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<br />
<br />
<br />INTRODUOTIQl!f
<br />
<br />Most of the major drainage basins and many of tlie minor ones of
<br />California have provided fishing for niaiiy years and have been the sub-
<br />jects of considerable investigation, but the Colorado, one of the great
<br />rivers of America, has received little notice from either fishermen or
<br />fisheries biologists until recently. Until the erection of the series of dams
<br />belonging to or allied with the Boulder Canyon Project, it had hut 1 ittle
<br />-===-- fishing mjts lower course. Almost overnight-as its silt-laden waters
<br />i have cleared":"':we ha:veseen thecreation-o!a spoI1;Jil'll1_~Y of considerable
<br />magnitude. ~:----
<br />The bass fishery at Lake Mead was the first to attraet attention,
<br />There, where the river f.ound its first master in Boulder Dam, it dropped
<br />its load of silt as it entered the reservoir. The muddiest stream in the
<br />world became a clear and sparkling lake. This change, from conditions
<br />almost intolerable for many fishes, gave rise to an abundance of large
<br />bass which aroused Nation-wide interest~
<br />
<br />FIG, 45, The Colorado River downstream from Topock. 1942,
<br />
<br />Below Boulder Dam where the Colorado forms the boundary line
<br />between Arizona and California the fishery had a later origin. It wa.'
<br />not until the completion of Parker and Imperial damS in 1938 that thL~
<br />section of the river became well known fishing water. Since that time the
<br />two-States responsible for the administration of its aquatic resour~t'5
<br />have had to face an entirelv new set of problems.
<br />The area so concerned" is a vast one: The river section is almo5t ~~l
<br />miles in length, and much of it is inaccessible except by boat. A.I,'Il\! Its
<br />
<br />( 110 )
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<br />--~ -_....:::..:._----
<br />THE FISHERY OF '. THE. LOWER COLORADORiVEB-=-~-nI';'''''c'~-~~~~c~,
<br />
<br />'~~~ected witli its channel lie large ~~f quiet water, local1~'.;
<br />!' some of which are but little known even to residents. In"'
<br />. ' these there are hundreds of mUes 'of artificial waterways
<br />drainage ditches which checker the fertile valleys and support
<br />_t ~anges have already occurred, and we can expect further
<br />the river and its fauna whieh may increase itsproblems;>-
<br />,.h.the hope of enumerating these problems, Mr. Chester Wood-
<br />the author made a reconnaissance of the lower stream in 1942.
<br />'_c rk in this area (between Needles and Yuma) was carried out
<br />nnary 12th to February 26th, and from May 6th to May 25th.
<br />..other short trips to the area since then were concerned with a
<br />'.., .., ro1Mm,.themuUet-.fishery-&f-the.-Salton..Sea,L.MQ.st of this
<br />.: devoted to a physical and biological survey of thi:f river; its- '
<br />~waters, and the man-made proj~cts (dams and diversions)
<br />."...,directbearing on the fishery. ' Fisheollections were made
<br />. Jl!.offic,es of the private and Federala.gencies utilizing the rive:
<br />
<br />,"e-eoto.pletion of the field work, considerable time was spent
<br />~u er information not only on the biological, but also on the ..
<br />~geographical, engineering and human aspects of the lower'
<br />".' h.of this information had heretofore existed only scattered
<br />~Q~ published and unpublished documents, in the files of
<br />.e~es, or in the minds of individuals. " Because of the size
<br />".',-and the probable future importance ,of its fishery, it has
<br />'.... ble to present this assemblage of facts in some detail here
<br />., haUt may be available in an easily accessible and concentrated
<br />..fUture reference.
<br />;,slIof the data gathered have as yet been worked up. Much of
<br />:detailed information is of immediate interest onlv' to the admin-
<br />~<:lfield workers of the California Division of Fish and Game
<br />.' izona Game and Fish Commission. Such data are filed in
<br />form. In combination with them, this report is intended to
<br />.,"_.p,ep.dium of the existing knowledge of the fishery of the lower
<br />f!9'andof the manner in which it is being affected by the natural
<br />~.;.:made features of the river.
<br />. ;!!~~st be emphasized, however, that this is by no means a COffi-
<br />{conclusive report. It merely seeks to describe the existinfJ' con-
<br />the river, to outline its problems, and to serve as a guide for
<br />d~tailed studies necessary for sound fish manacrement,
<br />,;~ ,n' "
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<br />ACKNOWLEDGMENTS
<br />
<br />_,~Ch compilation as this would be impossible without the aid of
<br />"ies and many individuals. The author is especially apprecia-
<br />,assistance in the preliminary field work of Mr. Chester Wood-
<br />Or: Aquatic Biologist of the California Division of Fish and
<br />, '.~ entrance into the armed forces. Mr. Leo Rossier, State
<br />,JIJne Warden formerly in Imperial County, also helped with
<br />l.k,and his knowledge of the lower river was invaluable. Other
<br />,..the Division who have contributed useful data are Messrs.
<br />1!ett, D. A. Clanton, J. W. Harbuck, H. C. Jackson, and
<br />
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