632 
Fishery Bulletin 95(3), 1997 
the study was similar (P>0.10) for marked and con- 
trol fish, indicating that marking did not affect 
growth. Again, mortality was zero. 
Histological examination of flatfish indicated that the 
marks were nonirritating and nontoxic. Necropsy of 
the flatfish revealed no evidence of damage to skin or 
musculature and no alteration in the structure of dyed 
tissue. All liver hepatocytes were normal, indicating 
no toxic exposure. There was no evidence of increased 
macrophage aggregations in the liver or hyperplasia 
in the gills to suggest cellular responses to dyes. 
120 
irks (%) 
OO o 
o o 
HP HP ™ US) 
lLj i_j h n m 
'"m- — •- - 
1 60 
3 
w 
ft 40 
Blue H 
Orange (UV) — 
Orange 
O 
o 
< 
20 
0 
'♦ 
i i i i 
♦ 
i i t 
0 40 80 120 
160 200 240 
Figure 3 
Percentage of acceptable jet-injected marks on juvenile sablefish 
by color: alcian blue dye and fluorescent orange acrylic paint. 
Dashed line is orange marks viewed under ultraviolet light (UV), 
and dotted line is orange marks viewed under fluorescent light. 
Discussion 
Marine fish can be jet injected rapidly with many indi- 
vidual marks, often without anesthesia. For example, 
in this study we marked several nonanesthetized flat- 
fish per minute. Jet-injected alcian blue dye produced 
a highly visible intradermal mark that was retained 
for at least 8 months by juvenile sablefish, 3 months by 
juvenile flatfish. Detection of alcian blue dye marks on 
flatfish is easy and requires minimal handling. Usu- 
ally marks can be detected without anesthesia and 
without turning fish over. Increased visibility of 
jet-injected marks, however, could make fish more 
conspicuous to predators. Fluorescent orange 
acrylic paint marks, however, faded rapidly, mak- 
ing marks less visible to predators but necessi- 
tating the use of UV light for detection. 
Mark retention was similar to that reported for 
other species. Thedinga and Johnson (1995) re- 
ported 96% retention of alcian blue dye and fluo- 
rescent orange acrylic paint marks on the caudal 
fin of juvenile coho salmon, Oncorhynchus kisutch, 
and sockeye salmon, O. nerka, after nearly 4 
months, and Herbinger et al. ( 1990 ) reported 96% 
retention of alcian blue dye-marked Atlantic 
salmon, Salmo salar, after 6 months. Few stud- 
ies have been published that used marked juve- 
nile sablefish or flatfish, and only one used a dye 
mark. Kelly (1967) injected Fast Blue 8GXM and 
hydrated chromium oxide by needle into the heads 
of juvenile winter flounder, Pleuronectes ameri- 
canus, and had 100% retention after 4 months. 
Jet-injected marks did not affect growth or 
mortality. Unlike Petersen disc and roll tags, 
which depressed growth rates (Andersen and 
Table 2 
Mean initial total length (mm) and weight (g) and mean absolute growth rate in length and instantaneous growth rate in weight 
of marked (jet-injected with alcian blue dye) and control juvenile yellowfin sole, rock sole, and halibut 90 d after marking. Stan- 
dard error is in parentheses. 
Initial size 
Growth rate after 90 d 
Marked 
Control 
Marked Control 
Length 
Yellowfin sole 
67.9(1.04) 
74.2 (1.45) 
0.198(0.067) 
0.196(0.054) 
Rock sole 
59.7 (0.92) 
71.6 (1.56) 
0.161 (0.068) 
0.137 (0.073) 
Halibut 
72.3 (0.81) 
71.8 (0.88) 
0.228 (0.059) 
0.241 (0.050) 
Weight 
Yellowfin sole 
3.5 (0.49) 
5.2 (0.64) 
0.823 (0.144) 
0.841 (0.120) 
Rock sole 
2.3 (0.32) 
5.2 (0.68) 
0.610 (0.171) 
0.817(0.153) 
Halibut 
4.1 (0.36) 
4.1 (0.36) 
1.193 (0.109) 
1.175(0.111) 
