A Biological Examination of Lake St. Clair - Primary Source Edition PDF Download
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Author: Michigan. State Board Of Fish Commission
Publisher:
ISBN: 9781293418130
Category :
Languages : en
Pages : 74
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Author: Michigan. State Board Of Fish Commission
Publisher:
ISBN: 9781293418130
Category :
Languages : en
Pages : 74
Get Book Here
Book Description
Author: Jacob Ellsworth Reighard
Publisher:
ISBN:
Category : Freshwater animals
Languages : en
Pages : 86
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Author: J. E. Reighard
Publisher:
ISBN: 9781331967941
Category : Science
Languages : en
Pages : 74
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Excerpt from A Biological Examination of Lake St. Clair The remedy does not lie in restrictive legislation; it lies rather in an increasing of the effectiveness of methods of artificial propagation and perhaps also in an increase of the annual output of artificially hatched fish. "The first view is held for the most part by fish culturists, who favor restrictive legislation and increased facilities for artificial propagation. "The second view is held for the most part by fishermen, many of whom are not yet convinced of the value of artificial propagation. "When one who is neither fish culturist nor fisherman attempts to discover the grounds upon which the various opinions are based, he very soon finds that there are but few recorded facts. "In order to know whether the number of whitefish is increasing or diminishing for any locality or for all localities, it is necessary to have statistics extending over a term of years. Statements based on statistics which are taken in two years separated by an interval of five or ten years are nearly valueless for purposes of comparison for the reason that such statistics do not and cannot take into account the climatic conditions which make one year favorable and another year unfavorable. The fact that in the year 1880 the number of whitefish marketed was greater than in 1890 does not prove that the number of whitefish has diminished in this interval; it proves only that the number caught in 1890 was less than the number caught in 1880. This may have been due to a diminution in the number of fish, but it may also have been due to storms during the fishing season of 1890. Statistics to be conclusive should enable us to compare the average yield for the ten years 1870 to 1880 with the average yield for the ten years 1880 to 1890. "No such continuous series of statistics is in existence, so that.the assertions concerning a diminishing yield of whitefish rest either on a comparison of these statistics of isolated years or on the statements of fishermen concerning certain localities. "If we inquire into the facts concerning the sufficiency of the present methods of artificial propagation, we find that so far as concerns the whitefish there is no question as to the success of the earlier stages of the process. Several hundred million ova are taken annually and placed in the hatcheries and of these usually from 80 to 90 percent are hatched and placed in the waters of the Great Lakes - 165,000,000 in Lake Erie alone in 1888. "This is very nearly all that is known about these young whitefish. About their food habits we know only that in captivity that they eat certain species of Crustacea. Whether in their natural habitat they eat other animals in addition to these Crustacea or in preference to them we do not know. It is uncertain at what age they begin to take food or how much they require. We do not know their natural enemies. We do not know whether they thrive best in running water or in standing water, in shallow water or in deep water, whether at the surface or near the bottom. What changes of habitat or of food habits the fish undergo as they grow older is a still deeper mystery. "Our problem is to place young whitefish in the Great Lakes under such conditions that as large a number as possible of them shall grow into adult fish. It is clear that of one of the elements in this problem namely, the whitefish, we know but little. "What, then, do we know of the other elements of the problem, the Great Lakes themselves? About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com
Author: A. J. Pieters
Publisher:
ISBN:
Category :
Languages : en
Pages : 22
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Author: Jacob Ellsworth Reighard
Publisher:
ISBN:
Category :
Languages : en
Pages : 60
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Book Description
Author: United States. Bureau of Fisheries
Publisher:
ISBN:
Category : Fisheries
Languages : en
Pages : 894
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Author: Michigan
Publisher:
ISBN:
Category :
Languages : en
Pages : 1498
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Author: Michigan. Legislature
Publisher:
ISBN:
Category : Michigan
Languages : en
Pages : 1206
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Author:
Publisher:
ISBN:
Category : Michigan
Languages : en
Pages : 1448
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Author:
Publisher:
ISBN:
Category : Water
Languages : en
Pages : 808
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