20 



Fishery Bulletin 97(1), 1999 



2.5 



2.0 



1.0 

 0.5 



0.0 



1.00 



0.75 



0,50 



£" 0.25 

 o 



=i 0.00 



d) 

 o 



-' -025 

 •0.50 

 -0.75 

 -1.00 



Pre-recruits 

 Recruits 



14.8-20.9 



B 



< 14.8 



14.8-20.9 



>20.9 



0.5 - 



0.0 



Pre-recruits 

 Recruits 



111 



7.8-14 4 14.4-20.6 20.6-26.5 



Surface temperature (C) 



Figure 6 



(Al Mean catch of L. pealei. iB) mean ratio of Z,. pealei prerecruit to re- 

 cruit catches, (C) mean catch of/, illecebrosus. and (D) mean ratio of/. 

 illecebrosus prerecruit to recruit catches by .surface temperature for po.si- 

 tive catches of prerecruits and recruits. 



wine (1983) reported relatively high 

 catches at shallow (27-55 m) and also 

 intermediate depths (111-185 m). In this 

 study, however, depth affected catches of 

 juvenile and adult L. pealei differently. 

 Most shallow-water catches comprised 

 juveniles, and this finding indicated that 

 nearshore waters of the continental shelf 

 constitute a preferred habitat of L. pealei 

 juveniles during autumn. Catches of ju- 

 veniles also decreased at greater depths. 

 In contrast, catches of L. pealei adults 

 peaked at depths near the edge of the 

 continental shelf We detected a bathy- 

 metric pattern of larger L. pealei with 

 increasing depth. This pattern was also 

 reported by Vovk (1978) on the basis of 

 distant water fleet catches of L. pealei and 

 is similar to the ontogenetic descent re- 

 ported for some other loliginids (L. gahi, 

 Hatfield et al., 1990; L. vulgaris reynaudii, 

 Augustyn et al., 1992). 



In comparison with L. pealei, the effect 

 of depth on /. illecebrosus was similar but 

 less pronounced. This difference was 

 probably due to the fact that /. illece- 

 brosus utilize a wider range of depths 

 than do L. pealei as they feed in shallow 

 nearshore areas and undertake long dis- 

 tance migrations in continental slope 

 waters (O' Dor and Dawe, in press). None- 

 theless, the empirical patterns of /. 

 illecebrosus catches in relation to depth 

 in our study area were consistent with 

 those from different areas. In particular, 

 Whitaker (1980) reported that /. illece- 

 brosus catches were relatively low at 

 depths less than 56 m and peaked at 

 depths between 186 and 366 m in waters 

 south of Cape Hatteras, whereas Grinkov 

 and Rikhter'' reported that /. illecebrosus 

 catches peaked at depths of 100-150 m 

 along the edge of the continental shelf off 

 Nova Scotia. In our study, much of the /. 

 illecebrosus catch occurred at depths of 

 roughly 80-150 m. As with L. pealei, we 

 found that depth affected the catch of/. 

 illecebrosus juveniles and adults differ- 



Grinkov, Y. A, and V. A. Rikhter. 1981. Some 

 data on distribution of groundfish and short- 

 finned squid along the oceanic slopes of the 

 Scotian Shelf in spring. 1979. Northwest Atlan- 

 tic Fisheries Organization (NAFO) SCR Doc. 81/ 

 VI/63, sen no. N347, 13 p. 



I 



