YANG ET AL.: CULTURE EXPERIMENTS OF LOLIGO OPALESCENS 



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Yang, unpublished 

 Yang eta/. (1980) 



Spratt (1978) 

 Fields (1965) 



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Age (mths) 



Figure 17.— From estimates of growth rate in mantle length oiLoligo opalescens. Fields (1965) used 

 population data. Spratt (1978) combined age (statolith ring counts) and ML data and calculated a 

 mean (horizontal line), range (vertical line) and standard deviation (vertical bar) values for 3-month 

 intervals throughout the life cycle. Yang et al. data are from laboratory rearing studies (1980b, 1983a, 

 this report) (modified from figure 7.1, Hixon 1983). 



determine if and how statolith rings are correlated 

 with age. 



A major gap in fisheries studies concerns where 

 the hatchlings go from the spawning grounds. Very 

 few young squid have been captured (Okutani and 

 McGowan 1969; Recksiek and Kashiwada 1979) even 

 in the vicinity of spawning grounds. Hatchlings are 

 positively phototaxic and this may serve to disperse 

 them immediately from the spawning grounds. 

 Thereafter their movements are unknown, although 

 rarely young squid 3.5 to 7.0 mm ML have been 

 caught in neritic plankton samples, usually at depths 

 of 25 to 40 m nearshore in water between 12.5° and 

 21.0°C (Okutani and McGowan 1969). Detailed 

 knowledge of water currents between spawning 

 grounds and nearshore, combined with monitoring 

 of plankton abundance (especially copepods and lar- 

 val fish) by surface, bottom and oblique tows may 

 provide important clues about movements and feed- 

 ing patterns of young-of-the-year squid. Laboratory 

 studies indicate that squid can swim well enough to 

 hold their position against a current by 10 mm ML, 

 or about 40 to 45 d posthatching. By 15 mm ML (ca. 



60-80 d) they can form and maintain well-formed 

 schools. The functions of schooling in nature prob- 

 ably relate to defense, feeding and migratory 

 behavior. 



The California squid fishery has nearly collapsed 

 since El Nino of 1983, and the squid population has 

 been generally displaced northward as far as south- 

 ern Canada. Some small spawning populations are 

 still present in southern and central California. It 

 may be rewarding to investigate feeding and migra- 

 tory patterns of young and adult squid to better 

 understand population recruitment into this ecologi- 

 cally and economically important fishery resource. 



Biomedical Research Applications 



Loligo opalescens has proved to be a suitable model 

 for giant axon preparations (e.g., Llano and 

 Bezanilla 1980). However, for most axon experi- 

 ments the largest axons (>400 fim diameter) are 

 needed; this requires the largest squid taken in the 

 fishery, usually 150 mm ML and larger. Our largest 

 squid, 116 mm ML, had an axon about 240 ^m in 



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