261 
Abstract— The coastal Pacific Ocean 
off northern and central California 
encompasses the strongest seasonal 
upwelling zone in the California Cur- 
rent ecosystem. Headlands and bays 
here generate complex circulation 
features and confer unusual oceano- 
graphic complexity. We sampled the 
coastal epipelagic fish community of 
this region with a surface trawl in the 
summer and fall of 2000-05 to assess 
patterns of spatial and temporal com- 
munity structure. Fifty-three species 
of fish were captured in 218 hauls at 
34 fixed stations, with clupeiform spe- 
cies dominating. To examine spatial 
patterns, samples were grouped by 
location relative to a prominent head- 
land at Point Reyes and the resulting 
two regions, north coast and Gulf of 
the Farallones, were plotted by using 
nonmetric multidimensional scaling. 
Seasonal and interannual patterns 
were also examined, and representa- 
tive species were identified for each 
distinct community. Seven oceano- 
graphic variables measured concur- 
rently with trawling were plotted by 
principal components analysis and 
tested for correlation with biotic 
patterns. We found significant dif- 
ferences in community structure 
by region, year, and season, but no 
interaction among main effects. Sig- 
nificant differences in oceanographic 
conditions mirrored the biotic pat- 
terns, and a match between biotic and 
hydrographic structure was detected. 
Dissimilarity between assemblages 
was mostly the result of differences 
in abundance and frequency of occur- 
rence of about twelve common spe- 
cies. Community patterns were best 
described by a subset of hydrographic 
variables, including water depth, 
distance from shore, and any one of 
several correlated variables associ- 
ated with upwelling intensity. Rather 
than discrete communities with clear 
borders and distinct member species, 
we found gradients in community 
structure and identified stations with 
similar fish communities by region 
and by proximity to features such as 
the San Francisco Bay. 
Manuscript submitted 7 May 2010. 
Manuscript accepted 18 March 2011. 
Fish. Bull. 109:261-281 (2011). 
The views and opinions expressed 
or implied in this article are those of the 
author (or authors) and do not necessarily 
reflect the position of the National Marine 
Fisheries Service, NOAA. 
Regional and seasonal patterns 
of epipelagic fish assemblages 
from the central California Current 
Jeffrey A. Harding (contact author) 
Arnold J. Ammann 
R. Bruce MacFariame 
Email address for contact author: Jeff.Harding@noaa.gov 
Santa Cruz Laboratory 
Southwest Fisheries Science Center 
National Marine Fisheries Service, NOAA 
110 Shaffer Road 
Santa Cruz, California 95060 
Twenty five percent of marine fish- 
eries catch comes from regions that 
encompass a mere five percent of the 
world’s oceans: within the Benguela, 
California, Canary, Peru, and Soma- 
lia currents (Jennings et al., 2001). 
Management of these highly produc- 
tive coastal upwelling ecosystems 
has historically been based on single 
species assessments, although the 
science informing management has 
long recognized the limited power of 
this approach. After the dramatic and 
unexpected collapse of several major 
small-pelagic fisheries worldwide circa 
1945-72, scientists began to advocate 
the need to incorporate climate, ocean 
conditions, and other sources of uncer- 
tainty into management (Freon et al., 
2005; MacCall, 2009). In the last two 
decades the momentum to achieve this 
goal has increased, and some form of 
ecosystem-based management is now 
a stated policy objective of government 
agencies in several nations (Link et 
al., 2002; Ecosystem Principles Advi- 
sory Panel 1 ). Ecosystem manage- 
ment plans have now been proposed 
for most U.S. fisheries including the 
U.S. west coast and large portions 
of the California Current ecosystem, 
1 Ecosystem Principles Advisory Panel. 
1999. Ecosystem-based fishery man- 
agement. A report to Congress by the 
National Marine Fisheries Service, 54 
p. National Marine Fisheries Service, 
Office of Science & Technology, 1315 
East-West Highway, Silver Spring, MD 
20910. 
and various agencies and institutions 
are actively collecting the biological 
and environmental data that will be 
needed to bring these plans to action 
(Ecosystem Plan Development Team 2 ). 
The high productivity of the Cali- 
fornia Current (CC) is primarily the 
result of local wind-driven season- 
al upwelling and the interaction of 
alongshore currents with prominent 
coastal features such as capes, head- 
lands, and bays that advect upwelled 
water masses into complex patterns 
of offshore filaments and coastal re- 
tentive eddies (Davis, 1985; Gan and 
Allen, 2002). The zone of maximum 
spring and summer wind stress and 
wind-driven upwelling occurs be- 
tween Cape Blanco in southern Or- 
egon (43°N) and Point Conception 
in central California (34°N) (Nel- 
son, 1977). Headlands in this region 
including Cape Mendocino, Point 
Arena, Point Reyes, and Point Ano 
Nuevo are the main locales of newly 
upwelled water. Bays located down- 
current act as retention zones where 
eddies form and trap aging upwelled 
water (Paduan and Rosenfeld, 1996), 
allowing concentrated phytoplankton 
blooms to develop nearshore (Vander 
2 Ecosystem Plan Development Team. 
2010. Ecosystem fishery management 
planning for U.S. west coast fisheries. A 
report to the Pacific Fisheries Manage- 
ment Council, 35 p. Pacific Fisheries 
Management Council, 7700 N.E. Ambas- 
sador PL, Ste. 101, Portland, OR 97220. 
