Abstract. Statolith micro- 

 structural analysis was applied to 

 126 specimens of the oceanic bo- 

 real clubhook squid, Onychoteuthis 

 borealijaponica, for estimation of 

 age and growth rates. Specimens 

 were captured from the western, 

 central, and eastern North Pacific 

 between approximately lat. 38° N 

 and 47°N by driftnet fishing, 

 trawling, and jigging in the sum- 

 mers of 1990 and 1991. Results 

 suggest that increments were de- 

 posited at a rate of one per day. 

 Both sexes live approximately one 

 year; males mature at smaller 

 sizes and younger ages than fe- 

 males. Exponential growth models 

 suggest that growth in length was 

 similar for males and females 

 (0.80% ML/day) in the central 

 North Pacific, while growth in 

 weight was higher for females 

 ( 1.90% WT/day) than males (1.40% 

 WT/day). Females in the western 

 North Pacific exhibited faster 

 growth rates than individuals 

 from the central North Pacific. O. 

 borealijaponica were estimated to 

 have hatched year round based on 

 back calculation of statolith incre- 

 ments from the time of capture. 

 Post-recruit individuals exploited 

 in the O. borealijaponica jig fish- 

 ery and Ommastrephes bartramii 

 driftnet fishery typically hatched 

 from late summer to early winter. 



Age and growth of the oceanic 

 squid Onychoteuthis borealijaponica 

 in the North Pacific 



Keith A. Bigelow 



Honolulu Laboratory, Southwest Fisheries Science Center 

 National Marine Fisheries Service. NOAA 

 2570 Dole Street, Honolulu, HI 96822-2396 



The oceanic boreal clubhook squid 

 Onychoteuthis borealijaponica 

 Okada, 1927 is common in subarc- 

 tic waters of the North Pacific. This 

 species ranges from the western 

 coast of the United States and 

 Canada to the eastern coast of 

 Hokkaido, Japan, and the Kurile 

 Islands, but does not occur in the 

 Sea of Okhotsk or Bering Sea 

 (Young, 1972; Murata et al., 1976; 

 Naito et al., 1977a; Fiscus and 

 Mercer, 1982; and Kubodera et al., 

 1983). Onychoteuthis borealijapon- 

 ica has commercial value through- 

 out its range. Between 1971 and 

 1979, commercial landings aver- 

 aged 1,171 metric tons (t) per year 

 from a jig fishery in oceanic waters 

 east of Hokkaido, Japan (Okutani 

 and Murata, 1983), and approxi- 

 mately 254 and 2,705 t of O. bor- 

 ealijaponica were caught in 1990 

 and 1991, respectively, by Japan, 

 Korea, and Taiwan in the Ommas- 

 trephes bartramii highseas driftnet 

 fishery (DiNardo and Kwok, in re- 

 view 1 ). Based on exploratory fish- 

 ing, Fiscus and Mercer (1982) sug- 

 gested that O. borealijaponica 

 could be commercially exploited by 

 a jig fishery from the Gulf of Alaska 

 westward to the Aleutian Islands, 

 and Murata (in Okutani, 1977) in- 

 dicated that the potential fishery 

 yield of O. borealijaponica may be 

 50,000-200,000 t in an area west of 



Manuscript accepted 26 July 1993 

 Fishery Bulletin 92:13-25 (1994) 



1 DiNardo, G. T., and W. Kwok. In review. 

 Estimates offish and cephalopod catch in 

 the North Pacific high-seas driftnet fish- 

 eries, 1990-91. 



long. 152°E and lat. 40-45°N. If a 

 commercial fishery does develop, 

 accurate life-history information is 

 essential for management purposes. 



The general biology and feeding 

 ecology of Onychoteuthis borealija- 

 ponica have been investigated 

 (Naito et al., 1977b; Okutani and 

 Murata, 1983); however, little in- 

 formation is available on age and 

 growth. Average growth rates have 

 been inferred from length-fre- 

 quency distributions of sequential 

 jigging samples (Murata and Ishii, 

 1977). This study suggested that 

 the lifespan for boreal clubhook 

 squid is approximately one year; 

 females grow faster and attain a 

 larger size (370 mm mantle length 

 (ML)) than males (270 mm ML). 

 Growth estimates from driftnet 

 studies (Kubodera et al., 1983; 

 Kubodera, 1986) were inconclusive 

 because length-frequency modes 

 were impossible to detect, possibly 

 because of protracted spawning 

 seasons or variable individual 

 growth rates within a population. 



The accuracy and precision of 

 cephalopod growth estimates have 

 been greatly enhanced through the 

 use of daily increments within sta- 

 toliths (Natsukari et al., 1991). 

 Ageing by counting statolith incre- 

 ments allows the estimation of size 

 at age and may provide informa- 

 tion on individual age and growth 

 rates. Hatchdates can be estimated 

 by back calculation of daily incre- 

 ments. Age and growth estimates 

 derived from statolith analysis 



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