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dietary prefer~.;_: ~ ,. ~_ ~ti~or~s ha e ch;zng~d vary la ._ :- .
<br />past ld0 year ~ -,rnable to speculate that Jolt . ~ - ~ _ - ..-
<br />would have si,-_. ~ ~~ t,~r,~>t ~ ;tidied l0U years ago.
<br />Age and Growth
<br />Barly workers did not study t.h4, gage and growth of Bonneville cutthroat from
<br />either stream or Take popu'atiorr;. ~~ maximum size of 425 to 4511 mm (17 to 18
<br />inches) with a mean of somewhat !~ ss that 300 mm (12 inches) was reported for
<br />Bonneville cutthroat taker. near ~k";. Bridger, Wyoming, from the Bear River
<br />drainage (Suckley~ 18'r 4'~- ~"arrow r '_874) reported fish from 2.3 to 2.'7 kg t5 to 6
<br />]bs) and up to 650 mrrk . `h5 inch - in length were caught from the Timpanogos
<br />River (Provo River', in `~~ta:~. 'I ~ ~ -~~ larger rivers undoubtedly provided better
<br />habitat and more f~aod f,ar '<<?~~. n the smaller headwater tributaries. lake
<br />populations of Bonneva~~+<.~ c=ztth~~~ ,a in Utah Lake attained a size of ? kg (15.5
<br />lbs) and 762 mm (~s~} inclEes) is length.
<br />Cutthroat sampled iii F3ird7 Crs~ek, Beaver County, Utah, during 1974-7 ;had
<br />a meanlength ar~d ,ve:~;l,t of" 12f ~~ ~m (5 inches) and 27 g (0.061bs1, respective~!y.
<br />The largest of 214fist w~;s 2.~ _ ~:.~ (9.3 inches) in total length and weighed 135 g
<br />(0.301bs). Sampling of"I' ~>ut C~~~ ~ !~, Deep Creek Mountains, by Utah Division of
<br />Wildlife Resources per7onnel ~~~ ~ ~ tiled that S. c. Utah, had a slightly greyter size
<br />in both length and >v~i, ht. a".~ mean total length of the 91 fish sampled ici
<br />October 1975, was i48 r~;rz f 5.7 ~ ~ ~ hes) with an average weight of 36 g (Q.OS lbsl,
<br />'This difference in aver>3ge sloe ci>uld be a reflection of better habitat in Trout
<br />Creek associated witi~~ . gre,z+_er average stream flow (Figure 5).
<br />Informationpertair~in~ to agc cufS. e. ut¢h was lacking in historicalsurvey-sof
<br />the Bonneville Basin. It, -.ent ~a~,empts to provide some age data was under-
<br />taken of S. c. utar~ c~..'i~°~~~ ~.~~1 fr n; Birch Creek in September 19734 and in June
<br />1975. Fish were pre-~r~ ~~~.' :°. ICS percent formalin. Scales, from preserved fish,
<br />were taken aboat half~~. ~y betwF~en the origin of the dorsal fin and the lateral
<br />line,, mounted on numl4~~red g~a4med paper, and impressed on cellulose acetate
<br />using heat and pressure. t3ge determination and measurements of scales w~x~
<br />made on an E~ber~back prcij~~c-e~-. Back calculation of growth from scale im-
<br />pressions have been deter-ni ~ ed to be the same as from actual scales (Butler aY.d
<br />Smith 1953).
<br />Scales first Forrn on cutthraa. when they are 25 to 66 mm "t i to `~.5 inches) iiz
<br />total length (Carlander 1969s rat high elevations or in cold streams and lakes,
<br />annuli may nit be termed during the first year of life (Brown and f3ailF~- 1952;
<br />Laasko 1955). In t'~; e Log an hl ~ ~~ e.r, Utah, all cutthroat trout formes scales d~~ritrg
<br />their first yea, of ~ ifs ~~~t nct ,~; i formed annuli (Fleener 1952?. 4'-ro~a from Birch
<br />Creek appearecE t.t fna~r;~ rsn ~~~ Lulus during the first year of life. In most try nt,
<br />the annulus t-vas ~}~=.'i-~,,~~ ~ ~ some it was faint. Annulus- for~,nation in trout
<br />from Birch Cre~:k ~~~a~s ~;ot ~ ~~ ~ : ~ mined because fish were only ~ ~: ~ ~~ 1 able from two
<br />samples.
<br />Various matlxom.~t~c,:? ~ ~~r±~~ls (direct proportion, linear and curvilinear re-
<br />]ationships}have 1~~ ~ r~ ~_.-~ ~~: • - valculate the lengths of cutthi°oat trout at the end
<br />of each growl r.~; seas~;n. ~ ~ 7: ar relationship (r = 0.87) fit the data from $i.rert
<br />Creek cutthroat tr°_3w;t ~~,;1~' ~ ~~., used as the mathematical r~iatioraship to back-
<br />calculate grown; sFi;~~~~ the length-weight relationship for a5 cutthroat
<br />trout from B_xc~ l: _ _ ~ h, was log W = 5.047 - ~~.053 log TLa with a.
<br />correlationcoef`~~~,r~~~;~~,~ ~~~`:'._(F'igure7).Femalegrewfasterthanmalesforthe
<br />first two years e ',. ~ -. mean lengths (Figure 8) but differences were not
<br />statistically gig ~_t ;~sa the data were combined (Table 5).
<br />°Samples take ~~r and G_T. klar, Cooperative Fish Unx>., I .t- ~tsn ~r:vc=r.-~~y
<br />Kogan, G'tah Wit'
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