determine the maximum size and age obtainable by oysters in these waters and the percentage of mortality to be expected according to age and environmental conditions.

Operation of an experimental oyster farm in South Carolina is providing considerable information on the relative value of the various types of bottom for seed-oyster production. On the Gulf coast, where oyster production has been at a low level for a number of years, the staff is cooperating with oystermen and with State conservation departments in formulating programs for the development and maintenance of natural oyster grounds and for the creation of new grounds by planting shells and seed oysters.

Methods of controlling starfish were tested under a variety of field and laboratory conditions by the staff and are being put into practice by many New England and Long Island oyster growers in a vigorous effort to diminish the losses caused by this abundant animal. Oyster drills, which are a serious menace to oysters in the Middle Atlantic States and are now becoming more numerous in Long Island Sound, have been found capable, when only 1 month old, of destroying approximately five oyster spat a day. Because of the heavy depredations of the boring clam, another oyster enemy found in Gulf coast waters, an investigation of the life history of this little-known mollusk has been undertaken at the Pensacola (Fla.) Station.

The study of the effects of pulp-mill pollution on the oysters of the York River, Va., has been completed and a final report on this investigation will be made early in the fiscal year 1941.

Sponge investigations.-During the summer of 1939 samples of diseased sponges were received from Florida and subjected to microscopical examination. All were found to be infected with the fungus organism that had been discovered and tentatively identified during the preceding year by one of the Bureau's biologists in surveys of the Bahama Island waters and the Florida Keys. From Key West, where the disease first manifested itself in the United States, it spread to Tarpon Springs, and by the end of December mortality of commercial sponges had proceeded to such a point that fishing was discontinued on bars situated below eight fathoms. At the end of the calendar year 1939 the number of sponges brought to the Tarpon Springs Sponge Exchange had noticeably diminished, causing considerable concern for the future of this resource. During the spring of 1940 there was evidence that the disease had abated and that a large crop of small sponges was in evidence. However, two or three years may be required for a substantial restoration of the commercial-sized supply.

Aquicultural investigations.—Studies concerned with the management of fresh-water sport fisheries are conducted along three prin

cipal lines. The first is related to the artificial propagation and rearing of game fishes; the second to the problem of controlling the parasites and diseases of fish which frequently curtail the output of hatcheries; and the third to field problems relating to fish management, such as the comparative survival and growth of hatchery and wild trout under natural conditions, the ecological requirements of different species of game and food fishes, and the possibility of increasing fish production in natural waters.

In connection with studies of the artificial propagation and rearing of trout, progress has been made toward developing economical diets without sacrifice of growth. Other experiments have demonstrated that overfeeding of trout brood stock is distinctly detrimental in that it reduces the number of eggs that hatch, while experiments in selective breeding have more than doubled both the rate of growth and the production of eggs.

Studies of the pond culture of largemouth black bass were carried on in Florida with a view to determining the role of fertilizers and forage fish as they affect the production of bass fingerlings per acre. Similar work on a somewhat smaller scale has been conducted in West Virginia. Here, also, field studies of the spawning and survival of smallmouth black bass are being made in selected tributaries of the Potomac River.

The most important result of the studies in fish pathology during the year was the development of a safe, practical, and economical method of controlling the external parasites of fish. Other investigations contributed to an understanding of the causes and prevention of the Western type of gill disease and of the importance of several parasites of trout and bass. In addition to the hatchery studies, losses among wild fish in the field were investigated by the staff. The most important problem of this nature that is currently under study concerns the attacks of fungus organisms which inflicted considerable losses on adult chinook salmon and steelhead trout liberated in the Entiat River in connection with the Columbia River salvage operations.

One

Fish-management studies on trout waters were carried on at the Pittsford (Vt.) and Leetown (W. Va.) Stations, in the Pisgah Game Preserve in North Carolina, and in Utah, Idaho, and California. of the surprising results of the "test water" studies conducted in Vermont is the finding that fishing is maintained chiefly by natural reproduction of wild fish, and that stocking with hatchery trout has had little effect. Under conditions obtaining in those waters, stocking with legal-sized fish in the fall has been found to be wasteful, and tests are being made to discover whether stocking with smaller fish will yield better results. In the Pisgah Game Preserve, where the

