NEW ZEALAND TROUT

Dominion, Volume 13, Issue 311, 25 September 1920, Page 11

NEW ZEALAND TROUT

HOW TO MAINTAIN THEIR QUALITY |THE QUESTION OF FOOD SUPPLY. (To the Editor.) : Silr,—l have read Dr. Tillyard's leftter re food supply for trout in the HotorUa i: and Taupo districts, and his remarks that "his survey of the region quickly conI vinced him that the balance of nature had been completely upset by tihe introduction of trout" which he considered had eaten out all tho, food supply. Now, Sir, is it possible, for anyone to arrive at any opinion in regard to tho poor condition of the lb-out and the cause thereof, without, making regular visits of at least a- week's duration to the districts five or silt-times eatfh year, and for a number of years,'instead of a flying yisiilsuch as the above remarks appear to suggest? He would just have to take for granted what he was. told by those whose business it was to make the most of whaj; had been done or had not been dono in regard. ;>) improving the condition of tho rainbow.' - Professor Prince,- .who' has mado a study of fish and their habits and thei'r food supply for mally years in America, has distinctly'stated, in his report sent to tho Government that there is a superabundance of food supply in tlie Rotorua and Taupo districts. , JS T o doubt he mado the statement-because' lie understood; apart from the abnormal quantities of koura, enanga. ,tadpoles, frogs, etc., which abound in all the lakes to-day, that tho fish are cannibals and prey on each other; and that .is why they so readily take,the spoon and minnow, because tlhey take these baits for a young.trout. <• Whei'e there is plenty of food and wellbredlfish, nature will assert itself, 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.tho, •last fifteon years or more, because- tho Natives ana. others are allowed to take all the' best spawning fish during the closß-sea9on. 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-olass. well-bred trout that would be:siifficiently vigorous to chase the weaklings of either brown or -rainbow trout for food; tlhese would become an easy prey. The mere att of: chasing for their food supply 'invigorates and strengthens the trout. . As, it is,/at the present time many of' Jhe fish are too badly bred and too weak' to try to catch tlie -smaller trout.' . - Thousands Of the ••'best breeding • fish havo been taken out during June, July, and Aiigust of this year, and the %laugnter still goes on. 'Why was a olose serts6n- fixed by law, and "why is' it-ig-nored in these districts?- How can tho 'condition of the fish improve under thesu oircunistancDS? Of course, .wheii Eotorua Lako was teeniing with inferior anij, dineased'fish, 'the only thing to do wns to-destroy: by netting , and other means,' but this state of affairs -.would not ; have been - brought about if the bfeeding'had been from the best fish instead of thei worst. -No lietting shouldbd done' during . opdn fieason ( - Many more trout could .be taken, with the liiinnow aild spooii' trolling, and ut very much' lais cost.' There would .bo,no harm netting: at the mouth, of tho rivei's during the' close season to eliminate any fish - that. Showed signs, of disease, also; iaiiy weaklings arid . slabs, but no spawning'fish should,..be. ; taken, because, from, them- comes a large portion of the food •supply of'the,lake3.. ,

•To ..try.-and impress on • visitors ,tho shortness: of food,'they; have been told how. 1 the trout eat stones for-want .of food.-, but I. cannot.'think anyone would credit such an- .absurdity.» T-re.ut swallow stones by mistake ■when ,tliey....are ! hunting koura, - etc./ and the. stones uro' the IsSt to be'..ejected from'the stomach.' Pumicoj will also be found in tho .fish, but -this is also swallowed by mistake .when, taking other, food i .ofton when the •Waikato Elver'is in big* flood the trout bvmistuke tiik'e so.Much floating'pumice, and pumice that .is rollinir along tho rived bed or where a river empties intoa Juke..that many are. killed by it. Stone and other.hard,substances will be sometimes found, in every..-fish that swims, according to the'nature of :tho food'they feed UDon.

•• • Koura."is a stablo.food for trout,;and' there-are as manyvin the lakes to-day as tli eye' ever, was, but the largest and best trout_ are' reared, from a mixed- diet; that is why in. a dry winter and summer tlic trout; are 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 thero are. lione.. This appliea ■to all rivers in New .Zealand, as well .as the Hot Lake District, i

The, late Eip'ht Hon.. TC. J. Seddon, on my recommendation* intended- to, Btart a koura hatchery at Taupo, to rear an-: nually.millions of kourii for, liberation in. all the, rivers and lakes of the distriot,; but it is much to be regretted that. lie. did nob live long. enough' to : bring' this rood work about, t It can still be done, with. benefit to the food.supply. .Tlio! 'fresh water mussel that-thrives,so well ..to many .'English and Scotch waters-, and which fix - themselves' on to the stono and ' 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 tho ißotorua. and Ta.upo districts. The English water snail, could easily be acclimatised. and ipake feood.food for the fish. I do - not think it is necessary, to import . flies or moths, because, .these, with the (rreen 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 i stomach of the trout full of. the' Rreen;-beetle, especially when the foliage fringes or overhangs any part of the ■lakes; -and on the rivers on a windy day when these insects are blown into the ■jater, they are greedily devoured by the'trout to the exclusion of other food.

Pish are very -peculiar in their habits: If they are feeling out, of sorts'and the wind is cold and m the 60uth-east. they will not take anything, except a few of tlio most vigorous and well-bred fish which" are nearly always on the feed more or less. • Badly-bred fish and weaklings -are more subject to non : feeding moods.than well-bred fish; they will only hunt food easy to obtain, and sometimes will-not hunt at all.

The taking .of- tlie fish during';close' season completely changes tho'habits of tho fish v - Every , fish mates, and if'its mate is .caught it does not ep.iwn till much-later, and the following season it goes up lute to spawn. : Many .of thn :slabs'in the lakes are simply fish that have spawiied as late as November and December in each year, and these fish are not in. condition till the ond of May or. beginning of June. ' I am satisfied that if tihe fish aretproperly. protected during the. close season, they will soon get back to' their old condition and size,, because the food supply for the young fry will be enormously increased by an unlimited supply of ova, and this ova will rear lfliai. fish in four months instead of ljin. as reared now. It is like feeding a calf on unskimmed milk—it gives a good start—and the same applies to the, young, fish. . At four months, old, a lflin. fish is so vigorous that, jt at once starts ■ 60 feed 011 the weaklings probablv hatched at tho .same time, '

Eoto-Aira would be of no use for n food sanctuary because it is very inconveniently situailed; besides, if.tile tiout are already in the lako they can never bo taken out!, even if thousands of pounds were, spent on the work. There' is a small native fish which enters that lake at certain tiimes of tho year from a subterranean river,.and the supply is unlimited.. These could be caught and placed in all' tho streams having a subterranean source and would bo a fine change in the food supply of the trout. The last paragraph in Dr. Till.vard's article clearly shows tlliat his remarks aro based on information and reports received. and not from personal observation, otherwise 110 would not advocato a more vigorous policy of netting in open season and the limitation of the spawning area. .If his suggestion were carried ouii, tho whole population .would bo up in arms against its being done. Already strong protests from several sources havo boon Font to tho Government strongly against nettling. . I .Kugeeis'lod to the Government to put an olectric barrier at the mouth, of the fll.reams runninir into Tfotorua Lake. Tin's would hold.back t.lie. flsli and'enable the nettinir in close season.,to he carried out to .elimiimlfa all inferior, fish and only allow first-alnss snawners to'. nnc« ' Hio barrier: tlvw has Ih>piiSHccP?--.fulh" .111 other par.fs of;the world—l am, etc., " (Signed) CECIL A. WHiTNEY. - Auckland.