Dams and Fisheries; Mettur and Its Lessons for India
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DAMS AND FISHERIES; METTUR AND ITS LESSONS FOR INDIA By B. SUNDER RAJ (Communicated by Prof. A. Subba Rau) Received July 31, 1941 POWER, irrigation, navigation and flood control darns are indispensable for the proper exploitation of a country's natural resources. Any artificial obstruction which prevents the free passage of migratory fish to and from their spawning ground is naturally detrimental to Fisheries, as it is bound mate- rially to reduce, or even to prevent, the propagation and perpetuation of stock by the loss of upstream spawning and rearing grounds. To fishery admin- istrators, the salmon and allied industries, and those interested in sport and the conservation of wild life, dams which unduly interfere with the normal life of fish have always caused grave concern or considerable apprehension. The adverse effects of dams on fisheries and their remedial measures have therefore engaged the serious attention of fishery officers, industrialists, sportsmen, biologists, and engineers for many years, especially from the middle of the nineteenth century. Where dams were found indispensable, the accepted remedy till recently has been the construction of fish passes, ways, ladders, lifts and locks, which are devices to enable migratory fish to surmount dams or weirs. These are, however, expensive to build and to operate, but when suitably designed and properly worked have led to a satisfactory revival of fisheries destroyed by dams. Fisheries, being often an economically subordinate consideration, are apt to be ignored even in the advanced West, where their scientific and economic importance is fully realised and, a strong and well-informed public opinion presses for their recognition. In India the need to conserve all avail- able water for dririking or irrigation, combined with the conditions in the rivers, which flow only during the rains or the season of melting snows on the Himalayas, renders fish passes relatively more difficult to build and to operate than in countries with perpetually flowing rivers and a super-abundance of water. Consequently two questions arise which require the most careful and thorough consideration ; first, to what extent dams prejudice fisheries in India; and secondly, where darns are shown to be injurious, what remedies are the most economical to adopt. 341 B1 342 B. Sunder Raj Historical It is perhaps not generally known that the earliest fishery investigation in India, excepting those connected with the historic Pearl Fisheries, were inspired by a fear of possible damage to fisheries by dams or weirs. Dams have existed in Indian rivers from time immemorial, but they had mostly fallen into disrepair before the British occupation. It was not until the nine- teenth century that the most important of them across the principal rivers in India were constructed or renovated. The middle of the nineteenth century witnessed a great revival of interest in salmon passes in England and America. Though primitive types of fish passes may be traced for several years previ- ously, the most important types of fish passes were invented during this period. Among the early inventors of distinctive types the names of Smith, Cail and Malloch in Great Britain, and Brackett, Foster, Brewer and Mac- Donald in America, are well known. In response to a wide-spread demand for legislation, the Salmon Fisheries Acts of 1862 and 1868 in Scotland, and 1871 in England, were passed. Frank Buckland, a great champion of fish passes, during his term.of office as Inspector of Salmon Fisheries in England, from 1866-88, designed and constructed several passes in England. Though the principles he enunciated have survived, not a single pass constructed by him remains. 1 9In the meantime, in response to several appeals, the U.S.A. Commission of Fisheries was set up in 1871. Among the urgent fishery prob- lems to which it devoted attention was the provision of fish passes, z Actuated no doubt by the clamant public opinion at that time in the West, Sir Arthur Cotton, to whose skill and vision we owe many of the great irrigation systems, was the first to call the attention of Government in 1867 to the possible damage to Indian fisheries which might accrue from the seven weirs then completed. Dr. Day, who was at that time working on fishes in India, was immc~liately commissioned to investigate the question, and was subsequently appointed Inspector-General of Fisheries 3 in India. Thus it happened that simultaneously with the West, fish passes received attention in India. With characteristic energy and enthusiasm Day not only condemned dams as barriers to the passage of fishes and therefore highly detrimental to fisheries4 but actually set himself to design a pass--a modified form of under- sluice--which was tried at the Lower Anicut on the Coleroon River in South x T. E. Pryce-Tennatt, Fish Passes, 1938, 6. 