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Fishery Bulletin 95(4), 1 997 
plankton samples in July and that 95% 
of fish were captured between May and 
August. Adults begin to mature in early 
March (Clark, 1930) and spawn off south- 
ern California from April to August. Peak 
spawning activity is in May and June 
(Skogsberg, 1939). 
Size and age at settlement 
The smallest larvae caught during the 
present study were 6-7 mm SL, which 
would seem to indicate that white 
seabass begin to settle at about this size. 
However, white seabass as small as 4.2 
mm SL were collected along the open 
coast north of San Diego County in 1988 
and 1989 with a trawl containing 2-mm 
mesh in the codend (Allen and Franklin, 
1992); therefore the smallest settled 
larvae were probably not retained by 
our net. More than 20% of the individu- 
als collected in that study were <5 mm 
SL and 50% were <7 mm SL. This size distribution 
suggests that many larvae caught off San Diego 
County had settled at lengths of 4-5 mm SL. Larvae 
up to 7.2 mm SL have been collected from the water 
column (Moser et al., 1983), indicating that some in- 
dividuals settle at >5 mm SL. 
Given that many white seabass settled at 4-5 mm 
SL, the average age at settlement must be less than 
one month. The 10 smallest fish caught and aged in 
this study ranged from 6.2 to 9.2 mm SL and were 
26-32 d old (Fig. 8). Although smaller (4-5 mm SL) 
fish were not aged, they were probably much younger. 
In the laboratory, white seabass reared at 15°C hatch 
at a length of 2.8 mm SL after 2 d and grow to 4 mm 
SL in 10 d and to 5 mm SL in 15-19 d (Moser et al., 
1983; Orhun, 1989). At this rate of growth, a 4-5 mm 
SL settled fish would have spent only 12-21 d in the 
pelagic habitat. 
Allen and Franklin (1992) hypothesized that most 
white seabass larvae that settle along the coast of 
southern California are spawned off Baja California 
and advected northward. However, a short pelagic 
phase of 2-3 weeks suggests that many of these lar- 
vae are spawned within the Southern California 
Bight (SCB). The direction of larval transport is dif- 
ficult to predict because the behavior and position of 
white seabass larvae in the water column is un- 
known. During spring and early summer, poleward- 
flowing undercurrents over the continental slope and 
equatorward-flowing surface currents over the con- 
tinental shelf (Hickey, 1993) could transport larvae 
along the coast in either direction. However, mean 
seasonal current velocities in the SCB region in 
spring and early summer are generally less than 20 
cm/s, although short-term velocities can be higher 
(Hickey, 1993). At 20 crn/s, larvae could be trans- 
ported a maximum of 200-360 km in 12-21 d. It 
therefore seems unlikely that the 4-5 mm SL white 
seabass caught in the northern and middle SCB by 
Allen and Franklin (1992) were spawned off Mexico. 
These larvae, which represented a large proportion of 
the total catch, were almost certainly spawned off Cali- 
fornia. Of course older larvae collected in the middle 
SCB or young larvae caught off San Diego County could 
have been spawned off either California or Mexico. 
Nursery location 
The depth distributions of settled white seabass on 
the coast and within bays suggests that these fish 
prefer shallow water beyond the surf zone. Along the 
open coast, nearly all fish were caught at depths of 
4-8 m, a region which begins just beyond the break- 
ing waves. In the bays, all 10 fish were caught just 
beyond the shore break at a depth of 0-1 m. Previ- 
ous observations in other regions are consistent with 
this conclusion. Settled white seabass have been col- 
lected beyond the breaking waves along semi- 
protected and exposed shores in and around Long 
Beach Harbor (Allen and Franklin, 1988). White 
seabass were not collected along protected shores, 
but depths <1.5 m were not sampled. On the open 
coast north of San Diego County, settled white 
seabass were also more abundant along the 5-m 
