trolled by blocking side channels in order to get all the water together. Improvements in the character of the water have sometimes been made by decreasing the amount of water standing on decomposing muck and by keeping the stream moving along more rapidly. Small dams, faced with boards, readjustment of boulders to form rocky pools, deflectors which turn the water, and many other constructions are useful. It is the aim to do this work economically, using logs and boulders available at the stream, and to put the stream in as good condition as possible with the means at hand. Elaborate work is neither justified nor desirable, and no one likes to see artificial-looking work along trout streams. Permanence is an essential, of course. There is reason to believe that properly constructed improvements will last many years. Inspection of two improved streams hit by the flood of last July indicated total damage not exceeding 10 percent, which is remarkable considering the extreme violence of this flood. Most of the modifications are along lines for which Nature sets the pattern. Usually, in looking over a stream, a good working basis can be derived from study of the best of the natural places. In checking the results of stream-improvement work, there is an important handicap in that it has not proven practicable to study each of the many streams intensively for a long period before and after the work. In checking over a number of samples of the work done last year, I have been well satisfied that more good-sized trout can be carried than before improvement. I do not mean that any and all improved streams are fishermen's paradises. A small stream, without good pools, produces only a few fish of legal size. Improve it and it produces more. It still remains a small stream, easily fished out of large fish. Fishing pressure acts to keep large fish scarce on improved as well as unimproved streams. The degree of success would need to be measured by catch records before and after improvement, not by measuring what is left in the stream. Unfortunately, catch records on each of the streams are at present impossible to obtain. It may seem surprising that catches of trout are made a year after improvements, in areas formerly unsuited to production of legal-sized fish. Most streams, if any good at all for trout, have quite a number of young fish toward their headwaters. Such young fish soon take possession of improved areas and after growing 1 year are likely to be legal-sized fish unless hindered by excessively cold water or poor food supply, such as is induced by excessive crowding. The management of unfavorably balanced populations in lakes and streams is a subject requiring much investigation of principles and applied methods. In fact, such work as has been done is to be regarded as more or less in the nature of pioneering. The growth-rate investigations of the Biological Survey have disclosed a great range of rapidity of growth of trout, bass, perch, and some other species. We have lakes where perch run large and lakes where they are small and also very numerous. Our survey reports have pointed out that lakes frequently develop large populations of such fish as perch, sunfish, and rock bass, crowded, stunted, and of slight attraction to the angler but keeping the lake 57282-3629 in a state of poor production. You might say, well then, plant heavily with young bass or other species to forage down these others. But where we have a crowded population of 3- to 5-inch rock bass, some of which are over 5 years old, it is hardly logical to expect that stocked fish can increase against this competition. The only parallel that I can think of would be for a farmer to sow his corn down in his scrub pasture or woodlot instead of in carefully prepared ground. Even on plowed land he gets no crop unless he cultivates to remove weeds. When we do progress sufficiently, and it will take time and money, of course, in the field of removing excess fish the technique should be patterned after the cultivation of field crops in that it will be a problem of controlling what is locally undesirable rather than giving any species a black eye and trying to exterminate it in all waters. Some of the principal unfavorable environmental conditions that the surveys have brought to light as more or less prevalent in the waters of the State can be listed as follows: (1) High temperatures (affecting trout especially): To some extent subject to control through ditching of spring, narrowing of streams, and planting of shade. (2) Poor pool conditions, uniformly shallow areas where fish find. little shelter, especially in low water: Most of the stream improvement done has been devoted toward remedy of such conditions. (3) Unbalanced population conditions: Particularly prevalent is overcrowding of relatively less valuable forms of fish life, and overcrowding and stunting of game fish. Some species are undesirable in the particular waters they inhabit and interfere with species. which would otherwise do well in these waters. Competition is often too severe to allow each individual the food supply that it should have in order to produce a fish of valuable size. Barrier dams have been used to keep undesirable fish, particularly perch and pickerel (northern pike) from migrating up into trout waters. (4) Depletion of the more sought-after species: This tends to upset the balance already mentioned, by allowing unfavorable species to increase. This is difficult to control. The work done has increased water areas and probably added slightly to chances for escape of fish. (5) Parasites: Particularly important here are the grubs which affect the value of fish to the angler and internal parasites which affect the health of the fish. Possibly other diseases than those caused by parasites should be listed, although there is as yet little information available on the seriousness of most diseases in wild waters. Decrease of ponded areas may have a limiting effect on pond snails, the intermediate hosts of grubs. Work done, so far, has probably had slight effect on parasite conditions. (6) Unfavorable spawning places: Dams, both those built by humans and beavers, should be listed here with respect to their action under some circumstances in blocking fish from reaching their spawning grounds. This factor is supposed to have been responsible for the extermination of the natural run of the Atlantic salmon, for example. Wherever it has been practicable to remove barriers, clean out spring runs, and increase gravel beds, spawning areas have been favored. It is doubtful if lack of spawning areas constitutes