709 
Abstract .—White seabass, Atract- 
oscion nobilis, is a valuable recreational 
and commercial species, but much of its 
early life history is undescribed. The 
coast and two bays of San Diego County 
were sampled each month for two years 
with a depth-stratified sampling design 
to determine habitat, food habits, age, 
and growth rate of recently settled fish. 
Age was estimated from otolith incre- 
ments and validated with fish of known 
age, reared in the laboratory. A few re- 
cently settled fish were caught in the 
bays at depths <1 m, but most inhab- 
ited shallow water (4-8 m) along the 
coast from May to October. This depth 
distribution coincides with that of the 
mysid Metamysidopsis elongata. Fish 
abundance in this zone was low, how- 
ever, reaching a maximum of 24/ha in 
July. The smallest white seabass col- 
lected were about 7 mm SL and 26 d 
old, but previous studies indicate that 
smaller and presumably younger fish 
were probably extruded through the 
trawl. According to combined results, 
most larvae settled 2-3 weeks after 
being spawned. Juveniles remained at 
a depth of 4-8 m for 2-3 months, fed 
primarily on abundant mysids, and as- 
sociated with drifting macrophytes 
(r=0.52, P=0.015, n=21). Growth dur- 
ing this period was 1.3 mm/d, similar 
to that observed in the laboratory. At 
about 100 mm SL (-100 d old), juve- 
niles appeared to move out of the area. 
The shallow waters just beyond the 
breaking waves may be preferred by 
young white seabass because abundant 
food and warm water promote rapid 
growth and drifting macrophytes pro- 
vide a refuge from predators. 
Manuscipt accepted 30 May 1997. 
Fishery Bulletin 95:709-721 (1997). 
Age, growth, distribution, and food 
habits of recently settled white 
seabass, Atractoscion nobilis, 
off San Diego County, California 
Christopher J. Donohoe 
Department of Biology 
San Diego State University 
San Diego, California 92 1 82 
Present address: Department of Fisheries and Wildlife 
Nash Hall 1 04, Oregon State University 
Corvallis, Oregon 97331-3803 
E-mail address: donohoec@mother.com 
White seabass, Atractoscion nobilis 
(family Sciaenidae), is a highly de- 
sired recreational and commercial 
species found in waters off the 
coasts of southern and Baja Califor- 
nia as well as in the Gulf of Califor- 
nia. Adults inhabit the nearshore 
zone over rocky bottoms and in kelp 
beds and can attain a weight of 38 
kg (Young, 1973). Population size 
has not been estimated, but since 
the 1920’s, commercial and recre- 
ational landings off California have 
continued to decline and the range 
of the species has contracted (Collins, 
1981; Methot, 1983). Management 
efforts to stabilize and restore the 
population have been largely unsuc- 
cessful. Reductions in the catch and 
distribution of white seabass have 
been attributed largely to overfish- 
ing (Thomas, 1968; Vokovich and 
Reed, 1983; MacCall, 1986), but the 
importance of other mechanisms, 
such as increased natural mortal- 
ity of fish at early life history stages, 
has not been evaluated. 
Despite the historic value of this 
species, much of its early life his- 
tory was unknown until recently. 
Moser et al. (1983) described the 
development of the early life stages 
and historic distribution of larvae 
in the California Cooperative Oce- 
anic Fisheries Investigations 
(CalCOFI) sampling area off south- 
ern and Baja California. In several 
laboratory studies, growth, sur- 
vival, energetics, and feeding be- 
havior of larvae have been exam- 
ined (Kim, 1987; Dutton, 1989; 
Orhun, 1989), as well as the devel- 
opment of sensory systems and 
predator-avoidance behavior (Mar- 
gulies, 1989). 
Less is known about the early ju- 
venile stage because few early ju- 
veniles have been caught until re- 
cently. Early studies suggested that 
juveniles inhabit either the surf 
zone or kelp canopy along the open 
coast, or bays and estuaries (Tho- 
mas, 1968; Feder et al., 1974; Max- 
well 1 ). Allen and Franklin (1988, 
1992) have since demonstrated that 
late larvae and early juveniles in- 
habit shallow water along the open 
coast of southern California and 
Channel Islands and semiprotected 
embayments in the vicinity of Long 
Beach Harbor. However the nurs- 
ery area for white seabass has not 
been clearly defined and the rela- 
tive importance of the open coast 
and bays as nurseries has not been 
1 Maxwell, W. D. 1977. Progress report of 
research on white seabass, Cynoscion 
nobilis. Calif. Dep. Fish Game, Mar. 
Resour. Admin. Rep. 77-14, 14 p. [Avail- 
able from Calif. Dep. Fish Game, 330 
Golden Shore, Suite 50, Long Beach, CA 
90802.] 
