Laidig: Influence of ocean conditions on the timing of early life events for Sebastes mystmus 
443 
Table 1 
Location, year, sampling date, number of samples col- 
lected, and size range of blue rockfish (Sebastes mystinus) 
examined for settlement marks in otoliths. 
Location 
Year 
Sample 
date 
Number 
of 
samples 
Size range 
(mm standard 
length) 
Mendocino 
1993 
2 Jun 
11 
37-48 
Monterey 
1993 
3 Jun 
11 
38-48 
Mendocino 
1994 
26 Jul 
13 
44-52 
Monterey 
1994 
20 Jul 
13 
42-60 
Mendocino 
2001 
11 Sep 
10 
48-70 
Monterey 
2001 
5 Sep 
10 
53-68 
Mendocino 
2002 
13 Aug 
12 
47-66 
Monterey 
2002 
18 Jul 
13 
45-58 
Mendocino 
2003 
4 Sep 
10 
58-73 
Monterey 
2003 
1 Aug 
9 
47-59 
the timing of settlement, birth dates, and length of 
the pelagic larval and juvenile stages of blue rockfish. 
Upwelling indices and sea level anomalies were used to 
evaluate the influence of oceanographic conditions on 
the timing of recruitment (settlement) for blue rockfish 
in the two regions. 
Materials and methods 
Juvenile blue rockfish were collected in two areas, 
approximately 335 km apart — one off northern Califor- 
nia in Mendocino County (39°14'N lat., 123°46'W long.) 
and the other off central California along the southern 
edge of Monterey Bay in Monterey County (36°38'N lat., 
121°55'W long.; Fig. 1). Each area is typified by large 
kelp beds that extend from shore to approximately 20 
m depth. The Mendocino site is dominated by bull kelp 
( Nereocystis luetkeana) and the Monterey site by giant 
kelp ( Macrocystis pyrifera). These kelp-bed areas com- 
prise high-relief bedrock interspersed with low-relief 
cobble and sand areas. Both beds are exposed to open 
ocean conditions, although the Monterey site is slightly 
buffered from southerly seas by the tip of the Monterey 
Peninsula. 
Fish were collected throughout the kelp beds by div- 
ers using small spears at depths of 5-20 m and were 
frozen for later analysis. Fish were collected during late 
spring and summer at both sites during five noncon- 
secutive years (1993, 1994, 2001-2003). Years for data 
analysis were selected on the basis of three criteria: 
1) there were at least nine individuals collected from 
each area; 2) sampling dates at each study site in a 
particular year were reasonably close (approximately 
one month or less apart); and 3) samples were collected 
after 1 June to allow for complete settlement of the 
juveniles (Table 1). 
39°N 
i Mendocino 
Pt. Arena 
V 
38°N - 
\ 
San Francisco • 
Pacific 
Ocean 
37°N 
XX 
50 
.km 
Monterey 
-124°N 
-1 23°N 
-122°N 
Figure 1 
Map of the two study areas along the California coast. 
Black stars indicate areas where samples of blue rockfish 
(Sebastes mystinus) were collected for otolith analysis to 
determine the timing of early life history events. 
Otolith data 
Sagittal otoliths were removed and ages were deter- 
mined visually by counting growth increments with a 
compound microscope at 1000 x magnification (Laidig 
et al., 1991), beginning at the first increment after the 
extrusion check (a mark in the otolith formed when the 
larvae were released from their mother). No validation 
of the rate of deposition of these growth increments was 
performed during this study, and none was available 
from the literature. However, based on validation studies 
for other co-occurring rockfish species, such as shortbelly 
rockfish (S. jordani [Laidig et al., 1991]), bocaccio (S. 
paucispinis) , chilipepper ( S . goodei ), widow rockfish (S. 
entomelas), and yellowtail rockfish (S. flavidus [Wood- 
bury and Ralston, 1991]), increments were assumed to 
be deposited daily. Also, the calculated birth dates of the 
blue rockfish in this study occurred within the months of 
larval release for this species (Wyllie-Echeverria, 1987). 
The duration of the pelagic larval and juvenile stages, 
age at settlement (the total duration of pelagic larval 
and juvenile stages), settlement date, and birth date 
were calculated by identifying specific marks in the 
otolith that indicate transitions from one life stage to 
