HUGHES: PACIFIC SAURY OF NORTHEASTERN PACIFIC 



more available in the northern portion of the 

 study area. 



Low availability has evidently hampered 

 Japanese attempts to establish new fishing 

 grounds in the eastern Pacific. Operations by 

 about 15 Japanese saury vessels in 1970 and 19 

 vessels in 1971 met financial failure. Conse- 

 quently, major fishery firms such as Nihon 

 Sui-san, Hoko Suisan, and Nichiro have 

 reportedly abandoned attempts to exploit the 

 eastern Pacific saury resource."' 



DISCUSSION 



It seems pertinent to propose some general 

 hypotheses about the life history of the eastern 

 Pacific saury based on information presented 

 here and in papers by Ahlstrom and Casey 

 (1956). Ahlstrom (1968), and Smith et al. (1970). 



The coastal stratification of saury by size and 

 age composition during at least August- 

 September is probably due to a northerly 

 migration by many adults from California 

 waters. Sea surface temperatures and position 

 of warm-cold fronts strongly influence migra- 

 tion patterns and rates of movement of saury 

 in the western North Pacific Ocean (Fukushima. 

 1956, 1962). Several factors indicate a similar 

 situation exists in the eastern Pacific Ocean. 

 Our surveys indicated eastern Pacific saury 

 display narrow limits of thermal preference 

 and are found most often near areas of up- 

 welling. Furthermore, there is an excellent 

 correlation between the apparent spacial and 

 temporal distribution of saury and average 

 month-by-month sea-surface temperature data. 

 Using Johnson's (1961) 12-year monthly means 

 andathermal preference range of 14.0° to 17.0°C, 

 it is a]:)parent that large quantities of saury 

 would not begin a northerly migration from 

 California waters before June. Migration into 

 northern Oi'egon and Washington waters would 

 not be expected to occur before July. Rapid 

 warming during July and August produces a 

 favorable temperature regime along the coasts 

 of Washington, Vancouver Island, and into 

 Queen Charlotte Sound. While temperature 

 conditions remain favorable in September, 



' J. H. Shohara (Compiler). 1972. 12 Japanese vessels 

 licensed for distant-water saury fishing [Excerpted from 

 Shin Suisan Shimbun Sttkuho. July 18 and July 29, 1972]. 

 U.S. Dep. Commer.. Natl. Oceanic Atmos. Admin., 

 Natl. Mar. Fish. Serv., Foreign Fish. Inf. Release 72-27, 

 p. 3. (Processed.) 



seasonal cooling occurs off Vancouver Island 

 and Washington during October and continues 

 through Oregon and northern California waters 

 in November. Thus, it appears that in addition 

 to influencing the time and patterns of saury 

 migration, temperature conditions could also 

 restrict the bulk of the stock to oceanic areas 

 between Baja California and Queen Charlotte 

 Sound or the southern Gulf of Alaska. 



From the data presented, the degree of 

 migration appears to be dependent on size and 

 age of fish, and many young adults and 

 juveniles apparently remain in California 

 waters throughout the year. 



Fish exceeding 300 mm in length (primarily 

 ages 4, 5, and 6) reach maturity during the 

 migration in August and release their mature 

 mode of eggs (1.8-2.0 mm) in late August or 

 September. Since Hatanaka's (1956) work on 

 maturity in the western North Pacific Ocean 

 (three modes of eggs, 0.6, 1.1, and 1.9 mm) is in 

 close agreement with this study, it seems 

 reasonable that eastern Pacific saury release 

 modes of eggs at about the same intervals — 2 

 months between the first and middle mode. 

 Thus, the second spawning of large fish would 

 probably take place in October or November 

 and the third spawning during the winter while 

 off California. Younger adults, sexually 

 inactive during August-September, probably 

 mature and spawn during the following winter 

 and spring while in more southerly waters, 

 primarily off California. It is not known 

 whether 2- and 3-year-old fish spawn more than 

 one mode of eggs per year. 



The above hypothesis would account for the 

 reported low abundance of eggs in California 

 waters during August-September (Smith et al., 

 1970) when most spawning saury occupy a 

 northerly regime. The spawning of younger 

 age groups coincides with peak egg abundance 

 in California during April, May, and June. 

 Such an extended spawning season would 

 account for spring-born, autumn-born, and 

 some intermediate growth patterns detected 

 from scale samples, as well as the fact that 

 three-quarters of the samples displayed the 

 spring-born growth characteristic. 



There seems to be little likelihood that spring- 

 and fall-born fish constitute different races, 

 since both types were observed spawning to- 

 gether in the same school. Furthermore, 

 statistical comparisons of length-weight and 



129 



