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200 THANS, Al\1Elt FISH, SOc., 1%9, NO.2 T.~IILI: 5,-Mclln clI/curated totallen~th,j and increments, Colorado chub, Green River, 1964 1966 \ Mean Number Mean calculated length (mm) al annulus A~c lolal length of J,:'TOllp Tnxon1 (ml11) lish 2 3 4 5 6 7 I 65 80 49 II 114 81 51 93 III 165 56 55 96 143 IV rt 230 16 59 114 166 210 bl 323 5 62 113 1~3 2,54 V rt C)""l'- 13 62 113 173 218 260 -'1 hi 341 39 fi3 106 15\! 237 314 VI TI 334 11 64 114 175 229 272 31.5 hi 36::! 20 6.1 lO'l 183 288 332 353 VII rl 357 <) 62 112 In 224 270 308 340 hi 379 3 6.1 13(; 2(;0 34\! 357 367 373 ----------------------------------------------------------------------------------------- HOllnc.hail Crand I\\'crng:l' It.'llJ.:lh .55 !)\! 1.5(; 2]8 267 312 340 Number 01 fish 2(;6 186 lO,5 4\! 33 20 9 Average Ieng-th increment 5.5 44 52 48 44 41 32 A\'erag~ cakulatcd weight (g)~ I 9 34 94 174 282 367 n()n~1ail Grand average length 5.'; 100 ISH 25H 322 355 373 r\umbt"f of fish. - 28.1 20-1 1::!3 67 (;2 23 3 A \'crage length increment 55 43 55 8\l 63 20 6 Av~ragc calculated weight (g)2 1 S 31 129 240 315 364 1 rt = roundlail; bt = bonylail. ~ Call'11lated from length-weight equalitlll. and was used for back-calculations of length. Colorado chubs of all age groups from 0 to VII were taken (Table 5). The Colorado chub was treated as one taxon through its third year of life since fish in this size range could not be classified as either roundtail or bony. tail. Above age III the two subspecies were morphologica lIy distinct, and bonyta ils were longer than roundtails at successive ages I Figure 6), After the third year of life the Illlll)'lail grew faster than the roundtail and added ils largest lenglh increment during the fourth year after which the increments de- l'n~ased ahruptly. ^nnual growth increment (Iellglh) for the roul\lltail was greatest dur- ing the first year and decreased gradually in the following years. No difference in growth rate in length was observed between sexes, Considerable variability was observed among calculated lengths at the same annulus for bolh subspecies, A "goodness of growth" test (Hill', PHI) indicated slower growth in post. impoundment years (1963-1%5) for both roundtails and bony tails (Table 4). Most rapid growth occurred in 1962 when lite I'erl'cnlage dl'vial ion frolll the lI1ean an. nual increment for the roundtail and bony tail was +9.4 and +7.0, respectively. Poorest growth was in ] 965 when percenlage devia. tion for the two forms was -13,3 and -7,6, respectively, Within-season growth of age groups I-III was described by a length-frequency analysis (Figure 7) , Y oung-of-the-year fish were longer in 1966 than those at the same dates in 1964. and 1965, probahly due to an earlier spawning period that year. Growth of yearlings began in late May and ceased in October. The growth pallern was similar in 196.}' and 1965, with the 19M fish having slightly longer mean lengths throughout Ihe season, In June, ]966, year. ling chubs wen: smaller tllan those at cor- responding times of the previous two years. hnt they grew fasln and were longer hy the end of the SLJmnH'r than yearlings of the two prevIOus years, LEXGTH.WEIGIIT HELATlO!\SllIl' Colorado Squaw/ish A linear regression was filled to Colorado squawfish length.weight data by the method of least squares: log W = -S,-1l77 + 3.126 log L whcn~ L = total hocly ],:nglh in millimc'lers and \V = weight in grams. The regression co- efficient of 3.126 was significantly higher Ihan ~,O U kst, Jll levcll, indicating that the weip:ht of the squawfish increased slightly faster than the !:ube of its length.