48 



Fishery Bulletin 104(1) 



(PDI) based upon distributions determined 

 in the Southern California Bight (Zeidberg 

 and Hamner, 2002). 



Materials and methods 



35° - 







-125° 



The CDFG database for commercial Cali- 

 fornia market squid landings from 1981 to 

 present includes weight, date, location (based 

 on CDFG 10x10 nm blocks), and gear type. 

 Accounting for general physical oceanographic 

 properties (Harms and Winant, 1998; Bray 

 et al., 1999: Brink et al., 2000; Hickey et 

 al., 2003) and following our previous stud- 

 ies (Nezlin et al., 2005), we organized the 

 landings data into six areas to look at subtle 

 differences between them: MB = northern 

 coastal (because the majority of the land- 

 ings in this area occur in southern Monterey 

 Bay), CC=central coastal, SB = Santa Barbara 

 Channel, SCB = Southern California Bight, 

 SM= Santa Monica, and SD = San Diego. Also 

 we grouped the fishery into two larger regions 

 April (APR, equal to MB above) and October 

 (OCT, a combination of the other five areas) 

 based upon the month of greatest recruit- 

 ment (Fig. 1). For the purpose of our study, 

 recruitment is the aggregation of reproductive 

 adults on the spawning grounds. When CDFG 

 reports squid data, they make a distinction 

 at Point Conception, thus our MB and CC 

 areas are grouped as the "north" and our SB, 

 SCB, SM, and SD are named "south." For this 

 fishery we defined CPUE as the recorded tons 

 landed in a day, divided by the number of 

 seine vessels that landed these squid. Those 

 days in which there were no landings were 

 assigned a value of zero. This CPUE is impor- 

 tant because, although not truly a quantifying effort, it 

 does provide a means for estimating the abundance of 

 squid by providing some basis for the amount of time 

 taken to make a landing. Lampara, brail, and light boat 

 data were not included because of increased variability in 

 landings and effort and the fact that these vessels have 

 dwindled from ten to zero percent since 1981. 



The landings and boat data for each area were summed 

 for each block by day. For example, assume that on a 

 particular day fishermen caught 10,000 metric tons with 

 four boats in the area of SM, 18,000 tons from three 

 boats in SCB, and 12,000 tons from three boats in SB. 

 We would calculate a CPUE of 2500 tons/vessel-day in 

 SM, 6000 tons/VD in SCB, and 4000 tons/VD in SB, 

 respectively. Thus for every date for which there was a 

 landing we were able to calculate CPUE value for each 

 area. Until 2002, there had never been a landing in Mon- 

 terey in January, when one vessel captured 75 tons. Data 

 such as this produce misleadingly high CPUEs; therefore 

 all months with less than seven vessel-days for the en- 

 tire 22-year period were removed from the analysis. 



April 



recruitment 



(APR) 



October 



recruitment 



(OCT) 



km 



--F= 



-120 = 



Figure 1 



The California coast with the fishery areas for the California market 

 squid (Loligo opalescens) identified. Areas were classified according 

 to physical oceanographic features: Northern Coast (MB), Central 

 Coast (CC), Santa Barbara Channel (SB), Southern California Bight 

 (SCB), Santa Monica Bay (SM), and San Diego (SD). Regions were 

 also classified by fishery recruitment month: April recruiting (APR: 

 same as MB area) and October recruiting (OCT: CC, SB, SCB, SM, 

 and SD areas combined). Block 526 (indicated with a slender arrow) 

 is where the majority of the MB-APR landings occur. Shaded area 

 indicates the location of the paired-net surveys used to generate the 

 paralarvae density index (PDI). 



Physical oceanography data were gathered from the In- 

 ternet for sea surface temperature (SST),'- upwelling in- 

 dex (UI),'^ southern oscillation index (SOI),^ and NIN03.5 

 Upwelling index (UI) is an Ekman offshore water trans- 

 port (mVs per 100 m of the coastline) estimated from 

 fields of atmospheric pressure (Bakun, 1973). Southern 

 Oscillation index (SOI) is the difference between the 

 standardized measurements of the sea level atmospheric 



- NOAA (National Oceanic and Atmospheric Administration). 

 National Data Buoy Center. 2000. Website: http://facs. 

 scripps.edu/surf/buoys.html [Accessed on 24 April 2003.1 



^ NOAA Pacific Fisheries Environmental Laboratory. 2003. 

 Website: http://www.pfeg.noaa.gov/products/las.html 

 [Accessed on 20 March 2003.1 



* Australian Government Bureau of Meteorology. 2005. 

 Website: http://www.bom.gov.au/climate/current/soihtml. 

 shtml [Accessed on 29 March 2003.1 



^ IRI (International Research Institute for Climate Pre- 

 diction). 2005. Website: http://ingrid.ldgo.columbia.edu/ 

 SOURCES/.Indices/.nino/.EXTENDED/.NIN03/ [Accessed 

 on 20 April 2004.1 



