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<br />850
<br />
<br />sucker and bony tail chub, Fin plugs were cut from
<br />the mid-portion of the left pelvic tin with a 5-mm
<br />dermal biopsy punch obtained from a surgical sup-
<br />plier, Muscle tissue was sampled with a 4-mm der-
<br />mal punch, which cut to a depth approximately
<br />equal to the diameter of the plug. The plug was
<br />then lifted free with tissue forceps,
<br />Extraction of liver tissue was more involved be-
<br />cause a small surgical incision is needed to reveal
<br />the organ and remove tissue without damage to
<br />adjacent organs, Dissection of trout and razorback
<br />suckers indicated the posterior margin of the liver
<br />could be readily exposed by a l5-mm incision
<br />through the lateral musculature on the left side of
<br />the tish, at a place anterior to the pelvic girdle and
<br />just clear of the distal ends of the ribs, Dissection
<br />of bony tail chub revealed that access to the liver
<br />was obstructed by fatty tissue on the left side, but
<br />not on the right side, Hence, the incision for bony-
<br />tail chub conformed to the description given for
<br />the other species except that it was made on the
<br />right side, A small (approximately 1.5 X 3-mm
<br />diameter) piece of tissue was removed from the
<br />margin of the liver with a 3-mm dermal biopsy
<br />punch, A small, flat wooden utensil (l mm X 5
<br />mm X 126 mm) was placed under the liver to
<br />facilitate a clean cut Nonabsorbent 3,0-mm Eth-
<br />elon sutures (four sutures per incision) were used
<br />to close the wound, All instruments and hands
<br />were rinsed with 10% povidone-iodine solution,
<br />which also was swabbed on the tish before and
<br />after surgical procedures, Fish were kept wet dur-
<br />ing the entire procedure, After surgery, the tish
<br />were placed in freshwater until they were able to
<br />maintain equilibrium and then were returned to a
<br />holding tank,
<br />Rainbow trout,-Adult rainbow trout were pro-
<br />vided by the Jones Hole National Fish Hatchery,
<br />The tish were placed in hatchery raceways sup-
<br />plied with l40C spring water and fed a daily ration
<br />of pelleted food equal to about 4% of body weight
<br />The tish were assigned to one of six treatments by
<br />selecting individuals randomly, and then assigning
<br />successive individuals to each treatment group in
<br />sequence (Tl, T2, , , . , T6; Tl, T2, , , , T6; etc)
<br />until each group contained 12 tish, Fish in the
<br />control group (Tl) were measured (standard
<br />length), weighed, and returned to the tank; they
<br />were not handled again until the next set of ob-
<br />servations was made, All other tish were anesthe-
<br />tized with tricaine methane sulfonate (160 mg/L)
<br />before being measured, weighed, and subjected to
<br />treatment
<br />Rainbow trout were not marked individually, but
<br />
<br />TYUS ET AL.
<br />
<br />each tish could be identitied as a member of a
<br />particular group by a combination of marks left by
<br />the treatments and by use of a small piece of silken
<br />thread placed through the adipose tin (except tish
<br />in Tl, which were unmarked), One group (T2) was
<br />used to assess the effect of anesthetic alone be-
<br />cause previous work has shown a potential for det-
<br />rimental effect (Summerfelt and Smith 1990);
<br />black thread was placed in the adipose tin to aid
<br />future identitication, Another treatment (T3) was
<br />used to evaluate the effect of incision and suturing
<br />(no tissue removed), and red thread was placed in
<br />the adipose tin, The remaining treatments (T4- T6)
<br />were designed to evaluate the effects of removing
<br />tissue from one or two locations, In treatment T4,
<br />a 4 X 4-mm muscle plug taken from the upper
<br />right side of the body, just posterior to the insertion
<br />of the dorsal tin, and a green thread was placed in
<br />the adipose tin. In T5, a plug was punched from
<br />the left pelvic tin, and a sample of liver tissue was
<br />removed; a green thread was placed in the adipose
<br />tin, In T6, a muscle plug was taken from the upper
<br />left side of the body, and a sample of liver tissue
<br />was removed; a black thread was placed in the
<br />adipose tin,
<br />Experiments with trout were performed on 6 and
<br />9 July 1990. All tish were inspected on 25 Sep-
<br />tember 1990, Final weights and lengths were de-
<br />termined when the study was terminated on 7 De-
<br />cember 1990. Rainbow trout experiments were
<br />conducted initially to practice and retine tech-
<br />niques before they were used on the endangered
<br />tish species,
<br />Razorback sucker and bony tail chub.-Hatchery-
<br />reared razorback suckers and bony tail chub were
<br />obtained from Dexter National Fish Hatchery,
<br />Dexter, New Mexico on 13 June 1990, and trans-
<br />ported to hatchery facilities at Ouray National
<br />Wildlife Refuge, Ouray, Utah, Each species was
<br />placed in separate 3,790-L outdoor tanks with cir-
<br />culating well water (l50C) and were fed a daily
<br />ration of pelleted food at a rate of about 4-5% of
<br />body weight In September, all tish were moved
<br />indoors and kept in circulating well water (130C),
<br />At the beginning of the study, individuals were
<br />assigned to treatment groups, in the manner de-
<br />scribed for rainbow trout Fish in all groups, except
<br />the control (Tl), were anesthetized with tricaine
<br />methane sulfonate (200 mg/L) , Fish were then
<br />weighed and measured (total length), and a PIT
<br />tag (Biomark, Inc" Boise, Idaho) was implanted
<br />for individual identitication. The PIT tag was
<br />placed in the body cavity through the incision in
<br />those tish subjected to surgery, In tish not sub-
<br />
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