46 



Abstract — The California market 

 squid iLoligo opalescens) has been 

 harvested since the 1860s and it 

 has become the largest fishery in 

 California in terms of tonnage and 

 dollars since 1993. The fishery began 

 in Monterey Bay and then shifted to 

 southern California, where effort has 

 increased steadily since 1983. The 

 California Department of Fish and 

 Game (CDFGl collects information 

 on landings of squid, including ton- 

 nage, location, and date of capture. 

 We compared landings data gathered 

 by CDFG with sea surface tempera- 

 ture (SST), upwelling index (UI). the 

 southern oscillation index (SOI), and 

 their respective anomalies. We found 

 that the squid fishery in Monterey 

 Bay expends twice the effort of that 

 in southern California. Squid land- 

 ings decreased substantially follow- 

 ing large El Nino events in 1982-83 

 and 1997-98, but not following the 

 smaller El Niiio events of 1987 and 

 1992. Spectral analysis revealed 

 autocorrelation at annual and 4.5- 

 year intervals (similar to the time 

 period between El Nino cycles). But 

 this analysis did not reveal any 

 fortnightly or monthly spawning 

 peaks, thus squid spawning did not 

 correlate with tides. A paralarvae 

 density index (PDI) for February 

 correlated well with catch per unit 

 of effort (CPUE) for the following 

 November recruitment of adults to 

 the spawning grounds. This stock- 

 recruitment analysis was significant 

 for 2000-03 iCPUE = 8.42 + 0.4lPDI. 

 adjusted coefficient of determina- 

 tion, r2 = 0.978, P=0.0074). Surveys 

 of squid paralarvae explained 97. 89^ 

 of the variance for catches of adult 

 squid nine months later. The regres- 

 sion of CPUE on PDI could be used to 

 manage the fishery. Catch limits for 

 the fishery could be set on the basis 

 of paralarvae abundance surveyed 

 nine months earlier. 



The fishery for California market squid 

 {Loiigo opalescens) (Cephalopoda: Myopsida), 

 from 1981 through 2003 



Louis D. Zeidberg 



Monterey Bay Aquarium Research Institute 

 7700 Sandholdt Rd. 

 Moss Landing, California 95039-9644 

 E-mail address: zelo g mbari org 



William M. Hamner 



Dept. ol Ecology and Evolutionary Biology 



Univ, California, Los Angeles 



621 Charles E. Young Drive South 



Box 951606 



Los Angeles, California 90095-1606 



Nikolay P. Nezlin 



Southern California Coastal Water Research Proiect 



7171 Fenwick Lane 



Westminster, California 92683-5218 



Annette Henry 



California Department of Fish and Game 

 Southwest Fisheries Science Center 

 Marine Region, La Jolla Field Office 

 8604 La Jolla Shores Drive 

 La Jolla, California 92037 



Manuscript submitted 7 May 2004 

 to the Scientific Editor's Office. 



Manuscript approved for publication 

 20 June 2005 by the Scientific Editor 



Fish. Bull. 104:46-.59 12006). 



The recent discovery of falsification in 

 Chinese fisheries reporting has led to 

 the realization that the majority of the 

 world's fisheries surpassed sustain- 

 ability in 1988 (Watson and Pauly, 

 2001). The food chain has been fished 

 down by removal of apex predators 

 like swordfish and snapper beyond 

 sustainability, and fisheries have 

 subsequently shifted to prey items 

 like sardine and mackerel (Pauly et 

 al., 1998). We have reached the point 

 where cephalopods are regularly the 

 largest biomass of all commercial spe- 

 cies harvested. Since 1970, groundfish 

 landings of flounders, cods, and had- 

 docks have either decreased or main- 

 tained their levels while landings in 

 cephalopod fisheries have increased 

 (Caddy and Rodhouse, 1998). Some of 

 the larger cephalopod landings may be 

 due to increased demand, but lower 

 levels of predation and competition 

 from finfish, and the shorter lifespan 



of squid may have allowed cephalopods 

 to increase in abundance worldwide. 

 Loiigo opalescens is a small squid 

 (130 mm mantle length) that occupies 

 the middle trophic level in Califor- 

 nia waters, and it may be the state's 

 most important forage species. Mar- 

 ket squid are principal forage items 

 for a minimum of 19 species of fishes, 

 13 species of birds, and six species of 

 mammals (Morejohn et al., 1978). The 

 effective management of this fishery 

 is of paramount importance not only 

 to the fishermen involved but also to 

 the millions of fishes, birds, and mam- 

 mals that compete for this resource. 

 Because cephalopods eat mostly zoo- 

 plankton (Loukashkin, 1976), if we 

 also deplete the squid population, it 

 is not clear how oceanic food chains 

 will respond. If the subannual popu- 

 lation of L. opalescens fails to recruit 

 a large biomass in a given year, the 

 long-lived predators of this species in 



