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<br />
<br />144
<br />
<br />CALIFOR~-u. FISH .ll.1> GAME
<br />
<br />game, refuges on the Salton Sea and on the Colorado afiol'd some com.
<br />pensatory protection. '
<br />Parasitism
<br />
<br />No study of the parasites of the fishes was carried out. Nematoues
<br />(round-worms) were noted in the "Viscera of lar.g~mo~th bass and those
<br />of several other species, However, such parasItism IS common among
<br />warm-water species in California. No 11llusual complement of ,,"oT.ms
<br />or other parasites was observed which would be expected to ~e harmi:tl.
<br />
<br />THE FISHES
<br />
<br />The fi~h f~;-~~-~f-tb;C~lo~;}do R1Yerls-~snI~'iio~- "'ell Known, ~Ild
<br />offers one of the most fertile fields for mvestlg~~IOn ~ ~ort~ Amenca,
<br />With full recognition that their list needs reVISIOn, It 18 of mterest to
<br />note the fishes recorded by Gilbert an~ S~ofield (18~8) from the lo~'er
<br />Colorado and Gila Basin, Based on collectIOns m.ade 1ll.1890 and records
<br />of fishes credited to this area up'to 1898, they lIst: ~ mtroduc~d fr:sh-
<br />water species (the carp) ; 19 native fresh-water speCIes; 2 marIne fi"hes
<br />from the mouth of the Colorado River. T~e fresh-w~~r :fishes --:ere
<br />represented by only four families (Catost?mldae, ~!prlll1dae, Cypl'~no-
<br />dontidae, and Poeciliidae). Two familIes, (Gobudae ~d Parahch-
<br />thyidae) represented the marine fishes, and these are not an llltegral part
<br />of the river's fauna. . fi
<br />To their list we can now add records o.f at least 1~ specI~ and ye
<br />other families in the lower Colorado: Elopldae (1 natrve sp~cles) ;. S~l-
<br />monidae (1 native species; 1 exotic) ; Ameiurid~e (4 e~otrc speCieS) ;
<br />Poeciliidae (1 exotic species) ; :Mugilidae (1 natrve speCIes) ; Central'-
<br />chidae (5 exotic species) , . " ' . , \"
<br />With but few exceptions, the fishes of paramount lI?portance tf:\1~,
<br />both in abundance and interest to the angler have been mtroduced from
<br />other waters.13 On the other hand, the native fishes ar,e apparent1~'
<br />scarce today in the lower river. It is possible that. the natIve f~un~ 1,:1,
<br />not diminished to as great an extent as the collectl.ons of 194~ mdlC,a,e.
<br />Further collectillO' at different seasons. and espeCIally ?y seme. ml~ht
<br />reveal the presen;e of more individuals and species, StIlL of the nlltJ\"
<br />fresh-water fishes recorded by Gilbert and Scofield (1898) whic? could h~
<br />expected in the luma-to-Keedles section only one was seen dur~ng almo:,
<br />three months of collecting in 19-12, and this upon on~y on~ occaslO,n, :-r()~.
<br />fett (1942 and 1943) has also'made recent collectIons III the rIver Jl,l,t
<br />below Boulder Dam and in Lake :Mead, He records on1~ three lH1:1'e<'
<br />species from these areas and has but few remarks on theIr abund(lhC :
<br />Furthermore. there' was an absolute agreement among the maIl~
<br />residents interviewed (fisherme.n, .irrigation company ;vorkers, l~~
<br />tenders, rivermen, etc.) that the mdlgenous fishes were qUIte rare no ~d
<br />:Many accounts of the disappearance of these fishes have been I:eard. a
<br />there is a very fair agreement that the decline ~eca~e most eVIdent dU;~
<br />ing the 1930s, The following statements of Cahforllla game wardens a
<br />_ " "h C I ad River i. ".'!
<br />,. A detailed discussion of the origm of ~xotlC specIes, In th,e t 0 or f t'he Intrn(\uced
<br />Included here. as this subject ...-iII be treated m a forthcommg IS ory 0 ~
<br />fishes of California (Dill. ms,). , leI'" ',he!""
