876 
Fishery Bulletin 95(4), 1997 
Overall, retention rates of T-anchor and disk-an- 
chor tags averaged 100% and 99.2%, respectively, 
after 30 days (Table 2). Fish size at the time of tag- 
ging did not significantly affect internal anchor tag 
retention rates (df=l, F=0.3, P=0.64). Retention rates 
did not differ significantly between disk- and T-an- 
102 n 
100 - 
O 
o 
98 - 
O 
5 ? 
96 - 
0 
c 
o 
94 - 
c 
CL) 
0 
92 - 
V 
CD 
03 
1- 
90 - 
88 - 
V 
86 - 
□ 
o o o 
V 
O Tag retention at 3 d 
S 7 Tag retention at 30 d 
□ Tag retention at 60 d 
chor-tagged fish or among time periods (for both com- 
parisons, df=l, F= 0.8, P=0.43). There were also no 
significant differences in survival (df=2, F=0.7, 
P-0.55) or growth (df=2, F=0.03, P=0.10) among 
treatments . Survival rates of T-anchor- and disk-an- 
chor-tagged fish averaged 97.0 and 91.9% at 14 and 
30 days after tagging, respectively (Table 2). 
Nearly all (80%) fish with internal anchor 
tags examined at 30 days had inflammation 
or a proliferation of epithelial cells at the tag 
insertion site. Of the ten disk-tagged fish ex- 
amined after the second trial, six fish had an- 
chors encapsulated in the peritoneum, two fish 
had anchors inserted in the swim bladder or 
gastrointestinal tract, and two fish had an- 
chors freely moving in the peritoneal cavity. 
Of the ten T-anchor-tagged fish examined, two 
fish had anchors encapsulated in the perito- 
neum, one had an anchor inserted in the swim 
bladder, and seven had anchors that were 
freely moving in the peritoneal cavity. 
84 -| 1 1 1 1 1 1 
50 60 70 80 90 100 110 120 
Discussion 
Size at tagging (mm) 
Figure 1 
Retention rates of coded wire tags and average size (standard 
length) of juvenile snook at the time of tagging. 
The high retention rates of CWT’s reported in 
this study (85-100%) indicate that CWT’s are 
effective for marking age-0 common snook and 
that the cheek musculature is appropriate for 
tagging. CWT’s did not affect snook survival 
or growth during the first 
30-60 days after tagging, 
indicating that CWT’s have 
negligible adverse effects 
during this time period. 
CWT retention rates in- 
creased with initial fish 
size (Fig. 1) from 87-92% 
for snook with an initial 
mean size of 62 mm SL to 
95-100% for snook with 
initial mean sizes of 71- 
117 mm SL. Several au- 
thors have noted the impor- 
tance of fish size or target 
tissue size in the retention 
of CWT’s (Heidinger and 
Cook, 1988; Szedlmayer 
and Howe, 1995). Our study 
also shows a relation be- 
tween initial tagging size 
and CWT retention. 
Most tag loss occurred 
between 3 and 30 days (Fig. 
2). Other studies have noted 
Trial 1, SL=92 2 mm 
Trial 2, SL=1 15.3 mm 
Trial 3, SL=61 .5 mm 
Trial 4, SL=62.9 mm 
Trial 5, SL=81.5 mm 
Trial 6, SL=73.6 mm 
Time (days) 
Figure 2 
Retention rates of coded wire tags in fish 3, 30, and 60 days after tagging. The key shows 
mean initial size (SL) of fish in each trial. 
