8242

• UCREFRP Catalog Number: 8242
• Author: Haines, G. B., S. H. Severson and T. Modde
• Title: Evaluation of Razorback Sucker and Colorado Squawfish Batch Marking Techniques
• USFW Year: 1998
• USFW - Doc Type: The Progressive Fish-Culturist
• Copyright Material: YES

MARKING RAZORBACK SUCKERS AND COLORADO SQUAWFISH

273

pare the operculum (razorback suckers) and lower
jaw (Colorado squawfish) and the base of the anal
fin as locations for elastomer injection.

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Methods

The freeze branding apparatus used in this study
was similar to one described by LaJeone and Ber-
gerhouse (1991). It contained a 2-L reservoir of
liquid nitrogen and a metal branding iron extend-
ing through the wall of the reservoir. The branding
iron terminated in a V-shape. The left side of the
fish, anterior to the origin of the dorsal fin, was
held against the iron for approximately 6 s for
marking. Four colors (green, blue, red, and orange)
of fluorescent elastomer, obtained from Northwest
Marine Technology, were injected subcutaneously
with a I-mL insulin syringe and 28-gauge needle.
Two-hundred and forty razorback suckers (mean
TL = 127 mm) and 1,015 Colorado squawfish
(mean TL = 150 mm), all containing PIT tags for
individual identification, were divided into three
groups. Each group (hereafter called trial) was
marked between 6 and 13 June 1995. Each fish
had three potential marking locations: the left
operculum (razorback suckers) or lower jaw (Col-
orado squawfish) and base of the anal fin for elas-
tomer implantation and the left side for freeze-
branding. The treatments were assigned randomly
to each fish. Half of each group received a freeze
brand, and the other half received no brand (con-
trol). One-fifth of each group received one of the
four colors or no mark (control) on the operculum
or lower jaw and base of the anal fin. For all trials,
the same person marked with freeze-brand and
elastomer to reduce variation associated with in-
consistencies in application. Before marking, the
fish were anesthetized with tricaine methanesul-
fonate (MS-222). (Authorization for using MS-222
for the culture of endangered fishes is provided in
the 6 February 1996 memorandum from the Office
of the Director, U.S. Fish and Wildlife Service,
regarding the "use of unapproved drugs in cul-
turing endangered and threatened fish species.")
After marking, razorback suckers were placed in
a 0.08-ha pond, and the Colorado squawfish were
placed in two 0.08-ha ponds. The fish were har-
vested, PIT tags were read, and marks were iden-
tified after 5 and 15 months (Colorado squawfish,
24 September) or 16 months (razorback suckers,
23 October). The elastomer marks were observed
under an ultraviolet (black light) lamp in a dark-
ened room.
The elastomer data were analyzed by means of
two-way analysis of variance (2 marking locations

TABLE I.-Percent recognition of marks 5 and ]6
months after marking young razorback suckers with e]as-
tomer implants at the base of the anal fin and on the oper-
culum and freeze branding (side). Percentages are means
of three tri also Percentage for mean excludes control fish.
Location Correctly
and color Number identified Number of
or type observed (%:':: SO) deaths
5 months
Anal fin
Control 48 100 :':: 0 0
Green 45 54 :':: 27 6
Blue 47 68 :':: 14 2
Red 46 85 :':: 14 4
Orange 47 94 :':: 6 2
Mean 75
Operculum
Control 48 100:':: 0 0
Green 46 39 :':: 27 4
Blue 46 30 :':: 25 4
Red 48 46:':: 32 0
Orange 46 63 :':: 31 4
Mean 45
Side
Control 118 99:':: I I
Freeze 115 99:':: 5 4
16 months
Anal fin
Control 44 98 :':: 4 8
Green 39 34 :':: 32 19
Blue 43 41 :':: 19 10
Red 41 86:':: 19 15
Orange 44 91 :':: t5 8
Mean 63
Operculum
Control 45 95 :':: 4 6
Green 41 60:':: 19 15
Blue 43 36 :':: 23 10
Red 40 67 :':: 45 17
Orange 42 69:':: 29 13
Mean 58
Side
Control 106 100:':: 0 12
Freeze 105 100:':: 0 13

x 4 marks) and blocked by trial. There was no
replication within blocks; thus, we were unable to
test for interactions between marking locations and
marks. Mark retention rates were log transformed.
If treatment effect (elastomer color) was signifi-
cant (P < 0.05), then Tukey's honestly significant
difference multiple-comparison test was used to
determine differences among colors. The SYSTAT
software (Wilkinson 1990) was use to compute the
statistics.

Results and Discussion

Freeze brands were more easily recognized than
elastomer marks for both razorback suckers (Table
1) and Colorado squawfish (Table 2). The V-
shaped freeze brand blackened tissues and de-