Abstract — The Pacific sardine ( Sar - 
dinops sagax) is distributed along the 
west coast of North America from Baja 
California to British Columbia. This 
article presents estimates of biomass, 
spawning biomass, and related biolog- 
ical parameters based on four trawl- 
ichthyoplankton surveys conducted 
during July 2003-March 2005 off 
Oregon and Washington. The trawl- 
based biomass estimates, serving as 
relative abundance, were 198,600 t 
(coefficient of variation [CV] = 0.51) 
in July 2003, 20,100 t (0.8) in March 
2004, 77,900 t (0.34) in July 2004, 
and 30,100 t (0.72) in March 2005 
over an area close to 200,000 km 2 . 
The biomass estimates, high in July 
and low in March, are a strong indi- 
cation of migration in and out of this 
area. Sardine spawn in July off the 
Pacific Northwest (PNW) coast and 
none of the sampled fish had spawned 
in March. The estimated spawn- 
ing biomass for July 2003 and July 
2004 was 39,184 t (0.57) and 84,120 t 
(0.93), respectively. The average active 
female sardine in the PNW spawned 
every 20-40 days compared to every 
6-8 days off California. The spawning 
habitat was located in the southeast- 
ern area off the PNW coast, a shift 
from the northwest area off the PNW 
coast in the 1990s. Egg production in 
off the PNW for 2003-04 was lower 
than that off California and that in 
the 1990s. Because the biomass of 
Pacific sardine off the PNW appears 
to be supported heavily by migratory 
fish from California, the sustainabil- 
ity of the local PNW population relies 
on the stability of the population off 
California, and on local oceanographic 
conditions for local residence. 
Manuscript submitted 22 October 2008. 
Manuscript accepted 29 December 2009. 
Fish. Bull. 108:174-192 (2010). 
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. 
Biomass and reproduction of 
Pacific sardine ( Sardinops sagax ) 
off the Pacific northwestern United States, 
2003-2005 
Nancy C. H. Lo (contact author) 
Beverly J. Macewicz 
David A. Griffith 
Email address for contact author: Nancy.Lo@noaa.gov 
Southwest Fisheries Science Center 
8604 La Jolla Shores Dr. 
La Jolla, California 92037 
Pacific sardine ( Sardinops sagax ; here- 
after “sardine”) are distributed widely 
off the west coast of North America 
from Baja California, Mexico, to Brit- 
ish Columbia, Canada; the majority of 
the population is located off California 
(Felin, 1954; Murphy, 1966; Emmett 
et ah, 2005; McFarlane et ah, 2005; 
Smith, 2005). Tagging studies have 
shown that sardine migrate along the 
west coast (Janssen, 1938; Clark and 
Janssen, 1945). The sardine popu- 
lation reached a peak in the early 
1930s at 3.5 million metric tons (t) 
and declined rapidly in the mid-1950s 
(Marr, 1950). The sardine fishery off 
California and British Columbia dates 
from 1916 (Fig. 1). Pacific sardine 
was one of the economically impor- 
tant species off California and British 
Columbia in the 1930s when a fishery 
began off Oregon and Washington (the 
Pacific Northwest: PNW). The PNW 
catch peaked at nearly 50,000 t in 
1938 (Marr, 1950; Mosher and Eckles, 
1954; Murphy, 1966). In the 1960s, 
however, a moratorium on sardine 
fishing was established in U.S. waters 
because of low catches (Murphy, 1966; 
MacCall, 1976). In the mid 1980s, sar- 
dine became common as bycatch in 
fisheries off Baja California and Cali- 
fornia state (Wolf, 1992; Deriso et al., 
1996) and reappeared from Oregon 
to British Columbia in 1992 (Emmett 
et al., 2005; McFarlane et al., 2005), 
apparently in response to the 1992-93 
El Nino event. The sardine population 
now supports a relatively large fish- 
ery with annual catches over 50,000 
t in recent years (Fig. 1). Sardine 
also serve as important food for tuna, 
salmon, marlin, mackerel, sharks, and 
some groundfish species, as well as 
many seabirds, seals, sea lions, dol- 
phins, and whales (Snodgrass and 
Lowry, personal commun. 1 ) (Preti et 
al., 2001, 2004; Emmett et al., 2005). 
The reappearance of sardine popula- 
tions in the north California Current 
ecosystem adds another forage base for 
predators and an emerging resource of 
consumer interest to the ecosystem. 
Pacific sardine off the PNW are 
considered to be a part of the north- 
ern subpopulation, the majority of 
which is distributed off the western 
United States and Canada (Smith, 
2005), as determined from historical 
tagging studies (Clark and Janssen, 
1945), size at age, and other biological 
characters. Historical tagging studies 
indicated that some large sardine mi- 
grate from California to the PNW in 
late spring and early summer to feed, 
and that the majority of the large 
sardine off the PNW move south to 
California in the winter to spawn in 
the spring (Clark and Janssen, 1945). 
The major spawning area of this 
northern subpopulation was believed 
to be located off southern California 
before the 1960s (Ahlstrom, 1948; 
Marr, 1960; Smith, 2005). Spawning 
also may have occurred in the PNW 
because young fish were caught by 
commercial boats in Canadian wa- 
ters in 1940 (Hart, 1943). However, 
1 Snodgrass, Owyn. 2009. Southwest 
Fisheries Science Center, La Jolla, CA. 
Lowry, Mark. 2009. Southwest Fisher- 
ies Science Center, La Jolla, CA. 
