558 



Fishery Bulletin 105(4) 



shift (such as juvenile salmonids) will be more influ- 

 enced by interannual variability in the availability 

 and quality of prey. Species exhibiting extensive feed- 

 ing migrations through the NCC system, such as Pa- 

 cific hake and Pacific sardine, may be less influenced 

 by localized prey limitation because critical feeding 

 for recruitment success can occur in other regions 

 with different physical and biological parameters. 

 Interannual and interdecadal comparisons of spe- 

 cies distribution and community structure of pelagic 

 nekton have demonstrated that the northern Califor- 

 nia Current ecosystem can vary between months and 

 years (Brodeur et al., 2005). As fishery management 

 shifts away from single-species towards multispecies 

 or ecosystem-based fishery management (Pikitch et 

 al., 2004), detailed information on the trophic interac- 

 tions within this pelagic ecosystem as presented here 

 will become indispensable for development of manage- 

 ment plans and ecosystem models. Further analysis 

 of the relationships between major nekton and their 

 prey is warranted to elucidate differences in trophic 

 relationships between major upwelling regions, es- 

 pecially those that are influenced by strong climatic 

 variability. 



Acknowledgments 



We thank R. Emmett, J. Fisher, C. Bucher, P. Bent- 

 ley, R. Baldwin, and S. Pool for field and laboratory 

 support and the captains and crew of the FV Sea 

 Eagle and FV Frosti for help with sampling. H. Li, B. 

 Pearcy (both at Oregon State University), Ed Casillas 

 (Northwest Fisheries Science Center, Seattle), and 

 three anonymous reviewers provided valuable com- 

 ments on earlier drafts of the manuscript. This work 

 was funded in part by a Mamie Markham Fellowship, 

 the U.S. GLOBEC Northeast Pacific Program, and 

 the Bonneville Power Administration. This article 

 is contribution number 540 of the U.S. GLOBEC 

 Program. 



Literature cited 



Ainley, D. G., L. B. Spear, and S. G. Allen. 



1996. Variation in the diet of Cassin's auklet reveals 



spatial, seasonal, and decadal occurrence patterns of 



euphausiids off California, USA. Mar. Ecol. Prog. Ser. 



137:1-10. 



Brodeur, R. D., J. P. Fisher, R. L. Emmett, C. A. Morgan, and 



E. Casillas. 



2005. Species composition and community structure of 

 pelagic nekton off Oregon and Washington under vari- 

 able oceanographic conditions. Mar. Ecol. Prog. Ser. 

 298:41-57. 

 Brodeur, R. D., J. P. Fisher, D. J. Teel, R. L. Emmett, E. Casillas, 

 and T. W. Miller. 



2004. Juvenile salmonid distribution, growth, condition, 

 origin, and environmental and species associations in the 

 northern California Current. Fish. Bull. 102:25-46. 



Brodeur, R. D., H. V. Lorz, and W. G. Pearcy. 



1987. Food habits and dietary variability of pelagic nekton 

 off Oregon and Washington, 1979-1984. NOAA Tech. 

 Rep. NMFS 57:1-32. 

 Brodeur, R. D., and W. G. Pearcy. 



1986. Distribution and relative abundance of pelagic 

 nonsalmonid nekton off Oregon and Washington, 

 1979-84. NOAA Tech. Rep. NMFS 46, 85 p. 



1990. Trophic relations of juvenile Pacific salmon 

 off the Oregon and Washington coast. Fish. Bull. 

 88:617-636. 



1992. Effects of environmental variability on trophic 

 interactions and food web structure in a pelagic upwell- 

 ing ecosystem. Mar. Ecol. Prog. Ser. 84:101-119. 

 Carr, M. E. 



2002. Estimation of potential productivity in eastern 

 boundary currents using remote sensing. Deep-Sea 

 Res. II 49:59-80. 



Chavez, F P., J. Ryan, S. E. Lluch-Cota, and M. C. Niquen. 



2003. From anchovies to sardines and back: multidecadal 

 change in the Pacific Ocean. Science 299:217-221. 



Corwith, H. L., and P. A. Wheeler 



2002. El Nino related variations in nutrient and 

 chlorophyll distributions off Oregon. Prog. Oceanogr. 

 54:361-380. 



Emmett, R. L., and R. D. Brodeur. 



2000. Recent changes in the pelagic nekton community 

 off Oregon and Washington in relation to some physical 

 oceanographic conditions. Bull. North Pac. Anadrom. 

 Fish. Comm. 2:11-20. 

 Emmett, R. L., R. D. Brodeur, T. M. Miller, S. S. Pool, P. J. 

 Bentley, G. K. Krutzikowsky, and J. McCrae. 

 2005. Pacific sardine (Sardinops sagax) abundance, 

 distribution and ecological relationships in the Pacific 

 Northwest. Calif Coop. Oceanic Fish. Invest. Rep. 

 46:122-143. 

 Emmett, R. L., and G. R. Krutzikowsky. 



In press. Nocturnal feeding by Pacific hake (Merluccius 

 productus) and jack mackerel {Trachurus symmetri- 

 cus) off the mouth of the Columbia River, 1999-2004: 

 implications for juvenile salmon predation. Trans. Am. 

 Fish. Soc, 

 Feinberg, L. R., and W. T Peterson. 



2003. Variability in duration and intensity of euphau- 

 siid spawning off central Oregon, 1996-2001. Prog. 

 Oceanogr. 57:363-379. 



Francis, R. C, and S. R. Hare. 



1994. Decadal-scale regime shifts in the large marine 

 ecosystems of the North-east Pacific: a case for histori- 

 cal science. Fish. Oceanogr. 3:279-291. 

 Hand, C. H., and L. Berner. 



1959. Food of the Pacific sardine (Sardinops caerulea). 

 Fish. Bull. 164:175-184. 

 Harvey, J. T 



1989. Food habits, seasonal abundance, size, and sex 

 of the blue shark, Prionace glauca, in Monterey Bay, 

 California. Gal. Fish Game. 75:33-44. 

 Hood, R. R.. M. R. Abbott, and A. Huyer. 



1991. Phytoplankton and photosynthetic light response 

 in the coastal transition zone off northern California in 

 June 1987. J. Geophys. Res. 96(C8):14769-14780. 

 Hunt, S. L., T. J. Mulligan, and K. Komori. 



1999. Oceanic feeding habits of chinook salmon, On- 



