HABITS OF TROUT

Marlborough Express, Volume XLVIII, Issue 88, 16 April 1914, Page 2

HABITS OF TROUT

» THE RAINBOW SPECIES. MIGRATION TO THE SEA. REASON FOR DEGENERACY. CANADIAN COMMISSIONER'S I VIEWS. ■. _ | Some interesting remarks upon the habits and diseases of trout were j made by Professor E. E. Prince, : Canadian Commissioner of Fisheries; j in an interview with an Auckland ' Herald representative last week. j One question of general interest to ! anglers is .what becomes of the rain- j bow trout when they leave the rivers. • such as the Waikato, and go down to the sea. Professor Prince was asked if he oould elucidate ithis point. He replied that most of the Pacific Coast trout are known to migrate to the sea, and others linger in the estuaries and never migrate far afield. The rainbow and steel-head trou.t had more or less distant feeding grounds. "In my opinion there is no doubt that the rainbow trout are seeking some feeding grounds such as they are ancestrally accustomed to," said the i-roressor, "and that they really lost their bearings and are unable to ge/ u back to their original rivers and lakes. My colleague on the International' Commission, under Canada's treaty of 1908 with the United States Dr. David . Starr Jordan, holds the opinion that members of the salmon and trout families descending to the: sea return largely by accident to their ■own rivers. . Authorities, however, differ on this i>oint, and I am one of those who hold that salmon and trout are as a whole irue to their own rivers, and m the usual course of events find their way back to the streams in which they were originally hatched and reared. The fact that the ram oow trout does not apparently return is, I think, due to the tact that their feeding grounds are so far distant, causing them to get lost. 35 DETERIORATION IN CONDITION. The. deterioration in the condition of the rainbow trout in the North Island streams, through Taupo., and down the Waikato River, was a subject next referred/ to Professor Prince. It was mentioned that there are hundreds of miles of river on that line of route stocked with fish once the finest in the world—rainbow trout up to 201b having been often taken; also that a few years ago the fish in these waters .were generally all bujtter fat, whereas to-day they have gone down in average weight and condition, have large heads and attenuated bodies, and are known by the popular name of "slabs." RESULTS' OF CANADIAN EXPERIENCE:, Asked if he could account for this, the Professor said he could only speak generally pending his personal investigations, but the introduction of non-indigenous fish into new waters in his view proved two (things; first, that some species improved in all their qualities—game, size, and so on—and, secondly, that other, species were found in course of time to deteriorate. Canada had had some experience in this direction, but not such an extensive one as New Zealand. The English brown troujt introduced into the Eastern Canadian waters (Nova Scotia, etc.) had degenerated and wholly lost their game qualities. This was due in Canada to a superabundance of food. "Fish that have a surfeit of good food become indolent and lose their aqtive game qualities,"" said the .Professor. "These qualities imply that rood has to be sought out and captured. A similar result, -namely, loss of quality and vitality, iii the rainbow trout appears to have arisen from the opposite condition in New Zealand. SCIENTIFIC REMEDY POSSIBLE. "I am arranging rt;o make an examination of the fish and their conditions, but meantime I incline to the opinion that a lack of food has much to do with the degeneracy of the rainbow trout,"said the Professor. "When these fish degenerajte and lose, their vivacity they become very subject to disease. Researches carried on in Canada at the three biological stations under my direction have shown that species which lose condition are very prone to become victims of diseases—especially parasitic < diseases, which often reach serious dimensions. However, I think it is quite within the bounds of possibility to deal quite effectually with this matter by scientific methods." The Professor was asked if he could" recommend- any other Jnsh which could- co-exist with the rainbow trouit, and which there would be | a possibility of establishing in New Zealand. DIFFERENT SPECIES CAN CO-EXIST. "As to that, it has been; proven in Canada that it is quite possible to have two or more species of game fish in some waters without harm to either," was »the reply, "but everything depends on the .character of each particular lake or river." Professor Prince preferred to defer any further remarks on this subject, and also as to trawling and the contr°l and distribution of sea fish until after his coming visit (to the Dominion's fisheries. . INTERESTING ITINERARY. An interesting itinerary has been I mapped out for Professor Prince, j a? d _ approved by the Minister for Marine (Hon. F. M. B. Fisher). ! . Accompanied by Mr L. F. Ayson | (chief inspector of New Zealand i fisheries) the Professor left Auckland & , the, Main Tr"nk express on [Wednesday, en route for Wellington. !1 he trip will be made via theWanga;mu River to Aramoho, thence through the Manawatu Gorge and ' down through the Wairarapa, over the Rimutaka, arriving in Wellington on Saturday night. Professor Prince and Mr Ayson will leave Wellington next Tuesday by the Government steamer Hinemoa to begin the examination, of the fishing grounds which the visitor has been asked by t the Government to make. ' He will first proceed down the east coast of the South Island, and com- ■■ meneo his investigations on the fishing grounds some distance north of Lyttelton, trying the. various grounds all down the coast ,<to Stewart Island , and the Foveaux Strait, where he will exammo the dredge oyster beds. - From there the Professor will go up the west coast, through the Sounds, : ;uid will examine some of the fishino- : grounds on. that coast as far up as i Nelson Tliemre lie will go through ' tho Marlboro i igh Sounds fisheries : afterwards returning to Wellington '-■ ' An inspection of the North Island ' sea fisheries will follow, and while. ! here _ Professor Prince' will also ; examine the various rock-oyster beds Later, the trout streams of the North s

Island are to receive rthe visitor's attention.