FISHERY BULLETIN: VOL. 72. NO. 1 



and November in water temperatures of 12.5 

 to 13.5 °C. Data obtained from night-light 

 station observations off California indicated 

 that in the California Cooperative Oceanic 

 Fisheries Investigations area saury occurred 

 most frequently in waters north of San Fran- 

 cisco in a band 40-120 miles offshore (Smith, 

 Ahlstrom. and Casey. 1970). Peak availability 

 occurred during November. Results of egg 

 surveys suggested peak spawning activity 

 occurs off California during April, May. and 

 June and that the standing stock in the eastern 

 North Pacific Ocean was at least 450,000 to 

 500.000 tons (Ahlstrom, 1968; Smith et al.. 

 1970). 



METHODS 



The method of finding schools of Pacific 

 sauiy was similar to procedures employed by 

 commercial Japanese saury vessels. The Japa- 

 nese technique has been reviewed by Inoue and 

 Hughes (1971). The Japanese use artificial 

 lights during hours of darkness to visually 

 locate schools near the surface and to attract the 

 fish alongside the vessel for eventual capture. 

 Sonar was also used to assist in detecting 

 concentrations during 1970 and 1971. Our 

 surveys were generally restricted to areas where 

 surface water temperatures were between 13° 

 and 17 °C. Typically, they were conducted along 

 a zig-zag track designed to cross boundaries 

 between warm and cold water masses. Once 

 detected and concentrated under the vessel's 

 alluring lights, the total weight of each school 

 was derived by estimating the percentage of 

 the school captured, weighing our catch, and 

 then computing the weight of the remaining 

 fish. 



During 1969. surveying was confined to 

 waters off California and fishing was conducted 

 with a Japanese-style boke-ami (Andreev, 1962). 

 Operations were conducted off the Washington 

 and Oregon coasts in 1970 and extended to 

 include waters off Vancouver Island, B.C., 

 during 1971. During those periods fishing was 

 conducted with a small purse seine designed for 

 capturing saury (Ellis and Hughes, 1971). 



Table 1 summarizes times and locations 

 where fishing was conducted and samples 

 retained for biological studies. Catches were 

 randomly subsampled aboard ship. All samples 

 collected were returned to the laboratory for 



Table 1 . — Fishing areas and number of Pacific saury 

 collected, 1969-1971. 



* Sample captured with variable mesh gillnet. This sample used 

 only in the growth analysis. 



processing. Samples taken in 1969 were iced, 

 whereas those collected in 1970 and 1971 were 

 frozen. Only length frequency data were taken 

 from the 1969 samples. Biological data from 

 individual fish obtained during 1970 and 1971 

 included knob length- measured to the nearest 

 millimeter, body weight to the nearest gram, 

 sex, and maturity. Scales were removed for 

 later examination. 



Sex determination of fish measuring less than 

 230 mm was generally difficult. When gross 

 examination of gonads proved inadequate, 

 samples were further subsampled — the gonads 

 cross-sectioned and examined for the presence 

 of a lumen under 10 X binocular microscopes. 



Age was determined from plastic impressions 

 of scales (Clutter and Whitesel, 1956) examined 

 with a microprojector device (Mosher, 1950). 

 Age determination of Pacific saury has long 

 been a point of contention between Soviet and 

 Japanese scientists working in the western 

 Pacific (Kotova, 1958; Hotta, 1960). Details 

 of assessment criteria by which ages were 

 determined for this report have been documented 

 bv Mosher.^ 



- Knob length (Kiniura, 1956) — the distance between 

 the tip of the lower jaw and the posterior end of the 

 muscular knob on the caudal base — has been accepted 

 internationally as the unit of length measurement for saury. 



3 K. H. Mosher. Age determination of eastern Pacific 

 saury using scales. Natl. Oceanic Atmos. Admin., Natl. 

 Mar. Fish. Serv., Northwest Fish. Center, Seattle, Wash. 

 Unpubl. inanuscr. 



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