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<br />170
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<br />CALIFORN!A FISH AND GAME
<br />
<br />Size. oclyPa few bluegms were seen in angler's catches so It is impos- '
<br />sible to state the a.erage size, or size range of those usually caught. How-
<br />ever, fish from 5 to 7 inches long were well represented in hoop-net col.
<br />lections at most points, and angling (with No. 12 or 10 fiy or with a 3-0
<br />spinner) produced fish of this size at these same localities. The largest
<br />fish seen were 7.7 inches long.
<br />
<br />Reproduction. Although 242 bluegills were examined during ~lay 1:'42.
<br />tbe number of small fish collected was not sufficient to determine the siz~
<br />_ at which-they..!-' ~picallY" come to :first maturity. During May 1942,
<br />sixty-five blue gills were exammed from habitats representative of the
<br />river and its connected lakes. Sixty of these fish (ranging ffom 4,4 to
<br />7.7 inches in length) were sexually mature. Five (ranging from 3,3 to
<br />4.8 inches) were classed as immature. Since all but four of the adult fish
<br />exceeded the latter size range, the sample must be considered inadequate
<br />for the derivation of exact conclusions.
<br />Se.enty fish (1.4 to 2.9 inches long) collected from the lower Gila
<br />Ri.er on May 11th were still immature. Only four other blue gills were
<br />taken here. One of these, a male 2,5 inches long, l1ad flowing milt: the
<br />others were adults 4.8 to 5.7 inches in length.
<br />The largest number of small mature bluegills were taken from
<br />Haugbtelin Lake. All fish (103) examined from bere were sexually
<br />mature. They ranged from 2,1 to 7.7 inches in length. Sixteen of these
<br />(all males) were less than 2,7 inches long; the smallest mature females
<br />(4) were 3.0 inehes.
<br />It is certain then that in some localities (Haughtelin Lake! blue.
<br />gills mature at a .ery small size, at least 2,1 inches iI\ males and at least
<br />3,0 inches in females.
<br />The month of May (in 1942) appeared to mark the height d the
<br />spawning season, The examination of 60 adult bluegills taken from
<br />various points on the ri.er itself from ~lay 8th to the 21st showe..l ;hat:
<br />15 (12 males; 3 females) had swollen gonads; 36 (24 males; 12 females'!
<br />were ripe; 9 (S males; 1 female! were spent, Of 72 mature fish from
<br />Haugbtelin Lake taken on May 6th and 7th, :3 (all males) had swollen
<br />gonads; 50 (-i3 males; 7 females) were ripe; 19 (10 males; 9 femules i
<br />were spent, Four mature fish taken from the lQ\\"er Gila River on )!ay
<br />11th had greatly swollen or ripe gonads,30
<br />It is generally considered that bluegills haye an extended spaw11ing
<br />season and, in certain localities, are said to spawn throughout the SllmWer,
<br />
<br />Food. Stomachs containing food were examined from 22 adult blne~ills
<br />(range, 4.1-6.3 inches in lengtb) taken from several points along tLt' n\"~r
<br />in early 1942. Stomachs from different localities varied markellly ID
<br />their contents, and it was not considered that a lumping of the saU1ples
<br />would give a true expression of the food preferences of this species, Bo'"
<br />ever, certain items, whether measured by frequency of occurrence. ~r'
<br />cent;3.ge of total volume, or any other method, were clea1'ly outstand:~.
<br />These were chironomids, backswimmers, small crustacea (mal )
<br />c1adocerans), and higher plants. Other important foods represented
<br />
<br />10 Thirty-one other mature fish from Haughtelin Lake 'Were examined \~ ~
<br />but the exact condition of the gonad 'Was not recorded, It should be noted we.." ~~eJ
<br />may have been some confusion between fish not yet presumed to have 'l-''': iti<4
<br />("llWollen") and those presumed to have spawned once ("spent"). All fish dOl.'
