Some fisheries problems on the Great Lakes
No abstract available.
SEARCH · Geology Reports
Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
No abstract available.
No abstract available.
No abstract available.
The need for knowledge concerning the prevention and control of fish diseases has never been greater than it is in this present era of economy when two fish must be raised in the same water which once supported but one. Fish pathologists have contributed a great deal to our knowledge of fish diseases, but there is still much to be learned, particularly concerning better methods of preventing and eliminating diseases among our trout. In this era of circular pools and raceways, our disease elimination is way back in the early days of standard troughs.
No abstract available.
During the summer and fall of 1939 four experiments were conducted at the Patuxent Research Refuge, Bowie, Maryland, to determine the protein requirements of bobwhite chicks. A total of 816 chicks were used to compare six levels of protein, namely, 22,24,26, 28, 30, and 32 per cent.....From the three standpoints of survival, rate of growth, and efficiency of feed utilization for the first ten weeks of life, the 28 per cent level of protein gave the best results. During the ninth and tenth weeks, the highest efficiency of feed utilization was obtained on the 22 per cent level. The results indicate that after the birds have reached about twothirds of their mature weight, the difference in efficiency between a diet containing 28 per cent of protein and one containing 22 per cent may be small enough to justify, in the interest of economy, the use of a diet containing the lower percentage of protein.
No abstract available.
No abstract available.
No abstract available.
During the summer of 1933, lesions of a disease were noted among some fingerling brook, rainbow, blackspotted, and lake trout at the Cortland (New York) trout hatchery. Although these lesions bore a marked superficial resemblance to those of furunculosis, they were sufficiently atypical to warrant further investigation. A more detailed examination of the lesions proved them to be of a distinct disease, which for lack of a better name is herein called "ulcer disease," for the lesions closely resemble those described by Calkins (1899) under this name. Because of the marked resemblance to furunculosis, ulcer disease has not been generally recognized by trout culturists, and any ulcer appearing on fish has been ascribed by them to furunculosis without further question.
No abstract available.
The first reference to a pathological condition of the gill tissues of salmonid fishes was made by Osburn in 1910. This author in describing a progressive infolding of the opercula of trout, commonly known to hatcherymen as "short gill covers," mentioned a marked proliferation on the gill epithelium as accompanying this condition. Osburn assumed that the club-like appearance of the gill filaments due to the proliferated epithelium was the result of continual irritation of the delicate gill tissue in the absence of the usual protection offered by the normal opercula. Although such a conclusion seems quite logical, it is also possible that Osburn was dealing with "short gill covers" complicated by the unknown bacterial gill disease which was subsequently described by Davis.
No abstract available.
No abstract avaiable.
This paper reports on a qualitative and quantitative analysis of the contents of 4,979 lake trout stomachs (593 examined in 1930 and 1,253 collected in 1931 from southern Lake Michigan, 1,446 from northern Lake Michigan and 1,687 from Green Bay in 1932), and of a total of 1,528 lawyer stomachs (172 examined in 1930 and 734 collected in 1931 from southern Lake Michigan, 612 from northern Lake Michigan and 10 from Green Bay in 1932). The food of the trout consisted of 98 per cent by volume of fish of which Cottidae and Coregonidae were the principal constituents. Cottidae were dominant in southern Lake Michigan (72 per cent by volume), Coregonidae in northern Lake Michigan (51 per cent) but the lake shiner, Notropis atherinides, was most important in Green Bay in the spring of the year (64 per cent). The lawyer food consisted of 74 per cent by volume of fish and 26 per cent invertebrates. Dominant items were Cottidae (76 per cent by volume) in southern Lake Michigan, Coregonidae (51 per cent) and Pontoporeia (37 per cent) in northern Lake Michigan, and Percopsis (34 per cent) and Mysis (26 per cent) in Green Bay. Data are also presented on the frequency of occurrence (number of stomachs) of the food items and its variation with the sizes of the trout and lawyers, depths of water, seasons, and localities; on the number of individual fish of each species destroyed by the trout and lawyers; and on the calculated volume of the food fishes preceding digestion. The lake trout and lawyer are competitors for the same food, are both predators of the commercially important Coregonidae, and the lawyer through its consumption of invertebrates is a food competitor of the Coregonidae.
This study is based on 120 whitefish collected in northern Lake Champlain (Missisquoi Bay) in 1930 and on 175 whitefish taken in southern Lake Champlain in 1931. Since the whitefish population had not been exploited commercially after 1912 in United States waters and after 1915 in Canadian waters, its study should be of interest in showing the characteristics of a population practically untouched by man. Data have been presented on length frequencies, age composition, growth, coefficient of condition, sex ratio, standard length-total length relationship, and feeding habits. The data indicated that the Missisquoi Bay population was disturbed (probably by the early fall seining of 1930) before our samples were taken so that the original length distributions no longer existed. The southern Lake Champlain material, however, showed a consistency which indicated that the population had not been exploited to any extensive degree, if at all. When the northern population was compared with the southern the former was found to differ from the latter in the following respects, which differences pointed to some disturbance of the northern stock in the lake 1. By possession of lower modes and smaller grand averages of length. 2. By absence of very old individuals. 3. By absence of a series of equally abundant age groups or, in other words, by the presence of a decided dominance of one or two age groups. 4. By a radical disagreement between the sexes in their age-frequency distribution. 5. By a disagreement between the sexes with respect to maximum lengths attained. All of the differences between the two collections could, however, not be attributed to exploitation. The following characteristics indicated the presence of two distinct populations in the lake 1. Presence of a spawning ground at each end of the lake. 2. Differences in calculated lengths and increments of length (growth rates). 3. Differences in the actual lengths and weights of corresponding age groups at capture. 4. Differences in the coefficient of condition and the length-weight relationship. The discovery of the presence of apparently two separate populations of whitefish in Lake Champlain was wholly unexpected by us.
A largemouth black bass fingerling preserved in formalin was sent to the U.S. Bureau of Fisheries Pathology Laboratory at Seattle, Washington, during the autumn of 1937, by a hatchery employee at Miles City, Montana. The fish exhibited several wart-like protuberances on the caudal peduncle, which aroused the curiosity of Mr. H. C. Topel, in charge of fish distribution at Miles City. He had observed the gradually increasing numbers of these lesions on the fish at this station for several years previous to 1937. Mr. Topel estimated that in 1937, 20 per cent of the adult bass were infected at the time of distribution, and lesions were noted on the fingerling and yearling stock as well.
The prevention or control of epidemics of fish diseases by applying a disinfecting solution in a uniform concentration directly to the water supply of a fish pond or trough for a definite period of time has been exceedingly slow in development. In so far as can be determined, the original idea should be credited to. Marsh and Robinson (1910). In their work on the control of algae in fish ponds by the continuous application of dilute copper sulphate solution, administered to the inflowing water supply by means of a floating syphon, they suggested this method as a possibility in the treatment of fish diseases. Following their work, this commendable idea seems to have remained quite dormant and apparently forgotten until Hess (1930) revived it twenty or more years later. This worker found that a prolonged immersion in a dilute disinfecting bath was more efficacious in remowng fluke parasites from goldfish than was the customary short "hand dip" method. Kingsbury and Embody (1932) later adapted the idea of a prolonged treatment to running water by the use of a float valve for maintaining a constant level in a reservoir, resulting in a constant flow to the pond or trough to be treated. Shortly thereafter, Fish (1933) modified the floating syphon of Marsh and Robinson, as it was a simpler apparatus than that of Kingsbury and Embody.