Love et al.: Declines in rockfish recruitment and populations 
495 
O-Hi i t T"T"“T™T"T"T“T“T“T“i i m i r 
10 30 50 70 90 110 130 150 170 190 210 230 250 270 290 310 330 350 
X> 
6 
10 30 50 70 90 110 130 150 170 190 210 230 250 270 290 310 330 350 
10 30 50 70 90 no 130 150 170 190 210 230 250 270 290 310 330 350 
200 P Blue rockfish 
150- 
100 - 
50- 
o-*-i 1 1 
1 — T""" i 1 1 1 1 1 r 
10 30 50 70 90 no 130 150 170 190 210 230 250 270 290 310 330 350 
Length (mm) 
Figure 2 
Length frequencies (standard length mm ) of the four most commonly observed 
rockfishes in the Southern California Edison impingement studies, 1977-93. 
Short lines above bars indicate mean length. 
that most of the rockfishes impinged 
were between 0 and 2 years old (Love 
and Westphal, 1981; Love et al., 1990; 
Love and Johnson, in press). 
The life histories of these six spe- 
cies encompass a range of habitat 
preferences and behaviors. Olive 
rockfish and blue rockfish are near- 
shore, midwater fishes. Grass rock- 
fish and treefish are shallow-water 
benthic species, usually inhabiting 
high relief. Brown rockfish are found 
primarily along sand-rock interfaces 
or over low relief. Bocaccio are mid- 
water fish; the young are found in 
shallow water and they migrate into 
deeper water as subadults (Feder et 
al., 1974). 
We analyzed abundance patterns 
over time for all rockfishes combined 
and separately for the six most com- 
mon species. Since the inception of 
the survey in 1977, mean catch rates 
for all rockfishes combined have 
dropped substantially (Fig. 3). Catch 
rates peaked in the early 1980s, 
dropped precipitously (by a factor of 
over 100) to a low in 1984 and have 
generally remained low through 
1993. The exception was a one-year, 
nearly tenfold rise between 1987 and 
1988 which was due primarily to a 
large influx of young bocaccio, al- 
though olive, brown, and grass rock- 
fish catches also increased slightly 
during this period (Fig. 4). 
Despite very different life histo- 
ries, the six most abundant species 
showed generally similar impinge- 
ment patterns over time (Fig. 4). In 
all six species, peak impingement 
occurred in the late 1970s or early 
1980s. Maximum catches occurred in 
1977 (bocaccio), 1980 (grass, blue, 
and brown rockfish), or 1981 (olive 
rockfish and treefish). Between 1983 and 1993, with 
only one exception, impingement of these six species 
was either extremely low or nonexistent. The excep- 
tion occurred in 1988, when relatively large num- 
bers of bocaccio were impinged. The 1988 peak in bocac- 
cio abundance was the result of catches at only two 
stations, Redondo and San Onoff e, in May of that year. 
Between the late 1970s and early 1990s, there was 
a sharp drop in the amount of rockfish impingement 
in the SCE coastal generating stations. We believe 
that this pattern reflects the abundance of these 
fishes in nearshore waters at the time. To address 
this issue, we compared our impingement data for 
olive rockfish, blue rockfish, and bocaccio with that 
from visual diving surveys conducted on transects 
in King Harbor, Redondo Beach (Stephens 4 ). The vi- 
sual surveys primarily record juvenile abundance 
4 Stephens, J. 1997. Department of Biology, Occidental Col- 
lege, 1600 Campus Rd., Los Angeles, CA, 90041. Unpubl. data. 
