WHAT TROUT EAT

Evening Star, Issue 20310, 19 October 1929, Page 20

WHAT TROUT EAT

BAD EFFECT OF CLEARING CONCLUSIONS OF RESEARCH STUDENT. For somo time expert fiserraen have suspected that many of the trout rivers of Nev. Zealand, particularly in the ,Wellington district, have been failing to support as many trout as might hare been expected. In order to investigate the matter the Wellington Acclimatisation Society made an annual grant of £4OO a year, two years ago, to pay the expenses of a qualified research student. Captain J. S. Phillips, the student selected, has now made a report on the subject ot very considerable interest to fishermen. It is worth noting that to-day many other acclimatisation societies have adopted similar systems, but all credit for originating the idea must go to the Wellington Society. DISCOVERIES IN THE WATER. Until this research was carried out little was known of the food supplies of trout liberated in New Zealand rivers. During the preliminary period when the rivers and streams round Wellington were being examined by Captain Phillips, numerous aquatic organisms were discovered that were still unknown to science. Even to-day their life history is a matter of conjecture. After carefully investigating the food supplies of the trout it has leen proved conclusively that the removal of riverside bush has had decidedly adverse effects. Not only is there lack of cover for the flying stages of aquatic insects, but those that contrive to survive have formed* a bountiful source of food supply not to the trout, but to birds. Besides, amongst other things, the increased scouring has swept away other types of food supply and incidentally removed the shelter so beloved of trout. CONTENTS OF STOMACHS OF FISH. As an example of what the effect of the removal of riverside bush can do sample catches of trout food were taken in the Hutt River 200yds above its junction with Belmont Stream. At this spot the banks are bare. Only a

few unappetising pupae and larvae were discovered. In the Belmont Stream itself, with its willow-lined banks, such proved favourites as the caddis larvae, May fly larvae, and creeper were caught in enormous numbers. In fact, a careful examination of the stomachs of a largo number of _ trout has shown most clearly that caddis and May fly form between them something like 90 per cent, of tho food eaten by trout. Just after spawning, however, when a rich, plentiful spring diet is vitally important, these articles of diet are at their scarcest. _ But for the arrival of the whitebait at a most opportune moment the trout would be in very poor condition at the beginning of the fishing season. . TROUT EAT SAND FLIES. Beetles, far from forming an article of diet, are, with one minor exception, a distinct disadvantage. Besides feeding on caddis fly and other trout food, they have been known even to capture young trout fry in a most audacious manner. Sand flies, Captain Phillips declares, undoubtedly form quite an appreciable diet of the trout. Many fishermen will agree nevertheless with Captain Phillips when he remarks that there is no need to encourage or oven protect this abundant form of trout food.