DIMINISHING TROUT.

Taranaki Daily News, 26 April 1930, Page 17 (Supplement)

DIMINISHING TROUT.

PROBLEM FOR SOCIETIES.

(By

“C.M.H.”)

Acclimatisation societies throughout the Dominion are exercised in mind respecting the falling off in trout angling during the past five or six yearn. From nearly all districts reports emphasise -the fact that both in quantity and quality trout are on the decline. With the exception of those districts situated around Taupo and other lakes trout aie , not holding their own. As there does not appear to be any special disease or epidemic that is adversely affecting trout there must be some other, outstanding reason to account for the diminishing number in rrood fishing waters. It would appear that the principal cause is an ever-de-creasing food supply. Each summer and autumn secs most of our rivers running fairly low in volume of water, with the result that there is a lessened supply of feeding for the trout. It has been found that where rivers often give excellent promise of good angling in the spring of the year, as the season advances the trout disappear. There seems to be no doubt that where possible all trout make periodical excursions to the sea. A river may be practically depicted of trout of takeable size in the latter end of summer and early autumn, yet when the spring of the year comes the same stream will show very fair numbers of trout from two to four pounds in weight. • ■, ff v It has been proved beyond question that when a prolific year for white bait occurs trout will ’be found in much rrreatcr numbers in our streams than is the case when a poor whitebait season obtains. The trout season in Taranaki just closing bears full evidence that this is the case. Last spring the run of whitebait was late and comparatively small. These little bright-coloured fish are all born in the sea, and. when they enter the mouths of streams they are .eagerly pursued by trout, with the rcI suit that a heavy toll is taken. In addition considerable quantities of whitebait’ are gathered by fishermen. This, of course, means that only a limited number of whitebait get far up our rivers and grow into adult minnows for trout feed. ■ Very soon no supply of feeding from this source is left for tnc trout,“with the result that' they mi-, grate to the sea and feed on other small fish available. If the season of the green beetle is early the trout .will remain in the. streams for a further two months, particularly if the beetle is numerous, Upon this source of feeding trout will gorge and grow plump. With the disappearance of the beetle the fish again drop down to the sea and remain ;£liere until the urge of spawning drives them back into the streams to lay their wealth of eggs. - .- ■

In volume 58, part 4 of the Transactions and Proceedings of the New Zealand Institute, Mr. D. Hope had an article dealing with this question of I trout food. Fro'm this source the folI lowing -expert opinion should be very i valuable to acclimatisation societies. “The introduction of trout into New Zealand waters was attended with such immense success that the results exceeded the expectations of the most sanguine; the fish rapidly attained to a size and to numbers unheard of in the parent stock, and in a very few years all our rivers were stocked with heavy fish from their sources to the sea. The fact that their introduction has proved such a phenomenal success would suggest that in our New* Zealand waters, they had found a-food-supply which waseminently -suited to ■ their- needs; and which induced rapid growth. In the ease of Salmo fario (brown trout) this can be safely attributed to the whitebait, which from their habits and rapid growth formed the staple food-supply of the trout for the greater part. of the year. In those early days they entered our rivers in millions, and ascended to the sources of all the main streams and tributaries, rapidly growing into the adult ,or Inanga stage, until every pool and backwater was peopled with, enormous numbers. The trout followed the shoals Upstream, and' finding an unlimited supply of food remained there all tlie summer, thus providing e±cellent fishing, in any part of our streams. In the autumn the Inanga migrated to the sea for the purpose of spawning, and were absent from the rivers during the winter months; this, however, did not affect the trout to any appreciable extent, as from practical experience I have found that they feed very, little or not at all during the winter months, and after spawning in the upper . waters, drop down to the brackish waters to -recuperate. In the early spring they again commence to feed, and they, then feed ravenously. It was just at this period that the whitebait made their appearance, leading them upstream, where they . rapidly regained condition. At the present time, however, conditions have altered considerably, through the increase in population and the consequent increase in the. demand for whitebajt as a table de-, licacy. The greater portion are now taken at the mouths of our rivers an they enter, and in comparison very few are” allowed to ascend. In consequence, very few Inanga are now found upstream, and few descend to the sea in autumn to perpetuate their species. This has had a very marked effect upon our trout fishing. With the decline of the Inanga there has been a corresponding decline of the trout; the latter have deserted the upstream waters, and are now found only near the mouths of our large rivers. The whitebait fishery is a most important industry, and from an economic point of view a very valuable national asset; but under the present system of fishing the whitebait is in extreme danger of extermination. At the present time there is not even a defined season for taking whitebait; they may be taken from'the time they make their first appearance until they cease running. In the case of our native and imported game, a season is provided, and if it U deemed necessary a closed season is I enforced. As each individual white- ! bait is potentially an Inanga capable of ' reproducing its species, this indiscri--1 minate fishing without restriction must eventually lead to disaster, unless steps are taken to conserve them before it is too late.”