2 ,, U. S. Comm. of Fish and Fisheries," Comm. Report, 1872-73. a F. Day, Rep. on the F. Water Fish and Fisheries of India and Burma (Calcutta, 1873), 1 ; also Fishes of India, 1878, Pref. p. 1. 4 F. Day, Ibid., 7-14. Dams atzcl Fisheries ; Mellur alzd [/s Lesso~zs for India 343 India, and a model of which was placed in the Buckland Museum in 1869.5 Hilsa, however, for which his pass was primarily designed, could not be induced to ascend it. Since Day's first pass, now in disrepair, so far as I can trace some seventeen other passes have been constructed in India ; eleven in the Punjab, 6 two or three in the United Provinces 7 and one in Orissa. 8 The cost of construction of the more recent passes in the Punjab, to which province belongs the credit of having done the most in this direction, is estimated at over 689lakhs of rupees, besides the annual cost of repairs and the loss of water to agriculture. According to Southwell, the initial observations for a year in 1916 did not justify the fish pass at Cuttack (Orissa), while Edye did not consider the ladder at Haridwar (U.P.) effective. Hora and Mukherji 9 quote the secretary of the Dehra Dun Fishery Association's statement, that " it is true ' fish ladders' have been provided at places like Bhimgoda and Majapar, where the Northern Ganges canals take off but no one believes that fish of any size can come up these ladders." Fuller reports exist about the ladders in the Punjab. In the latest, 1~ dated 1940, Dr. Khan concludes that most of these also are ineffective. If ladders in India have not justified the expenditure and effort involved, it need not surprise us. Even in Europe and America, the perfect pass does not yet exist and the good ones are still in a minority.}1 "The devising of a fish pass is fraught with uncertainty, because it is almost impossible to pro- phesy the behaviour of fish and quite impossible to anticipate the vagaries of water. The subject involves a working knowledge of hydraulics, and while hydraulic engineers conversant with the habits and requirements of fish are rarely to be found, the rules and assumptions of hydraulics themselves are apt to be disconcertingly upset when applied to the functioning of a fish pass. The subject is by no means within sight of finality. ''12 The report on a sym- posium on " Dams and the problem of migratory fishes" of the American Society of Ichthyologists13 recently held at the Stanford University also shows that only a beginning has been made in the study of the subject. To a casual 5 F. Day, "Fish Culture," Int. Fish Exhib. Lit., Lond., 1884, 2, 95. 6 Harnid Khan, " Fish Ladders in the Punjab," Journ. Born. Nat. Hist. Soe., 1940, 41, No. 3. Edye, E. H. H., Rep. on the Fisheries of the U. P., 1923, 14. 8 Dept. of Fisheries Bengal Bihar & Orissa, Bull. No. 11, 1918, 4. a Hora, S. L., and Mukerji, D. D., " Fishes of the Eastern Deons, U. P.," Rec. hzd. Mus.. 38, Pt. II, 135. x0 Hamid Khan, "Fish Ladders in the Punjab," Journ. Born. Nat. Hist. Soc., 41, No. 3, 561. tt T. E. Pryce-Tennatt, Fish Passes, 1938, 38. 12 Ibid., 7. t3 Stanford Ichthyological Bull., Stanford Uni/. Califo nia, May 1940, 1, No. 6. 344 B. Sunder Raj observer, the building of a fish pass may seem a straightforward engineering enterprise, requiring only the application of conventional fish way designs and practices, but to no one with an intimate knowledge of modern fish ladders and of Indian requirements does the task seem so simple. Research and experi- ment have not reached the stage when general principles governing all dams can be enunciated. For success the design and operation of a pass must be adapted to the fish and to the physical conditions of the dam for which it is intended. Recent experience in England and America makes this self-evident proposition all the more clear. For instance, in one and the same river--the Columbia--and for the same fish--the' sockeye' and the ' chinook' salmon and the ' steelhead ' trout--while ladders were possible and successful across the Bonneville and Rock Island Dams in the lower river, they had to be abandoned as impracticable for the Grand Coulee (350 ft. high) and Shasta (560 ft. high) Dams. 14 Moreover it was found that for one reason or another the lessons learned at one place, e.g., Bonneville, would not directly apply to Grand Coulee or Shasta. If the task is so complex even with reference to a single river and the same fish, about whose instincts and habits so much is known, where are we in India ? Despite the fact that fish passes attracted early attention in India, there is no evidence of any intensive" study of the problem in the light of modern research and experience, even in the Punjab with its many fish passes.