398 



AbStPSCt.— Research was conducted 

 to test the hypothesis that spawning of 

 the oceanic squid Ommastrephes bar- 

 tramii in the central North Pacific is 

 related to the proximity of the Hawai- 

 ian Archipelago. Paralarvae were col- 

 lected during five plankton surveys 

 near the Hawaiian Island chain during 

 the 1991-93 spawning seasons. In to- 

 tal, 1,720 O. bartramn paralarvae were 

 collected from 406 tows. Estimation of 

 ages and hatch dates of all squid was 

 inferred from analysis of statolith mi- 

 crostructures from 85 specimens. A 

 well-defined relationship existed be- 

 tween the number of statolith growth 

 increments and the dorsal mantle 

 length of the paralarvae. Estimated 

 hatch dates of individuals collected 

 during the three years surveyed ranged 

 between mid-January and early April. 

 Spawning sites were then estimated 

 from hatch dates by backcalculating 

 with physical data on the speed of ocean 

 currents near the archipelago. Al- 

 though estimated spawning of O. 

 bartramii did often occur along the is- 

 land chain, spawning was not limited 

 to nearshore waters. Some animals 

 hatched, on the basis of estimated cur- 

 rent speeds, at least 646 kilometers 

 away from the archipelago. Projected 

 hatching locations of more than 72% of 

 all collected paralarvae were at least 

 10 kilometers from shore. Data do not 

 support the hypothesis that the loca- 

 tion of the spawning grounds in this 

 region is solely related to the position 

 of the Hawaiian Archipelago. 



Estimated paralarval drift and inferred 

 hatching sites for 

 Ommastrephes bartramii 

 (Cephalopoda: Ommastrephidae) 

 near the Hawaiian Archipelago 



John R. Bower 



Department of Oceanography, University of Hawaii 



1000 Pope Road, Honolulu, Hawaii 96822 



Present address: Research Institute of North Pacific Fisheries, Faculty of Fisheries 



Hokkaido University, 3-1-1 Minato-cho, Hakodate, 



Hokkaido 041, Japan 



Manuscript accepted 5 February 1996. 

 Fishery Bulletin 94:398-411 ( 1996). 



The neon flying squid, Omma- 

 strephes bartramii (Lesueur), is an 

 oceanic species occurring worldwide 

 in subtropical and temperate wa- 

 ters (Roper et al., 1984). In the 

 North Pacific, O. bartramii para- 

 larvae have been collected from sev- 

 eral areas: from January through 

 May, paralarvae are found south- 

 east of Honshu Island, Japan (Oku- 

 tani, 1968, 1969; Saito and Kubo- 

 dera, 1993); and during May, para- 

 larvae are found along 25— 26"N lati- 

 tude between 143-166°E longitude, 

 and along 29°N latitude between 

 161-160°E longitude (Hayase, 1995). 

 Paralarvae also occur near the Ha- 

 waiian Archipelago from February 

 to May (Young and Hirota, 1990; 

 Hayase, 1995; Bower et al. 1 ; Ha- 

 yase 2 ). A study of paralarvae col- 

 lected near the Hawaiian Archi- 

 pelago during 1991-93 found no 

 systematic relationship between the 

 distribution and abundance of O. 

 bartramii paralarvae and distance 

 from the archipelago ( Bower et al. 1 ). 

 This study, however, did not account 

 for the effects of age and paralarval 

 drift on the distribution patterns 

 found. The present study attempts to 

 identify more clearly possible spawn- 

 ing areas by considering these factors. 

 Statoliths from teuthoid squids 

 commonly contain growth incre- 

 ments that can be used for age de- 



termination. After conducting a de- 

 tailed age analysis of Loligo opal- 

 escens, Spratt (1978) argued that 

 some increments in the statolith 

 were deposited daily, as in fish 

 otoliths. Since then, a number of 

 studies have been conducted to de- 

 termine the frequency of increment 

 formation (Dawe et al. [1985] on 

 Illex illecebrosus; Hurley et al. 

 [1985] on /. illecebrosus; Lipinski 

 [1986] on Alloteuthis subulata; 

 Jackson [1989, 1990]; and Naka- 

 mura and Sakurai 1 1991] on Toda- 

 rodes pacificus: also see reviews by 

 Rodhouse and Hatfield [1990] and 

 Jackson [1994]). The data provide 

 strong support for the hypothesis 

 that growth increments form at the 

 rate of one per day in both loliginid 

 and ommastrephid squids. Al- 

 though validation of the growth in- 

 crements of O. bartramii has not 

 been accomplished, I have assumed 

 that they form daily for this study. 



1 Bower, J. R., R. E. Young, J. Hirota, P. 

 Flament, M. Seki, and K. Bigelow. 

 1996. Distribution and abundance of 

 cephalopod paralarvae near the Hawaiian 

 Archipelago. In prep. 



2 Hayase, S. 1989. Cruise report of flying 

 squid spawning survey by the Hokuho 

 Maru in the North Pacific in April-May 

 1989, 21 p. Document submitted to the 

 Annual Meeting of the International North 

 Pacific Fisheries Commission, Seattle, 

 Washington, 1989 October. 