Forest Service has complete control over all streams, management programs worked out by the Bureau of Fisheries have been in operation. Good results were already apparent in 1939, and during this and the 1940 season it was possible to accommodate more anglers and to permit a longer open season than in previous years. Management studies in the intermountain region have been concerned chiefly with the fisheries problems of Fish Lake, Utah, and of Bear Lake, which is situated almost equally in Utah and Idaho. In California, while experiments on the survival of hatchery trout after planting are still under way, the attention of the staff has been given principally to the problem of devising a plan for salvaging salmon whose migration will be blocked by the Shasta Dam. This dam will be approximately 560 feet high and will cut off all salmon spawning areas above it in the Sacramento, Pit, and McCloud Rivers and their tributaries. The value of these salmon runs has been calculated at $95,000 annually in returns to commercial fishermen. After surveys of potential spawning areas below the dam and of possible sites for trapping the runs for transfer to such areas, a preliminary report embodying recommendations for the salvage operations was issued in June 1940. Water quality investigations.-One of the major activities of the aquatic physiologists during the past year was a study of the effects of various components of larvacides and herbicides on fresh-water fishes and their associated aquatic food organisms. These studies have now provided evidence that in waters treated with even small quantities of arsenicals and several other materials commonly used as mosquito larvacides, there is impairment of the growth and nutrition of fishes.

Application of physiological, biochemical, and metabolic methods to the study of fishes from irrigation waters has demonstrated that the physiological condition and reproductive capacity of such fish is often below par, a condition traceable to the concentrations of mineral salts discovered in many return irrigation waters. The same methods of study applied to fishes from waters polluted with mine wastes revealed that chronic injuries result from much higher dilutions of the wastes than heretofore have been recognized.

During the summer of 1939 intensive studies of stream pollution were made along the Atlantic seaboard and throughout the greater part of western United States, resulting in the collection of much new information on the nature and effects of polluted waters.

Studies of impounded waters were continued at Elephant Butte Reservoir in cooperation with the Reclamation Service and the National Research Council, and at Lake Mead in cooperation with the same agencies and the National Park Service.

Protection of fish runs from engineering developments.-The establishment, early in the year, of a section on hydraulics within the Division of Scientific Inquiry provided for the application of biological and engineering skill to fishery problems created by the construction of dams, reservoirs, and diversions for the purposes of power, irrigation, navigation, and flood control.

The work of the Hydraulics Section during the first year of its existence has been devoted to three general phases of fish protection: (1) Supervision of the construction of four large fish screens in Federal irrigation canals and the operation of Federal screens already constructed; (2) consultative services in connection with fish-salvage problems at the Shasta Project on the Sacramento River; and (3) the review of Federal water projects from the standpoint of fish protection. Advice in connection with fishway and screen problems has also been furnished the conservation agencies of several States.

APPROPRIATIONS

Appropriations for the Bureau for the fiscal year aggregated $2,259,400, as follows:

Salaries, Bureau of Fisheries

Propagation of food fishes___

Construction of fish screens

Maintenance of vessels_.

Inquiry respecting food fishes

Fishery laboratory, Little Port Walter, Alaska....

Fishery industries

Fishery market news service_

Alaska fisheries service‒‒‒‒‒

Enforcement of Black Bass and Whaling Treaty Acts..

Mississippi Wild Life and Fish Refuge_

Library

Travel expense

Total

$183, 000

949, 400

10, 000

214, COO

322, 000

7,500

80, 000

76, 000

268, 200

17,000

17, 000

600 114, 700

2,259, 400

GRAZING SERVICE

R. H. Rutledge, Director

World events during the past year brought to American citizens

a deeper realization of the significances of range conservation to our national welfare. The vital importance of a continuous, adequate supply of food and clothing to meet the needs of citizens under possibly extraordinary conditions was recognized. Protection and wise use of the source of these products took on a new and realistic meaning in our national planning. Conservation of the Federal grazing lands from which is derived a large part of the meat, wool, and leather essential to our continued well-being was accepted as an important and integral part of our nationaldefense program.

The Grazing Service exerted an important influence on western land use planning during the fiscal year just closed. Considering the importance of all land resources to a permanent program of national preparedness and economic welfare, the program was given added significance.

As custodian of 142,000,000 acres of public lands in 10 Western States, this Service directed its program toward the main objectives necessary to bring about coordinated use and planning for resource conservation. Not only was this effort directed to the public lands but also to correlating that use with 125,000,000 additional acres of State, county, and private lands intermingled with the public lands. Planning included management collectively with all related agencies, groups, associations, and individuals in an effort to harmonize this use in the greatest public interest.

Industrial and military forces of the national program must be adequately clothed and fed. In this connection the stockmen of the west realizing that they have a dual responsibility looked to the Grazing Service for guidance. Working together with stockmen, farmers, sportsmen, agencies, industries, and groups the Grazing Service has taken the position that something deeper than the grazing of livestock underlies the whole job of public-land administration.