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<br />Copeia, 1984(3). pp. 790-793
<br />@ 1984 by the American Society "Of
<br />Ichthyologists and Herpetologists
<br />
<br />HEMA TOLOGY OF FOUR RARE COLO-
<br />RADO RIVER FISHES.- The razorback suck-
<br />er (Xyrauchen texanus), Colorado squawfish
<br />(Ptychocheilus lucius), humpback chub (Gila cy-
<br />Pha) and bony tail chub (G. elegans) are native to
<br />the Colorado River system. The Endangered
<br />Species Act of 1973 protects P. lucius, G. cYPha
<br />and G. elegans and their habitat; statutes of sev-
<br />eral Southwestern states protect X. texanus. Re-
<br />covery plans for each species call for propaga-
<br />tion, reintroduction into portions of their
<br />historic range and studies of their response to
<br />environmental contaminants. Fish culture and
<br />stocking can be aided by use of clinical tests to
<br />determine fish health, but hematology of healthy
<br />fish must be known. Reported here are hema-
<br />tological characteristics for certain life stages of
<br />the four Colorado River fishes.
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<br />Materials and methods.-All fish were hatched
<br />and reared at the Willow Beach National Fish
<br />Hatchery, except for G. elegans, which was reared
<br />at Dexter National Fish Hatchery, Fish were
<br />transported to the Utah Water Research Lab-
<br />oratory, Logan, Utah, for behavioral (Pimentel
<br />and Bulkley, 1983) and hematological studies,
<br />Only large P. lucius (300-390 mm SL) were
<br />mature, but the small number of specimens
<br />available precluded sacrificing them for sex de-
<br />termination.juvenile G. cYPha, G. elegans and P.
<br />lucius were too small (69-91 mm SL) to be sexed
<br />reliably. The X. texanus were larger and there-
<br />fore could be sexed by gonadal inspection.
<br />Blood was collected from species other than
<br />X. texanus after the fish were held for one month
<br />at 14 C. Blood was collected by severing the tail
<br />at the caudal peduncle, or, for adult P. lucius,
<br />by puncturing the caudal peduncle. Analyses
<br />for glucose, chloride, hematocrit, erythrocyte
<br />and leucocyte count, and leucocyte differential
<br />were conducted by standard methods (Wede-
<br />meyer and Yasutake, 1977). A refractometer
<br />and Hb-meter (both from Ameritan Optical
<br />Corp., Buffalo, NY) were used to determine to-
<br />tal protein and hemoglobin levels because the
<br />low cost and simplicity of these tools make them
<br />suitable for field use. However, these hand-held
<br />instruments are less accurate than spectropho-
<br />tometers. Therefore, the field and laboratory
<br />methods were compared by using blood from
<br />
<br />adult P. lucius and X. texanus. The refractom-
<br />eter gave total protein values about 0.5 g/100
<br />ml higher than those given by the spectropho-
<br />tometer; and the Hb-meter gave hemoglobin
<br />values about 2.0 g/100 ml higher (Kehoe and
<br />Berry, 1982).
<br />Blood was collected from X. texanus before
<br />and 17-21 h after transportation to evaluate
<br />the effects of hauling. About 700 X. texanus
<br />(150--300 mm SL) were transported in a 1,000-
<br />liter tank in which oxygen (6-8 mg/I) and tem-
<br />perature (12 C) were controlled, Loading den-
<br />sity was about 60-65 g/l. No sodium chloride
<br />or anesthetic was added; 5 mg/I Furacin was
<br />added to prevent bacterial infection. Water
<br />quality at the Utah Water Research Laboratory
<br />differed widely from that at Willow Beach in
<br />total hardness (Utah Water Laboratory, 174
<br />mg/l; Willow Beach Hatchery, 358 mg/I) and
<br />total dissolved solids (Utah Water Laboratory,
<br />164 mg/l; Willow Beach Hatchery, 730 mg/l).
<br />
<br />Results and discussion.-Hematological profiles
<br />(Table 1) of the Colorado River species were
<br />generally similar to those of other teleosts
<br />(Satchell, 1971); however, only a general com-
<br />parison can be made because of species specific
<br />differences in hematological characteristics, The
<br />data presented for X. texanus were collected at
<br />Willow Beach Hatchery, Because no differences
<br />were found between sexes (t-test, P > 0.05) or
<br />with length (r2 < 0.2), the data were pooled.
<br />juvenile G. cYPha were significantly different
<br />(t-test, P < 0.05) from G. elegans in all blood
<br />characteristics except hemoglobin and number
<br />of granulocytes. Interspecific differences in he-
<br />matology have been noted by others (Chlebeck
<br />and Phillips, 1969; Larsson et al., 1976). He-
<br />matological values were not correlated with fish
<br />length (r2 < 0.07). Sex was not determined but
<br />probably did not bias the data because all Gila
<br />were juveniles.
<br />juvenile P. lucius were significantly different
<br />(t-test, P < 0.05) from adults in all hematolog-
<br />ical characteristics except hematocrit and num-
<br />ber of granulocytes. Sex was not determined
<br />but probably did not influence the data from
<br />juveniles, However, adults were mature, al-
<br />though not ripe, and a sex effect on the data is
<br />possible,
<br />Blood cells were similar in structure and size
<br />to those reported in other fishes (Williams and
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