<br />a~ "ripe" produced either milt or E'ggs upon gentle presEure,
<br />
<br />
<br />THE FISHERY OF mE LOwERCt')LORADO':RIVER~~-'--~u1'r~;-
<br />
<br />'ght;r ~xtent we~e: .filamentous green algae; mayfti~B; terrestrial
<br />. . Nepldae, caddIsfties, and hydracarina were also found. ..,'
<br />}le 4 sho~s the .foods eaten by 51 smallbluegills irom the Gila
<br />~. ~ comparIson WIth thos.e eaten by 38 green sunfish of about the
<br />"~' from the same locahty. One might conclude from this that
<br />-the same. foods a.ailable blue gills have a greater dependence on
<br />er anImal foods than have green sunfish. .
<br />
<br />TABL.E 4
<br />
<br />,'. arill~n of the feeding habits of 51 bluegill ant! 38 green sunfish of the
<br />e Size,. taken.from the lIame habitat at, the lIame time. Gila River near
<br />f~:NZ~na).M:y 11..t94~..._A",~rag~.~~e of bluegill, 1.8 inches (range
<br />" " Inc, es. verage size of green'llunfisn.-r:r-tnc11es,--(-ran~'~
<br />"hell)' Sixty-two bluegill stomachs examined; 11 were em t .~SfXt:~-::
<br />,,}:i~,green sunfish stomachs examined; 25 were empty. p y y
<br />
<br />':;~__-: Clan of food Per ceMt of .t'o'ma'cl. ' t"
<br />"", " _' .. . , nl con 0""71,17 orllonilM
<br />",.. organISm Bluegill Green sunji8h '
<br />.', FilaIllento~ grei!n algae___________~--- 9,8 31.6
<br />Cladocera---------------------------- 76,5 26
<br />"Ostracoda :..________________________3,9 .
<br />.BackBwimmers (N otonectidae) _________ 7.8 28.9
<br />Ji~ei!tles, aquatic (Coleoptera) ----------- --
<br />'~dgela"ae (Chironomidne) ___________ 50.9 37.9
<br />,.:.Terrestrial insects ____________ 6.8
<br />~j5~osquitofish (- G07lIbu,ia) ------~~~~~~~= -- ~~:
<br />~,-,:.:...-
<br />.~. the'. Fishery: The bluegill is a valuable multi-purpose fisb, and
<br />eoruadered eltber as. a small game fish or pan fish, as a forage
<br />bass,. or even as a baIt fish. The sunfishes are specifically sought
<br />.~atlvelY few peop~e along the river. They are largely neglected
<br />,E ,ent bass fish~rman, and are too small-mouthed to be caught on
<br />,...~hunks ~f baIt used by the catD.sherman. They can be easily
<br />8Ilsmall baIted hooks or ,on small artificial lures such as flies or
<br />,,,p'I.:and could thus pr,oVlde a good deal of unrealized sport in
<br />"..,'~':: They are sometImes caught for use as live bait by bass
<br />men.
<br />
<br />'h~r;bluegill is considered by many to be one of the best forao-e
<br />~? lar~emouth bass. B,e~nett (1943), for example, states th~t
<br />but little food competItIon ,between them, and the two species
<br />","uently stocked together WIth good results. In Lake Mead
<br />,J~43). found tbe largemouth bass to be subsistinO' largely o~
<br />. andIt seems probable that they form a laro-e part of the diet
<br />bass throughout the lower river ~
<br />~~riwise, an overpopulation of biuegills (or otber sunfish) can
<br />IOUS to a bass fi~hery especially through tbeir predation on
<br />~d. young. Thel.r fe~undity is well, known, and-especially
<br />~bJected to heav) ~shing-they may illcrease in such numbers
<br />~ery a:> a ~hole IS harm~d. It is. n?t known whether any
<br />Jpon e~lSts ,In the lower rIver, but It IS very possible that it
<br />,: It 18 qUIte proba~le tbat such a condition now obtains in
<br />,;"Lake where there IS a large population of bluegills and but
<br />"'Unfortun~tely, most ,anglers plug for the bass while allowing
<br />>_cto remam unexplOlted.
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