrive at any opinion in regard to tne poor condition of the troiily and the causo thereof, without making regular visits of a* least a. week's duration to the districts fivp or six times each veal, and for a number of-rears, instead of a flying visit such as the above remarks appear to suggest.' He would just have to take for granted what bo was told by those whose business bto to make tho most of what had b*eri done or bad not been done in regard to improving the condition of the rainbow. Professor Prince, who has made a studv of fish and than- habits and their food supply for many years an America, has distinctly, stated in his report sent to the Government that there is a superabundance of food supply m tho Rotorua and Taupo districts. No doubt he made the statement because he understood.»apart from the abnormal Quantities of koura, enanga. tadpoles, nop. etc., which abound in all the lakes todav, that the fish are cannibals and prev on each other; and that is why thev so readily take the snoon and minnow, because they take these baits for a young trout. 4 BRED FROM WORST FIPH.

Where there is plentv of food arid well-bred fish. Nature will assert ltseU, i.e., the fittest will survive. But the fish are not well-bred; they have been bred from the worst fish in the lakes for the last fifteen vears or .more, because the natives and others are allowed to take all the best spawning fish during the close season. No steps have been taken by the; Government to . out a stop to this' Tuthless destruction' of fish, which should fill our lakes with first-class, well-bred trout (hat would be sufficientlv vigorous to chase the weaklings of either brown or rainbow trout for food: these would become an pasy prey. The mere act of chasinnr 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 th-? smaller trout. SLAUGHTER STTLL GOES ON.

Thousands of the best breeding fish have been taken out during .Time. July, and August of this year, and : the slaugh-: ter still goes on. Why was-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 wan 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 be done during open season. Many mop trout could be taken with the minnow and spoon trolling, and at very much Ipss cost. .ThCTe-would;be~no Jiarm .-,»©£-' ting at the.' mouth of" 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 la.rge portion of the food supply of the lakes. AN ABSURD STORT.

To try and impress on visitors trio 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 be found in the fish, but this is also swallowed by mistake when taking other food, often when the Waikato river is in big flood, the trout by mistake take so much floating pumice, and pumice that is rolling along' the river bed or where a river empties into a lake, that many are killed by it. Stone and other hard substances will tie. sometimes found in every fish that swims, according to the nature of the food they feed upon, Koura is a stable food for front, and there are as many in the lakes to-day as there ever was, but the largest and best trout are reared from a mixed -diet; that is why in ai dry" winter and summer the trout are not in nearly such good condition as In a wet season, ;jvhen there are large quantities of worms, ijlugs. etc., .washed down the rivers. In the dry season there are none; this applies to all rivers in New Zealand as well as the Hot Lake district. ' FOOD: A KOURA HATCHING.

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 nil the rivers and lakes of the. district, but it is much to be. regretted, that bo did not live long enough to bring this good work about.: It can still be done with benefit to the food supply. The freshwater mussel that thrives so well in many English and Scottish water, and which fix themselves on to the'stone and shingle of the river beds, affords /a fine food supply for the fteh, and could easily be brought to Npw Zealand and liberated in the lakes and rivers of tho Botorua and Taupo districts. The English water snail could oasilv be acclimatised rnd make good food for the fish. I do not think it necessary to ( import flies or moths, because these, with the green beetle, cricket, and grasshopper, abound in these districts at certain times of the year and make a -fine change of food for the trout. I have often found the utomach of the trout full of the green beetle, especially when-the folingo fringes or overhangs any part of the lakcis; and on the rivers on a windy day when these Insects are blown into the water, they ore greedily devoured by the trout to tho exclusion of other food. PECULIAR HABITS OF FISH.

Fish aro very peculiar in their habits — if they arc feeling out of sorts and the wind is cold and in the south-east they will not take anything, except a few of tho most vigorous and well-bred fish, which are . nearly always on the- feed more or lees Badly .bred fish and weaklings ore more subject ,to non-feeding moods thn d 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 seu6on completely changes the habits of the fish. Every fish mates, and if its mate is caught it does not spawn till mucb biter, and' tho following season it goes up lato to spawn Many of tho slabs in tho lakes ar<» simply fish that have spawned an late as November and December in each year, and these fish are not in condition till the end of May or beginning of June. PROTECTION WANTED.

T am Nvtisfied that if tho fob nre properly protected during tho <doso season thoy will soon get back to their old condition nnd size, because tho food supply for tho >ounff fry ■will bfi enormously inercnswl bj- an unlimited supply of ova, and this ova will rear lOin fish in four

months instead of t*in as reared now. It is like feeding a calf on unskimmed milk--it gives a good start, an.", tlw same applies to tho youns fish. At four mouths old a lOin fish is s.<> vigorous that it at once, starts to feed on the woaklinpj probably hutched at tb-i same time.

Boto-Aira would be of no use for a food sanctuary because it is very inconveniently situated; besides, if tho trout aro already in the lake they can never be taken out, oven if thousands of pounds were spent on th» \tork. Thero is a sm-ill native fish which ejiters that lako at certain times of the year from a subterranean river, and +he supply is unlimited. These could bo. caught, aud placed in" all the sti-oara« having a subterranean source and would be a flue in tho food supply «jf the trout. BASED "ON INFORMATION RECEIVP.D."

The last paragraph in Dr Tillyard's article clearly shows that, his remarks arc based on information -find roports received, and not from personal observation, otherwise ho would not advocate a more vigorous poller of netting- in open season ,md ths iimitacion ot .tho spawning area. If his suggestions were carried out i',\i wlvuio imputation would be up in arms against its being done. Already strong protests from several sources have been cent to the Government strongly ) rotating against netting.

I suggested to the Government to put an electric barrier at the mouth of the streams.running into Rotorua lake This would hold back the fish and' enable the netting in close season to be carried out to eliminate alt inferior fish and onl> allow first-class spawncrs to pass the barrier; this l.as been successfully dono in other parts of the world. Auckland, September 3rd.