FRESHWATER RESEARCH

Press, Volume LXXI, Issue 21465, 6 May 1935, Page 18

FRESHWATER RESEARCH

¥0 TI1» EDITOB Or TKK PRBSS. Sir,—ln "The Press" of April 20 there appears an article specially written by G. Stokell with reference to the investigation of trout waters in New Zealand. Probably very few of the readers of that article will have had the opportunity of reading the criticised paper (written by Professor Percival and published by the Marine Department in 1932 as Fisheries Bulletin No. 5). Intelligent anglers and others will understand that the investigation of trout waters is not a matter of the solution of a single simple problem, but the eluoida-' tion of a number of complicated problems by throwing light on the various factors involved, by sorting out the relevant facts, examining their validity and by drawing such conclusions as may be deduced from the facts. By the nature of the case it is not a oneman job, but a task that is greatly facilitated by collaboration and cooperation; especially when such collaboration is organised and co-ordin-ated and where such of the work as calls for special scientific or tcchmcal treatment is placed in the hands of a specialist. It is in this manner that (he New Zealand Freshwater Research Committee has, so far as_ its means allow, organised the investigations under its control. Now the investigation can oe nelped in the first place by anyone who is capable of providing facts or material that can be used as data for scientific analysis; which, of course, pre-sup-poses an intelligent and honest desire to supply reliable facts, fn the second place, it can be helped by anyone who will and can apply his mind rationally and honestly to criticising the value of the data that are used by the investigator, and criticising the conclusions that are drawn from them. For reasons that are no concern of the present writer, Mr Stokell has taken up the part of critic. Haying applied himself to the study of trout and salmon scales for several years he is better acquainted with the appearance of scales and with the interpretation of their varying character than is the average angler. However, his "somewhat tedious dissertation on the fundamental principles of scale reading," which constitutes a large of his article, and is the whole basis of his criticism, is open to counter-criti-cism not because it is tedious but because it is inaccurate. He knows something about the business, having worked at it as an amateur, but not quite enough to save himself from one of the pitfalls that await the critic who has merely a partial understanding Of the subject he is dealing with He is in error in stating that "the ability to calculate the increase in length made by a fish in any vear is due to the fact that-the length of the scale from the middle of the apex increases in the same ratio as does the length of the fish." The English of this is as sloppy as the biology, but one may gather that he is referring to the longitudinal diameter of <he scale, and that by apex he means th-a posterior point of this diameter. Unfortunately for the validity of Mr Stokell's conclusion this length is not the dimension that is used for 'he estimation of the length of .he fish. The anterior longitudinal radius—i.e., (lie distance from the central point or nucicus of the scale to its front edge —is the dimension used. It is used, among other reasons, to avoid the error which this amateur critic complacently assumes that our scalereader has fallen into. It is the part of Ihe scale that Mr Stokell calls the "apex" that is most subject to prespawning erosion. The anterior margin to which the radial -length is measured for growth estimations, is so little affected by erosion that it is often impossible to see any evidence of a spawning mark in this part of the scale. So the erosion of scales that precedes spawning does nol involve so much error in growth estimations as Mr Stokell by his faulty methods has been led to believe. Moreover, the growth during the years before maturity is attained, which are the most important years for growth studies, are not affected at all. Nor is the final length of the fish at death; and this, from the aspect of the point discussed by Professor Fcrcival in his paper, is practically the only thing that matters. There is this further serious objection to be raised against Mr Stokell's article. He chooses out one small portion of the whole paper, which is really rather a minor point, and subjects it to ill-informed ana partial criticism, as if the whole thesis led up to that and to nothing else. He further throws dust into the eyes of his readers by opening with the statement that "official investigation of trout waters in New Zealand has culminated in the publication of a Fisheries Bulletin (No. 5)." This statement is an unwarranted assumption which can most charitably be usjpbed to a complete misapprehension on the part of its ill-informed author. The Fisheries Bulletin in question is a paper (by Professor E. Percival) "On the Depreciation of Trout-fishing in the Oreti (or New river), Southland, with Remarks on Conditions in Other Parts of New Zealand." It deals primarily with the conditions in that Southland river, stating all the relevant facts thai could be ascertained, among the most useful being a record of one angler's catches from a definite part of that river from 1389 to 1930. Other sections of the paper are given under these headings:—"Observations on the Biology of the Brown Trout in New Zealand," "Consideration of the Food Organisms of Trout," "Food Relations in Trout Rivers and Lakes," "The Growth of Trout in New Zealand" (a portion of which is the object of Mr Stokell's criticism), "The Age of Brown Trout," "Deforestation and its Relation to the Depreciation of Fishing," "Details from Opuha Gorge Upper Opihi River, and Data from Waipukurau. Hawke's Bay." It is misleading'to call it an "official investigation," and it is no more the "culmination" of such investigations than the first kick at goal is the result of a football mutch. All that can be or need be claimed for it is that it represents the results of its author's labour umpaid, as well as unofficial, labour) in collecting ami presenting "a series of facts relevant to the various problems involved. Being the work of a scientist, it gives those facts so lhat a reader may judge for himself how they were obtained and see them in their relation to each other and to the conclusions drawn from them. No more than any other contribution to scientific literature does it represent the last word as to the facte nor a final conclusion regarding the problems. It is a contribution to our understanding of those problems and as such has a definite value that can be increased by rational and honest criticism and is not diminished by the sort of criticism that one regrets to* sec Mr Stokell spending his energies upon. He could find so much better use for them in getting a proper understanding of the subject so that eventually, if he applied himself with the single-minded desire for accuracy which is demanded of the scientific student, he might come along with some sound contribution to our knowledge or some really helpful criticism, which would be quite welcome if it were inspired by a desire to help the cause of fish research in New Zealand.—Yours, etc., A. E. HEFFORD, Chairman of the New Zealand Freshwater Research Committee. Wellington, May 2, 1935.

THE LAURIAN CLUB CONCERT

TO ra« KDITOB OF THK PRSSB Sir,—lt is evident that there are many musical people in this country who resent any comment on their programmes and performances, except that which is favourable. Our newspapers are partly to blame for this: some do not retain competent musicians as critics, with the result

that, at times, only moderate presentations of mediocre music receive extravagant praise, while praiseworthy efforts are merely reported or ignored. Serious-minded musicians who have cultivated the art of listening, and who realise that the level oi musical performance in New Zealand generally is not by any means a high one, shculcl welcome the appointment as musical critic of "The Press - ' of a musician with, the knowledge, experience, and practical ability that Mr Ernest Jenncr possesses.—Yours, etc., STUDENT OF MUSIC. May 4, 1935.