Laserfiche WebLink
2800' <br />2400 <br />2000 <br />1600 <br />a <br />h- 200 <br />~_ <br />W <br />3 <br />:'~ <br />LOG W = 3.18 LOG TL- 5.38 <br />n = 40 <br />r2= 0.82 <br />AGE M F <br />4 <br />5 ~ ~ <br />8 ^ ~ <br />7 ~ 0 <br />9 Q <br /> <br /> <br /> <br /> ~ <br />400 / <br /> / <br /> i~ <br /> ~~ i <br /> ._ ~~~~ , 1 <br />100 200 300 100 500 800 <br />TOTAL LE NGTN Imml <br />Fig. 3. Length-weight relation for male (M) and female (F) <br />razorback suckers from the Walker Wildlife Area (station <br />8-, Colorado River, 1974-75. (Ages refer to number of <br />growing seasons completed. <br /> 2400 <br /> LOG W= 2. 31 LOG TL 3.12 <br /> n = 28 <br /> r2 • 0 <br />38 <br /> 2000 . <br /> AGE M F <br /> 4 • <br /> 5 ~ ~ <br /> 1600 8 ~ ~ <br /> 7 ~ ~ <br />_ <br />_o 120 <br />F <br />I <br />~_ <br />W <br />800 <br /> <br /> , <br /> ~ <br /> 400 ~~ <br /> <br /> / ' <br /> / ' <br />i ~ <br />100 200 300 400 500 800 <br />TOTAL LENGTH Im ml <br />Fig. 4. Length-weight relation for male IM- and female (F) <br />razorback suckers from Echo Park (station 31, Green and <br />Yampa rivers, 1974-75. (Ages refer to number of growing <br />seasons completed.) <br />Reproduction <br />Water temperatures increased slightly in the study <br />area during 1978 (Holden and Crist 1979-. The higher <br />temperatures may also be beneficial to the rare native <br />fish. <br />Length-Weight Relation <br />The length-weight relation for razorback suckers <br />was best described by the logarithmic equation (Tesch <br />1971-: <br />Log W = b, Log TL - bo <br />where W =weight in grams; 6,, bo =empirical con- <br />stants, and TL =total length in millimeters. The <br />regression equation was fitted by using the computer <br />program "Shad II" (Nelson 1976-. <br />Inasmuch as the length-weight relations were not <br />significantly different for males and females, the sexes <br />were combined for the Yampa and Colorado rivers. <br />Although there was also no significant difference be- <br />tween the length-weight relations for fish from the two <br />river systems, the fish from the Colorado River (Fig. 3) <br />tended to be longer and heavier than fish of the same <br />estimated age from the Yampa River (Fig. 4-, and <br />females tended to be larger than males of the same <br />estimated age. <br />Fecundity <br />Because the razorback sucker is rare, no fish were <br />sacrificed for information on fecundity. However, 10 <br />specimens that were collected and preserved primarily <br />in 1964 were dissected and the ovaries removed. The <br />ovaries were soaked in water to remove excess for- <br />malin and blotted dry with paper towels; the eggs were <br />then separated from the ovarian tissue. Fecundity was <br />estimated gravimetrically. All weights were deter- <br />mined to the nearest 0.1 g, with atriple-beam balance. <br />A sample of about 10% of the entire ovary was ob- <br />tained from subsamples of the anterior, mid, and pos- <br />terior sections of the ovary. All maturing eggs were <br />counted in the sample and total fecundity was esti- <br />mated by direct proportion from the weight of the <br />sample and the entire ovary. The accuracy of the <br />method was determined by comparing the estimate of <br />fecundity with the total count of all maturing eggs <br />from two fish. <br />Fecundity varied considerably among individuals <br />(Table S-, perhaps in part because of differences in <br />localities of capture. Inasmuch as most of the fish were <br />collected in fall and were not nearing spawning condi- <br />tion, the development of the ovaries was not advanced, <br />and the ova weie relatively small. However, on the <br />basis of actual counts from two ovaries, sampling <br />