6 
Fishery Bulletin 1 13(1) 
Month 
Jan Feb Mar Apr May Jun July Aug Sept Oct Nov Dec 
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18 
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w 
3 
ST 
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Figure 2 
Mean seasonal depth (bars) and temperature (line) profiles from time-series 
records of 16 wild-caught white seabass ( Atractoscion nobilis) at liberty along 
the coast of California and Baja California, Mexico, throughout all months of 
the year. Collectively, the time-series data span from May 2008 to June 2011. 
Error bars indicate ±1 standard error of the mean. 
Depth probability plots summarized for 16 fish over a 
24-h period also exhibited increased vertical activity 
around dawn and dusk throughout all months of the 
year (Fig. 4, A-D). 
Consistent daily (24-h) and semidaily (12-h) peaks 
in spectral density were evident from FFTs of depth 
data for multiple individuals (n=16), indicating strong 
diel periodicities in vertical movement patterns (Fig. 
5A). Longer-term periodicities (0.02-0.14 cpd), on the 
scale of days to months, were not persistent among in- 
dividuals (Fig. 5B). Although variability in harmonic 
frequencies (cpd) was apparent between individuals 
(72 = 16), spectral density peaks were perceptible for 9 
individuals between 0.044 and 0.048 cpd (21-23 days). 
Five individuals also showed predominant peaks in 
spectral density at 0.033 cpd (30 days); however, corre- 
lation (coefficient of correlation [r]=0.01-0.19) between 
depth and lunar luminosity values were low. 
There was no significant difference in mean values 
ofVROM between day and night (paired £-test: £=0.49, 
df=32, P=0.625). However, the mean VROM was signifi- 
cantly greater during the twilight hours (48.9 m h' 1 
[SD 12.3] than during the day (39.6 m h _1 [SD 10.8]; 
paired £-test: £=8.16, df=32, P<0.0001) and nighttime 
(41.1 m fr 1 [SD 13.2]; paired £-test: £=5.30, df=32, 
PcO.0001). Similarly, VROM values exceeded 150 m 
h _1 most frequently around 0500 and 1900 PST (Fig. 
6A). In contrast, surface-oriented behavior (depths <5 
m) reached a minimum during twilight periods, and 
increased surface activity occurred from 0900 to 1600 
PST and from 2300 to 0300 PST (Fig. 6B). Collectively, 
surface-oriented behavior was heightened from May 
to September, with a peak in July, but was rarely ob- 
served from November to February (Fig. 7). 
Horizontal movements 
The locations of tag recoveries spanned an 820-km 
stretch of coastline between La Salina, Baja California 
Norte (32°01'N, 116°53'W), and Half Moon Bay, Cali- 
fornia (37°27'N, 122°28'W) (Table 1). The majority of 
tagged fish (72 =22) moved in a northwesterly direction 
(300-330° heading; mean: 317°) along the California 
coastline during their time at liberty. Five recaptured 
individuals moved southeast of their initial tagging lo- 
cation (135-158° heading; mean: 151°), 3 of which were 
recovered below the border of the United States and 
Mexico. The reported locations for more than half of 
the tag recoveries (77=22) were >100 km from the tag- 
ging site, and 21% of fish were recaptured between 20 
and 100 km from the point of release. After a mean 
time at liberty of 433 days (range: 9-1154 days), 11 
individuals were recovered within 20 km of their initial 
tagging site. There was no relationship between fish 
size and net displacement or between time at liberty 
and net displacement (Table 1). 
