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<br />176
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<br />CALIFORNIA FISH AND GAME
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<br />The availa:1:>le data indicate, therefore, that most" of the ~ass spawn
<br />for the first time when three yearso1d.._~(Three-year-Old fish averagl'd.
<br />13 inches in length.) It is as yet unknown whether the attainment of
<br />sexual maturityjn this species in the Colorado is correlated more doseh-
<br />with age than with size. .d '_n__ ,- ..
<br />The bass of the lower river spawn throughout the March-.June period
<br />according to the report of local game wardens and fishermen,32 In l!Jt!.
<br />none of the bass observed in January and February were ripe althoulZh
<br />some exhibited swollen gonads. The author had no opporhmity to
<br />examine specimens during March or April. However, Mr, Leo Rossil'r
<br />_ reported -seeing-many-: bass-taken nel!-Lyaguna Dam and from the lakl'S
<br />above Imperial Dam containing ripe eggs in 'April, --During May (6th.
<br />21st) the author examined 32 adults to find: 1 alroost ready to spawn; 6
<br />ripe; 25 spent. Recently hatched bass were seen at Haughtelin Lake on
<br />April 16th. These were about 1 inch in length. On May 7th many schools
<br />of fish less than 1 inch long and a number of individuals about 2 inc-nes
<br />long were also observed here. Bass about 1 inch long were noted in the
<br />lakes above Imperial Dam on May 10th, Schools of bass of about the
<br />same size were plentiful near the head of the Alamo Canal on :.lay 11th.
<br />From the evidence available it is surmised that in 1942 the iH'ak of
<br />spawning occurred in April. The duration of the season and its peak
<br />undoubtedly vary in different years and in different sections of the ri\'er,
<br />It has already been noted that for the years of record the mean water
<br />temperature of the lower river reaches 650 F. in March or April and that
<br />it seems to be rather generally assumed that bass do not usually spawn
<br />before this temperature is attained.
<br />
<br />Food. Although 94 largemouth bass stomachs were examined, onl~' ~6
<br />of them contained food. The food items found in the stomachs of H
<br />yearling bass (34 examined) were as follows: backswimmers (7 tlm~:;
<br />beetles (5 times) ; mosquitofish (5 times) ; sunfish, crayfish, chiroIlmUlrl
<br />lar,ae, and hymenoptera (once each). The intestinal tract of lllo~t I.f
<br />these bass contained large numbers of backswimmers. Fifty stoll",\\'1':
<br />from fish two years of a1!e or over were examined; only 11 contained f,""]
<br />The larger items represented were; bluegills (4: times) ; crayfish (h\'\"~ :
<br />channel catfish (once J ; young passerine bird (once). A few beetl"" ,1\,';
<br />spiders were also found,
<br />A high percentage of empty stomachs seerosto be charal'teri~ll\' -:
<br />largemouth bass, especially large ones, and is probably to be eorrela!";
<br />witb irregular feeding babits. Nine out of 10 well_conditioned ba:'s 11,
<br />to 12,9 inches long seined from a bole on the lower Gila River had ~!li~l:'
<br />stomachs, Since this hole swarmed with tinv sunfishes and 111<''''I1\\tol1'O
<br />it is apparent that there was no lack of suitable food available IPr then:
<br />
<br />Place in the Fishery. This is the major game fish of the riyer all,l il C'
<br />eagerly sought by both resid~~t and ,isiting anglers. " . Ii,
<br />Young bass face competltIon by several fishes here, especIall~ b~-l
<br />otber centrarchids. A certain amount of competition is entirely nat\lrd':
<br />and there is as vet no evidence (except in Haughtelin Lake J that lit ~.
<br />llarmful to the bass fisherv. A few fishermen have commented l1\al I \Jr-
<br />iug the past two seasons ;omparatively few small bass have been s~fn ,of
<br />
<br />.. Mo!'(ett (1943) indicates that April-June Is the spa....ning season ,,{ ",[""no"'--
<br />bass and blu!:gllls in Lake ~ead.
<br />
<br />OF THE LOwttn:;OWRADOItI\"'ER:-
<br />
<br />~~~tch of largemouth bass from Martinez Lake April 5 1942
<br />';';}'~':'_ through courtesy of Joseph Lindsay. . .
<br />,~~~::;--'- - .
<br />")he}ars above Imperial Dam, and that their catehes have been
<br />rIi.lllp. y to bass three. pounds. or over in weight, These observa-
<br />:, eb can not be explal~ed easlly. Such a condition could be due
<br />tra-:;,~..~r .a combmat,lO?- of several factors: overpopulation of
<br />:,_.;~. 1 s, poor spawnmg seasons as because of water fluctua-
<br />
<br />~tb8.sS have but few enemies on the river other than man Thev
<br />~"bf ~~er fit~bes and. are believed to be largely responsible. for the
<br />.,.,--' _, I' na lve speCIes,
<br />
<br />Other Fishes Which May be Present
<br />
<br />'..~:~,v', ~;"ry likely ~hat senral other species of exotic fishes mav b
<br />, III we lower rIver, . e
<br />
<br />,~t, Ca:as~i~s auratlls (Linn,), have been imported from fish
<br />,_ ,,',c~ePt 111 lne-boxes at Lake Havasu for use as bait FI' h
<br />me that fi b b f ' s ermen
<br />. 0"'0 ' save es?aped rom,these boxes, and, of course, the
<br />'lInf eSC<lpe from balted hooks IS O'ood, In the fall of 1942
<br />;, ' ormed .me that be had" dumped oseveral buckets of O'oldfi h ~
<br />'.: amo :a1ver .so that" the bass would have morefeed." 0 Gold~sh
<br />the bhshe.d m many waters of C~lifornia, and it will be sur-
<br />~.'be y are not or do not bec?me resldents of the Colorado, If so
<br />C' iexpected to :-ompete wl~h other fishes in somewhat the sam~
<br />e,;pcarp. TheIr comparatIve value as food competitors and as
<br />,,~n,not be prognostIcated.
<br />alofish" 0 "b ff I " h
<br />hi a ,r u a o-carp ave been reported by residents as
<br />-ih'tte\ er~l pl~ces along the lower river (near X eedles, below
<br />. ,,~mperIal "\ alley). Some have described them as looking
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