Zeidberg et al : The fishery for Loligo opolescens from 1981 through 2003 



57 



size squid prey; this finding may indicate that the squid 

 stock moved offshore to find productive waters. Alter- 

 natively, San Nicholas sea lions may have been feeding 

 on squids from Baja California. Zeidberg and Hamner 

 (2002) suggested the possibility of a northern shift of 

 the squid population in El Niiio years, as has been 

 found for most zooplankton (Colebrook, 1977). 



However, the growth plasticity and fluctuating re- 

 productive success for Loligo opalescens should not be 

 underestimated. The possibility remains that the huge 

 fluctuations in squid landings during strong ENSO 

 events is due to the entire biomass of market squid 

 waning and waxing rather than to population migra- 

 tions away from traditionally fished spawning grounds. 

 Triennial groundfish surveys demonstrate that market 

 squid experienced a coast-wide population decrease, not 

 a poleward migration during the 1997-98 El Nino.*^ 



With the exception of El Nino years, the fishery in- 

 creased its landings each year until 2000. However, it 

 remains unknown if the capacity of the fishery is close 

 to reaching the total biomass of squid in California. 

 The California sardine {Sardinops sagax) fishery col- 

 lapsed in the 1960s, and a twenty-year moratorium was 

 required before there was recovery to a fraction of prior 

 spawning biomass (Wolf, 1992). Whether over-fishing or 

 large scale, multidecadal climatic regime shifts caused 

 this collapse is matter of debate (Chavez et al., 2003), 

 but without an effective management plan, squid will 

 continue to be fished because of market demand. Mar- 

 kets are driven by economic forces and traditionally 

 do not control themselves in a biologically sustainable 

 manner. A full recovery of the squid fishery occurred 

 from 1998 to 2000 and thus spanned four generations of 

 squid given a 6-9 month lifecyle; for the California sar- 

 dine (with a 6-8 year lifecycle), a proportionally similar 

 recovery period would be 24-32 years (Parrish^). 



In 1998-99 the fishery for Loligo opalescens decreased 

 to low levels during the El Nino event, then recovered 

 to record levels in the following years. This was most 

 likely due to the plasticity of squid development in rela- 

 tion to water temperature and upwelling and the short 

 (4-6 month) life span of squid. One should not assume 

 that the ability of this species to recover from environ- 

 mental stress like El Nino applies also to the recent 

 anthropogenic stresses associated with increasing fish- 

 ery capacity. It remains to be seen if the large decline 

 in southern California landings in the last five years 

 (119,780-24,449 tons/year) is due to the small El Nino 

 of 2002-03, the climate-regime shift in 1998, overfish- 

 ing, or some other factor such as increased water strati- 

 fication due to global warming. Although the short-lived 

 squid may not be able to recover from overexploitation 



" CDFG (California Department of Fish and Game). 2005. Fi- 

 nal market squid fishery management plan. Website: http:// 

 www.dfg.ca.gov/mrd/msfmp/index.html [Accessed on 6 June 

 2005.] 



' Parrish, R. 2005. Personal commun. Fisheries and 

 Marine Ecosystems Program, Pacific Fisheries Environ- 

 mental Laboratory, 1352 Lighthouse Ave. Pacific Grove, CA 

 93950-2097. 



in short order, the huge number of long-lived birds, fish, 

 and marine mammals (Morejohn et al., 1978; Lowry and 

 Carretta. 1999) that depend on squid as a key forage 

 species may not be able to recover rapidly from lack of 

 management foresight. The recent establishment of the 

 marine reserve system in the Channel Islands elimi- 

 nates 139f of key squid fishing grounds. This ecosystem- 

 based management approach may assist in protecting 

 not only the squid but also their predators. 



Acknowledgments 



This research was funded by a California Fish and Game 

 award (no. FG7334MR) and a Coastal Environmental 

 Quality Initiative Program grant (no. 783828-KH-19900) 

 and was supported in part by the David and Lucile Pack- 

 ard Foundation through the Monteray Bay Aquarium 

 Research Institute. Bruce Robison, Rich Ambrose, Peggy 

 Fong, and Dick Zimmer provided thoughtful reviews. 

 Andrea Steinberger assisted with data management. 



Literature cited 



Agnew, D. J., J. R. Beddington, and S. L. Hill. 



2002. The potential use of environmental information 



to manage squid stocks. Can J. Fish. Aquat. Sci. 



59:1851-1857. 

 Agnew, D. J., S. Hill, and J. R. Beddington. 



2000. Predicting the recruitment strength of an 

 annual squid stock: Loligo gahi around the Falkland 

 Islands. Can J. Fish. Aquat. Sci. 57:2479-2487. 



Aristegui, J., P. Tett, A. Hernandez-Guerra, G. Basterretxea, 

 M. F. Montero, K. Wild. P. Sangra, S. Hernandez-Leon, M. 

 Canton, J. A. Garcia-Braun, M. Pacheco, and E. D. Barton. 

 1997. The influence of island-generated eddies on chloro- 

 phyll distribution: a stufy of mesoscale variation around 

 Gran Canaria. Deep Sea Res. 44:7-96. 

 Bakun, A. 



1973. Coastal upwelling indices, west coast of North 

 America, 1946-1971, 103 p. NOAA Tech. Rep. NMFS 

 SSRF-671. 

 Botsford L. W., A. Hastings, and S. D. Gaines. 



2001. Dependence of sustainability on the configuration 

 of marine reserves and larval dispersal distance. Ecol. 

 Lett. 4(2):144-150. 



Bray N. A., A. Keyes, and W. M. L. Morawitz. 



1999. The California Current system in the Southern 

 California Bight and Santa Barbara Channel. J. Geo- 

 phys Res 104 C4:7695-7714. 



Breaker, L. C, and P. A. W. Lewis. 



1988. A 40-50 day oscillation in sea-surface temperature 

 along the central California coast. Estuar. Coast. Shelf 

 Sci. 26:395-408. 

 Breaker, L. C, P. C. Liu, and C. Torrence. 



2001. Intraseasonal oscillations in sea surface tempera- 

 ture, wind stress, and sea level off the central California 

 coast. Cont. Shelf Res. 21(6-7):727-750. 

 Brink, K. H., R. C. Beardsley, J. Paduan, R. Limeburner, M. 

 Caruso, and J. G. Sires. 



2000. A view of the 1993-1994 California Current based 

 on surface drifters, floats, and remotely sensed data. J. 

 Geophys. Res. Oceans. 105(C4):8575-8604. 



