The Disappearing Trout: A Challenge To The Acclimatisation Society

Press, Volume XCVII, Issue 28702, 27 September 1958, Page 5

The Disappearing Trout: A Challenge To The Acclimatisation Society

[Specially written for “The Press” by TRUTTA.]

REASON after season fewer fish are being caught by more fishermen using more deadly methods. This summarises the present state of affairs on most of the rivers and streams and some of the lakes of the trout-fishing waters of the North Canterbury Acclimatisation Society’s district. A few years ago anglers were willing to accept the view that the trouble was purely seasonal —caused by, the rivers being too high or too low—and would eventually right itself. But the decline has been continuous, and now, at the beginning of a new season, the trout fishermen wants to know what has been or is being done about the decline, and what could, be done about it. Until this season, when it has been decided to distribute to cne or two back country lakes a number of fish from Lake Lyndon, the Acclimatisation Society seems to have been following the line of doing nothing, believing that nothing it could do would improve matters. Even now it is doing nothing—except experimentally catching a few eels—for the formerly very good fishing waters of the smaller North Canterbury streams, the coastal tributaries of the Waimakariri, and the streams running into Lake Ellesmere. It owns a useful former hatchery property, it has large reserve funds, it has useful revenue (and could have more), but it does not rear trout to liberate La the waters under its control. Lakes Behind the policy followed in recent years stands the society’s emphasis on lake fishing and its faith in the opinion of the freshwater research division of the Marine Department, that artificial stocking of streams with trout fry is waste of eflfort, and. thas the natural breeding and growth of trout, without any liberations, will produce as many trout of takeable size as the food supply of the waters will support. These are very convenient conclusions if any organisation wants to avoid spending money, but they do not solve the angler’s problem. However, a closer examination of one of the basic pieces of research (the work of Mr J. R. Allen on the Horokivri stream, in the years 1939-41, published in popular form as Fisheries Bulletin No. 10a) shows that while the facts set out appear to sup-

port the conclusion that artificial stocking with tiny trout fry is unlikely to add to the angler’s catch unless undertaken on a tremendous scale, those facts do not rule out the possibility that stocking with larger fish—of takeable or nearly takeable size—• may be very useful indeed. Investigation The basic investigation by Mr Allen is an admirable demonstration of the application of scientific methods to a complicated problem. He finds that of 900,000 eggs produced by Horokiwi trout in one year about 400.000 are destroyed before they can develop into trout fry. In a flood year only 100,000 may hatch. Of every 1000 fry alive in October only 15 survive to be one year old, when they will be from seven to nine and a half inches long. At 18 months only four survive, and at two years only two, these two-year-olds being from 9£ to 13| inches long. Half a milliop fry have become 1000 just takeable trout. When faced with these facts it is not difficult to accept—as the Marine Department and the Acclimatisation Society have done—

Mr Allen’s conclusion that release of 20,000 or so tiny fry in a stream is comparatively; useless. . Release of that quantity of fry every year will probably add only 40 fish to the stock of takeable trout and less than a dozen of these will be taken by anglers. It is surprising, however, that the matter has been allov.ed* to rest so long at this point, especially in view of the steady decline in the number and size of fish taken, as experienced by all anglers.

The remarkable and constant increase in the number of fishermen since the war. and their greater mobility, is certainly in part responsible for the individu-

ally smaller catch. The total number of men’s whole season licences issued in New Zealand increased from about 11,000 in 1946-47 to 32,500 in 1956-57, and probably to nearly 35,000 in 195tf--58. Six years ago, in 1951-52, the number was just over half this, at 18.000. On numbers alone, without any consideration of greater frequency resulting from the fact that the motor-car and good roads bring all waters withm the range of a one-day fishing excursion, there is now three times the fishing pressure on the streams that there was 10 years ago, and twice as much as there was six years ago. Added to this is the fact that the development of new fishing equipment and techniques—notably the use of the fixed-spool reel—makes it easier to catch fish. In the larger open shingle rivers with unstable beds supplies of trout food are limited. But it is very difficult in the lakes and in those already-mentioned smaller and more stable streams of the outer plains—streams which* appear to be forgotten by members of the committee of the society, with their eyes fixed on ever more and more remote lakes and high-country waters. Trout Food Yet these smaller streams carry very large amounts of trout food in the form of caddis larvae, mayfly nymphs, fresh-water snails, shrimps, prawns, and other underwater life. Unfortunately even on these streams, in pools where a cursory examination of the stream-bed reveals the presence of abundant trout food, the fisherman nowadays sees only one or two fish rising or otherwise feeding, whereas formerly at the same hour he would see fish active in six pr eight places in that same pool. The answer to the problem is to stock the streams with hatch-ery-raised trout of takeable or nearly takeable size. This appears nowadays to be the general rule in the United States—a procedure forced upon the various state fishery authorities by the remarkable increase in angling streams. By re-establishing its hatchery, and re-planning it to carry fish to a size of seven inches or more (or to an age of one year) before being released, the Acclimatisation Society will

be able to replenish the stock of trout in the lakes of this district. The same research that discounts the value of stocking, with tiny trout fry shows that release of 100 fish of year-old size should produce in the following season about 20 fish of a takeable length of 10 inches or more. This is a much better proposition than releasing 12,000 to 15,000 fry in the hope of achieving the same result. The release of fish of a reasonable size is additionally preferable in waters where the presence of exceptional numbers of eels is likely to cause heavier than usual losses of fry. Costs Against all this is the argument of cost. It is easy to dismiss the present proposal by assuming that the cost of running a hatchery to produce a useful quantity of yearold "fish will be beyond the means

ot the society and out of proportion to the likely benefits. But the hard facts of the dwindling number of fish are a challenge, and if the challenge can be met only by spending money from reserve funds and by increasing licence fees, then those steps should be taken in the* interest ol the anglers the society represents. The society owns a suitable hatchery property, and it has reserve funds. Let part of those funds be spent on a new hatchery project. In 1939, when the fishing was many times better than it is now, a fishing licence cost £l. Just about everything else that cost £1 in 1939 now costs £3, but a fiishing licence has gone up only by 10s. Let the licence fee be increased to £3, and use the additional revenue to pay tor a scheme to provide anglers with the fish they seek. Only the unthinking will complain.