TROUT.'IN LAKE TAUPO.

Dominion, Volume 6, Issue 1713, 2 April 1913, Page 5

TROUT.'IN LAKE TAUPO.

SEIIIOUS DETERIORATION. (By telegraph.—Pi'ces Association.) ' Auckland, March 31. It is a great pity to have to record the fact that trout fishing in Lake Taupo has 'undergone serious deterioration. For many yeaiti past this lako has enjoyed the reputation of providing the finest angling iu the world, on account of the size and Quality of flio fish.' This 6sason, however, numerous fish ill the poorest of condition and devoid of any. fighting power have fallen to the bait of anglers. Two theories have been advanced to account for the deterioration of the trout in Lako M'aupo. The first is that, the fish have become diseased, owing to a small percentage of those caught having been found to be infected with the same worm which has caused a certain amount of trouble at Rotorua. On the other, hand, many anglers are of the opinion that the enormous natural increase in tho trout has overtaken tho food supply in the lake, and that "the poor condition of the fish is due in many cases to semi-starvation. It lVnleo stated that whilst tho fish are in this condition they are more prone to develop any of tho diseases to which they are subject. As regards tho worm theory, the ovil has been attributed in tho past shags, but a correspondent' of the "iierald" who lias gone closely into the matter puts forward a new theory as to the origin of tho worm. He describes the worm-infected native fish, the kokopu, which is to bo found in Lake Rotoaira, about 20 miles from Tokaanu. This lie' states is about tho thickness of a man's finger, and from 2in. to 4in. long. A number of these fish were inspected bv the correspondent a few days ago. lie found them all to^be'infested with a parasitical worm, rcddisn in colour, thread-like, and about 2in. iu length. The bodies of the kokopu Aye re full of these worms, which are idnntical with those found infesting Lie trout of Lakes Taupo and Kotorua, Out of consideration for the native food supply, Lako Rotoaira has not been stocked with trout, and a number ot cascades and waterfalls upon the outflowing stream prevent the trout from entering tho reserve. There is nothing, li'jwever, to prevent kokopu from migrating into thy lower levels of the Tongariro Itiver, and as it is known to have been olio ot the staple diets of-tho trout, it seeing' reasonable to tho correspondent to assume that it is from this fish 'that the worm parasite has sprung. As to how the- worm has infected tho trout .he suggests that it may have done so by direct feeding or through shags, who have taken kokopu as iood. So far as. tho correspondent has been able to ascertain, tho Government fishery experts who have been investigating tho disease in trout do not seem to have come across the kokopit. Nevertheless, he states ho has been informed by old Zvativcs that it has ■ been worm-infested as far back as they can remember. If the kokopu is tho actual source of disease in trout, it may throw a new light upon the investigation of a blight that sc-ems to threaten to exterminate trout so, far-as sluggish waters are concerned. To revert to tho starvation theory it is worthy of note that there is improvement, slight but marked none the loss in tho fish in Lake Rotorua this year. A.number of spawning fish have to bo destroyed, and netting is now checking the increase. In spite of their extraordinary fecundity the natural increase of trout at Rotorua can be easily checked at spawning time on account of small streams which- inn into tho- . lake. It is doubtful, however, whether anything can be. dime in a lingo lake such as Taupo 10, curtail tile natural increase. ■ In the AVaikato River there has also been numbers of trout, caught this season which have proved to be out of condition. It is considered that these fish limy have been new arrivals from Lake Taupo in search of food, as many of. tho JJYiukalo River li§h are-still iu |i£i'l'cct''comli.iiou.