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Fishery Bulletin 113(2) 
nual variations in the logCZ of Argentine shortfin squid. 
The model displayed steady results when these predic- 
tive parameters were consistently included as signifi- 
cant terms that incrementally added annual data from 
1998 through 2007. 
Effect of annua! catch per unit of effort 
In this study, the autocorrelation and GLM analyses 
indicated that the logt/ of the current year did not sig- 
nificantly relate to the log U of the previous year. Pierce 
and Boyle (2003) demonstrated that adding the previ- 
ous year’s landing per unit of effort did not significant- 
ly improve a regression model for another species of 
squid, Loligo forbesii. Bawe et al. (2000) also observed 
no significant autocorrelation in the year’s catch from 
multiple regression models for the northern shortfin 
squid (I. illecebrosus). Those studies outlined a poor 
stock recruitment relation. Squid are semelparous ani- 
mals that spawn and die after one reproductive cycle. 
There is initially no information other than the spawn- 
ing stock size on which to base an assessment of the 
potential recruitment strength and abundance of the 
next generation (Rodhouse, 2001). Beddington et al. 
(1990) showed that stock and recruitment relationships 
indicate that production of the squid fishery in a given 
year is weakly related to that of the subsequent year. 
Recent studies have shown that environmental factors 
could be critical factors that result in variation in dis- 
tribution and abundances of squid (Waluda et al., 1999; 
Peel and Jackson, 2008; Pierce et al., 2008). 
Effect of seawater temperature 
The environmental measurement used 
most frequently in analyses to reflect 
fluctuations in Argentine shortfin 
squid abundances is remotely sensed 
SST (Waluda et al., 1999, 2001a, 
2001b; Chen et al., 2007a, 2007b; Wu 
et al., 2009). Previous studies have in- 
dicated that abundances of Argentine 
shortfin squid are influenced by SST 
or subsurface seawater temperature 
in their spawning grounds, hatching 
zones, and feeding habitats (Middleton 
and Arkhipkin 2 ; Waluda et al., 2001a; 
Agnew et al., 2002; Bazzino et al., 
2005; Chen et al., 2007a, 2007b; Fang 
et al., 2013). Temperature is a proxy 
for other oceanographic factors, such 
as the position of the fronts affected 
by the convergence of the Brazilian 
and Falkland currents. These factors 
may affect larval survival either di- 
rectly (e.g., by affecting retention in 
favorable habitats) or indirectly (e.g., 
by influencing trophic relationships) 
(Anderson and Rodhouse, 2001). In ad- 
dition, temperature variation has the 
potential to dramatically affect the 
growth patterns and population structures of squids 
during their early exponential growth phase (Forsythe, 
1993). 
In our study, the squid abundance index (log!/) 
showed a significant negative correlations with sub- 
surface seawater temperature in the main feeding and 
growth habitats (the southern Patagonian shelf) during 
the primary fishing season (February-April). This re- 
sult indicates that cooler subsurface seawater tempera- 
tures are an important factor for high abundance of 
this squid species. Argentine shortfin squid aggregate 
in the cold seawater temperature area along the con- 
vergence of the Brazilian and Falkland currents (Chen 
et al., 2005), and feeding occurs on the Patagonian and 
Falkland Island shelves, where cold waters along the 
confluence boundary of those currents may result in a 
region of high productivity (Chen et al., 2007a). Squid 
grow rapidly into the maturing stage in this area be- 
fore they migrate to their spawning ground after April 
(Arkhipkin, 1993, 2000). Because squid growth is some- 
what slower in cold years than in warm years and be- 
cause immature individuals are larger in cooler tem- 
peratures (Peel and Jackson, 2008), the high CPUE in 
our study may have resulted from the large individual 
size of Argentine shortfin squid in cold years. 
2 Middleton, D. A. J.. and A. I. Arkhipkin. 2001. Environ- 
mental effects on the distribution and migrations of the squid 
Illex argentinus (Ommasterphidae) in Falkland islands wa- 
ters. ICES Council Meeting (C.M.) Documents 2Q01/K:20, 
30 p. 
