492 
Declines in nearshore rockfish 
recruitment and populations in the 
southern California Bight as measured 
by impingement rates in coastal 
electrical power generating stations 
Milton S. Love 
Jennifer E. Caselle 
Marine Science Institute, University of California 
Santa Barbara, California 93 1 06 
E-mail address (for M S. Love): love@lifesci.ucsb.edu 
Kevin Herbinson 
Southern California Edison Corporation 
RO- Box 800, 2244 Walnut Grove, Rosemead, California 91770 
Abstract .—We used data from fish- 
impingement studies of the coastal elec- 
tric generating stations of Southern 
California Edison Company to examine 
patterns of nearshore rockfish abun- 
dance in the southern California Bight. 
The impingement data spanned 17 
years (1977-93), comprised a minimum 
of several surveys per month and in- 
cluded power plants from throughout 
much of the Bight. Sixteen rockfish spe- 
cies were taken and six (olive rockfish, 
Sebastes serranoides\ brown rockfish, >S. 
auriculatus; bocaccio, S. paucispinis; 
blue rockfish, S. mystinus\ treefish, S. 
serriceps; and grass rockfish, S. rastrel- 
liger ) accounted for 99% of all rockfish 
caught. Most of these fishes were be- 
tween 0 and 2 years old. Catch rates 
for all six of these species have dropped 
substantially since the inception of the 
survey in 1977. Catch rates peaked in 
the early 1980s, dropped by a factor of 
over 100 to a low in 1984, and have gen- 
erally remained low through 1993. One 
species, blue rockfish, has not been 
taken since 1984. We compared our 
rockfish impingement data from one 
power station in King Harbor, Redondo 
Beach, with data from scuba transects 
conducted during the same period 
within King Harbor. The results of the 
two surveys strongly suggest that the 
catch rates of rockfishes by power 
plants reflect the abundance of these 
fishes surrounding the plants. We sug- 
gest that the reduction in the abun- 
dance of nearshore rockfishes in the 
southern California Bight is due to both 
decreased recruitment success, reflect- 
ing long-term adverse oceanographic 
conditions, and to overfishing. 
Manuscript accepted 26 January 1998. 
Fishery Bulletin 96:492-501 (1998). 
The oceanographic regime off south- 
ern California is extremely dy- 
namic, undergoing decadal changes 
in temperature, upwelling, and off- 
shore transport (Roemmich and 
McGowan, 1995; MacCall, 1996). 
Beginning in 1976, the waters of the 
southern California Bight (SCB) 
began to warm and temperatures 
have generally remained warmer 
than those of the previous four de- 
cades (MacCall, 1996), characteriz- 
ing part of a process of fluctuating 
water temperatures that has oc- 
curred for thousands of years 
(Soutar, 1967; Soutar and Isaacs, 
1974; Baumgartner et al., 1992). 
This warming trend is associated 
with a decline in upwelling and sub- 
sequent decreased zooplankton bio- 
mass (Roemmich and McGowan, 
1995; Hayward et al., 1996). In ad- 
dition, several studies in the SCB 
indicate that this change in the 
physical regime has led to changes 
in reef fish population size, commu- 
nity structure, and recruitment 
(Stephens et al., 1986; Holbrook and 
Schmitt, 1996). An ongoing 20-year 
survey at King Harbor, Redondo 
Beach, as well as one of 13 years du- 
ration at Santa Cruz Island, north- 
ern Channel Islands, has docu- 
mented population declines in many 
fish species (Stephens et al., 1994; 
Holbrook and Schmitt, 1996). In 
particular, the King Harbor study 
shows a severe decline in the abun- 
dances of rockfishes (genus Sebas- 
tes). Some species, such as the blue 
rockfish, S. mystinus, that were 
very common in the mid-1970s, vir- 
tually disappeared by the mid- 
1980s and have remained absent 
(Stephens et al., 1986, 1994). 
Despite widespread recognition 
that long-term data are essential for 
understanding population fluctua- 
tions and for correlating changes in 
population size with environmental 
events, most studies of reef fishes 
are limited in both temporal and 
spatial scales. The few cases where 
populations have been tracked for 
many years are limited in spatial 
scale. Both the Santa Cruz Island 
and the King Harbor studies, al- 
though of relatively long duration, 
have tracked fish populations at 
only a single site. A more accurate 
portrayal of fish abundances would 
come from multisite surveys, con- 
ducted over a number of years. Data 
from the fish-impingement studies 
