Zeidberg et al , The fishery for Loligo opalescens from 1981 through 2003 



47 



the California Current may encounter severe metabolic 

 stress. 



Since the decline of the anchovy fishery, market squid 

 probably constitutes the largest biomass of any single 

 marketable species in the coastal environment of Cali- 

 fornia (Rogers-Bennett. 2000). In the 1999-2000 season, 

 fishermen landed 105,005 metric tons of California mar- 

 ket squid [Loligo opalescens) with an exvessel (whole- 

 sale) revenue of $.36 million (California Department of 

 Fish and Game [CDFGJ landing receipts). These squid 

 deposit egg capsules on sandy substrates at depths of 

 15-50 m in Monterey Bay (Zeidberg et al., 2004) and 

 20-90 m in the Southern California Bight. The majority 

 of squid landings occur around the California Channel 

 Islands, from Pt. Dume to Santa Monica Bay, and in 

 southern Monterey Bay. The fishery comprises chiefly 

 light-boats with high wattage illumination to attract 

 and aggregate spawning squid to the surface, and seine 

 vessels that net the squid (Vojkovich, 1998). 



Management to date has followed methods that are 

 not dependent upon an estimate of population abun- 

 dance because no estimate of squid biomass exists. In 

 addition to limiting the catch and the number of ves- 

 sels, management of the fishery has included weekend 

 closures north of Point Conception since 1983, and these 

 closures have recently extended to all of California 

 coastal waters. This regulation is designed to allow 

 a 48-hour period each week for undisturbed spawn- 

 ing. For Monterey Bay, the weekend closure resulted 

 in highest landings on Mondays and decreasing daily 

 landings through Friday (Leos, 1998). Since 2000, light 

 boat and seine vessel operators have been required to 

 complete logbooks for CDFG, such that CPUE can be 

 estimated from data on the cumulative effort required 

 to land squid. 



Because of their short lifespan, many squid popula- 

 tions have been more effectively correlated with local 

 oceanographic conditions than have pelagic fish spe- 

 cies with life spans of 4-8 years. Squid landings from 

 all regions of the world fluctuate in conjunction with 

 the temperatures of the previous season. Mclnnis and 

 Broenkow (1978) found positive temperature anomalies 

 preceded good Loligo opalescens landings by 18 months, 

 and poor squid catches followed periods of anomalous 

 low temperatures in Monterey Bay. Robin and Denis 

 (1999) found similar results. Warmer waters (mild win- 

 ters) were followed by increased cohort success for Lo- 

 ligo forbesi in the English Channel, but this effect was 

 not constant throughout the year. Conversely, Roberts 

 and Sauer (1994) found Loligo vulgaris reynaudii land- 

 ings in South Africa to increase with upwelling that 

 coincided with La Nina (cold water) conditions in the 

 equatorial Pacific. Rocha et al. (1999) also found an 

 increase in squid paralarvae of many species during 

 upwelling conditions on the Galacian-coast. 



Modern instruments for monitoring coastal ocean con- 

 ditions, including weather buoys and satellites, provide 

 a vast amount of information on the physical environ- 

 ment of fish and squid populations. The correlation 

 between cold, upwelled nutrient-rich water at the sea 



surface resulting from Eckman transport and phyto- 

 plankton blooms a few days later is well established 

 (Nezlin and Li, 2003). Mesoscale eddies generated by 

 coastal processes and islands also serve to concentrate 

 phytoplankton (Falkowski et al., 1991; Aristegui et al., 

 1997; DiGiacomo and Holt, 2001). The subsequent effect 

 upon zooplankton grazers rapidly follows the cycles of 

 upwelling and relaxation (Wing et al., 1995; Graham 

 and Largier, 1997; Hernandez-Trujillo, 1999). 



Waluda et al. (1999) found that the CPUE for the II- 

 lex argentinus fishery was not related to monthly local 

 sea surface temperature (SST), but CPUE was inversely 

 related to SST on the hatching grounds for the previous 

 July, when hatchlings were in their exponential growth 

 phase (Yang et al., 1986; Grist and des Clers, 1998). 

 The largest catches followed cold water. Waluda et al. 

 (2001) found a large CPUE when the Brazilian Current 

 dominated and frontal waters diminished in the location 

 where squid hatching occurs. Agnew et al. (2000, 2002) 

 found that CPUE for Loligo gahi was inversely corre- 

 lated with SST for hatching areas six months earlier. 

 Sakurai et al. (2000) found that Todarodes pacificiis 

 CPUE was highest following periods when there were 

 large regions of hatchling-favorable habitat (17-23°C 

 waters). They found a positive correlation between the 

 density of paralarvae and the catch per unit of effort 

 (CPUE) of adults in the same year (r~ = 0.91) and also 

 in the CPUE of the following year (r2 = 0.77). 



The CDFG has an extensive database of landings 

 data from 1981 to the present for market squid. Be- 

 cause there is no record of effort prior to 2000 and be- 

 cause the market is driven by demand, it is difficult to 

 use landings and vessel-day data to calculate a CPUE 

 and therefore estimate biomass. Fishermen report that 

 even if squid are available, they may not be harvested 

 when processors are not accepting squid (Brockman^). 

 However, there is no other database as large and wide- 

 spread temporally and spatially as fishery data. Even 

 though there are no data recorded when boats attempt 

 to catch squid and fail, we can still use landings and 

 vessel-days to create a CPUE. This CPUE therefore is 

 not a methodically collected estimate of biomass, but 

 is still a robust enough estimate of abundance to draw 

 preliminary conclusions as we wait for logbook data to 

 accumulate. 



It is important to determine the effects of the envi- 

 ronment on the California market squid fishery so that 

 we can predict future landings from present conditions. 

 Our investigation uses California market squid landings 

 for 1981-2003 to examine correlations of landings and 

 CPUE with physical oceanography. We compare land- 

 ings data (time, location, vessel-days, and landings [in 

 pounds]) to sea surface temperature (SST), upwelling 

 index (UI), the Southern Oscillation index (SOI), the in- 

 dex of sea surface temperature in the eastern equatorial 

 tropcial Pacific NIN03, and their respective anomalies. 

 We also compare CPUE to a paralarvae density index 



Brockman, D. 2002. Personal commun. Davie.s Locker 

 Sportfishing, 400 Main St. Newport Beach, CA 92611. 