<br />" ......ile it I~ true that nongame fi.hes often escape thehatte'1t~ohn of an!!:'l" \.'i.,wed
<br />'" u _ '( t d nd Intake~) were l.s are eas . 'I'
<br />are many points along the rIver as ,a amsLaa D' fl h are stranded t.enlI'N~r: ~
<br />For example. during sluicing ope,ratlOns at guna am. s
<br />In potholes on the downstream SIde.
<br />
<br />
<br />
<br />'THE FISHERY OF THE LOWER' COLORADO" RIVER -. ------145--~.__.7;;__:::_.,-:
<br />
<br />J", ,'",',','.',-,",',-,....
<br />-~,~ -":~1 ~;-~~
<br />
<br />~ ~
<br />~~ .~ii
<br />, -ltf~
<br />,I,..t
<br />.t, "'~tl,'.,,,:~,.l
<br />1::;t'
<br />'4"
<br />
<br />
<br />of j;hese: "In allmy time in Imperial County [1932-1935] I never
<br />limpback sucker in the Colorado River, but all the natives told me
<br />J:;:they were very numerousbef1)re 1930. · · ., I have seen:
<br />lthe so-called Colorado River salmon · · · some as large as '
<br />e)>ut they were scarce in 1932." (Letter of Mr. J. W. Harbuck to
<br />)~lr~ February 14" 1943.) }Ir-. W. C. Blewett has patrolled the_._ ----,-,,--.~=-:._-
<br />,'ce 1939, In a letter of April 9,1944, he says: "In my five years
<br />"pon of the fish life of the Colorado River I have observed about
<br />'yetails and about the same number of humpback suckers. I have seen
<br />J{).rado River' salmon'." From 1941 until the close of 1942, Mr, Leo
<br />etwas stationed in Imperial County and made extended checks of
<br />~ er. He writes: "I never saw a bony-tail, 'salmon,' or humpback
<br />e FpatrolledtheriVef~-:-Une-oilly nears-tu:monrof'sucnnsh'---=-
<br />ent." (Letter of April 9, 1944.) It may be noted that the
<br />Qted.a1so disclaim any knowledge of the other native minnows or
<br />, f:theColorado. There are some who claim to have noted the
<br />, 'und 1925; others say that it was most evident shortly after
<br />Dam was completed (1935).
<br />emory of observers is often faulty, and an increase in abundance
<br />}:ripted. more quickly than a decrease. The following facts seem
<br />however. (1) The native fishes of the river were once abun-
<br />ose noted most frequently by residents were: the humpback
<br />,ny-tail, Colorado River squawfish. (2) Their decline was
<br />l~shortly before or after 1930. (3) As this decline became evi-
<br />-Was also noted that there was a great increase in the numbers of
<br />)~'species, especially the channel catfish and largemouth bass,
<br />ease in channel catfish was apparent even before 1930 but both
<br />,neother exotic fishes increased tremendously after Boulder Dam
<br />t.(4) At about the same time there were several periods of great
<br />..,m the river and there were some heavy floods, At such times
<br />_Asaf dead fish" (native) were observed,
<br />eloSs of fish at Parker Dam in 1939, due to flood and the subse-
<br />,. en demand created by the decomposition of organic debris,
<br />'dy been related. Several occurrences which appear to be similar
<br />one have been described to me bv "old timers," Extreme low
<br />.yoi:1ld raise the river temperature ~nd strand fish, Such processes
<br />_ j'}fcourse, been going on for many years in the unstable Colorado.
<br />;it-seems probable that the native fish populations have undergone
<br />::':atk periods of rise and fall, But each period of destruction' was
<br />. ":by a period during which the population could rehabilitate
<br />.;'~J3efore the dams were built the native fishes were at the mercy
<br />f~verse physical environment, but the deleterious effect of pr~-
<br />"xotic fishes must have been slight, That is, the population of
<br />fishes was small before the creation of Boulder Dam, and floods
<br />.hts must have worked just as severe a hardship-and probably
<br />them. Because of the unfavorable water conditions around the
<br />....es it seems possible that the population of native fishes sank
<br />Jts low points, and that the coincidental advent of clear water
<br />B,oulder Dam brought about a heavy production of bass and
<br />'~)ishes which preyed upon the already reduced nath-es, Com-
<br />well as direct predation may have played a large part in this
<br />es'truction.
<br />
<br />~_~ ,-r.-
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<br />.I'IL', .r.rl. ~~~~;:;'~f';'~..~'
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