ANGLING

Otago Daily Times, Issue 22834, 19 March 1936, Page 4

ANGLING

By Dby Fly.

RECENT REPORTS A correspondent at Roxburgh writes as follows: —"Eleven members of the Teviot Angling Club visited the Pomahaka at the week-end and had the best trip of the season so far—Bs fish were taken with the dressed weight of 67_lb. The Lest catch was 12 fish weighing lljlb and the next 15 fish weighing lOjlb. The heaviest fish was 6lb. The river is running full, and the fish are in excellent condition. "Two anglers visited Lake Onslow and had a very rough trip, with snow and sleet showers most of the time. Only four fish were taken." FISHING IN THE NORTH " The weather throughout the whole period was exceptionally changeable, and generally anglers experienced a difficult time," states the fortnightly report upon fishing in the Rotorua, Taupo, and Bay of Plenty districts, prepared by the conservator of fish and game, Mr A. Kean. "Exceptional rains have raised Lake Rotorua to such a height that wading in several favoured places has become impossible, and boats have now to be used in connection with fishing," says the report. "Anglers fly fishing from boats at Hamurana at times had good sport, amongst the most successful being Mr A. Hamilton, of Canada, who accounted for 23 rainbow during two day 6 and a-half fishing. His largest fish weighed 61b. Trolling parties reported good sport when the weatner was favourable.

"Rotoiti fished fairly well, and several good catches were reported by trailers and fly. fishermen. The largest catch was taken by a party trolling from Mararoa. This catch consisted of 25 rainbow, averaging 521 b. The heaviest fish weighed 71b. As usual at this time of the year, Tarawera was quiet, and very few anglers fished there. The only catch reported was one of nine taken by Major Gordon. This bag was taken on the fly, and averaged just under 61b. Several fine rainbow of 101 b were taken at Okataina. Mr E. E. Clarke, of Melbourne, who has completed Ins annual visit to Rotorua. accounted for 528 rainbow, averaging* 2.531 b. Bay of Plenty rivers were mostly high and discoloured, but cleared about February 23, when fair bags were taken. "Anglers usingl the dry fly did well below Huka Falls. Fly fishing in the Waikato in the vicinity of Rotokawa resulted in bags of seven to eight fish being taken, and specimens up to 71b were landed. Fishing in the vicinity of Atiamuri has been fair, but owing to the high state of the river there many anglers have not fished this portion of the Waikato. Fishing was generally good when favourable weather prevailed at the north end of Lake Taupo, fly fishermen and trailers returning with very satisfactory catches. One party of three Australian anglers took 180 rainbow, averaging 4Jlb, with the heaviest fish 7ilb. During four days' fly fishing at Whakaipo Bay. and Rangatira and Mine Points another large catch was taken by a party of three Hamilton rods, who lauded 96 during three (days' fishing in Whakaipo Bay. This catch averaged 421 b, the heaviest fish being 61b. The Waitahanui outlet fished well at times, and should produce good fishing from now on, when suitable conditions prevail. "The rainbow were all in good condition, and numerous specimens of 81b and 91b were taken. The opinion expressed by several anglers of experience at Taupo is that the fish are generally in better condition than they have been since 1927. The rivers entering the southern portion of the lake were very dirty, and in flood for most of the period. Consequently very little fishing was done. Anglers had satisfactory sport at the Delta, where the fishing has improved and several limits were taken. The heaviest fish accounted for in this vicinity was one of 10_lb, landed by Mr Hamilton, of Canada, whilst fly fishing. "The trout are now working towards the mouth of the rivers, and no doubt will run under favourable circumstances." TROUT IN NORWAY ■ Recently an opportunity was given the writer (says " Black Gnat" in the Christchurch Press) of studying an intensely interesting paper written by Mr Knut Dahl, best known of all overseas investigators of fresh-water fishing problems. The paper dealt with the growth and conditions ot life of the brown trout in Norway. One of the questions discussed and probably the most interesting to us was that of inbreeding. Mr Dahl found that in certain parts of Norway there were trout ot vastly differing powers of growth and set out to ascertain whether these characters were' inherent or whether they were brought about by the conditions under which the trout existed. There was a vast difference in the development of the trout on the eastern elopes of'the mountain region of Southern Norway, from the trout of the western slopes. The trout in the east grew better and lived longer although conditions were at first sight less suitable for them. It was found that for the first three years of life trout from both regions grew equally well, but after that the ones in the west failed to develop. Investigation proved that there was a distinct shortage of food suitable to adult fish in the west, and also that they became sexually mature earlier than those in the east.

Mr Dahl shows that the smaller fi6h produce relatively smaller eggs, and that fish hatched from small eggs start life at a disadvantage.compared with those hatched from larger eggs. In any discussion on degeneration of trout caused through inbreeding no comparison can be made with any warm-blooded animals, as it was found that the growth of trout was more like the growth of plants than of any domestic animals. Giving an example to illustrate the process of degeneration as he understands it, Mr Dahl ..writes: — " Let us suppose that we have a lake in which the trout grows quite sturdily and produces a big roe. What will row happen if throughout little fishing is done in this water? Clearly the stock will increase. As soon as the number of trout exceeds the balance point which is permitted by the food supplies, their development will be reduced and the more trout there are there, the worsg will the development be and the size of the fish will steadily fall. When the size of the fish, as a whole, falls, the sizj of the spawning fish will also fall and the size of the roe spawned will diminish. The fish produced from these eggs will possess poor powers of development and will therefore spawn small roe and they will also, as we have previously seen, be relatively more fruitful than the bigger fish and will further lower the development of the fish. Throughout the whole of this steady and automatically acting process the power of development of the fish will fall and fall and fall until it must be assumed to approach a kind of nil point below which the development and life duration of the fish cannot be lowered.

" This is the ' degeneration' or ' inbreeding ' process among trout and it will lie seen that it must work more rapidly wherever fish spawn when young as is the ease in the west country waters than in the mountains where the fish grow big and old before they spawn, and they coincide also with the experience as to where this process occurs. "My experiments have shown that a poor degenerated development can be rapidly changed by the reduction of the stoek and by the consequent improvement of feeding conditions, and such reduction should not be considered alone as improving the development of the ' degenerated ' fish, but through the same process which has been described above, should contribute to assist the fish to spawn bigger roe and relatively fewer eggs and as a consequence produce a brood of better f.nd better powers of development. From this it would appear that no trout can be said to have any determined or inherited tendency to a definite type of development, but development in all cases scents to-be n product of external influences. Among these the quantity of food stuff is evidently the most important, and this works in various ways. It acts directly on the rapidity of development of the fish. Indirectly, the development of the- progeny is affected for better or for worse, according to the size of the eggs, and the relative fertility which results from the condition as regards nourishment of the mother and from her ege. If the trout does possess inheritable and fixed characteristics which are independent of its surroundings, it would seem that rate of growth is not among them, and the question as to how far such characteristics exist must be attained from other angles."