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<br /> <br />-204'-~ <br /> <br />. . . - CALIFORNIAFI8H-A~"D- eA!-fE~-=:'_~'--n" <br /> <br />-. In. a study such as this it has not been possible to collect or anah-Zl' <br />enoug-h data to justify detailed conclusions as to the general econom; of <br />the Colorado River and tbe many processp-s invol\"t~d in the prr,'lnction <br />and utilization of food by its aquatic population. The Colnr,hto na.. <br />always been a changeable rivpr, and is still in a process of chan),Ze, FI~ <br />__'__~ droughts, ~h~fts in the ch~nnel, pl,ant su~cession-~ll ~ave played impC)f. <br />--,,--:::-'tantTOles 1ll.lU eonfigurahon-and,ltshabltatsfor '\\:lldlIf~, The new da~ <br />have further altered such basic physical factors as flow, clarity, ternpt'n, <br />ture, and even water chemistry. The introduction of exotic species. both <br />vertebrates and invertebrates, has brought further changes j in fact. th~ <br />last few years have witnessed what may be a major biological revolution. <br />With but incomplete factual data and with the realization that th~ <br />river and its fauna are still in a state of flux, it is none the less possible to <br />make certain general statements. Inadvertently, man has improwJ mIlS! <br />of the physical conditions for game fishes on the Colorado; and fortunately <br />he had already introduced some fishes (bass, catfish) which, w1Jile tb~ <br />mayhave caused the decline of the native species, we~e well fitted to tail <br />advantage of these physical changes and to create a sport fisherv "hm <br />nonehad ej:isted before. ' . <br />'He has also created some new hazards. He has introduced SpecifS <br />(the carp, for example) wbich may have been detrimental to his QIlJJ <br />interests. He has constructed diversions which cause some fish loss. H, <br />has built roads and boat landings; has created resorts; has held" priv <br />fish contests," advertised the sport on the river, and otherwise in crea,...,j <br />the exploitation of its fishery. It must be admitted however that thest <br />are all legitimate enterprises, and that up to a certain point he eaptur't <br />of fish is not onlv not destructive to the fisherv but actually be!1eficia! <br />When we sp;ak in terms of "beneficial" or t, detrimental:' w,~ u5ualb <br />think only of those changes which seem to affect us personally, Thercf,)!'" <br />it must be agreed that the "new Colorado" has been benefited b\' :~. <br />changes and that the sum total of these changes far outweighs sUl.h ]",;."-"! <br />as have occurred and may continue to occur. It seems certain that + <br />entire biological production of the river (whatever its components 1I;'\' <br />be) has increased tremendously. <br />A biologist must regret that a limited but interesting natura! a5St'~. <br />blage of species has had so many additions that its original !Jatme t~ <br />been destroyed, He must also regret that some species appear to bt' wr: <br />ing on extinction, at least in the lower riyer. But he must also "11mit.tt~\ <br />the rise of the new population of exotic fishes has brought r('crealJl'i~: <br />and utilitarian values which exceed those of distant davs. The yaIue '.~ <br />some sport fisheries of California and Arizona (trout, for exarnpk;, 0;:-' <br />be measured mainly in terms of the pleasure and relaxation they br:n:::"- <br />the angler; or it can be reckoned, to the merchant, in terms of the bU5,n: <br />createIT bv sales to the fishermen. In the vallevs of the Colorado the \"3.