a prin cipal limiting factor in most of the streams concerned, although this subject needs study. (7) Unfavorable physical and chemical conditions in the water: These are various. Most conspicuous is the low oxygen supply of many waters due to decomposition. Several projects in lake and stream work have involved removal of decomposable debris. (8) Low natural fertility: Many waters, especially those which are very pure and cold, do not produce many fish merely because there are insufficient amounts of fertilizing substances to supply abundant amounts of the necessary plant life which is basic to the development of a food supply for fish. Practicable means for modification of this limiting factor are not available. The improvement of environmental conditions for the purpose of improving fish yields constitutes a problem in applied ecology. This type of management requires research, in that the limiting factors of each environment need to be determined. The accomplishment of the changes which are indicated as desirable requires practical application of improvement methods by skilled field crews. In New York State field surveys of approximately five-sixths of the streams and lakes of the State have been completed in the last 10 years by the Bureau of Biological Survey of the Conservation Department. The information resulting from this extensive field work goes far toward providing the necessary scientific basis for planning improvements. Requirements along lines of practical application have been met by field workers of the Civilian Conservation Corps organization and of the Conservation Department. (No discussion.) STREAM IMPROVEMENT IN PENNSYLVANIA AND ITS RESULTS (By O. M. DEIBLER, Commissioner of Fisheries, Harrisburg, Pa.) The subject of stream improvement or stream farming has become one of paramount importance. Especially is this true in the highly industrialized States of the East, where the fishermen have been observing from year to year the diminishing of their fishing waters at an alarming rate. At the same time it was noted that each year a heavier toll of fish life was being taken from our remaining available public waters. This loss of public streams that formerly afforded fishing has been brought about by three factors. First, and by far the most important, is the matter of pollution. In Pennsylvania, where we have two large coal basins-namely, the anthracite field, which covers a large portion of northeastern Pennsylvania, and the bituminous region, which extends from the central part of the State west and south to our borders-while industrial and municipal pollutions are serious, yet the mine drainage is even more threatening and affects approximately three-quarters of the mileage of our major streams. Second in importance is the leasing or purchasing of many of our most worth-while streams by private individuals and clubs, until today 1 mile out of every 7 on our trout waters in Pennsylvania is closed to public fishing. The third factor is the posting against public fishing, by individual owners. This has been brought about largely by the fishermen themselves, not the sportsmen. Shrinkage of fishable waters to less than one-quarter of what they formerly were, in addition to the ever-increasing number of fishermen, who today have more time and leisure to fish than at any other time in our history, has created an unusually heavy demand on the remaining waters that still offer any fishing. Since 1930 in Pennsylvania we have been confronted with another situation that was so grave that the matter of stream improvement was most forcibly brought to our minds. I refer to the serious drought conditions through which we have passed during the past 5 years. During this period, previously never-failing springs, and streams that had formerly carried a substantial flow and offered excellent protection to fish life, became dry or virtually dry, only little trickles and a few pools remaining. As an additional menace, our wardens and fishermen observed another threat to our various fresh-water species of fishes, occasioned by great migrations of all types of fish predators. Never in the memory of our oldest anglers were so many watersnakes seen on our streams, nor had there been noted before such great numbers of fish-eating birds which had migrated to the State during the drought period. The white egret, for instance, which had rarely if ever been seen on our streams, was now observed in flocks numbering as many as two dozen birds. These egrets, with the blue heron, many types of bittern and other shore-wading birds, found it easy, during low-water periods, to feast on fish life which had little if any protection. Nature seems to have an amazing and unique system of communication or instinct whereby information of this kind is broadcast among predatory birds and animals. The board of fish commissioners in 1931 started an extensive and comprehensive survey of the waters of our Commonwealth. This was forced upon us by the necessity of finding suitable waters in which to plant the fish which we then had in our rearing ponds, as many streams that were formerly stocked were now in no condition to be stocked. After the first reports of our field men came in, we found, very much to our surprise, that we were receiving a great deal of information which had not been anticipated when the survey was first ordered. This survey was carried on for 4 years, until we had completed by watersheds the whole water system of the State. It furnished us with a comprehensive picture, for the first time, of the exact mileage of polluted waters, waters which had been closed to the public for fishing, and acreage of our ponds and lakes. The survey likewise furnished us with first-hand authentic information as to the various species of fishes best adapted to waters throughout the State. However, some of the results of this survey were most alarming and brought to the sportsmen, for the first time, the necessity for carefully guarding and protecting the few remaining miles of clean waters we still had. Yet the facts reveal that for each mile of stream still suitable for support of fish life, we had approximately 41⁄2 miles of water so highly polluted that no type of aquatic life could exist in it. These facts also reveal to us the astounding fact that should our anglers all go astream on the same day, available fishing waters would be so congested that each fisherman would have available only 90 feet of stream as his territory. With these figures before us we were faced with a problem somewhat similar to that of the farmer during the post-war period when |