- <br />of the ga~e fish as food is also an important on'e. There are man~' fa.Jlli>~ <br />wbose subsistence in part on fish ser...es to alleviate their condition, <br /> <br />administrarors of the two Stat~s ~ es~b.lish a. marked de~ree of .::ontrr,; <br />over the fishery and to change WeIr POhCIes qUIckly and WIth a minimu!!; <br />of effort whenever it appears advisable. <br /> <br />OONOLUSIONS <br /> <br /> <br /> <br />'::;,;'..;, '. , OF THE LOWER. COLORADO RIVER.,=.2G5-=--=---.-.- <br /> <br />'~tt..'lie sport fishery of th . <br />-"all-"- th ' ',e 1'1ver appears to bein a he lth . <br />",',",."t:r.o'.-..::~", 1 e suthccess of, angling varies from season t,o s:asQ'Jn <br />L",t' "'" ..lonO' € stream. T rt . ' ' , <br />,'-.1~'-~ifi~-' .0 . r.oa ce am extent this a <br />,~~Wl~ .varlatIons m flow and turb'd't hi h ,ppears <br />.D.~sattempt ro h th. 1 1 Y weare a con. <br />"'Lf" . amess erlver, and there is little that th' <br />".alS c.onservation agen . d e <br />",c-,.,u ,-, -, ," - Cles can 0 or say to tr I <br />eneral;th 'd fi h ' .' con 0 such <br />., .:(.~:c>'-, ereSl ent s ermen are well satisfied with the <br /> <br />''ot'.!eit that we can or nef'd t . t' ' -- <br />.",.."f ',,';;"'hi, ,h', 'il" ." 0 ms Itute any elaborate form of <br />_ ,!! c W1 Improve It Th dd" <br />;i,l!eo'fishes t 1 d' , e a ltlon of new species, either <br />,..." ,0 an a rea v complex a~ bl . <br />~o~,.isit believed that the .fisherv 'uld~mb age IS not recom- <br />,#8.':existing--game fishes;-- .co ,e e~e~ted ~y further <br />i:innumbers of some spec~ ~fO'~~~r hafn~ It IS beh~vedthar~--::- <br />'some extent if the an " e 0 :alue. This can be ' <br />,fisb.eswhic,h,h 1 glelr.:vill turn hIS a.ttention towards <br />", ,". ,'"",. e now arge ~ Ignores It' <br />uttfeit1J.er co . . . " n Ime, 'It may be of <br />,', ,ct:hiSi;err.:mer~lalfishmg or State control of undesirable <br />,t.~::.;::-F:/ ry 0 great water areas such control will prob- <br /> <br />'1ikotSfream or lake im " ' <br />7.",".,.,','.,'.'.,'...,-",. ' pro' ement can be suggested <br />ow suell an attem t ld b' ' nor can <br />;iil,jliec-&he. pcou e easIly carried out or be of <br />.,." '~:ch . ry " , <br />..ii1Vl;ti, ,1$ still embryo' h . . <br />. ..:teas full .' mc, .as great potentialities. It <br />""<ibrlah"an extent as poss1~le with the reminder that <br />~I11'clna .~ve much more pressmg needs for investigation, <br />',"" ,> Yf .', J r form of management sugO'ested' th <br />ee 0 a set of l' . 0' IS e con- <br />. om' Th regn atlOns whIch are uniform in both <br />,-,',~lme. e,-in,Iat'L~ d~ to~es suggeste~ here differ somewhat from <br />:..:o~=:., "LUS 18rlct, and are m . <br />?~:vegueinother parts of C rf so~e respects m~re len~ent <br />'{)~ what is known of th ~,11 or~lla, As ~ar as IS pOSSIble <br />,rM, and are ' . e 10 oglC!l1 req~rements of the <br />_.-~lJ.ermen ana: ~~mpatIble as pos.'SI,ble WIth the expressed <br />}~i.neeonr knowledO': p~ece~~nts w!llch. have already been <br />.', .;.elat]ons-of fi h t'= fi o{ mdlvlduallife hIstories is still sliaht <br />_,~pJ1,_~ized tha; theO su~apasnteddfifsh to fifsherman still not ;ell <br />>,:.Ln.e 'sh ul eo - arms 0 managem t 1 <br />".,y, 0 d be chanO'ed a' 0 lId en are on v <br />~"C:L , . ' 0 ~ ur mow e ge of the fishery grow~, <br /> <br />Tf",,~'UMMARY OF RECOMMENDATIONS <br />~----",,~'- . <br /> <br />~~t:a district. alon.g t~e lowe.r Colorado River in which <br />~~3~~,'f,:,' or CalIforma lIcenses IS permitted. See p, 197, <br /> <br />.iltJ~~}ame fishes or forage fishes. <br /> <br />i;;:.>:C:_~;- <br />.~'~;:1~~roughout the year for all fish. <br />'.:'X;h,its <br /> <br />;b.~~~10~~sh: n?t to ~xceed 15 pounds and 1 fish daily or <br />.,,,~~~m SIZe lImIt 10 Inches (total length), , <br /> <br />:.i~"",...,.' <br />